DE102022122839B4 - Temperature measuring device for measuring a temperature of a capillary, system and gas chromatograph with the temperature measuring device and method for calibrating the temperature measuring device - Google Patents

Abstract

Temperature measuring device (2) for contactless measurement of a temperature of a capillary (4) of a gas chromatograph (6), with- an infrared sensor (36) with a sensor surface (40) that receives infrared radiation for measuring the temperature of the capillary (4),- a reflector unit (46) that interacts with the infrared sensor (36) and has a reflection surface (50, 50') that reflects infrared radiation, and- a holding device (12) for holding the capillary (4),wherein- the infrared sensor (36) has a first side (42),- the reflector unit (46) has a second side (52),- the holding device (12) is arranged on the first side (42) of the infrared sensor (36),- the holding device (12) is arranged on the second side (52) of the reflector unit (46), andwherein- the reflection surface (50, 50') is directed towards the infrared sensor (36) for reflecting a measurement area (56, 56') emitted infrared radiation is arranged aligned with the sensor surface (40) of the infrared sensor (36), wherein a section of the capillary (4) can be arranged in the measuring area (56, 56'), characterized in that the temperature measuring device (2) has a tempering device (60a, 60b) for cooling or heating the holding device (12).

Description

The present invention relates to a temperature measuring device for contactless measurement of a temperature of a capillary of a gas chromatograph. The invention further relates to a system comprising a capillary and a temperature measuring device of the above type. Furthermore, the invention relates to a gas chromatograph, in particular a temperature gradient gas chromatograph, with a capillary and a temperature measuring device of the above type. The invention also relates to a method for calibrating a temperature measuring device of a system of the above type or for calibrating a temperature measuring device of a gas chromatograph of the above type.

The gas chromatography method, for which the invention was made in particular, is known from the prior art. It represents a method for separating mixtures of volatile substances into the substances underlying the mixture and is used in particular in the context of a chemical analysis of mixtures of substances.

In gas chromatography, a separation capillary (often also referred to as a separation column) is actively and specifically temperature-controlled. A coating can be applied to an inner surface of the separation capillary. A mixture of substances to be analyzed and a carrier gas are fed into an inlet of the separation capillary. Depending on the temperature in the separation capillary, a substance-specific phase equilibrium is established between a portion of the mixture of substances to be analyzed that is in the carrier gas and a portion of the mixture of substances that is adsorbed or absorbed on the coating of the separation capillary. The temperature of the separation capillary and the temperature-dependent phase equilibrium of a substance primarily determine the transport speed of the substances contained in the mixture in the separation capillary. This makes it possible for different substances in a mixture of substances to be transported from the inlet of the separation capillary to its outlet at different speeds. A strong interaction between a substance in the mixture to be analyzed and the coating of the separation capillary leads to a slow transport of the substance along the separation capillary and a weak interaction leads to a fast transport. A detection device, such as a mass spectrometer, can be connected to the outlet of the separation capillary, with which the substances in the mixture can be successively detected.

In a special type of gas chromatography, namely temperature gradient gas chromatography, a temperature along the separation capillary is influenced in a locally specific and time-dependent manner. The concept of temperature gradient gas chromatographs is based on the observation that substances have a characteristic temperature below which no significant mass transport takes place in a separation capillary. In temperature gradient gas chromatography, the separation capillary has a negative temperature gradient from its inlet to its outlet, so that substances in a mixture of substances, after being fed into the separation capillary in a first step of the gas chromatographic analysis, collect at specific points on the separation capillary where the previously mentioned characteristic temperature for significant mass transport is not reached. Due to a homogeneous temperature increase in the separation capillary carried out in a further step of the gas chromatographic analysis, the substances in the mixture of substances are transported through the separation capillary. The substances thus successively reach the exit of the separation capillary, where the substances can be detected by a detection device.

To heat the separation capillary of a temperature gradient gas chromatograph, the separation capillary can be heated electrically, for example, with any heat introduced being concentrated on the separation capillary or its immediate surroundings. The electrical heating can be implemented, for example, by an electrical conductor which is arranged around and/or on the separation capillary. When electrical energy flows through an electrical conductor, part of the electrical energy is dissipated to heat. If such an electrical conductor is arranged around and/or on a separation capillary, the heat generated by dissipation can be precisely concentrated on the separation capillary along the electrical conductor. Thus, essentially only the separation capillary is heated. The electrical conductor can be a separation capillary itself, for example. For this purpose, an electrically conductive separation capillary, which can be made of metal, for example, can be heated directly electrically. Alternatively, for example, a non-conductive polyimide-coated quartz glass separation capillary can be inserted into a heatable sheath capillary and heated. The sheath capillary can then be the electrical conductor or have one.

The temperature of the separation capillary is mainly determined by the electrical energy supplied, which is dissipated into heat in the separation capillary and/or the sheath capillary, and the heat dissipated. The dissipated heat essentially concerns convection of the air surrounding the separation capillary and/or the sheath capillary as well as Infrared radiation emitted by the separation capillary and/or the sheath capillary.

The separation capillary and the sheath capillary are regularly distinguished in gas chromatography. However, a differentiation between the separation capillary, the sheath capillary and the separation capillary surrounded by the sheath capillary is usually not necessary for the subject matter of the invention. Therefore and for the sake of readability, here and in the following the separation capillary, the sheath capillary and the separation capillary surrounded by the sheath capillary are referred to as capillaries. Unless otherwise stated, the term capillary can therefore mean the separation capillary, the sheath capillary and the separation capillary surrounded by the sheath capillary.

In gas chromatography, particularly in temperature gradient gas chromatography, precise temperature control of the capillary is important so that the substances in a mixture of substances to be analyzed with a gas chromatograph can be separated precisely in space and time in the capillary. Precise temperature control of the capillary requires precise measurement of the temperature of the capillary. There is therefore a desire for precise temperature measurement of the capillary.

It has been difficult to measure the capillary temperature accurately up to now. This is because capillaries are usually easy to change in temperature and have a small diameter of 1 mm or less. Temperature measuring devices used in practice for non-contact temperature measurement often have a measuring spot with a diameter of more than 1 mm. A temperature of a body that is smaller than the measuring spot cannot be measured accurately. This is because when the temperature of the body is measured, the temperature of the background in front of which the capillary is arranged is also measured. This means that an average temperature of the body and its background is determined. The measuring spot is discussed in more detail below.

The easy temperature changeability means that the temperature of the capillary can be changed by even weak external influences. On the one hand, this property of the capillary can be desirable because the capillary should, for example, be able to be quickly heated to a desired temperature or a desired temperature profile with a temperature gradient along the capillary. On the other hand, this property of the capillary can be disadvantageous, for example for measuring the temperature of the capillary. In general, temperature measurements are often carried out in practice using contact measuring methods. Contact measuring methods are measuring methods that require mechanical contact between a measuring device and an object to be measured, for example temperature measurement with thermocouples. The use of contact measuring methods for measuring the temperature of a capillary is hardly possible, or is associated with inaccurate measurement results. This is because if contact measuring methods are used to measure the temperature of capillaries and the measuring devices used have a different temperature than the capillary, the contact of the measuring device with the capillary leads to a local temperature change in the capillary due to the easy temperature changeability of the capillary. This distorts the temperature measurement result. In addition, the accuracy of the chemical analysis of the mixture of substances carried out using the gas chromatograph is negatively affected.

Due to the above-mentioned disadvantages of temperature measurement using contact measuring methods, it may be useful to measure the temperature of the capillary using non-contact measuring methods.

Non-contact temperature measurement is based on the physical effect that every physical body with a temperature of more than 0 Kelvin emits radiation with a wavelength from the infrared wavelength range. Infrared light, for example, has a wavelength of 780 nm to 1000 nm. In practice, this radiation is also referred to as infrared radiation. The intensity and the exact range of the wavelength of the infrared radiation emitted by a body depend on the temperature of that body.

By means of a temperature measuring device for non-contact temperature measurement, it is possible to detect the infrared radiation emitted by a body and, based on the intensity and wavelength range of the detected infrared radiation, to measure the temperature of the body from which the infrared radiation was emitted.

Temperature measuring devices for non-contact temperature measurement, for example, have an imaging optics, an optical sensor and a processor.

The imaging optics project the body whose temperature is to be measured, or the infrared radiation emitted by this body, onto the optical sensor in accordance with the rules of physical optics known from the state of the art. It is possible for the optics to project the body whose temperature is to be measured onto the optical sensor in an optically enlarged or optically reduced size. In practice, for example, infrared cameras ras are known as temperature measuring devices for contactless temperature measurement. Infrared cameras often detect bodies with a size of several centimeters to several meters and display the captured image in a reduced size on an optical sensor with a size of several millimeters.

The imaging optics of a temperature measuring device for contactless temperature measurement can be, for example, an optically transparent lens. Additionally or alternatively, the imaging optics can have a plurality of lenses that interact with one another. Furthermore, additionally or alternatively, the imaging optics can also have one or more mirrors that reflect the emitted infrared radiation. The mirror or mirrors can in particular be one or more concave mirrors. In practice, the use of lenses is often preferred over the use of mirrors.

The optical sensor is, for example, an infrared sensor with a sensor surface that absorbs infrared radiation. In particular, the infrared sensor can be an infrared temperature sensor with a sensor surface that absorbs infrared radiation. The sensor surface that absorbs infrared radiation can absorb infrared radiation and generate an electrical signal from it. The sensor surface can also absorb radiation in the near infrared range, for example. Radiation in the near infrared range has, for example, a wavelength of approximately 780 nm to 3000 nm. In practice, the infrared sensor can be designed, for example, as a thermal sensor or a photoelectric sensor. A thermal sensor is, in particular, a bolometer, a pyroelectric sensor or a thermopile made of thermocouples. A photoelectric sensor can, in particular, be a photocell, a photomultiplier, a CCD sensor or any other photoelectric component with which infrared radiation can be absorbed and converted into an electrical signal. The electrical signal generated by the optical sensor is transmitted to the processor.

The processor receives the electrical signal from the optical sensor and uses the received signal to determine a temperature of the body from which the infrared radiation was emitted. The processor can be electronically connected to an output unit which outputs the determined temperature to a user of such a temperature measuring device. Additionally or alternatively, the processor can have an interface to a computing unit.

In practice, non-contact temperature measurement of large bodies is already easy and accurate. In contrast, measuring the temperature of small bodies can be difficult in practice. In particular, in practice, there is a limit to the minimum size of a body whose temperature is to be measured with a temperature measuring device for non-contact temperature measurement.

The reason for this limitation is a combination in particular of a limited optical resolution of the available imaging optics and a limited optical resolution of the infrared sensor of a temperature measuring device.

The minimum size of a body whose temperature can be measured with a certain temperature measuring device for contactless temperature measurement is referred to in practice as the measuring spot of this temperature measuring device. In terms of measurement technology, the measuring spot can correspond to approximately three times the size of a so-called smallest detectable object detectable by means of a temperature measuring device. The smallest detectable object is the part of a body that is imaged on a pixel of a sensor surface and depends on the distance of the body to the temperature measuring device. For example, a temperature measuring device for contactless temperature measurement can have an optical resolution of 3 mrad. In addition, a distance between a body whose temperature is to be measured and the exemplary temperature measuring device can be 0.1 m. In this case, the smallest detectable object has a diameter or edge length of 0.3 mm and is imaged as a pixel on the sensor surface of the infrared sensor. The measuring spot of this exemplary temperature measuring device can be approximately 0.9 mm at the above distance.

The size of the measuring spot can vary for different temperature measuring devices. Temperature measuring devices for non-contact temperature measurement with measuring spot diameters of 0.8 mm or more are currently commercially available. Such temperature measuring devices for non-contact temperature measurement are suitable for accurately determining the temperature of bodies, for example capillaries, with a diameter of 1 mm. The disadvantage of such temperature measuring devices, however, is that the distance between a body whose temperature is to be measured and the temperature measuring device must be set precisely in order to achieve the small size of the measuring spot of up to 0.8 mm. The precise setting of this distance between the body and the temperature measuring device requires the position of the imaging optics to be precisely adjustable. Adjustment units used for this purpose are often complex in design, difficult to manufacture and/or expensive. In addition, accurately adjusting the distance between the body whose temperature is to be measured and the temperature measuring device can be difficult.

Further difficulties and measurement inaccuracies with the currently commercially available non-contact temperature measuring devices arise when the temperature of a body smaller than 0.8 mm is to be measured. For example, it is difficult to measure the temperature of a capillary with a diameter of less than 0.8 mm.

Since in this case the size of this capillary is smaller than the measuring spot, a part of a background in front of which the capillary is arranged is also imaged by the imaging optics on the sensor surface of the infrared sensor. In other words, the measuring spot is composed of the capillary whose temperature is to be measured and the background of this capillary. Thus, a direct temperature measurement of this capillary cannot be carried out. Instead, an average value of the temperature of this capillary and the part of the background contained in the measuring spot in front of which the capillary is arranged is measured. As a result, in temperature measuring devices for non-contact temperature measurement with a limited minimum size of the measuring spot, the measurement accuracy of a temperature measurement of a capillary that is smaller than the measuring spot of the temperature measuring device decreases as the diameter of the capillary decreases. There is therefore a desire for an accurate non-contact temperature measurement of capillaries whose size is smaller than 1 mm.

Regarding the state of the art, reference is made to the US 2008/0225925 A1 , the US 2021/0018368 A1 as well as the EN 10 2014 004 286 B3 referred to.

Due to the difficulties mentioned above, the object of the present invention is to provide a temperature measuring device for contactless temperature measurement of a capillary of a gas chromatograph, wherein the temperature measuring device is designed particularly simply compared to the prior art and allows a particularly accurate temperature measurement of capillaries with a diameter of 1 mm or less. The invention is also based on the object of providing a system comprising a capillary and a temperature measuring device of the above type. The invention is also based on the object of providing a gas chromatograph, in particular a temperature gradient gas chromatograph, with a capillary and a temperature measuring device of the above type. The invention is also based on the object of providing a method for calibrating a temperature measuring device of a system of the above type or for calibrating a temperature measuring device of a gas chromatograph of the above type, wherein the method enables a particularly accurate measurement of the temperature of the capillary with the temperature measuring device.

According to the invention, these objects are achieved by the objects or the method with the features of the independent claims. Further features of the invention emerge from the following description, the appended claims and/or the appended drawings.

A temperature measuring device according to the invention for contactless measurement of a temperature of a capillary of a gas chromatograph comprises an infrared sensor with a sensor surface that absorbs infrared radiation for measuring the temperature of the capillary. The temperature measuring device also comprises a reflector unit with a reflection surface that reflects infrared radiation and interacts with the infrared sensor, as well as a holding device for holding a capillary. The infrared sensor has a first side and the reflector unit has a second side, wherein the holding device is arranged on the first side of the infrared sensor and on the second side of the reflector unit. In the temperature measuring device according to the invention, the reflection surface is arranged aligned with the infrared sensor for reflecting infrared radiation emitted by a measuring area onto the sensor surface of the infrared sensor, wherein a section of the capillary can be arranged in the measuring area.

The holding device is a device for holding a capillary whose temperature is to be measured and/or an object connected to this capillary. This capillary and/or the object connected to this capillary can be held by means of the holding device in such a way that a section of this capillary can be arranged or positioned precisely in the measuring range of the temperature measuring device during a temperature measurement. For this purpose, the holding device can be a mechanically rigid or substantially mechanically rigid structural component. For example, the holding device can be a housing of a temperature gradient gas chromatograph in which a capillary can be arranged or is arranged. Alternatively, the holding device can be, for example, a structural component that can be arranged or is arranged in a temperature gradient gas chromatograph and on or in which a capillary can be arranged or is arranged.

The infrared sensor with a sensor surface that receives infrared radiation for measuring a temperature of a capillary is, for example, an infrared sensor known from the prior art, which is described above. In particular, the infrared sensor can be a CCD sensor. Additionally or alternatively, the infrared sensor can in particular have a flat sensor surface. The infrared sensor can have a sensor housing with a plurality of sides, wherein within the scope of the present invention the first side can be designed as one side of the sensor housing and the first side can be connected or is connected to the holding device.

The reflector unit with the reflection surface reflecting infrared radiation is the imaging optics of the temperature measuring device according to the invention for contactless temperature measurement. The reflector unit has, for example, at least one reflector body, the reflection surface and the second side, wherein the reflection surface and the second side are arranged or can be arranged on the reflector body. For example, the reflector body can be a component of any shape and the reflection surface can be a first section of a surface of this component. In addition, the second side can be, for example, a second section of the surface of this component. The second side is intended to be connectable or connected to the holding device.

By arranging the holding device on the first side of the infrared sensor and on the second side of the reflector unit, the holding device, the reflector unit and the infrared sensor can be arranged in a fixed position relative to one another. In particular, the holding device, the first side of the infrared sensor and the second side of the reflector unit can be arranged or are arranged geometrically relative to one another such that an angle α between a first line connecting the measuring area to the reflection surface and a second line connecting the reflection surface to the sensor surface is between 0° and 170°, preferably between 0° and 90°, particularly preferably between 0° and 45°. The term line here means a straight line between two points. By this arrangement, the radiation emitted by a section of a capillary held in the measuring area by means of the holding device can be projected from the reflection surface onto the sensor surface of the infrared sensor.

In the following, the imaging on the sensor surface and the measuring range are first explained before additional or alternative features of the reflection surface are described.

The imaging of the measuring area and/or a section of a capillary arranged in the measuring area on the sensor surface means a targeted reflection of radiation onto the sensor surface of the infrared sensor. If a capillary emits radiation and this capillary is arranged in the measuring area, the radiation emitted by the capillary is at least partially reflected by the reflection surface onto the sensor surface of the infrared sensor. According to the invention, the reflection surface is arranged aligned with the infrared sensor for this purpose. If the aforementioned capillary is arranged outside the measuring area, the radiation emitted by this capillary can also be reflected by the reflection surface, but the radiation is then not reflected onto the sensor surface of the infrared sensor.

The measuring area is a spatial area in front of the reflection surface in which a section of a capillary can be arranged. The measuring area includes all points in the spatial area in front of the reflection surface from which radiation is emitted directly and unhindered onto the reflection surface and reflected from the reflection surface onto the sensor surface of the infrared sensor. In other words, the measuring area is a space that the sensor surface "sees" through a reflection in the reflection surface and in which a section of a capillary can be arranged. The measuring area has a spatial depth in a direction that is parallel to the first line connecting the measuring area to the reflection surface. This spatial depth of the measuring area can be infinitely large or limited. A limitation of the depth of the measuring area can be realized, for example, by an optically opaque component or by the shape of the reflection surface. The measuring area also includes a cross-sectional area that is oriented orthogonally to the first line connecting the measuring area to the reflection surface. The cross-sectional area may have a constant size or a varying size along the depth of the measuring range.

The measuring spot of the temperature measuring device is contained in a cross-sectional area at a specific spatial distance from the reflection surface. The specific spatial distance of the measuring spot from the reflection surface can depend on the relative position of the sensor surface to the reflection surface. Additionally or alternatively, the position of the measuring spot within the measuring range can depend on the shape of the reflection surface. For example, the measuring spot can be infinitely far away from the reflection surface if the reflection surface is flat. In comparison, the measuring spot can be arranged closer to the reflection surface if the reflection surface has a concave curvature, for example.

The size of the measuring spot depends in particular on the optical resolution of the reflection surface and the optical resolution of the sensor surface of the infrared sensor. The optical resolution of the reflection surface depends, for example, on the size of the reflection surface, the shape of the reflection surface and the reflectivity of the reflection surface. For example, a large, concavely curved reflection surface with high reflectivity can have a high optical resolution. The optical resolution of the sensor surface depends in particular on the size of the sensor surface and the size of the pixels contained on the sensor surface. For example, a large sensor surface with small pixels can have a high optical resolution. Furthermore, the pixels in a CCD sensor are, for example, photodiodes.

If a section of a capillary is arranged in the measuring spot located within the measuring area, it is possible that the radiation emitted by the capillary is reflected onto the sensor surface with the greatest possible accuracy.

The reflection surface can be designed as a one-piece surface, for example. In particular, the reflection surface can be a one-piece, reflective surface. It is then, for example, a mirror. Alternatively, the reflection surface can be, for example, a reflective surface composed of several reflective surfaces. Because the imaging optics are designed as a reflector unit and not - as is usual - as a lens or system of lenses, the imaging optics only require an extremely small installation space. This is because a lens or a system of lenses is regularly arranged between the infrared sensor and the measuring area. Such an arrangement requires a large installation space because radiation is guided from a position behind the lens to a position in front of the lens, i.e. essentially in one direction. The installation space is further increased if focusing of the lens(es) is required. In comparison, the installation space can be smaller if the radiation is guided by means of the reflector unit from a first position in front of the reflection surface to a second position in front of the reflection surface, i.e. essentially in two directions. This means that the installation space can be optically large and structurally small.

For the purpose of optically imaging a capillary arranged in the measuring area on the sensor surface, the reflection surface can, for example, reflect radiation with a wavelength in the range of, for example, 780 nm to 3000 nm. It is also possible for the reflection surface to only reflect radiation with a wavelength in a sub-range or in several sub-ranges of the range from 780 nm to 3000 nm, provided this is suitable for the invention. Additionally or alternatively, it is also possible for the reflection surface to reflect radiation with a wavelength in a range other than the range from 780 nm to 3000 nm, provided this is suitable for the invention.

It should be mentioned only as an addition that the temperature measuring device according to the invention can have a lens or a plurality of lenses if this is suitable for the invention. For example, a lens can be used to focus and/or defocus radiation reflected from the reflection surface. The lens(es) is/are also a component of the imaging optics and serves to image radiation emitted by the measuring area and reflected from the reflection surface onto the sensor surface of the infrared sensor.

• - weil die Temperaturmesseinrichtung die Temperatur dieser Kapillare kontaktlos misst,
• - weil ein Abschnitt dieser Kapillare für eine Messung der Temperatur dieser Kapillare mittels der Haltevorrichtung genau in dem Messbereich anordbar ist,
• - weil die Haltevorrichtung, die Reflektoreinheit und der Infrarotsensor positionsfest aneinander anordbar oder angeordnet sind,
• - weil die Reflexionsfläche die von dem in dem Messbereich angeordneten Abschnitt der Kapillare emittierte Strahlung genau auf die Sensorfläche reflektieren kann, und
• - weil auch die Infrarotstrahlung einer von der Sensorfläche des Infrarotsensors abgewandten Seite der Kapillare mit gemessen wird.

The measurement of the temperature of a capillary with the temperature measuring device according to the invention is overall very accurate,

• - because the temperature measuring device measures the temperature of this capillary without contact,
• - because a section of this capillary can be arranged exactly in the measuring area for measuring the temperature of this capillary by means of the holding device,
• - because the holding device, the reflector unit and the infrared sensor can be arranged or are arranged in a fixed position next to each other,
• - because the reflection surface can reflect the radiation emitted by the section of the capillary arranged in the measuring area precisely onto the sensor surface, and
• - because the infrared radiation from a side of the capillary facing away from the sensor surface of the infrared sensor is also measured.

Measuring the temperature of a capillary with the temperature measuring device according to the invention is also very simple because there is no need to precisely set a distance between a capillary whose temperature is to be measured and the temperature measuring device. Measuring the temperature of a capillary with the device according to the invention is also cost-effective because there is no need for an adjustment unit for precisely setting a distance between a capillary whose temperature is to be measured and the temperature measuring device. In addition, the temperature measuring device according to the invention is very compact because there is no need for an adjustment unit for setting a lens.

In a suitable development of the temperature measuring device according to the invention, the reflection surface can additionally or alternatively be a curved reflection surface. The curved reflection surface has a focal point and the holding device is designed such that a capillary held in the holding device can be arranged at least partially in the focal point of the reflection surface. The focal point is arranged at a distance of a focal length from the reflection surface on a straight line which extends from the reflection surface.

In the prior art, the straight line extending from the reflecting surface is known as the optical axis of the reflecting surface, which is generally the axis of symmetry of an imaging optic. Furthermore, the focal point is known in the prior art as the point of an imaging optic at which rays of radiation incident on the imaging optic parallel to the optical axis of the imaging optic intersect on the optical axis after the refraction or reflection of these rays at the imaging optic.

If the optical axis is a straight line and the focal point is a point, then the reflection surface is rotationally symmetrical about the optical axis. Rotationally symmetrical means that the reflection surface can be represented on itself after a rotation about the optical axis by an angle β (with β < 360°). For example, the angle β can be 90°. In this case, the reflection surface can be rotationally symmetrical by a rotation of 90° about the optical axis. Alternatively, the angle β can be 1°, for example. In this case, the reflection surface can be essentially rotationally symmetrical about the optical axis. In this case, the reflection surface can be rotationally symmetrical about its optical axis with any angle β < 360°.

Alternatively, the optical axis in the sense of the present invention can also be designed as an optical plane, which is a plane of symmetry of the reflection surface. In this context, the focal point can also be designed as a focal line arranged in the plane of symmetry. If the optical axis is designed as an optical plane and the focal point is a focal line, then the reflection surface is not rotationally symmetrical, but rather mirror-symmetrical to the optical plane.

If the temperature measuring device according to the invention has a curved reflection surface with a focal point and an optical axis, then the measuring range of the temperature measuring device is formed around the optical axis and the focal point is arranged in this measuring range. If the temperature measuring device according to the invention has a curved reflection surface with a focal line and an optical plane, then the measuring range of the temperature measuring device is formed around the optical plane and the focal line is arranged in this measuring range. Furthermore, if the curved reflection surface has a focal point or a focal line, the measuring spot is formed around the focal point or the focal line at a distance of the focal length from the reflection surface. The spatial depth of the measuring range can also be limited by a multiple of the focal length of the curved reflection surface if the curved reflection surface has a focal point or a focal line. The multiple of the focal length can be, for example, ten times the focal length, five times the focal length or twice the focal length.

Because the measuring area is formed around the focal point or the focal line and the holding device is additionally designed such that a capillary can be arranged at least partially in the focal point or the focal line of the reflection surface, it is possible to image a large proportion of a radiation emitted by the section of the capillary arranged in the focal point or the focal line in a bundled manner on the sensor surface of the infrared sensor by means of the reflection surface. In contrast, a smaller proportion of a radiation emitted by the capillary is imaged in a bundled manner on the sensor surface of the infrared sensor by means of the reflection surface if the holding device is designed such that a capillary held in the holding device cannot be arranged with a section in the focal point or the focal line of the reflection surface.

If the holding device is designed in such a way that a capillary held in the holding device can be arranged at least partially in the focal point or focal line of the reflection surface, a particularly favorable ratio can be achieved overall between a small size of the temperature measuring device and the amount of infrared radiation absorbed by the sensor surface. The amount of infrared radiation absorbed by the sensor surface is the intensity of the infrared radiation integrated over the duration of a temperature measurement and absorbed by the sensor surface. This makes it possible to measure the temperature of a capillary particularly precisely with a small size of the temperature measuring device.

In a further development of the temperature measuring device according to the invention, the curved reflection surface can additionally or alternatively be the reflection surface of a spherical concave mirror or a cylindrical concave mirror. A spherical concave mirror in the sense of the invention is a mirror with a concave, spherically formed reflection surface or with a concave, essentially spherically formed reflection surface. In this case, the reflection surface is rotationally symmetrical with respect to the optical axis or essentially rotationally symmetrical with respect to the optical axis and it has a focal point. A cylindrical concave mirror in the sense of the invention is a mirror with a concave reflection surface in the form of a lateral surface of a cylinder sector or essentially in the form of a lateral surface of a cylinder sector. In this case, the reflection surface is mirror-symmetrical with respect to the optical plane or essentially mirror-symmetrical with respect to the optical plane and it has a focal line.

If the curved reflection surface has the shape of a spherical or cylindrical concave mirror, the radius of the reflection surface is identical to twice the focal length of the reflection surface. If a body is at a distance from the reflection surface of the spherical or cylindrical concave mirror and the distance is greater than the radius of the reflection surface, the body is represented optically reduced in size by the reflection surface according to the rules of physical optics known from the prior art. For the present invention, an optical reduction in size of a body, in particular a capillary, is not useful. In this respect, the measuring range can be limited to an area that extends from the curved reflection surface to twice the focal length of the reflection surface. This limitation of the measuring range can be realized, for example, by arranging the sensor surface of the infrared sensor at a distance from the curved reflection surface that corresponds to twice the focal length of the curved reflection surface.

Alternatively, the curved reflection surface can also be designed in the form of a parabolic concave mirror. Alternatively, the curved reflection surface can be designed in the form of a concave mirror with a parabolic outer surface. Common spherical concave mirrors and common parabolic concave mirrors reflect radiation that hits these concave mirrors in a very similar way. Parabolic concave mirrors have a slightly better focused focal point than spherical concave mirrors, but parabolic concave mirrors are more difficult to manufacture than spherical concave mirrors. In principle, both types of mirrors (spherical concave mirrors and parabolic concave mirrors) can be used identically for the present invention. The same applies to cylindrical concave mirrors and concave mirrors with a parabolic outer surface.

According to a further embodiment of the temperature measuring device according to the invention, the holding device can additionally or alternatively have guide parts for holding the capillary in a fixed position, with at least a subset of the guide parts being arranged adjacent to the measuring area. The guide parts can be connected or connected to the holding device in a fixed position and at a distance from one another. If a capillary is arranged in or on the guide parts and is thus arranged on the holding device, the positions of the guide parts on the holding device specify the position of the capillary that can be arranged or is arranged therein or thereon in relation to the holding device. This can specify a path along which the capillary is arranged on the holding device. By arranging the guide parts adjacent to the measuring area, a particularly precise temperature measurement is possible. This is because a capillary held in the guide parts is stored as close as possible to the measuring area and can therefore be positioned precisely without the guide parts themselves being arranged in the measuring area and thus influencing the result of the temperature measurement.

For example, each of the guide parts has a guide section. A capillary can be arranged in or on the guide section in a precise position. For example, a capillary is or can be inserted in the guide section in a precise position. Additionally or alternatively, a capillary can be suspended and carried in a precise position by the guide section.

The guide section has, for example, a surface section that is in contact with a capillary that can be arranged or is arranged in or on the guide section. This surface section is designed in such a way that a contact surface between the guide section and a capillary is small. The small contact surface can, for example, be smaller than a tenth of the cross-sectional area of the capillary or smaller than 0.1 mm ² . For the purpose of creating a small contact surface, the surface section of the guide section can in particular have one or more curvatures. The contact surface can therefore be a contact line or a contact point. A small contact surface between the guide section and a capillary that can be arranged therein makes it possible for only a small amount of heat to be exchanged between the capillary and the guide part. A low transfer of heat into the capillary and/or out of the capillary is important for a high accuracy of a chemical analysis of a mixture of substances flowing in the capillary. Further details on this are described below. As a result, a capillary with the guide parts can be positioned particularly precisely within the measuring range. range which is suitable for a temperature measurement with the temperature measuring device according to the invention, wherein a chemical analysis of a mixture of substances flowing in the capillary is only minimally influenced by the guide parts.

An example of a guide part of the type described above can be a guide part in the form of a two-pronged fork, wherein a handle of the fork is connected to the holding device and a capillary can be arranged between the two prongs of the two-pronged fork in a guide section. The fork width, i.e. the distance between the two prongs, can in this example be identical or essentially identical to the diameter of the capillary. In addition, the two prongs of the two-pronged fork can be inclined towards each other with the free ends pointing away from the handle and/or bent towards each other. A capillary is then inserted into the guide part by elastically bending the two prongs of the two-pronged fork apart and arranging the capillary between the two prongs. The two prongs then spring back elastically so that the capillary is fixed radially in every direction.

The guide parts can in particular be made of high-temperature polymer. High-temperature polymers have a sufficiently high strength to hold the capillary and they are suitable for use at temperatures of up to 400°C. In particular compared to metals, high-temperature polymers also have a low absolute heat capacity and a low thermal conductivity, so that the temperature of a capillary arranged in the high-temperature polymer guide parts is not or essentially not influenced by the guide parts. Examples of high-temperature polymers are polyimide (PI), polyethersulfone (PES), polyetherimide (PEI), polyamideimide (PAI) and/or composites thereof. Additionally or alternatively, other high-temperature polymers that are suitable for the invention can also be used.

In a further development of the temperature measuring device according to the invention, the holding device can additionally or alternatively have a first holding device side and a second holding device side opposite the first holding device side. The infrared sensor is then arranged on the first holding device side of the holding device and the reflector unit is arranged on the second holding device side of the holding device, so that the sensor surface of the infrared sensor and the reflection surface of the reflector unit are opposite each other.

In this case, the measuring range of the temperature measuring device is a space between the sensor surface of the infrared sensor and the reflection surface of the reflector unit. The measuring range can be the entire space between the sensor surface of the infrared sensor and the reflection surface of the reflector unit. Alternatively, the measuring range can be a subset of this entire space, for example if the reflection surface is a concavely curved reflection surface. Radiation emitted by a capillary is imaged onto the sensor surface of the infrared sensor by means of the reflector unit if a section of this capillary is arranged in the measuring range established between the sensor surface and the reflection surface.

If the sensor surface of the infrared sensor and the reflection surface of the reflector unit are opposite each other and the measuring area is a space in between, the angle α between the first section connecting the measuring area to the reflection surface and the second section connecting the reflection surface to the sensor surface can be in particular 0° or substantially 0°. This means that the measuring area is arranged in particular centrally or substantially centrally in front of the reflection surface and in front of the sensor surface.

A temperature measuring device in which the sensor surface and the reflection surface are opposite one another is particularly simple to construct because the first side of the infrared sensor, the second side of the reflector unit, the first holding device side, the second holding device side and a capillary that can be arranged in the holding device can be arranged at angles of in particular 0°, 90°, 180° and/or 270° to one another. In other words, the first side of the infrared sensor, the second side of the reflector unit, the first holding device side, the second holding device side and a capillary that can be arranged in the holding device can be arranged in particular at right angles and/or parallel to one another. Right angles and parallels can be constructed particularly simply and manufactured particularly precisely. Furthermore, the reflector unit and the infrared sensor can be arranged particularly simply and precisely on the holding device. In this context, simple and precise arrangement means that the reflector unit and the infrared sensor can be arranged on the holding device with very little effort and that the measuring area can be located exactly in the intended position in relation to the holding device after arrangement, which was predetermined for the temperature measuring device. The arrangement of the reflector unit and the infrared sensor on the holding device can, for example, by connecting using tongue and groove, clips and/or screws.

If the sensor surface of the infrared sensor and the reflection surface of the reflector unit are arranged on the holding device so that they face each other, the imaging of the radiation emitted in the measuring area onto the sensor surface can be particularly precise and thus a high intensity of infrared radiation can be recorded by the sensor surface over the duration of a temperature measurement. This is because it is then possible that a proportion of the emitted radiation that is scattered undirectly on the reflection surface and thus cannot be used to measure the temperature is minimal. Additionally or alternatively, it is possible that the range of the wavelength of the radiation is not shifted or is only shifted as slightly as possible by the reflection because the angle of incidence of the emitted radiation on the reflection surface can be as small as possible. In practice, a shift in wavelengths is referred to as redshift or blueshift. It can lead to inaccuracy when measuring a temperature.

In a still further development of the temperature measuring device according to the invention, a first positioning device can additionally or alternatively be provided for changing a relative position of the reflection surface to the holding device or of the reflection surface to a section of the holding device. With the first positioning device, either the reflection surface or at least a section of the holding device can be moved. Alternatively, the reflection surface and at least a section of the holding device can be moved with the positioning device. If the holding device or a section of the holding device in which the capillary is arranged is moved, the capillary arranged therein is also moved. By changing the relative position of the reflection surface to the holding device or of the reflection surface to a section of the holding device, it is possible to coordinate the measuring range of the temperature measuring device and a capillary that can be arranged or is arranged in the holding device or in the section of the holding device. For example, the measuring range can be shifted in relation to the capillary by shifting the reflection surface, or the capillary can be shifted in relation to the reflection surface and thus to the measuring range, so that a section of the capillary and the measuring spot of the temperature measuring device overlap or almost overlap.

Coordinating the measuring range, in particular the measuring spot, with the position of a capillary that can be arranged or is arranged in the holding device or in the section of the holding device is particularly important because temperature influences can lead to a thermally induced expansion or a thermally induced contraction of the temperature measuring device. By expanding or contracting the temperature measuring device, the position of the measuring spot of the temperature measuring device can be changed in relation to the holding device. The measuring range of the temperature measuring device can even be changed in such a way that it no longer images a capillary arranged in the holding device on the sensor surface. Thus, an active change, for example a shift, of the position of the measuring range or a position of a capillary arranged in the holding device can be desirable in order to be able to coordinate the position of the measuring range and the position of the capillary.

The displacement of the reflection surface in relation to the holding device or a section of the holding device in which the capillary can be arranged can be realized, for example, in that the reflector unit has the first positioning device in addition to the reflector body, the reflection surface and the second side. The reflector unit can then be connected to the holding device, for example with the second side arranged on the first positioning device. In addition, the reflection surface can be arranged on the reflector body and the first positioning device and the reflector body can be connected to one another in a displaceable manner, for example.

The displacement of the holding device or of a section of the holding device in which the capillary can be arranged in relation to the reflection surface can be realized, for example, in that the first positioning device has a fastening section, the first positioning device is connected to the holding device in a fixed position with this fastening section, and the first positioning device has a receiving section for receiving a capillary that is displaceably connected to the fastening section. If a capillary is arranged in the receiving section, the displacement of the receiving section can cause the capillary arranged therein to be displaced in relation to the reflection surface. In this context, it is possible for the receiving section to be designed as the above-mentioned section of the holding device. Additionally or alternatively, it is possible for the receiving section to be designed as the guide parts or at least the subset of the guide parts.

Furthermore, in addition or as an alternative, the temperature measuring device according to the invention can be provided with a second positioning device for changing a relative position of the sensor surface to the reflection surface. With the second positioning device, either the sensor surface or the reflection surface can be moved. Alternatively, the sensor surface and the reflection surface can be moved with the second positioning device. If the position of the sensor surface is changed in relation to the position of the reflection surface, the measuring range of the temperature measuring device is also moved due to the rules of physical optics known from the prior art. The second positioning device thus also serves to change the position of the measuring range in relation to a capillary that can be arranged or is arranged in the holding device and is associated with the same advantages as the first positioning device.

If the first positioning device and the second positioning device are provided, the position of the holding device (or the position of a section of the holding device carrying the capillary) and/or the position of the reflection surface and/or the position of the sensor surface can be shifted overall. Each of these shifts is suitable for locally coordinating the position of the capillary and the position of the measuring area, in particular the measuring spot.

In this context, it is possible to change the position of the reflection surface and/or the position of the sensor surface.

The second positioning device can in particular be a positioning device that is separate from the first positioning device. The second positioning device can be designed to be identical or substantially identical to the first positioning device. If only the position of the sensor surface is to be changeable and the position of the reflection surface is not to be changeable, the second positioning device can be the only positioning device. If the position of the sensor surface and the position of the reflection surface are to be changeable, it is also possible to design the first positioning device and the second positioning device in a common positioning device.

The displacement of the sensor surface in relation to the reflection surface can be achieved, for example, by the infrared sensor also having the second positioning device in addition to the sensor surface and the first side. The infrared sensor can then be connected to the holding device, for example, with the first side arranged on the second positioning device.

The temperature measuring device has a tempering device for cooling or heating the holding device. As explained above, temperature influences can lead to a thermally induced expansion or a thermally induced contraction of the temperature measuring device, so that the position of the measuring area, in particular of the measuring spot, and the position of a section of a capillary that can be arranged or is arranged in the holding device are not coordinated with one another. In addition, temperature influences can lead to a falsified measurement result of the infrared sensor. In the present invention, temperature influences that act on the temperature measuring device are in particular due to a heated capillary arranged in the holding device. By means of the tempering device for cooling or heating the holding device, it is possible to heat the holding device to a constant or essentially constant

Temperature independent of the temperature of a capillary arranged therein.

For example, the temperature control device can be a heater, in particular an electric heater, which is arranged in or on the holding device. This electric heater can in particular be functionally separated from the electric heating of the capillary. The temperature control device can heat the holding device to a constant temperature above the temperature of a capillary arranged in or on the holding device. At the constant, higher temperature, the position of the measuring area is regularly coordinated with the position of a section of the capillary in the holding device.

Alternatively, the temperature control device can be, for example, a cooling system, in particular a water cooling system, which is arranged in or on the holding device. In this case, the holding device can be heated to a constant temperature below the temperature of a capillary arranged in or on the holding device. At the constant, lower temperature, the position of the measuring area is regularly coordinated with the position of a section of the capillary in the holding device. If the cooling is a water cooling system, this water cooling system can be, for example, the water cooling system of a gas chromatograph on which the temperature measuring device is arranged.

Additionally or alternatively, it is also possible for a mechanical contact between a capillary arranged in the holding device and the holding device to be designed over a particularly small area in order to thermally decouple the capillary and the holding device or to substantially thermally decouple them. In this context, reference is made to the designs of the guide parts, which can be used for the purpose of a small-area mechanical contact. Furthermore, additionally or alternatively, thermal insulation can be arranged between the capillary and the holding device. Even further, additionally or alternatively, thermal insulation can be arranged between the holding device and the reflector unit and/or between the holding device and the infrared sensor. Thermal insulation can, for example, be a layer made of a ceramic, a glass fabric and/or a high-temperature polymer.

The present invention also relates to a system comprising a capillary and a temperature measuring device with at least one of the above or below features or with a combination of at least two of the above or below features. In particular, the above descriptions also explicitly relate to the system with the capillary and the temperature measuring device.

In a further development of the system, a cross-sectional area of the capillary can additionally or alternatively be smaller than the sensor area of the infrared sensor. The cross-sectional area of the capillary is the area of the capillary that is oriented orthogonally to the mixture of substances flowing through the capillary. If the cross-sectional area is smaller than the sensor area, it is possible for the sensor area to record a large proportion of the radiation emitted by the capillary and reflected by the reflection surface at a large angle. This makes it possible to record a particularly large amount of radiation emitted by the capillary with the sensor area integrated over the entire sensor area. This means that even the temperature of a capillary with a very small cross-sectional area can be measured precisely with the system according to the invention. In particular, it is possible for the capillary to be imaged optically enlarged on the sensor surface by the reflection of the radiation emitted by this capillary at the reflection surface if the sensor area is larger than the capillary. If a sensor surface with an optical resolution, for example a CCD sensor with a plurality of pixels, is additionally used, it may even be possible to spatially resolve the temperature of the capillary in the form of a temperature profile.

If the temperature measuring device of the system has the curved reflection surface described above with a focal point or a focal line, the measuring range can, in a further development of the system, additionally or alternatively be limited to a space that extends from the curved reflection surface to twice the focal length of the reflection surface. In addition, at least one section of the capillary can then be arranged in this measuring range.

The measuring range extending from the curved reflection surface to twice the focal length of the reflection surface can be realized, for example, by arranging the sensor surface and the curved reflection surface opposite one another, with the distance between the sensor surface and the curved reflection surface corresponding to twice the focal length of the curved reflection surface. The measuring range is thus limited, for example, to a space between the sensor surface and the curved reflection surface. A section of the capillary is also arranged in this space between the sensor surface and the curved reflection surface, with radiation emitted by the capillary being reflected by the reflection surface and able to be imaged onto the sensor surface. Because the section of the capillary in this example is arranged at a distance from the reflection surface that is smaller than twice the focal length of the curved reflection surface, the capillary can be imaged optically enlarged on the sensor surface.

The present invention also relates to a gas chromatograph, in particular a temperature gradient gas chromatograph, with a capillary. The gas chromatograph has a temperature measuring device for measuring the temperature of the capillary with at least one of the above or below features or a combination of at least two of the above or below features. In particular, the above descriptions also explicitly relate to the gas chromatograph, in particular the temperature gradient gas chromatograph, with the capillary and the temperature measuring device.

The concept of temperature gradient gas chromatography is, as described above, known from the state of the art. In a temperature gradient gas chromatograph, the temperature of the capillary is strongly dependent on the convection of the air surrounding the capillary.

A concept of temperature gradient gas chromatography that describes the convection of the capillary The method that makes targeted use of the surrounding air is flow field temperature gradient gas chromatography, which is used, for example, in EN 10 2014 004 286 B3 is disclosed. In flow field temperature gradient gas chromatography, convection of air around the capillary is controlled in a targeted manner so that cooling of the capillary can also be controlled. In the device disclosed in DE 10 2014 004 286 B3 for gas chromatographic separation and determination of volatile substances in a carrier gas via a chromatographic separation capillary, the separation capillary and/or a sheath capillary surrounding this separation capillary is/are electrically conductive. Furthermore, this separation capillary and/or the sheath capillary surrounding this separation capillary is/are heated with electricity in the form of an electrical resistance heater and cooled by a forced convective air flow in the form of a gradient flow field so that a continuous temperature gradient is established over the length of the separation capillary. The document describes that no thermal gradient field needs to be created around the separation capillary, which would only indirectly warm or heat the separation capillary to the desired temperatures. Rather, the temperature gradient is created as a result of the gradually changing heat balance, so that an accurate and fast-working gas chromatography system can be set up.

The gas chromatograph according to the invention can, for example, be a flow field temperature gradient gas chromatograph with the above features.

Additionally or alternatively, the gas chromatograph can have, for example, a hollow cylindrical support which carries the capillary and can have, for example, a diameter of approximately 20 cm. Furthermore, the capillary can be arranged in the hollow cylindrical support, for example, in a helical shape. In order to achieve a length of the separation capillary that is suitable for gas chromatographic analysis, several turns of the helical capillary can be arranged one above the other in the hollow cylindrical support, for example over a height of approximately 12 cm. With this design, a convective flow for cooling the separation capillary can, for example, enter at an end face of the hollow cylindrical support and exit at a lateral surface of the hollow cylindrical support.

Alternatively, the carrier can have a shape other than the shape of a hollow cylinder. Furthermore, the separation capillary can also have a shape other than the shape of a helix. For example, the carrier can be a flat carrier or a substantially flat carrier, in particular the carrier can be a grid or a type of grid. The capillary can, for example, be spiral-shaped and arranged aligned parallel to the flat carrier. The convective air flow in the form of the gradient flow field can, for example, flow orthogonally through the plane of the spiral-shaped capillary and have a flow velocity that increases or decreases from the center of the capillary to its outer radius.

In the gas chromatograph according to the invention, the carrier of the gas chromatograph can be, for example, the holding device of the temperature measuring device described above. In this case, the carrier is arranged on the first side of the infrared sensor and on the second side of the reflector unit such that the reflection surface of the infrared sensor is aligned to reflect infrared radiation emitted by the capillary arranged in or on the carrier and in the measuring area onto the sensor surface of the infrared sensor.

Alternatively, the carrier of the gas chromatograph and the holding device of the temperature measuring device can be separate components, wherein the holding device is, for example, connectable or connected to the carrier and the holding device and the carrier are arranged on one another such that the reflection surface of the infrared sensor is arranged so as to reflect infrared radiation emitted by the capillary arranged in or on the carrier and in the measuring area onto the sensor surface of the infrared sensor.

The present invention also relates to a method for calibrating a temperature measuring device of a system or a temperature measuring device of a gas chromatograph, wherein the system or the gas chromatograph has at least one of the above or below features or a combination of at least two of the above or below features.

• - Auswählen eines ersten, mittels der Haltevorrichtung in dem Messbereich gehaltenen Abschnitts der Kapillare,
• - Anordnen eines Mikrothermoelements in einem Innenraum des ersten Abschnitts der Kapillare oder eines zweiten Abschnitts der Kapillare, der an den ersten Abschnitt angrenzt,
• - Messen einer Temperatur im Innenraum des ersten oder des zweiten Abschnitts der Kapillare mittels des Mikrothermoelements,
• - Messen einer Temperatur einer Außenfläche des ersten Abschnitts der Kapillare mittels der Temperaturmesseinrichtung und
• - Abstimmen der mittels der Temperaturmesseinrichtung gemessenen Temperatur auf die mittels des Mikrothermoelements gemessene Temperatur.

The procedure for calibrating the system temperature measuring device or the gas chromatograph temperature measuring device comprises the following steps:

• - Selecting a first section of the capillary held in the measuring area by means of the holding device,
• - arranging a micro thermocouple in an interior of the first section of the capillary or a second section of the capillary adjacent to the first section,
• - Measuring a temperature in the interior of the first or second section of the capillary by means of the micro thermocouple,
• - measuring a temperature of an outer surface of the first section of the capillary by means of the temperature measuring device and
• - Matching the temperature measured by the temperature measuring device to the temperature measured by the micro thermocouple.

The first section of the capillary held in the measuring area by means of the holding device is the section whose temperature is to be measured according to the invention. The micro thermocouple is arranged in the interior of the first section or the second section of the capillary which is adjacent to the first section. Micro thermocouples are known in the prior art and allow precise and reliable temperature measurement. The calibration of the temperature measuring device on the basis of a measurement result with a micro thermocouple can therefore also be precise and reliable. Experience has shown that the temperature in the first section itself and in the second section of the capillary adjacent to the first section is essentially identical. For the calibration of the temperature measuring device, the temperature can therefore be measured with sufficient accuracy using the micro thermocouple and the temperature measuring device in or on the same section of the capillary or in or on two adjacent sections of the capillary.

To accurately measure the temperature of the capillary with the temperature measuring device, the temperature of the capillary measured by the temperature measuring device is adjusted to the temperature of the capillary measured by the micro thermocouple. In other words, the temperature of the capillary measured by the temperature measuring device is shifted to the temperature of the capillary measured by the micro thermocouple.

With the temperature measuring device calibrated in the manner described above, the temperature of the capillary can be measured contactlessly and accurately.

• - eine Außenfläche des ersten, mittels der Haltevorrichtung in dem Messbereich gehaltenen Abschnitts der Kapillare lokal optisch geschwärzt werden,
• - das Mikrothermoelement in dem Innenraum des zweiten Abschnitts der Kapillare angeordnet werden,
• - das Messen einer Temperatur mittels des Mikrothermoelements im Innenraum des zweiten Abschnitts der Kapillare erfolgen, und
• - das Messen einer Temperatur der Außenfläche des ersten Abschnitts der Kapillare mittels der Temperaturmesseinrichtung an der geschwärzten Außenfläche des ersten Abschnitts der Kapillare erfolgen.

In practice, the procedure can additionally or alternatively

• - an outer surface of the first section of the capillary held in the measuring area by means of the holding device is locally optically blackened,
• - the micro thermocouple is arranged in the interior of the second section of the capillary,
• - the temperature is measured using the micro thermocouple in the interior of the second section of the capillary, and
• - measuring a temperature of the outer surface of the first section of the capillary by means of the temperature measuring device on the blackened outer surface of the first section of the capillary.

The idea behind optically blackening the outer surface of the first section of the capillary, which is held in the measuring area by the holding device, is to increase the emissivity of this section in order to generate a stronger measurement signal for the temperature measurement with the temperature measuring device. By optically blackening the outer surface of the first section of the capillary, the emissivity of the first section of the capillary can be increased so that a measurement of the temperature of the capillary with the temperature measuring device can be particularly accurate. It should be noted that optical blackening does not necessarily mean creating a surface that appears black to the human eye. Rather, optical blackening means taking measures to increase emissivity. Emissivity is a measure of how strongly a material or body exchanges thermal radiation with its environment. The theoretically greatest possible value of emissivity is 1. A body with an emissivity of 1 is called a black body in practice. A body with an emissivity of 1 absorbs all electromagnetic radiation (e.g. infrared radiation) and therefore emits it to the maximum. The emissivity of the first section of the capillary is more than 0.9 and preferably more than 0.95 after the measures to increase the emissivity (i.e. after optical blackening).

The micro thermocouple can be arranged in particular in the interior of the second section of the capillary and a temperature in the interior of this section can be measured using the micro thermocouple. This arrangement and this procedure are suitable because, due to the locally increased emissivity of the first section, the temperature of the first section is regularly somewhat lower than the temperature of non-blackened sections of the capillary and the temperature of the non-blackened sections of the capillary is regularly relevant for the chemical analysis of a mixture of substances flowing in the capillary.

By means of the temperature measuring device, a temperature of the blackened outer surface of the first section of the capillary can therefore be measured and this measurement result can be transferred to the temperature measured by the micro thermocouple measured temperature of the second, non-blackened section of the capillary, the temperature of which is relevant for the chemical analysis of a mixture of substances flowing in the capillary. This makes the calibration and the temperature measurement with the temperature measuring device according to the invention particularly accurate.

• 1 eine schematische Darstellung eines erfindungsgemäßen Gaschromatograph, insbesondere eines Temperaturgradienten-Gaschromatographen, mit einer Kapillare und einer Temperaturmesseinrichtung in einer seitlichen Querschnittsansicht durch den Gaschromatograph;
• 2 eine schematische Darstellung eines erfindungsgemäßen Systems, umfassend eine erfindungsgemäße Temperaturmesseinrichtung und eine Kapillare, gemäß einer ersten Ausführungsform der Temperaturmesseinrichtung, in einer Querschnittsansicht durch die Kapillare;
• 3 eine schematische Darstellung eines erfindungsgemäßen Systems, umfassend eine erfindungsgemäße Temperaturmesseinrichtung und eine Kapillare, gemäß einer zweiten Ausführungsform der Temperaturmesseinrichtung, in einer Querschnittsansicht durch die Kapillare;
• 4 ein Ablaufdiagramm eines erfindungsgemäßen Verfahrens zur Kalibrierung der Temperaturmesseinrichtung des Systems aus 2 oder 3.

Further practical embodiments and advantages of the invention are described below in conjunction with the drawings. They show:

• 1 a schematic representation of a gas chromatograph according to the invention, in particular a temperature gradient gas chromatograph, with a capillary and a temperature measuring device in a lateral cross-sectional view through the gas chromatograph;
• 2 a schematic representation of a system according to the invention, comprising a temperature measuring device according to the invention and a capillary, according to a first embodiment of the temperature measuring device, in a cross-sectional view through the capillary;
• 3 a schematic representation of a system according to the invention, comprising a temperature measuring device according to the invention and a capillary, according to a second embodiment of the temperature measuring device, in a cross-sectional view through the capillary;
• 4 a flow chart of a method according to the invention for calibrating the temperature measuring device of the system from 2 or 3 .

In the following, the temperature measuring device according to the invention for the contactless measurement of a temperature of a capillary of a gas chromatograph, the system according to the invention with a capillary and the temperature measuring device and the gas chromatograph according to the invention with a capillary and the temperature measuring device according to a possible embodiment are described with reference to the figures. The figures serve to facilitate understanding. They are shown schematically and are not to scale. Identical components in the figures are provided with the same reference numerals.

With the 1 First, an overview of a gas chromatograph, in particular a temperature gradient gas chromatograph, with a capillary and the temperature measuring device is described. 2 and 3 Possible embodiments of a temperature measuring device are described. 4 shows a possible procedure for calibrating the temperature measuring devices.

1 shows a temperature measuring device 2 for measuring the temperature of a capillary 4 of a gas chromatograph 6, in particular a flow field temperature gradient gas chromatograph. The gas chromatograph 6 comprises a base 8, with which the gas chromatograph 6 can be set up securely, a hollow cylindrical support 12 arranged vertically on the base 8 and a cover 10, which covers an end face of the hollow cylindrical support 12 remote from the base 8. The hollow cylindrical support 12 carries the capillary 4. The hollow cylindrical support 12 has, for example, a diameter of approximately 20 cm and a height of approximately 12 cm. The hollow cylindrical support 12 is also the holding device 12 of the temperature measuring device 2.

In the embodiment described here, the capillary 4 is arranged in a helical groove in the carrier 12 and has the shape of a helix with a plurality of turns. The capillary 4 can, for example, comprise a non-conductive polyimide-coated quartz glass separation capillary and an electrically conductive sheath capillary surrounding it. An electrical current can flow through the electrically conductive sheath capillary, which is at least partially dissipated to heat in the sheath capillary. The heat dissipated in the sheath capillary heats the non-conductive polyimide-coated quartz glass separation capillary homogeneously or essentially homogeneously.

For gas chromatographic separation of a gas or gas mixture to be analyzed with the gas chromatograph 6, the gas or gas mixture to be analyzed can be introduced into the quartz glass separation capillary. For this purpose, an injector 14 is connected to the capillary 4. The gas chromatograph 6 also has a gas detector 16 for detecting the components of the gas or gas mixture to be analyzed and passed through the capillary 4. The injector 14 and the gas detector 16 are connected to the capillary 4 by means of transfer lines 18, 20 so that the gas can flow through them.

A cylindrically formed, porous sponge structure 24 is introduced into a cylindrical inner volume 22 of the hollow cylindrical carrier 12. Pores are formed in the sponge structure 24 in such a way that a fluid, in particular air, can flow through the sponge structure 24. A fan 26 is arranged on the cover 10, which can convey a fluid, in particular air, into the inner volume 22 of the hollow cylindrical carrier 12. If a fluid flow is generated with the fan 26 28 of a fluid is conveyed into the inner volume 22 of the hollow cylindrical carrier 12, the fluid flow 28 flows through the sponge structure 24. The fluid flow 28 can escape from the inner volume 22 of the hollow cylindrical carrier 12 through the groove in the carrier 12. As a result, the capillary 4 is convectively cooled by the fluid flow 28 flowing past it.

The sponge structure 24 generates a flow resistance that increases in the direction of flow of the fluid flow 28. In the 1 the flow direction of the fluid flow 28 is oriented essentially from the fan 26 to the base 8. Due to the flow resistance increasing in the flow direction, a larger proportion of the fluid flow 28 flows through the turns of the capillary 4 that are closer to the fan 26 (i.e. the upper turns of the capillary 4) than through the turns that are further away from the fan 26 (i.e. the lower turns of the capillary 4). As a result, there is a stronger convective cooling of the upper turns of the capillary 4 compared to the lower turns of the capillary 4. Since the capillary 4 is heated homogeneously or essentially homogeneously, a temperature gradient along the capillary 4 can be set by the convective cooling described above.

For a precise gas chromatographic separation of a gas or gas mixture to be analyzed with the gas chromatograph 6, an accurate measurement of the temperature of the capillary 4 of the gas chromatograph 6 is important. Therefore, the gas chromatograph 6, as mentioned above, has the temperature measuring device 2. The hollow cylindrical carrier 12 of the gas chromatograph 6 is the holding device 12 of the temperature measuring device 2. In principle, it is also possible for the hollow cylindrical carrier 12 and the holding device 12 to be separate components (not shown). The temperature measuring device 2 can, for example, be designed according to one of the 2 or 3 shown embodiments of the temperature measuring device 2, which are explained below.

The 2 and 3 show two possible embodiments of the temperature measuring device 2 or the system comprising the temperature measuring device 2 and the capillary 4.

In the 2 The embodiment of the system or temperature measuring device 2 shown for contactless measurement of a temperature of a capillary 4 of a gas chromatograph 6 has the holding device 12 for holding the capillary 4. In 2 a section of a cross section of the holding device 12 is shown. The section of the holding device 12 shown is essentially rectangular on the outside, the holding device 12 having at least a first holding device side 30 and a second holding device side 32 opposite the first holding device side 30. A recess 34 is formed between the first holding device side 30 and the second holding device side 32. The recess 34 can, for example, be the groove made in the hollow cylindrical carrier 12 in which the capillary 4 is arranged.

The temperature measuring device 2 further comprises an infrared sensor 36 with a sensor housing 38 and a sensor surface 40 that receives infrared radiation for measuring a temperature of the capillary 4. The infrared sensor 36 is an infrared temperature sensor. The sensor surface 40 is designed as a flat and rectangular pyroelectric detector surface made of lithium tantalate, which is arranged on the sensor housing 38. A diameter of the capillary 4 is smaller than a height of the sensor surface 40. By means of the pyroelectric detector surface made of lithium tantalate, an intensity of infrared radiation incident on this surface is integrated over a measurement period to measure a temperature and converted into an electrical signal. The electrical signal is sent to a processor (not shown). The processor calculates a temperature on the basis of the electrical signal. Alternatively, the sensor surface can also be designed, for example, as a thermopile or a CCD sensor, by means of which incident infrared radiation can also be integrated and thus converted into an electrical signal.

The infrared sensor 36 additionally has a first side 42, which in the embodiment described here is a surface of a second positioning device 44 of the infrared sensor 36. The second positioning device 44 and the sensor housing 38 are movably connected to one another. Details of the second positioning device 44 are described below. The first side 42 has the same orientation as the sensor surface 40. In addition, the first side 42 is connected to the first holding device side 30 of the holding device 12 in such a way that the sensor surface 40 borders on the recess 34 protruding through the holding device 12.

The temperature measuring device 2 further comprises a reflector unit 46 which interacts with the infrared sensor 36. The reflector unit 46 has a reflector housing 48, a reflection surface 50 which reflects infrared radiation, a second side 52 and a first positioning device 54. The reflection surface 50 is arranged on the reflector housing 48. It is designed as a flat, rectangular angular and polished metal surface. In other words, the reflection surface 50 is a flat, rectangular mirror. The second side 52 is a surface of the first positioning device 54 in the embodiment of the temperature measuring device 2 described here. The first positioning device 54 is movably connected to the reflector housing 48. Details of the first positioning device 54 are described below. The second side 52 has the same orientation as the reflection surface 50. In addition, the second side 52 is connected to the second holding device side 32 of the holding device 12 in such a way that the reflection surface 50 borders on the recess 34 protruding through the holding device 12.

By arranging the first side 42 on the first holding device side 30 and arranging the second side 52 on the second holding device side 32 opposite the first holding device side 30, the first side 42 and the second side 52 lie opposite one another. Furthermore, the sensor surface 40 and the reflection surface 50 also lie opposite one another and are arranged parallel to one another. Infrared radiation can thus be reflected unhindered or essentially unhindered from the reflection surface 50 through the recess 34 in the holding device 12 onto the sensor surface 40 opposite the reflection surface 50. In other words, the reflection surface 50 is aligned with the infrared sensor 36 to reflect infrared radiation emitted by a measuring area 56 onto the sensor surface 40 of the infrared sensor 36.

The measuring area 56 comprises the space in front of the reflection surface 50, from which infrared radiation is emitted and reflected via the reflection surface 50 onto the sensor surface 40. Since the sensor surface 40 and the reflection surface 50 are in the 2 shown embodiment are parallel planes, the infrared radiation emitted from any point in the space between the sensor surface 40 and the reflection surface 50 can be reflected by the reflection surface 50 onto the sensor surface 40. Thus, the entire space between the sensor surface 40 and the reflection surface 50 is the measuring area 56. Furthermore, since the sensor surface 40 and the reflection surface 50 are rectangular and lie parallel to one another, the space between the sensor surface 40 and the reflection surface 50 and the measuring area 56 are cubic.

The measuring area 56 is penetrated by a section of the capillary 4, the temperature of which is to be measured. The section of the capillary 4 is arranged in particular orthogonal to the connecting section connecting the reflection surface 50 and the sensor surface 40. Thus, infrared radiation can be emitted directly onto the sensor surface 40 from essentially the entire side of the section of the capillary 4 facing the sensor surface 40. In addition, infrared radiation can be emitted onto the reflection surface 50 from essentially the entire side of the section of the capillary 4 facing the reflection surface 50 and reflected from the reflection surface 50 onto the sensor surface 40. As a result, the intensity of the infrared radiation emitted by the capillary 4, which can be measured with the sensor surface 40, is particularly high.

To hold the capillary 4 in a fixed position in the holding device 12, guide parts 58 are arranged on the holding device 12. In 2 only one guide part 58 is shown, whereby all guide parts 58 can be identical. The guide part 58 shown as an example carries the capillary 4 and is arranged in a plane adjacent to the measuring area 56 behind the measuring area 56, so that the section of the capillary 4 whose temperature is to be measured is held particularly securely in the measuring area 56. Further guide parts 58 can be arranged along, for example, the capillary and the entire groove in the holding device 12.

The guide parts 58 can, as in 2 shown, be designed in the form of a two-pronged fork, wherein a handle of the fork is rigidly connected to the holding device 12 and the capillary 4 is arranged between the two prongs of the two-pronged fork in a guide section. The distance between the two prongs is therefore essentially identical to the diameter of the capillary 4. The capillary 4 can thus be held in a fixed position, i.e. in a predefined position. The handle and the prongs of the guide parts 58 designed as a fork are flat in the direction of extension of the capillary 4. They are preferably no wider than 0.1 mm in this direction of extension. Due to the flat design of the handle and the prongs, the guide part 58 designed as a two-pronged fork covers as small an area as possible between the sensor surface 40 and the reflection surface 50 when it is arranged in the measuring area 56. Thus, as little as possible of the infrared radiation reflected from the reflection surface 50 onto the sensor surface 40 is absorbed by the guide part 58.

In the embodiment described here, the guide parts 58 are made of a temperature-resistant high-temperature polymer. The formation of the guide parts 58 from the temperature-resistant high-temperature polymer and in the form of a two-pronged fork is particularly well suited for guiding the capillary 4. This is because the capillary capillary 4 can reach high temperatures of up to 400°C, which the temperature-resistant high-temperature polymer can tolerate without being damaged. Furthermore, only a small exchange of heat takes place between the capillary 4 and the holding device 12 because the temperature-resistant high-temperature polymer has a low absolute heat capacity and thermal conductivity. In addition, the exchange of heat between the capillary 4 and the holding device 12 is low because mechanical contact between the capillary 4 and the guide device is particularly low due to the flat shape of the guide parts 58. Direct mechanical contact between the capillary 4 and the holding device 12 can be avoided by the guide parts 58. As a result, overall only very little heat is transferred from the heated capillary 4 to the holding device 12.

In order to further reduce the influence of heat emanating from the capillary 4 on the measurement accuracy of the temperature measurement, a tempering device 60a, 60b for cooling or heating the holding device 12 is integrated in the holding device 12. The tempering device 60a, 60b is designed as a plurality of fluid channels 60a, 60b, wherein the fluid channels 60a, 60b extend above and below the recess 34 in the holding device 12. A tempering fluid, in particular water, flows through the fluid channels 60a, 60b. The holding device 12 is kept at a constant temperature by the tempering fluid. The holding device 12, the infrared sensor 36 and the reflector unit 46 are thus not heated or not heated significantly when the capillary 4 is heated. Furthermore, the holding device 12, the infrared sensor 36 and the reflector unit 46 are not cooled or not cooled significantly when the capillary 4 cools down. Due to the thermal decoupling of the capillary 4 from the temperature measuring device 2 achieved in this way, the temperature measuring device 2 measures particularly accurately during the entire duration of a contactless temperature measurement. In particular, a temperature-induced drift of the infrared sensor known from the prior art, i.e. a temperature-dependent shift in the measurement result of the infrared sensor, can be avoided.

Although the 2 In the embodiment of the temperature measuring device 2 shown, the entire space between the sensor surface 40 and the reflection surface 50 is the measuring area 56, it can be functionally useful if the position of the sensor surface 40 in relation to the reflection surface 50 can be changed. For this purpose, the reflector unit 46 has the first positioning device 54 for changing a relative position of the reflection surface 50 to the holding device 12. The first positioning device 54 is fastened with the second side 52 to the second holding device side 32 of the holding device 12. The reflection surface 50 is arranged on the first positioning device 54 so that it can be displaced orthogonally to the reflection surface 50. The displaceable arrangement of the reflection surface 50 on the first positioning device 54 is realized in the embodiment described here in that the reflection surface 50 is arranged on the reflector housing 48 and the reflector housing 48 is arranged on a first guide rail (not shown) of the first positioning device 54. The reflector housing 48 can be pushed with the reflection surface 50 along the first guide rail into the groove of the holding device 12 or pulled out of the groove of the holding device 12.

Additionally or alternatively, the first positioning device 54 can have a micrometer adjusting screw (not shown) which is suitable for pushing the reflector housing 48 with the reflection surface 50 further into the recess 34 in the holding device 12 or pulling it out of the recess 34 in the holding device 12. By moving the reflector housing 48 with the reflection surface 50, it is possible to change the position of the reflection surface 50 in relation to the capillary 4 and to the sensor surface 40. As a result, for example, a high proportion of the infrared radiation emitted by the section of the capillary 4 arranged in the measuring area 56 can be reflected by the reflection surface 50 onto the sensor surface 40.

With the second positioning device 44, the sensor housing 38 with the sensor surface 40 can also be moved orthogonally to the sensor surface 40. The second positioning device 44 is functionally designed like the first positioning device 54. This means that the second positioning device 44 is attached to the holding device 12 and the sensor housing 38 can be displaced, for example, along a second guide rail (not shown) arranged on the second positioning device 44. Due to the use of the first positioning device 54 and the second positioning device 44, it is possible to further increase the proportion of infrared radiation emitted by the section of the capillary 4 arranged in the measuring area 56 and reflected onto the sensor surface 40.

In 3 another embodiment of the system or the temperature measuring device 2 for contactless measurement of a temperature of a capillary 4 of a gas chromatograph 6 is shown. 3 shown embodiment differs from that in 2 shown embodiment by a different geometry of the reflection surface 50' compared to the geometry of the reflection surface 50. The reflection surface 50' is not designed as a flat, rectangular mirror, but as a curved, cylindrical concave mirror. Due to this design, the reflection surface 50' has a focal line that is arranged essentially parallel to the capillary 4. Furthermore, the measuring area 56' is limited to a partial area of the space arranged in the groove in front of the reflection surface 50'.

The measuring range 56' has the 3 shown embodiment essentially has the shape of a cylinder segment that extends between the reflection surface 50' and the sensor surface 40. Due to the 2 The temperature of the capillary 4 can be measured particularly accurately using the smaller measuring range 56' shown. This is because the capillary 4 is imaged enlarged on the sensor surface 40 and a small proportion of the infrared radiation detected by the sensor surface 40 is emitted from a background behind the capillary 4. However, the manufacture of a cylindrical concave mirror is more complex than the manufacture of a flat mirror.

As described above, the reflection surface 50' can be displaced by means of the first positioning device 54. This makes it possible to optimally arrange a measuring spot of the temperature measuring device 2 on the section of the capillary. In particular, the focal line can be arranged congruently with the capillary 4. This makes it possible to achieve an ideal enlargement of the capillary on the sensor surface 40. This ideal enlargement is characterized by the fact that the sensor surface 40 receives almost exclusively infrared radiation emitted by the capillary.

4 shows a flow chart with an exemplary sequence in which the method steps of the method according to the invention for calibrating a temperature measuring device 2 according to the invention can be carried out. The method can be used, for example, to calibrate the temperature measuring device 2 of the 2 or 3 The method can also be used, for example, to calibrate the temperature measuring device 2 of the 1 described gas chromatograph 6 can be used.

This in 4 The method shown schematically comprises a plurality of method steps. In a first method step A, an outer surface of a first section of the capillary 4, the temperature of which is to be measured with the temperature measuring device 2 according to the invention, is optically blackened locally. In particular, the outer surface of the first section of the capillary 4 is blackened across its entire circumference. The optical blackening increases the emissivity of the first section compared to an optically non-blackened section of the capillary 4. The first section with the blackened outer surface is held in the measuring area 56, 56' by means of the holding device 12. The first section can first be blackened and then arranged in the measuring area 56, 56'. Alternatively, the first section can first be arranged in the measuring area 56, 56' and then blackened.

In a second method step B, a micro thermocouple is arranged in an interior of a second section of the capillary 4. The second section of the capillary 4 is adjacent to the first section of the capillary 4. The second section is thus arranged adjacent to the measuring area 56, 56' when the capillary 4 is arranged as intended in the holding device 12. The micro thermocouple can be a sheath micro thermocouple, for example. It can be inserted into the capillary 4 and placed there loosely. It is not necessary to attach the micro thermocouple to the capillary.

In the third method step C, a first temperature in the interior of the second section of the capillary 4 is measured using the micro thermocouple. Measuring a temperature using a micro thermocouple is an established and very precise measuring method. It is therefore very suitable as a reference measurement when calibrating the temperature measuring device 2 according to the invention.

In a fourth method step D, a second temperature of the blackened outer surface of the first section of the capillary 4 is measured by means of the temperature measuring device 2. For details of the temperature measurement by means of the temperature measuring device 2, reference is made to the above descriptions of the temperature measuring device 2 according to the invention, the system according to the invention and the gas chromatograph 6 according to the invention.

In a fifth method step E, the second temperature measured by the temperature measuring device 2 is adjusted to the first temperature measured by the micro thermocouple. In other words, the second temperature measured by the temperature measuring device 2 is shifted by a difference to the first temperature measured by the micro thermocouple such that the first temperature is measured by the micro thermocouple and the temperature measuring device 2. Due to the spatial proximity of the second section of the capillary 4 to the first section of the capillary 4, an influence on the difference between the first temperature and the second temperature caused by the measurement of temperatures of different sections (namely the first section and the second section) is very small. The difference between the first temperature and the second temperature is therefore essentially based on the different measuring methods used, namely the measurement by means of the micro thermocouple and by means of the temperature measuring device 2 according to the invention. After adjusting the second temperature measured with the temperature measuring device 2 to the first temperature measured with the micro thermocouple, the temperature measuring device 2 according to the invention is calibrated and the micro thermocouple can be removed.

It is pointed out that the 4 described method is not limited to the sequence of method steps shown and described above. In an alternative sequence of method steps of the method according to the invention, method step D can take place before method step C or before method step B. Alternatively, method steps C and D can be carried out simultaneously.

The method is also not limited to the calibration of a temperature measuring device of a system according to 2 or 3 or a gas chromatograph according to 1 Rather, the method can be used to calibrate all embodiments of temperature measuring devices within the meaning of the present invention.

List of reference symbols

2

Temperature measuring device

4

capillary

6

Gas chromatograph

8th

Base

10

cover

12

carrier, holding device

14

Injector

16

Gas detector

18, 20

Transfer line

22

Internal volume

24

Sponge structure

26

fan

28

Fluid flow

30

first holding device side

32

second holding device side

34

Recess

36

Infrared sensor, infrared temperature sensor

38

Sensor housing

40

Sensor area

42

first page

44

second positioning device

46

Reflector unit

48

Reflector housing

50, 50'

Reflection surface

52

second page

54

first positioning device

56, 56'

Measuring range

58

Guide part

60a, 60b

Temperature control device, fluid channels

A, B, C, D, E

Process steps

Claims (14)

Temperature measuring device (2) for contactless measurement of a temperature of a capillary (4) of a gas chromatograph (6), with - an infrared sensor (36) with a sensor surface (40) that receives infrared radiation for measuring the temperature of the capillary (4), - a reflector unit (46) that interacts with the infrared sensor (36) and has a reflection surface (50, 50') that reflects infrared radiation, and - a holding device (12) for holding the capillary (4), wherein - the infrared sensor (36) has a first side (42), - the reflector unit (46) has a second side (52), - the holding device (12) is arranged on the first side (42) of the infrared sensor (36), - the holding device (12) is arranged on the second side (52) of the reflector unit (46), and wherein - the reflection surface (50, 50') is arranged towards the infrared sensor (36) for reflecting a measurement area (56, 56') emitted infrared radiation is directed onto the sensor surface (40) of the infrared sensor (36) is arranged, wherein a section of the capillary (4) can be arranged in the measuring region (56, 56'), characterized in that the temperature measuring device (2) has a tempering device (60a, 60b) for cooling or heating the holding device (12). Temperature measuring device (2) according to Claim 1 , characterized in that - the reflection surface is a curved reflection surface (50'), - the curved reflection surface (50') has a focal point which is arranged at a distance of a focal length from the reflection surface (50') on a straight line which extends from the reflection surface (50`), and in that - the holding device (12) is designed such that the capillary (4) held in the holding device (12) can be arranged at least partially in the focal point of the reflection surface (50`). Temperature measuring device (2) according to Claim 2 , characterized in that the curved reflection surface (50') is the reflection surface of a spherical concave mirror or a cylindrical concave mirror. Temperature measuring device (2) according to one of the preceding claims, characterized in that the holding device (12) has guide parts (58) for holding the capillary (4) in a fixed position, wherein at least a subset of the guide parts (58) is arranged adjacent to the measuring area (56, 56'). Temperature measuring device (2) according to Claim 4 , characterized in that the guide parts (58) are made of high-temperature polymer. Temperature measuring device (2) according to one of the preceding claims, characterized in that the holding device (12) has a first holding device side (30) and a second holding device side (32) opposite the first holding device side (30), wherein the infrared sensor (36) is arranged on the first holding device side (32) of the holding device (12) and the reflector unit (46) is arranged on the second holding device side (32) of the holding device (12), so that the sensor surface (40) of the infrared sensor (36) and the reflection surface (50, 50') of the reflector unit (46) lie opposite one another. Temperature measuring device (2) according to one of the preceding claims, characterized in that a first positioning device (54) is provided for changing a relative position of the reflection surface (50, 50') to the holding device (12) or of the reflection surface (50, 50') to a section of the holding device (12). Temperature measuring device (2) according to one of the preceding claims, characterized in that a second positioning device (44) is provided for changing a relative position of the reflection surface (50, 50') to the sensor surface (40). System comprising a capillary (4) and the temperature measuring device (2) according to one of the preceding claims. System according to Claim 9 , characterized in that a cross-sectional area of the capillary (4) is smaller than the sensor area (40) of the infrared sensor (36). System according to Claim 9 or 10 combined with Claim 2 , characterized in that the measuring range (56') is limited to a space between the curved reflection surface (50') and twice the focal length of the reflection surface (56'), and that at least a portion of the capillary (4) is arranged in this measuring range. Gas chromatograph (6), in particular a temperature gradient gas chromatograph, with a capillary (4), characterized in that the gas chromatograph (6) has the temperature measuring device (2) for measuring the temperature of the capillary according to one of the Claims 1 until 8th having. Method for calibrating the temperature measuring device (2) of the system according to one of the Claims 9 until 11 or the temperature measuring device (2) of the gas chromatograph (6) according to Claim 12 , which has the following steps: • selecting a first section of the capillary (4) held in the measuring area (56, 56') by means of the holding device (12), • arranging a micro thermocouple in an interior of the first section of the capillary or a second section of the capillary (4) which is adjacent to the first section, • measuring a temperature in the interior of the first or the second section of the capillary (4) by means of the micro thermocouple, • measuring a temperature of an outer surface of the first section of the capillary (4) by means of the temperature measuring device (2) and • adjusting the temperature measured by means of the temperature measuring device (2) to the temperature measured by means of the micro thermocouple. Procedure according to Claim 13 , characterized in that • an outer surface of the first, by means of the holding device (12) in the measuring area (56, 56') held section of the capillary (4) is locally optically blackened, • the micro thermocouple is arranged in the interior of the second section of the capillary (4), • the measurement of a temperature by means of the micro thermocouple takes place in the interior of the second section of the capillary (4), and • the measurement of a temperature of the outer surface of the first section of the capillary (4) takes place by means of the temperature measuring device (2) on the blackened outer surface of the first section of the capillary (4).

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