US20060130508A1

US20060130508A1 - Total heat exchanger

Info

Publication number: US20060130508A1
Application number: US11/166,707
Authority: US
Inventors: Tay-Jian Liu; Ming-Chun Lee; Shang-Chih Liang; Lien-Jin Chiang
Original assignee: Foxconn Technology Co Ltd
Current assignee: Foxconn Technology Co Ltd
Priority date: 2004-12-17
Filing date: 2005-06-24
Publication date: 2006-06-22
Also published as: TW200622161A; TWI295359B

Abstract

A total heat exchanger in accordance with a preferred embodiment includes air-guiding means (21), a heat-pipe heat exchanger (31) and a total heat exchange member (41). The air-guiding means is for providing a first airflow from outdoors and a second airflow from indoors. The heat-pipe heat exchanger includes at least one heat pipe (32) spanning across said first and second airflows simultaneously for conducting a sensible heat exchange between the airflows. The total heat exchange member is capable of exchanging sensible heat and latent heat between said first and second airflows, and defines therein a first air passage and a second air passage intersecting with and isolated from each other. A total heat exchange of sensible heat and latent heat between the first and second airflows is carried out in the total heat exchange member when the airflows flow through the first and second air passages respectively.

Description

TECHNICAL FIELD

The present invention relates generally to a heat exchanger, and more particularly to a total heat exchanger which may suitably be applied to a ventilation system for exchanging sensible and latent heat between airflows having different temperatures and humidities.

BACKGROUND

In our daily life, ventilation systems such as air-conditioners are commonly provided in working or living spaces, e.g., office buildings and apartments, for supplying fresh outdoor air and exhausting polluted indoor air simultaneously in order for keeping a favorable and healthy environment where we stay. Generally, the supplied air and the exhausted air have different temperatures and humidities. In this connection, a significant effect of energy saving could be expected if the exchange between the indoor and outdoor airflows can be achieved not only in heat but also in moisture. In order to satisfy such requirements, total heat exchangers, which can exchange sensible heat (temperature) and latent heat (moisture) simultaneously without mixing different types of air, are accordingly developed. Total heat exchangers are effective in energy saving as they can recover both sensible energy (temperature) and latent energy (moisture) between polluted indoor air and fresh outdoor air.
Total heat exchangers are typically classified into two types, i.e., stationary-type and rotary-type. The stationary-type total heat exchanger exchanges heat and moisture between different types of air by flowing through a total heat exchange member in a cross-flow manner, while in the rotary-type total heat exchanger, different types of air flow in parallel directions through a rotary wheel where the exchange of heat and moisture is conducted.
An example of a total heat exchange member of a stationary-type total heat exchanger is shown in FIG. 7. The total heat exchange member 1 has a multi-layer structure formed by a plurality of laminated partition plates 2, and a plurality of zigzag, wavy spacing members 3 inserted between the partition plates 2. Typically, the partition plates 2 are specially treated papers with the capability of heat conductivity and moisture permeability and may be made from a carbon-fiber-based material such as ceramic fibers, asbestos, fiber glass impregnated with a hydrophilic material. The spacing members 3, which are applied to maintain the spaces between the partition plates 2, are disposed between every two adjacent partition plates 2 with the wavy configurations of the spacing members 3 being alternately arranged at 90 degree to thereby define a first air passage indicated by arrow E-E for passage of a first airflow and a second air passage indicated by arrow F-F for passage of a second airflow, wherein the first air passage and the second air passage intersect with respect to but not communicate with each other. Each of the air passages includes a plurality of individual channels 4 defined by the spacing members 3. The first and second air passages enable the different types of air to flow therethrough in a cross-flow manner to conduct a total heat exchange of heat and moisture therebetween as the partition plates 2 possesses the capabilities of heat conductivity and moisture permeability.
Total heat exchangers are effective in keeping indoor air quality, as well as in energy saving, as is identified above. However, in order to exhibit its full advantages, many improvements still can be made on the design of a total heat exchanger. For example, as far as a stationary-type total heat exchanger is concerned, the exchange of heat and moisture between different air flows is conducted only in its total heat exchange member by resorting to the heat-conductivity and moisture-permeability capabilities of the partition plates 2, which results in a limited sensible heat exchange rate as the partition plates 2 typically have its focus placed on the capability of moisture-permeability rather than heat-conductivity. Moreover, the supplied air and the exhausted air to be heat-exchanged are typically directed by blowers. The airflows from the blowers flow in a direction which are not to enable the airflows to flow evenly over air channels of the total heat exchange member in the total heat exchanger. This greatly impairs the total heat exchange efficiency of heat and moisture between the supplied air and the exhausted air.
In view of the above-mentioned problems of the total heat exchanger, there is a need for a total heat exchanger which can improve the sensible heat exchange effect between different air flows conducting heat exchange in the total heat exchanger, and what is also needed is a total heat exchanger which can distribute the air currents to be heat-exchanged more evenly over the air channels of its total heat exchange member.

SUMMARY

The present invention relates to a total heat exchanger for being typically used in a ventilation system such as an air conditioner. According to embodiments of the present invention, the total heat exchanger includes air-guiding means, a heat-pipe heat exchanger and a total heat exchange member. The air-guiding means is for providing and guiding a first airflow from outdoors and a second airflow from indoors. The heat-pipe heat exchanger includes at least one heat pipe spanning across said first and second airflows simultaneously for conducting a sensible heat exchange between the airflows. The total heat exchange member is capable of exchanging sensible heat and latent heat between said first and second airflows, and defines therein a first air passage and a second air passage intersecting with and isolated from each other. A total heat exchange of sensible heat and latent heat between the first and second airflows is carried out in the total heat exchange member when the first and second airflows flow through the first and second air passages respectively.
Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, isometric view of a total heat exchanger in accordance with a preferred embodiment of the present invention;
FIG. 2 is an assembled view of FIG. 1, with some parts thereof being cut away for showing more details;
FIG. 3 is an isometric view of a heat-pipe heat exchanger of FIG. 1;
FIG. 4 is an isometric view of a total heat exchanger in accordance with another preferred embodiment of the present invention;
FIG. 5 is an isometric view of a heat-pipe heat exchanger of FIG. 4;
FIG. 6 is an isometric view of a heat-pipe heat exchanger in accordance with another embodiment suitable for the total heat exchanger of FIG. 4; and
FIG. 7 is an isometric view of a total heat exchange member of a stationary-type total heat exchanger in accordance with the conventional art.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 show a total heat exchanger in accordance with a preferred embodiment of the present invention, for exchanging sensible and latent heat between airflows having different temperatures and humidities. The total heat exchanger 10 includes a chassis 5, a variety of components attached to the chassis 5 and a cover 6.
The cover 6 cooperates with the chassis 5 to form a system enclosure for enclosing the various components therein. An interior of the system enclosure is divided into three parts, i.e., first housing 20, second housing 30 and third housing 40, with each housing for containing specific components.
The second housing 30 is located between the first housing 20 and the third housing 40, wherein the first and second housings 20, 30 are separated from each other via a first partition plate 50, and the second and third housings 30, 40 are spaced from each other via a second partition plate 60. The first housing 20 contains therein an air-providing mechanism 21 for guiding airflows from outdoors and from indoors. The air-providing mechanism 21 includes two blowers 211, 212 for driving the airflows. The second housing 30 contains therein a heat-pipe heat exchanger 31, which is sandwiched between the first and second partition plates 50, 60 and spans across the airflows from outlets of the air blowers 211, 212 of the air-providing mechanism 21, for increasing the sensible heat exchange between the airflows directed by the air-providing mechanism 21. A pair of openings 65, 66 is separately defined in the second partition plate 60 corresponding to the outlets of the blowers 211, 212 respectively, for providing communication between the second and third housings 30, 40. As is understandable, the first partition plate 50 also defines openings (not visible) in similar fashion, for providing communication between the first and second housings 20, 30. A total heat exchange member 41, which may be constructed in the same manner as shown in FIG. 7, is angularly arranged at the third housing 40 with respect to the system enclosure. The total heat exchange member 41 defines a first air passage (not labeled) extending through its opposite surfaces A and C, and a second air passage (not labeled) extending through its opposite surfaces B and D, wherein the first air passage and the second air passage intersect with respect to but not communicate with each other and each of the air passages includes a plurality of individual channels 42 for passage of air currents. Each corner of the total heat exchange member 41 is hermetically connected to an inner surface of the third housing 40 via a Y-shaped connecting member 45 for preventing the different air flows (i.e., exhausted air flow and supplied air flow) in the third housing 40 from being physically mixed.
The cover 6 includes a rectangular top wall 61 and a plurality of sidewalls depending from the top wall 61, of which a pair of opposite sidewalls 63, 64 each defines therein two groups of holes for acting as inlets and outlets of the air flows. For example, the first group of holes defined in the sidewall 63 and located adjacent to the blower 212 functions as an inlet 67 for indoor air to enter into the total heat exchanger 10, and the second group of holes defined in the sidewall 63 and located adjacent to the total heat exchange member 41 performs as an outlet 68 for outdoor air to enter indoors after the outdoor air is heat-exchanged in the total heat exchanger 10. Similarly, the first group of holes (not visible) defined in the sidewall 64 and located adjacent to the blower 211 functions as an inlet for the outdoor air to enter the total heat exchanger 10, and the second group of holes defined in the sidewall 64 and opposing the outlet 68 acts as an outlet 69 for the indoor air to leave the total heat exchanger 10 after it is heat-exchanged therein.
Referring also to FIG. 3, the heat-pipe heat exchanger 31 includes a plurality of heat pipes 32 and a plurality of spaced cooling fins 33 attached to the heat pipes 32. Each of the heat pipes 32 contains therein a working fluid for transferring heat by phase change. The heat pipes 32 and the cooling fins 33 are made from high thermally conductive materials such as copper or aluminum. A spacing member 35 is arranged at a central portion of the heat-pipe heat exchanger 31. When the heat-pipe heat exchanger 31 is positioned in the second housing 30, the spacing member 35 is in abutment with the first and second partition plates 50, 60 to thereby prevent the supplied air (outdoor air) and the exhausted air (indoor air) from mixing up in the second housing 30 when flowing through the heat-pipe heat exchanger 31 to conduct a sensible heat exchange therebetween. Preferably, a rectangular-shaped casing 37 is attached to a periphery of the heat-pipe heat exchanger 31 for keeping its integrity.
In the illustrated embodiment of the present invention, when the air-providing mechanism 21 directs the supplied air from outdoors and the exhausted air from indoors to pass through the heat-pipe heat exchanger 31, a sensible heat (temperature) exchange is conducted between the supplied air and the exhausted air as they have different temperatures. For example, if in summer, the supplied air generally has a higher temperature than that of the exhausted air. As the supplied air passes through one end of the heat-pipe heat exchanger 31, the supplied air heats the one end of the heat pipe 32 to cause the working fluid contained therein to evaporate, then the generated vapor moves towards the other end of the heat pipe 32 where the vapor is condensed to liquid state by releasing the heat to the exhausted air as it passes through the other end of the heat-pipe heat exchanger 31, wherein the cooling fins 33 attached to the heat pipe 32 can increase the total heat transfer area of the heat-pipe heat exchanger 31. The condensed liquid returns back to its original place and the cycling of evaporation and condensation of the working fluid goes on, thus continuously transferring heat from the supplied air to the exhausted air. After being heat-exchanged in the second housing 30, the supplied air and the exhausted air flow into the third housing 40, where a total heat exchange of heat and moisture between them is carried out by flowing through the first and second air passages of the total heat exchange member 41 in a cross-flow manner. Finally, the outdoor flesh air is supplied into indoors via the outlet 68 in the sidewall 63, and the indoor dirty air is exhausted to outdoors via the outlet 69 in the sidewall 64. In this embodiment, the sensible heat exchange between the supplied air and the exhausted air is conducted not only in the total heat exchange member 41 but also in the heat-pipe heat exchanger 31. The presence of the heat-pipe heat exchanger 31 greatly increases the sensible heat exchange efficiency between the supplied air and the exhausted air due to its high heat-conductivity. On the other hand, the spaced cooling fins 33 of the heat-pipe heat exchanger 31 can divide the supplied air and the exhausted air into many small flows and guide them into the third housing 40. As a result, the supplied air and the exhausted air are more evenly distributed over the channels 42 of the total heat exchange member 41. Thus, a better total heat exchange between the supplied air and the exhausted air is obtained by the total heat exchange member 41. Finally, since the channels 42 are oriented angularly relative to the sides the enclosure, the channels 42 can have a length longer than that when they are arranged parallel to the sides, whereby the total heat exchange effect is further improved by the total heat exchanger 10 in accordance with the present invention.
FIG. 4 shows a total heat exchanger 10 a in accordance with another preferred embodiment of the present invention. The total heat exchanger 10 a includes a first housing 20 a and a second housing 30 a separated from the first housing 20 a via a partition plate 50 a. The partition plate 50 a defines therein a pair of openings 65 a, 66 a for passage of air currents between the first housing 20 a and the second housing 30 a. Different from the above-mentioned first embodiment, the second housing 30 a contains therein a V-shaped heat-pipe heat exchanger 70 covering two adjacent surfaces A and B of the total heat exchange member 41. Referring to FIG. 5, the heat-pipe heat exchanger 70 includes a plurality of V-shaped heat pipes 71 and a plurality of cooling fins 72 attached to the heat pipes 71. A Y-shaped connecting member 74 is arranged at a central portion of the heat-pipe heat exchanger 70 for fittingly abutting a corner of the total heat exchange member 41 formed by the surfaces A and B. A block member 76 is attached to each end of the heat-pipe heat exchanger 70 for keeping its integrity. In this embodiment, a sensible heat exchange between the supplied air and the exhausted air is conducted in the heat-pipe heat exchanger 70 before they enter into the total heat exchange member 41 for further carrying out a total heat exchange of heat and moisture therebetween, to thereby increase the sensible heat exchange efficiency between the supplied air and the exhausted air. Meanwhile, the supplied air and the exhausted air to be heat-exchanged are more evenly distributed over the channels 42 of the total heat exchange member 41 by guidance of the cooling fins 72 of the heat-pipe heat exchanger 70.
FIG. 6 shows a heat-pipe heat exchanger 80 according to another embodiment, for suitably being applied to the total heat exchanger 10 a. Compared with the heat-pipe exchanger 70 as shown in FIG. 5, every two adjacent cooling fins 82 of the heat-pipe heat exchanger 80 are not identical in height and all of the cooling fins 82 commonly define a top planar surface. The heat-pipe heat exchanger 80 has an increased heat transfer area and can distribute the air currents more uniformly towards the total heat exchange member 41.
It is noticed that each of the heat- pipe heat exchangers 70, 80 can be attached to every two adjacent surfaces of the total heat exchange member 41, such as surfaces A and D, surfaces B and C, or surfaces C and D. Understandably, two heat-pipe heat exchangers 70 or/and 80 can be simultaneously attached to the total heat exchange member 41, for example, in FIG. 4, another heat- pipe heat exchanger 70 or 80 can be attached to the surfaces C and D of the total heat exchange member 41.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A total heat exchanger comprising:

air-guiding means for providing a first airflow from outdoors and a second airflow from indoors into the total heat exchanger;

a heat-pipe heat exchanger comprising at least one heat pipe spanning across said first and second airflows simultaneously for conducting a sensible heat exchange between the first and second airflows; and

a total heat exchange member defining therein a first air passage and a second air passage intersecting with and isolated from each other, a total heat exchange of sensible heat and latent heat between the first and second airflows being carried out in the total heat exchange member when the first and second airflows flow through the first and second air passages respectively.

2. The total heat exchanger of claim 1, wherein the heat-pipe heat exchanger further comprises a plurality of cooling fins attached to the at least one heat pipe.

3. The total heat exchanger of claim 2, further comprising a system enclosure for enclosing the air-guiding means, the heat-pipe heat exchanger and the total heat exchange member therein.

4. The total heat exchanger of claim 3, wherein the system enclosure is divided into a plurality of individual housings, and the air-guiding means, the heat-pipe heat exchanger and the total heat exchange member are contained in the individual housings, respectively.

5. The total heat exchanger of claim 4, wherein the heat-pipe heat exchanger is located between the air-guiding means and the total heat exchange member, and the first and second airflows flow successively through the heat-pipe heat exchanger and the total heat exchange member.

6. The total heat exchanger of claim 4, wherein every two adjacent housings are separated by a partition plate arranged therebetween.

7. The total heat exchanger of claim 3, wherein the system enclosure is divided into two housings, the air-guiding means is contained in one of the housings and the heat-pipe heat exchanger and the total heat exchange member are contained in the other housing.

8. The total heat exchanger of claim 7, wherein the heat-pipe heat exchanger has a V-shaped configuration and is disposed on the total heat exchange member for covering two adjacent surfaces thereof.

9. The total heat exchanger of claim 2, wherein the heat-pipe heat exchanger has a partition plate arranged at a central portion thereof for preventing the first and second airflows from mixing as the airflows flow through the heat-pipe heat exchanger.

10. The total heat exchanger of claim 3, wherein the total heat exchange member is angularly disposed in the enclosure with each common edge of every two adjacent surfaces, through which the first and second air passages extend respectively, hermetically attached to an inner surface of the enclosure.

11. The total heat exchanger of claim 10, wherein the common edge of the total heat exchange member is connected to the inner surface of the enclosure via a Y-shaped connecting member.

12. A total heat exchanger comprising:

an air-guiding member for providing a first airflow and a second airflow;

a sensible heat exchange member spanning across said first and second airflows for conducting a sensible heat exchange between the airflows; and

a total heat exchange member being capable of exchanging sensible heat and latent heat simultaneously between said first and second airflows, the total heat exchange member having a multi-layer structure formed by a plurality of partition plates made of heat-conductive and moisture-permeable material and a plurality of spacing members inserted between the partition plates, and defining therein first and second air passages intersecting with and isolated from each other for carrying out a total heat exchange of sensible heat and latent heat between the first and second airflows as the airflows flow through the air passages respectively.

13. The total heat exchanger of claim 12, wherein the spacing members are wavy-shaped, and the first and second air passages are defined by the spacing members being disposed between every two adjacent partition plates with the wavy configurations of the spacing members being alternately arranged at 90 degree.

14. The total heat exchanger of claim 13, wherein the sensible heat exchange member comprises at least one heat pipe and a plurality of cooling fins attached to the heat pipe.

15. A method for conducting heat exchange between first air flow and second air flow, comprising the following steps:

guiding the first air flow through one of two ends of a heat pipe and the second air flow through the other end of the heat pipe, wherein the two ends of the heat pipe are evaporating end and condensing end, respectively, the evaporating end absorbing heat and the condensing end dissipating the heat and the heat being transferred from the evaporating end to the condensing end through the heat pipe; then

guiding the first air flow and the second air flow through a total heat exchanger member to conduct sensible and latent heat exchange between the first air flow and the second air flow.

16. The method of claim 15, wherein the first air flow is an indoor air flow to be exhausted to outdoors and the second air flow is an outdoor air flow to be supplied to indoors.

17. The method of claim 15, wherein the heat pipe is provided with fins thereon, the first and second air flows being divided into small air flows by the fins when the first and second air flows through the heat pipe.

18. The method of claim 17, wherein the fins are located beside the total heat exchange member.

19. The method of claim 17, wherein the fins are located on the total heat exchange member.

20. The method of claim 15, wherein the total heat exchange member is enclosed in an enclosure having four sides, the total heat exchange member has four corners connected the four sides, respectively.