WO2024108096A1

WO2024108096A1 - Cold weather oxygen activated heater

Info

Publication number: WO2024108096A1
Application number: PCT/US2023/080232
Authority: WO
Inventors: Darko MARQUEZ
Original assignee: Rbce Tech LLC
Current assignee: Rbce Tech LLC
Priority date: 2022-11-17
Filing date: 2023-11-17
Publication date: 2024-05-23
Anticipated expiration: 2025-05-17
Also published as: EP4618818A1; CN120225101A

Abstract

A heater system includes a first heater and a second heater each including a metal and an electrolyte solution that exothermically react with oxygen to generate heat, where the first heater overlays the second heater. The heater system also includes an air-impermeable package enclosing the metal and the electrolyte solution, the air-impermeable package being configured to be opened to allow air access to the metal and the electrolyte solution. The heater system also includes a spacer, which is air permeable, disposed between the first heater and the second heater, in a direction the first heater overlays the second heater. The first heater at least partially covers the second heater.

Description

COLD WEATHER OXYGEN ACTIVATED HEATER

BACKGROUND

[0001] There is a need for portable, “on-the-go” instant heat in products across different industries. One example is the need for heat in environments colder than 5°C (41 °F). For objects, the need to be heated, or maintain a temperature for a period of time may be desirable in cold conditions. For example, a fluid that needs to be held at a use temperature of 23°C (73°F) for several hours in a cold environment could benefit from a heater system. Another example would be the need for instant, portable heat for hypothermia prevention.

[0002] Air activated heaters with sealed packaging are described in U.S. patent application No. 14/058,719, incorporated herein by reference. However, there is a practical desire for improvement in known heater systems with respect to providing a desired amount of heat for an extended period of time, and reliably securing a heating apparatus to a desired object.

BRIEF DESCRIPTION

[0003] According to one aspect, a heater system includes a first heater and a second heater each including a metal and an electrolyte solution that exothermically react with oxygen to generate heat, where the first heater overlays the second heater. The heater system also includes an air-impermeable package enclosing the metal and the electrolyte solution, the air-impermeable package being configured to be opened to allow air access to the metal and the electrolyte solution. The heater system also includes a spacer, which is air permeable, disposed between the first heater and the second heater, in a direction the first heater overlays the second heater. The first heater at least partially covers the second heater.

[0004] The aforementioned heater system can further include a plurality of heaters and a plurality of spacers, which are each air permeable. The plurality of heaters can include the first heater, the second heater, and a third heater, where the second heater overlays the third heater such that the second heater is interposed between and separates the first heater and the third heater. The plurality of spacers can include the aforementioned spacer, which is a first spacer disposed between the first heater and the second heater, and a second spacer disposed between the second heater and the third heater, in a direction the second heater overlays the third heater.

[0005] The heater system mentioned in the preceding paragraph or the paragraph before the preceding paragraph may further include an insulation layer formed from air-permeable material disposed over the first heater, at a side of the first heater opposite the second heater. The insulation layer, the first heater, the spacer, and the second heater are configured for being applied to an object to heat the object, such that the first heater at least partially covers the second heater with respect to the object. The insulation layer and any of the aforementioned spacers can be formed from the same material.

[0006] Any of the aforementioned spacers can have a thickness and porosity configured for delivering ambient air toward at least one of the respective heaters described above adjacent to the respective spacer.

[0007] Any of the aforementioned spacers can be formed from a lofty non-woven fabric. An outer edge of any of the aforementioned spacers can be exposed to ambient air from between at least two respective heaters. Any of the heaters can include an air-permeable film or fabric positioned within the air-impermeable package, and, if desired, one of the heaters can include a film or fabric having a greater permeability to air as compared to an air-permeable film or fabric associated with another heater.

[0008] Each of the heaters includes a respective electrolyte solution, which can be different among the heaters. For example, the first heater can include a first electrolyte solution, and the second heater can include a second electrolyte solution, and the first electrolyte solution can have a lower minimum operating temperature than the second electrolyte solution. The differing electrolyte solutions can include at least one of isopropyl alcohol, propylene glycol, ethanol ethylene glycol, and potassium hydroxide in differing proportions. For example, the first electrolyte solution can include at least one of isopropyl alcohol, propylene glycol, ethanol ethylene glycol, and potassium hydroxide in greater proportion than the second electrolyte solution. [0009] The aforementioned heaters can each be formed from a m ixture of activated carbon, zinc, and polytetrafluoroethylene placed on a porous fabric carrier. The at least one air-impermeable package can enclose the porous fabric carrier for each heater, for example the first heater and the second heater when two heaters are provided, and/or for multiple heaters when more than two heaters are provided. Alternatively, the at least one air-impermeable package can enclose the porous fabric carrier of a particular heater. For example, a first air-impermeable package can enclose the porous fabric carrier of the first heater, and a second air-impermeable package can enclose the porous fabric carrier of the second heater, and so on if more heaters are provided. In a more particular embodiment, each heater can include a mixture of at least 4 percent activated carbon, at least 41 percent zinc, and at least 5 percent polytetrafluoroethylene by weight, a saturated solution of sodium bromide added to the carbon, zinc, and polytetrafluoroethylene mixture, where the saturated solution weighs at least 15 percent as much as the carbon, zinc, and polytetrafluoroethylene mixture, and a layer of porous material, where the carbon, zinc, and polytetrafluoroethylene mixture including the saturated solution is added to a first side of the layer of porous material.

[0010] In a more particular embodiment of the heater system described above, the spacer can operate as an insulation layer formed as a band configured to be wrapped around an object to be heated such that the first heater at least partially covers the second heater with respect to the object when the band is wrapped around the object. In this embodiment, the first heater and the second heater can be portions of a larger heater separated by the spacer in the direction the first heater overlays the second heater, or the first heater and the second heater can be distinct and separated by the spacer in the direction the first heater overlays the second heater. Optionally in this embodiment, the band can include a first band intersecting a second band, where the first band intersects the second band at a location closer to a first end of the second band as compared to a second end of the second band, and the second band intersects the first band at a location closer to a first end of the first band as compared to a second end of the first band, and the first band defines an aperture offset from the second band, closer to the first end of the second band as compared to the second end of the second band. In this optional embodiment, a fastener connected with the second band at a location closer the first end of the second band as compared to the first end of the second band is configured to fix the band wrapped around the object, and the first heater and the second heater are disposed on the second band.

[0011] A method of heating an object can include providing a first heater and a second heater such that the first heater at least partially covers the second heater with a spacer, which is air permeable, disposed between the first heater and the second heater in a direction the first heater overlays the second heater. Each heater includes a metal and an electrolyte solution that exothermically react with oxygen to generate heat. The method further includes opening at least one air-impermeable package enclosing the metal and the electrolyte solution of the first heater and the second heater to allow air access to the metal and the electrolyte solution. The method can be employed with any of the heater configurations described above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic diagram of a heater system including a heater and an insulation layer provided on an object to be heated.

[0013] FIGS. 2 and 2A are schematic diagrams of the heater system including a first heater, a second heater, and a spacer provided on the object.

[0014] FIG. 3 is a schematic diagram of the heater system including a plurality of heaters and a plurality of spacers arranged in an alternating pattern.

[0015] FIG. 4 is a table showing results from a first set of tests.

[0016] FIG. 5 is a graph showing results from a first test in a second set of tests.

[0017] FIG. 6 is a graph showing results from a second test in a second set of tests.

[0018] FIG. 7 is a graph showing results from a third test in a second set of tests.

[0019] FIG. 8 is a graph showing results from a fourth test in a second set of tests.

[0020] FIG. 9 is a perspective view of a first heater setup and a second heater setup in a third set of tests.

[0021] FIG. 10 is an enlarged perspective view of the first heater setup.

[0022] FIG. 11 is another perspective view of the first heater setup and the second heater setup. [0023] FIG. 12 is an enlarged perspective view of the second heater setup.

[0024] FIG. 13 is a graph of results from the third set of tests.

[0025] FIG. 14 is a graph of averaged results from the third set of tests.

[0026] FIG. 15 is a top perspective view of a heater system and an object to be heated.

[0027] FIG. 16 is a top perspective view of the heater system and the object, with a first end portion of a first band wrapped around the object.

[0028] FIG. 17 is a top perspective view of the heater system and the object, with a second end portion of the first band wrapped around the object.

[0029] FIG. 18 is a perspective view of the heater system and the object, with a second band wrapped around the object.

[0030] FIG. 19 is a perspective view of the heater system and the object, with a fastener fixing the second band and the first band around the object.

DETAILED DESCRIPTION

[0031] Referring now to the drawings, wherein like numerals refer to like parts throughout the several views, FIG. 1 depicts a portable, self-contained, air-activated heater system 100 that, once deployed, is configured to produce heat via an exothermic chemical oxidation process. The heater system 100 includes a heater substrate 102 with an air-impermeable surrounding package 104, and a breathable or air-permeable insulation component, referred to as an insulation layer 110. The heater substrate 102 includes a metal and an electrolyte solution, examples of which will be described in more detail below, that exothermically react with oxygen to generate heat. Components of the heater substrate 102 with or without the surrounding package 104 can be referred to collectively as a heater 112. The insulation layer 110 is disposed adjacent at least one side of the heater 112 and may be formed from PET or other synthetic or natural materials, open-cell foams, and felts.

[0032] The heater system 100 can heat an object 114 toward a specific temperature for a specific time based on how components of the heater system 100 are arranged. This time/temperature regime is achieved through a combination of arrangement of the physical structure (e.g., by stacking, or placing layers of heaters 112 and associated air-permeable insulation layers 110 on top of or adjacent each other) and by managing heat output of the heater 112 itself.

[0033] In temperatures of 0°C and above, a single heater 112, without insulation, can begin an exothermic reaction as soon as it is exposed to ambient air. In cold weather conditions (e.g., below 0°C), layers of heaters 112 and insulation layers 110 may serve to 1 ) aid in the initiation of heating, and 2) maintain heating.

[0034] The heater system 100 can be used in a variety of ways. One heating implementation is shown in FIG. 1 . As defined here and for all examples, the insulation layer 110 may include multiple thicknesses of insulating material, and may include multiple materials. The surrounding package 104 is an air-impermeable package enclosing the heater substrate 102. The surrounding package 104 is opened to allow air access to the heater substrate 102 to initiate heating. The surrounding package 104 may include a peel away label that can be removed to allow air access to the heater substrate 102. The surrounding package 104 may include a peel away laminate layer that can be removed to allow air access to the heater substrate 102. The surrounding package 104 may an interlocking mechanism that when closed keeps out air, but when opened allows air access to the heater substrate 102.

[0035] To boost performance of the heater system 100 with respect to peak temperature and duration, at least one additional layer of heater substrate 102 may be employed as shown in FIG. 2. With reference to FIG. 2, the heater system 100 includes a first heater 120 and a second heater 122 which include similar features and function in a similar manner as the heater 112. The first heater 120 overlays the second heater 122 such that when the heater system 100 is applied to the object 114, the first heater 120 at least partially covers the second heater 122 with respect to the object 114. As shown in FIG. 2, the first heater 120 substantially covers the second heater 122 with respect to the object 114.

[0036] The heater system 100 includes a spacer 124 disposed between the first heater 120 and the second heater 122, in a direction the first heater 120 overlays the second heater 122, referred to herein as a stacking direction. The spacer 124 is breathable such that the second heater 122 is still able to access oxygen from the ambient air it needs to continue the exothermic reaction. [0037] In this regard, the spacer 124 is formed from a lofty non-woven fabric layered between the first heater 120 and the second heater 122. The spacer 124 has a porosity and a thickness in the stacking direction configured for delivering ambient air from an outer edge 130 of the spacer 124 to interior portions 132 of the first heater 120 and the second heater 122 otherwise covered from the ambient air. In an embodiment, the spacer 124 is formed from a metallized polyester material configured to retain heat between the first heater 120 and the second heater 122. More specifically, the spacer 124 may be formed from thermal batting such as those sold under the trade names Insul-Bright and Thinsulate. In an embodiment, the insulation layer 110 and the spacer 124 are formed from a same material, and each could include reflective properties.

[0038] The spacer 124 extends from between the interior portions 132 of first heater 120 and the second heater 122 toward outer edges 134 of the first heater 120 and the second heater 122. In this manner, the outer edge 130 of the spacer 124 is exposed to the ambient air from between the first heater 120 and the second heater 122 for delivering the ambient air to the interior portions 132 of the first heater 120 and the second heater 122.

[0039] While, in the depicted embodiment in FIG. 2, the surrounding package 104 is individually applied to the first heater 120 and the second heater 122, the surrounding package 104 (see FIG. 2A) may alternatively encase each of the heater substrate 102 of the first heater 120, the spacer 124, and the heater substrate 102 of the second heater 122. With this construction, a user operating the heater system 100 is only required to open the surrounding package 104 at a single location to begin the exothermic reaction for both the first heater 120 and the second heater 122. Because each of the insulation layer 110, the first heater 120, the second heater 122, and the spacer 124 are flexible, the heater system 100 may be wrapped, folded, or rolled up together, around the object 114 to be heated.

[0040] To further boost the heating with respect to peak temperature and/or duration, additional heaters and spacers similar to the first heater 120 and the spacer 124 may be added to the heater system 100. By alternating layers of the heaters 120, 122 with breathable spacers 124, all of the heaters 120, 122 may generate heat because oxygen is able to access each heater substrate 102 via the air-permeable cross section of the spacers 124.

[0041] In this regard, FIG. 3 depicts the heater system 100 including a plurality of heaters and a plurality of spacers arranged in an alternating pattern along the stacking direction. The plurality of heaters includes the first heater 120, the second heater 122, and a third heater 140. The second heater 122 overlays the third heater 140 in the stacking direction such that the second heater 122 is interposed between and separates the first heater 120 and the third heater 140. In this manner, when the heater system 100 is applied to the object 114, the first heater 120 at least partially covers the second heater 122 and the third heater 140, and the second heater 122 at least partially covers the third heater 140 with respect to the object 114. More specifically, as shown in FIG. 3, the first heater 120, the second heater 122, and the third heater 140 have similar sizes and shapes such that the first heater 120 substantially covers the second heater 122 and the third heater 140, and the second heater 122 substantially covers the third heater 140 with respect to the object 114.

[0042] The heater system 100 depicted in FIG. 3 includes a plurality of spacers arranged in an alternating pattern with the plurality of heaters along the stacking direction. The plurality of spacers includes a first spacer 142 and a second spacer 144 that have similar features and function in a similar manner as the spacer 124. The first spacer 142 is disposed between the first heater 120 and the second heater 122 in the stacking direction. The second spacer 144 is disposed between the second heater 122 and the third heater 140 in the stacking direction.

[0043] While, in the depicted embodiment of FIG. 3, the plurality of heaters includes three heaters, and the plurality of spacers includes two spacers stacked with the plurality of heaters in an alternating pattern, the plurality of heaters may include additional heaters, and the plurality of spacers may include additional spacers stacked with the plurality of heaters in the alternating pattern to increase an output of the heater system 100 without departing from the scope of the present disclosure. Also, while three different surrounding packages 104 are depicted in FIG. 3 each surrounding a respective heater substrate 102, one surrounding package 104 could be employed to surround all three (or however many were provided) heater substrates 102. [0044] The insulation layer 110 is formed from air-permeable material disposed over the first heater 120, at a side of the first heater 120 opposite the second heater 122. The insulation layer 110, the first heater 120, the first spacer 142, the second heater 122, the second spacer 144, and the third heater 140 are configured for being applied to the object 114 to heat the object 114 such that the first heater 120 at least partially covers the second heater 122 and the third heater 140 with respect to the object 114.

[0045] The heater substrate 102 contains a metal (e.g., iron or zinc), carbon, and a specific electrolyte solution at a specific concentration. Under conditions where the electrolyte could gel or freeze — thereby inhibiting or preventing the heating reaction — the electrolyte composition may be altered to minimize the tendency to gel or freeze. For example, where the electrolyte solution is a solution of sodium bromide, the addition of agents such as isopropyl alcohol, propylene glycol, ethanol or ethylene glycol may be used to depress the freezing point of the electrolyte solution. Added freezing-point depression agents may also result in a decrease of the effective salt concentration. Additionally, added agents may interfere with the ability of oxygen to interact efficiently with the carbon or zinc components of the heater substrate 102. Alternatively, an electrolyte solution made from potassium hydroxide (KOH), which is commonly called caustic potash, can be used instead of sodium bromide. For example, a concentration of 30.8% potassium hydroxide solution has a freezing point of -65 C. Depending on the storage conditions and use of the heaters 120, 122, 140, one or more of the heater substrates 102 may contain this altered electrolyte. The purpose of this altered heater substrate 102 is to “thaw or warm” the other heaters 120, 122, 140 and “kick-start” the reaction, which once initiated will continue to provide long-term heat.

[0046] With continued reference to FIG. 3, the first heater 120 includes a first electrolyte solution, the second heater 122 includes a second electrolyte solution, and the third heater 140 includes a third electrolyte solution. The first electrolyte solution is altered relative to the second electrolyte solution and the third electrolyte solution to have an inhibited tendency to gel or freeze in cold environments. To this end, the first electrolyte solution may include at least one of isopropyl alcohol, propylene glycol, ethanol and ethylene glycol in greater proportion than the second electrolyte solution and the third electrolyte solution, when each electrolyte solution is made from sodium bromide, for example. Alternatively, the first electrolyte solution may be made from potassium hydroxide, while the remaining electrolyte solutions are made from sodium bromide. Also, even though the first heater 120 in FIG. 3 is shown as outermore, the specific location of the freezing-point-depressed heater may not be critical, but it may be advantageous to have the freezing-point-depressed heater be in a location that is most accessible to ambient oxygen.

[0047] In this manner, the first electrolyte solution has a lower minimum operating temperature than the second electrolyte solution and the third electrolyte solution. As such, when the heater system 100 is activated in a cold environment, the first heater 120 is configured to thaw or warm the second heater 122 and the third heater 140 to kick-start exothermic reactions therein, which provide long-term heat relative to the first heater 120.

[0048] In an embodiment, the first heater 120, the second heater 122, and the third heater 140 are each formed from a mixture of activated carbon, zinc, and polytetrafluoroethylene placed on a porous fabric carrier. More specifically, the first heater 120, the second heater 122, and the third heater 140 each include a mixture of at least 4 percent activated carbon, at least 41 percent zinc, and at least 5 percent polytetrafluoroethylene by weight. A saturated solution of sodium bromide is added to the carbon, zinc, and polytetrafluoroethylene mixture, the saturated solution weighing at least 15 percent as much as the carbon, zinc, and polytetrafluoroethylene mixture. The carbon, zinc, and polytetrafluoroethylene mixture including the saturated solution is added to a first side of a layer of porous material. In a further embodiment, the first electrolyte solution is altered with a freezing-point depression agent to have a minimum operating temperature lower than -20°C, while and the second electrolyte solution and the third electrolyte solution have a minimum operating temperature of - 1 °C.

[0049] Airflow to the first heater 120, the second heater 122, and the third heater 140 may be further regulated by air-permeable films or fabrics positioned within the surrounding package 104 to respectively encase the heater substrates 102. In this regard, the first heater 120 includes a first air-permeable film or fabric, the second heater 122 includes a second air-permeable film or fabric, and the third heater 140 includes a third air-permeable film or fabric. The first air-permeable film or fabric has a greater permeability to air as compared to the second air-permeable film or fabric and the third air permeable film or fabric.

[0050] With this construction, the first heater 120 may receive oxygen more readily than the second heater 122 and the third heater 140, increasing a rate of heat generation by exothermic reaction. With relatively low oxygen intake to the second heater 122 and the third heater 140, the second heater 122 and the third heater 140 are configured to provide long lasting heat generation as compared to the first heater 120.

[0051] The heater system 100 can be used to heat a specific object, such as the object 114 described herein, or a local environment. Experiments were conducted according to the following.

[0052] A mix of 8% activated carbon, 82% zinc and 10% polytetrafluoroethylene (by weight) were combined and placed on a porous fabric carrier to form a heater substrate similar to the heater substrate 102 depicted in FIGS. 1 - 3. A saturated solution of sodium bromide (NaBr) was added to this mix (30% of the weight of C, Zn, and polytetrafluoroethylene). A semi-permeable, air-flow limiter made up of a perforated polypropylene film was placed adjacent to a non-coated side of the fabric carrier. The polypropylene film layer used in this example had a thickness of 0.0005 inches.

[0053] The heater substrate was placed inside a hermetically sealed flexible package film formed from a monolayer or laminate similar to the surrounding package 104 depicted in FIGS. 1 - 3, having minimal oxygen transmission rate properties. A metallized polyethylene terephthalate (PET) film was used to create the package, inside of which the heater substrate and the air-limiting film was sealed. The package was constructed such that a label could be removed therefrom to allow air access to the heater substrate, thereby initiating the exothermic reaction. The surrounding package adds minimal thickness, having an approximate thickness of 0.01 inches. In some examples, an insulating layer similar to the insulating layer 110, and at least one spacer similar to the spacer 124 depicted in FIGS. 1 - 3 was employed.

[0054] A first set of four tests were conducted on a glass bottle containing 250ml of aqueous fluid. Temperature measurement was recorded via a thermocouple placed inside the fluid. The starting temperature of the fluid was 23 degrees C. The external ambient temperature was maintained at -4 degrees C. For tests having one or more heaters, the procedure included activating the heater(s) by removing at least part of the surrounding package. For tests having one or more heaters or insulation layers, these elements were wrapped around the bottle. The bottle and any outer wrapping(s) were placed in a refrigerator maintained at 4°C, and temperature recording was initiated.

[0055] FIG. 4 depicts a table summarizing times at which the temperature of the bottle reduced to different temperatures. With reference to FIG. 4, Test No. 4 included alternating heater and insulation layers, and maintained the temperature for the longest period.

[0056] A second set of four tests were conducted to measure a temperature of the heater or heater system itself under subzero conditions, with no object to be heated. The purpose of these tests were to observe how the heater or heater system performed in subzero conditions. In such an instance, the heaters need not be wrapped around and in intimate contact with the object being heated. For example, the heaters may be used to insulate the object from the environment, for example the heater and the object may be placed in an insulated shipping box.

[0057] The same heaters as described above were stored in a freezer for at minimum one day prior to testing. The freezer temperature was -20°C. A thermocouple was attached to each heater to measure the heater temperature.

[0058] For each test in the second set, the freezer door was opened, the heater was activated (i.e., the surrounding package described above) was removed as quickly as possible, and then the freezer door was closed. Temperature recording was then initiated.

[0059] The four tests conducted in the second set include Test No. 1 , Test No. 2, Test No. 3, and Test No. 4. Test No. 1 was set to include one heater with no insulation layer. Test No. 2 was set to include one heater with an insulation layer disposed on each side thereof, such that the insulation layers sandwich the heater. Test No. 3 was set to include two heaters and a spacer sandwiched between two insulation layers, with the spacer disposed between the heaters. Test No. 4 was set to include four heaters and three spacers stacked in alternating layers, and sandwiched between two insulation layers. Thermocouples were employed in each of the four tests to record a temperature of each heater over time.

[0060] FIG. 5 depicts results from Test No. 1 . FIG. 6 depicts results from Test No. 2. FIG. 7 depicts results from Test No. 3. With reference to FIG. 7, Heater 2 is stacked on top of Heater 1 , such that Heater 2 substantially covers Heater 1. FIG. 8 depicts results from Test No. 4. With reference to FIG. 8, Heater 4 overlays Heater 3, Heater 3 overlays Heater 2, and Heater 2 overlays Heater 1 . With this construction, Heater 4, Heater 3, Heater 2, and Heater 1 are stacked in that order from a top to a bottom of the heater system test apparatus.

[0061] Results from the second set of tests demonstrate that heating is substantial when layers of heaters, spacers, and air-permeable insulation layers are added together. More specifically, additional layers of heaters and spacers provided in an alternating stack increases a duration at which the heater system may maintain a temperature in an object.

[0062] Results from the second set of tests further demonstrate an impact on insulation to the performance of the heater system. More specifically, a difference in temperature durations between Test No. 1 and Test No. 2 indicate that heat insulating aspects of the insulation layers improve the temperature durations of the heater system. Notably, this improvement occurs despite the insulation layers restricting ambient air flow to the heaters, slowing the exothermic reaction which generates the heat.

[0063] FIGS. 9 - 12 depict a third set of tests conducted to compare performance between a first heater setup 150 and a second heater setup 152. The third set of tests were conducted in a freezer with a temperature that was -20°C. A thermocouple 154 was attached to each heater to measure the heater temperature in each of the first heater setup 150 and the second heater setup 152. For each test in the third set, the freezer door was opened, the heater was activated (i.e. , the surrounding package described above) was removed as quickly as possible, and then the freezer door was closed. Temperature recording was then initiated. FIG. 10 depicts the first heater setup 150 with insulation layers 110 opened to show four heaters 112 arranged side- by-side with each other. As shown in FIG. 9, the heaters 112 in the first heater setup 150 are sandwiched between the insulation layers 110. As shown in FIG. 11 , the insulation layers 110 of the first heater setup 150 are formed from a continuous material configured for being folded around the heaters 112 to cover top and bottom sides of the heaters 112.

[0064] As shown in FIG. 12, the second heater setup 152 includes four heaters 112 stacked in an alternating pattern with three spacers 124. The heaters 112 and the spacers 124 are sandwiched between insulation layers 110. Referring back to FIG. 11 , the heaters 112 in the first heater setup 150 and the second heater setup 152 are each connected to thermocouples 154 for recording a temperature of the heaters 112 over time.

[0065] FIGS. 13 and 14 depicts results of the third set of tests conducted, based on temperature readings from the thermocouples 154. FIG. 13 depicts a graph showing an average temperature of the heaters 112 in the first heater setup 150 and the second heater setup 152, for each iteration of the third set of tests conducted. With reference to FIG. 13, graphed data recorded as Flat-TC1 , Flat-TC2, Flat-TC3, and Flat-TC4 respectively represent a reading from a respective thermocouple 154 attached to a respective heater 112 in the first heater setup 150. Data recorded as Stack-TC1 , Stack-TC2, Stack-TC3, and Stack-TC4 respectively represent a reading from a respective thermocouple 154 attached to a respective heater 112 in the second heater setup 152.

[0066] FIGS. 13 and 14 further depict an average value of Flat-TC1 , Flat-TC2, Flat- TC3, and Flat-TC4 over time as Flat Ave. FIGS. 13 and 14 also depict an average value of Stack-TC1 , Stack-TC2, Stack-TC3, and Stack-TC4 over time as Stack Ave.

[0067] As shown in FIGS. 13 and 14, the heaters 112 in the second heater setup 152 reach higher temperatures, and maintain those higher temperatures for a longer period of time as compared to the heaters 112 in the first heater setup 150. As such, the third set of tests conducted demonstrates that having the same number of the heaters 112 arranged in a stacked configuration with spacers 124 can provide a high temperature, long duration application of the heater system 100 as compared to arranging the heaters 112 side by side. Notably, because the heaters 112 in the second heater setup 152 are separated by the spacers 124, each of the heaters 112 in the second heater setup 152 is able to react with ambient air without requiring direct exposure to the surrounding environment through the insulation layers 110.

[0068] FIGS. 15 - 19 depict a method of assembling an embodiment of the heater system 100 where the object 114 to be heated is a container of fluid. As shown in FIG. 15, the insulation layer 110 is formed from air-permeable fabric, with a shape formed from a first band 160 and a second band 162 intersecting each other at a right angle. Because of the manner in which the second band 162 is wrapped around the object 114 (see FIGS. 18 and 19), the insulation layer 110 also operates as a spacer, similar to the spacers 124 described above. As discussed above, the insulation layer 110 and spacers 124 can be made from the same material, and therefore, can perform both the function of providing insulation to the heaters 120, 122, 140, and also the function of spacing one heater from another.

[0069] The first band 160 intersects the second band 162 at a location closer to a first end 164 of the second band 162 as compared to a second end 170 of the second band 162. The second band 162 intersects the first band 160 at a location closer to a first end 172 of the first band 160 as compared to a second end 174 of the first band 160. With this construction, the first band 160 includes a first end portion 180 and a second end portion 182 extending from opposite sides of the second band 162, and the second band 162 includes a first end portion 184 and a second end portion 190 extending from opposite sides of the first band 160.

[0070] The first band 160 defines a first aperture 192 in the first end portion 180 and a second aperture 194 in the second end portion 182. The first aperture 192 and the second aperture 194 are located offset from the second band 162, and configured for receiving the object 114.

[0071] In the method, the object 114 is positioned on the first end portion 180 of the first band 160 where, as shown in FIGS. 16 and 17, the first end portion 180 and the second end portion 182 of the first band 160 are wrapped around the object 114 such that a portion of the object 114 is inserted through the first aperture 192 and the second aperture 194.

[0072] With reference to FIG. 18, the heater system 100 includes a fastener 200 that is a band of flexible fabric fixed with the insulation layer 110 at the second band 162. The fastener 200 includes a hook and loop fastening device 202 and a main body 204 that is a band of fabric. The hook and loop fastening device 202 is configured for removably fixing the fastener 200 with at least one of the main body 204 and the insulation layer 110.

[0073] As shown in FIG. 19, the fastener 200 is configured for being wrapped around the object 114 over the first band 160 and the second band 162 to fix the fastener 200, the first band 160, and the second band 162 around the object 114. While, as depicted, the fastener 200 includes the hook and loop fastening device 202 for fixing the insulation layer 110, the fastener 200 may additionally or alternatively include clips, buttons, pins, and similar means as fastening devices configured for fixing the insulation layer with at least one of itself and the insulation layer 110 without departing from the present disclosure. Also, the fastener 200 may alternatively not include the main body 204, such that the hook and loop fastening device 202 is disposed directly on the insulation layer 110 and configured for fixing the insulation layer 110 with itself, around the object 114 without departing from the scope of the present disclosure.

[0074] Referring back to FIG. 15, in an embodiment, the heater substrate 102 included in the heater 112 features a mix of 8% activated carbon, 82% zinc, and 10% polytetrafluoroethylene (by weight) combined and placed on a porous fabric. A saturated solution of sodium bromide (NaBr) is added to this mix (30% of the weight of C, Zn, and polytetrafluoroethylene). A semi-permeable, air-flow limiter having a perforated polypropylene film is placed adjacent to the non-coated side of the fabric carrier. The polypropylene film layer used in this example has a thickness of 0.0005 inches.

[0075] The heater substrate 102 is placed inside the surrounding package 104, which is a hermetically sealed flexible packaging film (monolayer or laminate) that has minimal oxygen transmission rate properties. A metallized polyethylene terephthalate (PET) film is used create the package inside of which the heater substrate 102, the fabric carrier, and the air-limiting film are sealed. This surrounding package 104 is constructed such that a label could be removed therefrom to allow air access to the heater substrate 102, thereby initiating an exothermic reaction between the heater substrate 102 and ambient air. The surrounding package 104 adds minimal thickness, having an approximate thickness of 0.01 inches.

[0076] Embodiments of the heater system 100 can include layers of heaters 112 and air-permeable insulation layers 110 added together to increase heating capability or otherwise augment a heating profile of the heater system 100 with respect to thermal output over time. The insulation layers 110 can also operate as spacers between heaters. For example, a plurality of heaters 112 each provided with its distinct heater substrate 102 and surrounding package 104 can be positioned on the second band 162, which is formed from an air-permeable material. In such an example, one of the heaters 112, e.g., a heater positioned nearer to the second end portion 190 of the second band 162, can be a first heater that at least partially overlays a second heater, e.g. a heater positioned nearer to the first end portion 184 of the second band 162, when the second band 162 is wrapped around the object. Alternatively, a larger heater having a larger heater substrate 102 and surrounding package 104 can be positioned on the second band 162. In this embodiment, the first heater and the second heater are portions of the larger heater separated by the spacer in the direction the first heater overlays the second heater. Also, in either embodiment, only the second band 162 and accompanying heaters may be provided, e.g., the first band 160 may be omitted.

[0077] With reference to the test results provided in FIG. 4, an embodiment of the heater system 100 having one layer of heaters 112 formed from the mix including NaBr, C, Zn, and polytetrafluoroethylene and wrapped around a 250ml container of aqueous fluid without an insulation layer is capable of heating that fluid, such that the fluid’s temperature will be at or above 20°C for 0.5 hours, at or above 15°C for 1.5 hours, and at or above 10°C for 3.5 hours from a start time, where the fluid sample start temperature is 23°C and an ambient temperature is maintained at 4°C. An embodiment of the heater system 100 having one layer of heaters 112 formed from the above-described mix and wrapped around the container, and having one insulation layer 110 wrapped around the layer of heaters 112 and the container is capable of maintaining the fluid’s temperature at or above 20°C for 3 hours, at or above 15°C for 6 hours, and at or above 10°C for over 6 hours from a start time, where the fluid sample start temperature is 23°C and the ambient temperature is maintained at 4°C. An embodiment of the heater system 100 having two layers of heaters 112 formed from the above-described mix, and having an insulation layer 110 disposed between and on each outer side of the layers of heaters 112, wrapped around the container, is capable of maintaining the fluid’s temperature of at or above 20°C for over 6 hours where the fluid sample start temperature is 23°C and the ambient temperature is maintained at4°C. Notably, individual heaters 112 and insulation layers 110 in the pluralities may be modified to improve overall heating performance in the heater system 100.

[0078] The saturated NaBr solution is an example of an electrolyte that is contained within the heater substrate 102. According to Blagden's Law, the saturated NaBr solution will freeze at about -35 °C. To prevent this solution from freezing at very low ambient temperatures, the NaBr electrolyte solution can be mixed with an additive that will not freeze at low temperatures. An exemplary additive to saturated NaBr solution is various levels of propylene glycol (10%, 25% and 50%, w/w).

[0079] With this, an electrolyte solution may be adjusted to remain at least partially in liquid form at a temperature of less than -35°C. As such, in an embodiment of the heater system 100 having a plurality of heaters 112, at least one of the heaters 112 may have an additive, such as propylene glycol, to remain liquid at lower temperatures to warm the remaining heaters 112 in relatively cold working environments that would otherwise inoperably freeze the heaters 112.

[0080] Also heater substrates 102 provided with a perforated polypropylene film having more open area for greater air permeability can accelerate the exothermic reaction between the heater substrate 102 and ambient air, resulting in higher generated temperatures relatively early in the reaction. As such, in an embodiment of the heater system 100 having a plurality of heaters 112, at least one of the heaters 112 may have a relatively open area as compared to other heaters 112 for faster initial heating.

[0081] Tests were performed on different heater substrates having the perforated polypropylene film, and including the above-described saturated NaBr solution but with different percentages by weight of propylene glycol added to the saturated NaBr solution. An embodiment of the heater substrate 102 having the perforated polypropylene film, and including the above-described saturated NaBr mix without propylene glycol is capable of heating to a temperature of 23°C from a starting temperature of -20°C, and maintaining a temperature of at least 0°C for at least 0.5 hours, in an ambient temperature of -20°C. An embodiment of the heater substrate 102 having the perforated polypropylene film, and including the above-described saturated NaBr mix with 10% propylene glycol w/w is capable of heating to a temperature of 21 °C from a starting temperature of -20°C, and maintaining a temperature of at least 5°C for at least 0.5 hours, in an ambient temperature of -20°C. An embodiment of the heater substrate 102 having the perforated polypropylene film, and including the above-described saturated NaBr mix with 25% propylene glycol w/w is capable of heating to a temperature of 21 °C from a starting temperature of -20°C, and maintaining a temperature of at least 0°C for at least 0.4 hours, in an ambient temperature of -20°C. An embodiment of the heater substrate 102 having the perforated polypropylene film, and including the above-described saturated NaBr mix with 50% propylene glycol w/w is capable of heating to a temperature of 12°C from a starting temperature of -20°C, and maintaining a temperature of at least 0°C for at least 0.25 hours, in an ambient temperature of -20°C. Although the heater substrate including the aforementioned additives (e.g., at least one of isopropyl alcohol, propylene glycol, ethanol or ethylene glycol) described above were described with reference to an ambient temperature as low as -20°C, it is contemplated that the additives proposed above in the proportions described above would work in starting temperatures as low as -40°C. Accordingly, the above-described saturated NaBr mix with the propylene glycol additive can be used in at least one of the heater substrates among a stack to the kick-start exothermic reactions of the remaining heater substrates within the stack that do not need to include the propylene glycol additive. In a similar fashion, the above-described potassium hydroxide electrolyte solution can be used in at least one of the heater substrates among a stack to the kick-start exothermic reactions of the remaining heater substrates within the stack, which could include a more typical NaBr mix without any additive.

[0082] In an embodiment, the heater system 100 and object 114 to be heated are enclosed within an insulating container.

[0083] It will be appreciated that various of the above-disclosed embodiments and other features and functions, or alternatives or varieties thereof, may be desirably combined into many other different systems or applications. Also, various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

Claims

CLAIMS:

1. A heater system, comprising: a first heater and a second heater each including a metal and an electrolyte solution that exothermically react with oxygen to generate heat, wherein the first heater overlays the second heater; at least one air-impermeable package enclosing the metal and the electrolyte solution of the first heater and the second heater, the air-impermeable package being configured to be opened to allow air access to the metal and the electrolyte solution; and a spacer, which is air permeable, disposed between the first heater and the second heater, in a direction the first heater overlays the second heater, wherein the first heater at least partially covers the second heater.

2. The heater system of claim 1 , further comprising: a plurality of heaters including the first heater, the second heater, and a third heater, wherein the second heater overlays the third heater such that the second heater is interposed between and separates the first heater and the third heater; a plurality of spacers, which are each air permeable, including the spacer, which is a first spacer disposed between the first heater and the second heater, and a second spacer disposed between the second heater and the third heater, in a direction the second heater overlays the third heater.

3. The heater system of claim 1 or 2, further comprising an insulation layer formed from air-permeable material disposed over the first heater, at a side of the first heater opposite the second heater, wherein the insulation layer, the first heater, the spacer, and the second heater are configured for being applied to an object to heat the object, such that the first heater at least partially covers the second heater with respect to the object.

4. The heater system of claim 3, wherein the insulation layer and the spacer are formed from the same material.

5. The heater system of claim 1 , wherein the spacer has a thickness and porosity configured for delivering ambient air toward at least one of the first heater and the second heater.

6. The heater system of claim 1 , wherein the spacer is formed from a lofty non-woven fabric layered between the first heater and the second heater.

7. The heater system of claim 1 , wherein an outer edge of the spacer is exposed to ambient air from between the first heater and the second heater.

8. The heater system of claim 1 , wherein the first heater includes a first air- permeable film or fabric positioned within the air-impermeable package, and the second heater includes a second air-permeable film or fabric positioned within the air- impermeable package, wherein the first air-permeable film or fabric has a greater permeability to air as compared to the second air-permeable film or fabric.

9. The heater system of claim 1 , wherein the first heater includes a first electrolyte solution, the second heater includes a second electrolyte solution, and the first electrolyte solution has a lower minimum operating temperature than the second electrolyte solution.

10. The heater system of claim 9, wherein the first electrolyte solution includes at least one of isopropyl alcohol, propylene glycol, ethanol ethylene glycol, and potassium hydroxide in greater proportion than the second electrolyte solution.

11 . The heater system of claim 9, further comprising a third heater including a metal and a third electrolyte solution that exothermically reacts with oxygen to generate heat, wherein the second heater overlays the third heater such that the second heater is interposed between and separates the first heater and the third heater, and the first electrolyte solution has a lower minimum operating temperature than the third electrolyte solution.

12. The heater system of claim 11 , wherein the spacer disposed between the first heater and the second heater, in a direction the first heater overlays the second heater, is a first spacer having an outer edge directly exposed to ambient air from between the first heater and the second heater, and the first spacer has a thickness and a porosity configured for delivering ambient air from the outer edge of the first spacer toward interior portions of at least one of the first heater and the second heater, and the heater system further comprising: a second spacer disposed between the second heater and the third heater, in a direction the second heater overlays the third heater, wherein an outer edge of the second spacer is directly exposed to ambient air from between the second heater and the third heater, and the second spacer has a thickness and a porosity configured for delivering ambient air from the outer edge of the second spacer toward interior portions of at least one of the first heater and the second heater.

13. The heater system of claim 12, further comprising an insulation layer formed from air-permeable material disposed over the first heater, at a side of the first heater opposite the second heater, wherein the insulation layer, the first heater, the first spacer, the second heater, the second spacer, and the third heater are stacked together in that order and configured for being applied to an object to heat the object, such that the first heater at least partially covers the second heater and the third heater with respect to the object.

14. The heater system of claim 1 , wherein the first heater and the second heater are each formed from a mixture of activated carbon, zinc, and polytetrafluoroethylene placed on a porous fabric carrier.

15. The heater system of claim 14, wherein the at least one air-impermeable package encloses the porous fabric carrier for each of the first heater and the second heater.

16. The heater system of claim 14, wherein the at least one air-impermeable package is a first air-impermeable package enclosing the porous fabric carrier of the first heater, and further comprising a second air-impermeable package enclosing the porous fabric carrier of the second heater.

17. The heater system of claim 14, wherein the first heater and the second heater each include: a mixture of at least 4 percent activated carbon, at least 41 percent zinc, and at least 5 percent polytetrafluoroethylene by weight; a saturated solution of sodium bromide added to the carbon, zinc, and polytetrafluoroethylene mixture, wherein the saturated solution weighs at least 15 percent as much as the carbon, zinc, and polytetrafluoroethylene mixture; and a layer of porous material, wherein the carbon, zinc, and polytetrafluoroethylene mixture including the saturated solution is added to a first side of the layer of porous material.

18. The heater system of claim 1 , wherein the spacer operates as an insulation layer formed as a band configured to be wrapped around an object to be heated such that the first heater at least partially covers the second heater with respect to the object when the band is wrapped around the object, and wherein the first heater and the second heater are portions of a larger heater separated by the spacer in the direction the first heater overlays the second heater, or wherein the first heater and the second heater are distinct and separated by the spacer in the direction the first heater overlays the second heater.

19. The heater system of claim 18, wherein the band includes a first band intersecting a second band, wherein the first band intersects the second band at a location closer to a first end of the second band as compared to a second end of the second band, the second band intersects the first band at a location closer to a first end of the first band as compared to a second end of the first band, and the first band defines an aperture offset from the second band, closer to the first end of the second band as compared to the second end of the second band, and the heater system further comprising: a fastener connected with the second band at a location closer the first end of the second band as compared to the first end of the second band, wherein the fastener is configured to fix the band wrapped around the object, wherein the first heater and the second heater are disposed on the second band.

20. A method of heating an object comprising: providing a first heater and a second heater, each including a metal and an electrolyte solution that exothermically react with oxygen to generate heat, such that the first heater at least partially covers the second heater with a spacer, which is air permeable, disposed between the first heater and the second heater in a direction the first heater overlays the second heater; and opening at least one air-impermeable package enclosing the metal and the electrolyte solution of the first heater and the second heater to allow air access to the metal and the electrolyte solution.