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  
       [0001]     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  
       [0002]     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.  
         [0003]     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.  
         [0004]     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.  
         [0005]     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.  
         [0006]     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  
       [0007]     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.  
         [0008]     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  
       [0009]      FIG. 1  is an exploded, isometric view of a total heat exchanger in accordance with a preferred embodiment of the present invention;  
         [0010]      FIG. 2  is an assembled view of  FIG. 1 , with some parts thereof being cut away for showing more details;  
         [0011]      FIG. 3  is an isometric view of a heat-pipe heat exchanger of  FIG. 1 ;  
         [0012]      FIG. 4  is an isometric view of a total heat exchanger in accordance with another preferred embodiment of the present invention;  
         [0013]      FIG. 5  is an isometric view of a heat-pipe heat exchanger of  FIG. 4 ;  
         [0014]      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  
         [0015]      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  
       [0016]      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 .  
         [0017]     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.  
         [0018]     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.  
         [0019]     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.  
         [0020]     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.  
         [0021]     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.  
         [0022]      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 .  
         [0023]      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 .  
         [0024]     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 .  
         [0025]     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.