US20120037349A1

US20120037349A1 - Heat exchange element

Info

Publication number: US20120037349A1
Application number: US13/265,003
Authority: US
Inventors: Masaru Takada; Hajime SOTOKAWA; Hidemoto Arai; Takanori Imai; Akira Doi; Kunihiko Kaga; Masaru Shinozaki
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2009-04-28
Filing date: 2009-04-28
Publication date: 2012-02-16
Also published as: CN102414533A; JPWO2010125643A1; WO2010125643A1; TW201038906A; TWI421460B

Abstract

A heat exchange element includes a first flow passage and a second flow passage extending orthogonal thereto. The first flow passage is an undulating flow passage that has a rectangular cross section and is formed by positioning, a first wave-form plate member and a second wave-form plate member on top of each other and with a predetermined interval therebetween, and further causing spacers to hermetically close two lateral portions with respect to the traveling direction of the fluid. The second flow passage is a straight flow passage that has a substantially triangular cross section and is formed between a flat-plate-like member and one of the first and the second wave-form plate members, when the flat-plate-like member is positioned on the wave-like form of the one of the first and the second wave-form plate members so as to be in close contact therewith.

Description

TECHNICAL FIELD

The present invention relates to a heat exchange element in which a first fluid and a second fluid (e.g., air) are respectively caused to flow through a first flow passage and a second flow passage that are formed between plate members stacked in the manner of layers so as to extend in directions intersecting each other, so that a heat exchange process is performed between the two fluids.

BACKGROUND ART

Conventionally, popularly-used heat exchange elements such as the one described above are provided with partition members that separate the two fluids from each other and spacers that keep the partition members at an interval therebetween, as disclosed in, for example, Patent Literature 1. In such a type of heat exchange elements, a heat exchange process is performed between the two fluids while using the partition members as a medium. Generally speaking, because an object of heat exchange elements is to cause the fluids to perform a heat exchange process, it is more desirable if the amount of exchanged heat is larger.
There are two types of heat exchange elements such as cross-flow type and counter-flow type. The theoretical amount of exchanged heat per unit volume of the cross-flow type is smaller than that of the counter-flow type; however, the cross-flow type has advantages where, for example, the actual volume to be assembled into an apparatus is smaller, and also, the processing of the element itself is also easier, because the cross-flow type does not require a header (i.e., the part that divides the two fluids used for the heat exchange process and that introduces the divided fluids into the heat exchange element flow passages), which is structurally indispensable in the counter-flow type.
Ideas for how to increase the amount of exchanged heat in a cross-flow type heat exchange element include a conventional example in which spacers are shaped in the form of corrugated fins so as to make the spacers function as fins and to thereby increase the amount of exchanged heat, as disclosed in, for instance, Patent Literature 2 as a conventional example. To improve the performance thereof, however, the areas of the fins provided in the flow passages need to be enlarged by modifying bending of the fins, as described in, for example, Patent Literature 2. In that situation, because the flow passages are narrowed by the volume of the fins themselves, pressure losses that are caused when the fluids pass therethrough become larger. As a result, improvements on the amount of exchanged heat that are realized by using such fins are reaching a limit.
To cope with this situation, as described in Patent Literature 3, 4, and 5, some other methods that are able to increase the amounts of exchanged heat have been proposed where, for example, heat transfer coefficients of the surfaces of the partition members are improved for the purpose of increasing the amount of exchanged heat, by providing projections or the like that are able to alter the flows, instead of providing the fins.
Further, as disclosed in Patent Literature 6, 7, and 8, some other ideas have been proposed where the heat transfer area size per unit volume is increased for the purpose of increasing the amount of exchanged heat, by modifying the shapes of the flow passages.
Patent Literature 1: Japanese Patent Application Laid-open No. H4-24492
Patent Literature 2: Japanese Utility Model Application Laid-open No. H1-178471
Patent Literature 3: Japanese Utility Model Application Laid-open No. H3-21670
Patent Literature 4: Japanese Patent No. 3805665
Patent Literature 5: Japanese Patent Application Laid-open No. 2008-232592
Patent Literature 6: Japanese Utility Model Application Laid-open No. S58-165476
Patent Literature 7: Japanese Patent No. 3546574
Patent Literature 8: Japanese Utility Model Application Laid-open No. H5-52567

DISCLOSURE OF INVENTION

Problem to be Solved by the Invention

As for the improvements on the heat transfer coefficients of the surfaces of the partition members, however, in many situations, especially in ventilation-purpose heat exchange elements, the diameters of pipes are small in relation to the flow rates of the fluids so that the flows are in a laminar-flow state where the Reynolds number thereof is smaller (approximately 100 to 1000) than those in other types of heat exchangers. Further, in those regions, the advantageous effect of the improvements on the heat transfer coefficients realized by altering the flows of the fluids themselves is small. For this reason, instead of improving the amount of transferred heat, fins and projections can rather be a cause of a problem where the pressure losses become larger, especially in the regions having a smaller Reynolds number. Having a larger pressure loss is not desirable because the energy consumption of a power device used for forwarding the fluids to the heat exchange element becomes larger.
Consequently, it is desirable to adopt, as an alternative, other methods that are able to increase the heat transfer area size per unit volume. However, even if a method that is able to increase the heat transfer area size is used, conventional examples have a problem that can be explained as follows: FIG. 8 is a schematic cross-sectional view for explaining a manner in which dead water regions occur in a flow passage. In conventional examples, there are situations where, when projections and recesses are formed in flow passages with an intention to increase the heat transfer area size, dead water regions (i.e., where the flows do not travel along the surfaces of the partition members and thus become stagnant) DO occur in the recessed regions. In such situations, even if the heat transfer area size is seemingly increased, the heat transfer area size is, on the contrary, smaller in actuality.
Speaking of another aspect, in the field of designing apparatuses into which heat exchange elements are assembled, there has been a demand in recent years for heat exchange elements of which it is possible to freely determine the outside-diameter without any restrictions, so that it is possible to address various technical issues. To meet this demand, methods have been disclosed, for example, in Patent Literature 4 and 5 where a material is pressed into pieces having an identical shape so that the pieces can be stacked in the manner of layers. According to these methods, however, when it becomes necessary to change the exterior dimension of the heat exchange elements, it is difficult to address the situation because it is necessary to re-manufacture the pressing mold.
Further, in other examples of the endeavor to increase the heat transfer area size per unit volume as disclosed in Patent Literature 6, 7, and 8 listed above, because the shapes of the flow passages through which the two types of fluids respectively flow are totally different from each other, the pressure losses are largely different from each other even if the flow rates of the fluids are equal. In that situation, when the element is designed to perform a heat exchange process by using mutually the same type of fluids having mutually different temperatures, such as a heat exchange element to be used in a ventilation-purpose heat exchanger, the two fluids are caused to flow at a substantially equal flow rate in many examples. Thus, when designing the apparatus into which the element is to be assembled, it becomes necessary to configure, for example, the specifications of the power devices for the fluids flowing in the two flow passages so as to be different from each other, and the designing process can thus be more complicated. For this reason, it is desirable to arrange the pressure losses in the flow passages for the two fluids used for the heat exchange process so as to be as close as possible to each other. In addition, it is desirable if the flow passages have mutually the same shape or similar shapes.
In view of the circumstances described above, it is an object of the present invention to obtain a heat exchange element that has a larger heat transfer area size per unit volume without using fins, projections, or the like that can cause obstructions in the flows and without occurrence of dead water regions, and further, the flow passages provided therein are in mutually the same shape and have mutually the same level of pressure loss, the flow passages extending in the two directions and being configured so that the heat exchanging fluids flow therethrough. Also, it is another object of the present invention to obtain a heat exchange element of which, in addition to the characteristics mentioned above, it is easy to change the exterior dimension.

Means for Solving Problem

In order to solve the aforementioned problem and attain the aforementioned object, a heat exchange element according to one aspect the present invention is constructed in such a manner that a first fluid and a second fluid are respectively caused to flow through a first flow passage and a second flow passage that are formed between plate members stacked in a manner of layers so as to extend in directions intersecting each other, so that a heat exchange process is performed between the first fluid and the second fluid, and the first flow passage is an undulating flow passage that has a rectangular cross section and is formed by positioning, a first wave-form plate member that is shaped in a form of a wave undulating in a layer stacking direction toward a traveling direction of the fluid and a second wave-form plate member that is shaped in a form of a wave undulating substantially in a same cycle as the first wave-form plate member on top of each other and with a predetermined interval therebetween, and further causing spacers to hermetically close two lateral portions with respect to the traveling direction of the fluid, and the second flow passage is a straight flow passage that has a substantially triangular cross section and is formed between a flat-plate-like member and one of the first and the second wave-form plate members, when the flat-plate-like member is positioned on a wave-like form of the one of the first and the second wave-form plate members so as to be in close contact therewith.

Effect of the Invention

In the heat exchange element according to an aspect of the present invention, the two surfaces of almost all the areas of the plate members being used have the mutually different fluids flow thereon, and also, the flow passages each have a shape that makes it difficult for dead water regions to occur. As a result, substantially the entirety functions as an effective heat transfer area. Consequently, the heat transfer area size per unit volume is larger, and also, the amount of exchanged heat in the element is larger. Further, in the situation where it is acceptable to keep the amount of exchanged heat equal to that in the conventional example, it is possible to make, conversely, the volume of the element smaller. Thus, an advantageous effect is achieved where it is also possible to contribute to endeavors of saving resources.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a heat exchange element according to a first embodiment of the present invention.

FIG. 2 is a perspective view for explaining directions of fluids flowing through flow passages formed in unit structuring members positioned in mutually different layers.

FIG. 3 is a schematic drawing of an example in which an undulating flow passage has many dead water regions when the height of the flow passage is too high.

FIG. 4 is a schematic drawing of an example in which the flow passage has many dead water regions when a wave-form plate member is folded at apexes.

FIG. 5 is a schematic drawing of an example in which the flow passage has no dead water region when a wave-form plate member is curved at the apexes with an appropriate curvature.

FIG. 6 is a perspective view of a heat exchange element according to a second embodiment of the present invention.

FIG. 7 is a perspective view of a heat exchange element according to a third embodiment of the present invention.

FIG. 8 is a schematic drawing of flows for explaining an example in which the flows are not traveling along a wave-form wall surface.

FIG. 9 is a perspective view of a conventional heat exchange element used for a comparison.

EXPLANATION OF LITTERS OR NUMERALS

11 FIRST WAVE-FORM PLATE MEMBER
12 SECOND WAVE-FORM PLATE MEMBER
13 FLAT-PLATE-LIKE MEMBER
14 SPACER
20 UNIT STRUCTURING MEMBER
24, 24 a, 24 b PARTITION WALL
31 UNDULATING FLOW PASSAGE (i.e., FIRST FLOW PASSAGE)
32 STRAIGHT FLOW PASSAGE (i.e., SECOND FLOW PASSAGE)
101, 102, 103 HEAT EXCHANGE ELEMENT
A FIRST FLUID
B SECOND FLUID
D0, D1, D2 DEAD WATER REGION

BEST MODE(S) FOR CARRYING OUT THE INVENTION

In the following sections, exemplary embodiments of a heat exchange element according to the present invention will be explained in detail, with reference to the accompanying drawings. The present invention is not limited by the exemplary embodiments.

First Embodiment

FIG. 1 is a perspective view of a heat exchange element according to a first embodiment of the present invention. To explain the embodiments clearly, the directions are supplementarily described while using the coordinate axes shown in the drawings; however, the present invention is not limited to this example. A heat exchange element 101 according to the first embodiment is configured so that a plurality of unit structuring members 20 each of which has flow passages formed therein are stacked in the manner of layers while being turned by 90 degrees for each of the layers. Each of the unit structuring members 20 is configured with two wave-form plate members (i.e., a first wave-form plate member 11 and a second wave-form plate member 12) that are each shaped in the form of a wave and one flat-plate-like member 13. The heat exchange element 101 is obtained by stacking, in the manner of layers, the plurality of unit structuring members 20 each of which is made up of the three plate members described above and further adding another flat-plate-like member 13 to an end in the layer stacking direction.
First, an exemplary configuration will be explained while a focus is placed on the unit structuring member 20 positioned on the uppermost layer in FIG. 1. The first wave-form plate member 11 and the second wave-form plate member 12 are each substantially square and are shaped in the form of waves undulating in mutually the same cycle, by being folded in the thickness direction thereof (i.e., in the layer stacking direction, which is the Z-axis direction) from one side to the opposite side of the square (i.e., toward the direction of the Y-axis), so as to have a zigzag configuration in a cross-section thereof and so as to be generally in the form of the wave. The first wave-form plate member 11 and the second wave-form plate member 12 that are shaped as described above are positioned while being apart from each other by a predetermined distance (i.e., a height of the flow passage) in the layer stacking direction (i.e., the Z-axis direction). The first wave-form plate member 11 and the second wave-form plate member 12 are each processed into a size that matches the flat-plate-like member 13, when being projected onto a flat plane.
Interposed between the first wave-form plate member 11 and the second wave-form plate member 12 at both ends of the flow passages with respect to the width direction (i.e., both ends with respect to the X-axis direction) are spacers 14 each of which meanders in a zigzag configuration so as to fit the wave-like form, for the purpose of keeping the distance between the first wave-form plate member 11 and the second wave-form plate member 12 and for the purpose of hermetically closing both ends of the space between the first wave-form plate member 11 and the second wave-form plate member 12. Each of the spacers 14 is hermetically fixed to the first wave-form plate member 11 and the second wave-form plate member 12 so that the flowing fluid (i.e., air in the present example) does not leak. In this manner, the parts of the first wave-form plate member 11 and the second wave-form plate member 12 that correspond to the two lateral portions of the flow passage are hermetically closed by the spacers 14, for the entire length with respect to the flow passage direction. As a result, an undulating flow passage (i.e., a first flow passage) 31 that has a rectangular cross section is formed therein.
The flat-plate-like members 13 are positioned over the top and under the bottom with respect to the layer stacking direction of the first wave-form plate member 11 and the second wave-form plate member 12. (The upper flat-plate-like member 13 is the flat-plate-like member 13 added to the end described above.) The apexes (i.e., the ridges) of the wave-like forms of the first and the second wave- form plate members 11, 12 and the flat-plate-like member 13 are hermetically fixed to each other so that the flowing fluids do not leak. As a result, straight flow passages (i.e., second flow passages) 32 each of which has a substantially triangular cross section are formed between each of the first and the second wave- form plate members 11, 12 and a corresponding one of the flat-plate-like members 13.
As explained above, each of the unit structuring members 20 has formed therein the undulating flow passage 31 that has a rectangular cross section and that undulates in the layer stacking direction with respect to the traveling direction of the fluid; and the straight flow passages 32 each of which extends orthogonal to the undulating flow passage 31, has a substantially triangular cross section, and extends straight from the entrance to the exit thereof without meandering. Further, the plurality of unit structuring members 20 each of which is configured as described above are stacked in the manner of layers while being turned by 90 degrees for each of the layers, in such a manner that the directions of the waves intersect one another. In the example shown in FIG. 1, three unit structuring members 20 are stacked in the manner of layers along the layer stacking direction (i.e., the Z-axis direction).
FIG. 2 is a perspective view for explaining the directions of the fluids flowing through the flow passages formed in the unit structuring members 20 positioned in the mutually different layers. Although the reference numerals are omitted from FIG. 2 to keep the drawing easy to see, the configuration is the same as the one shown in FIG. 1. A first fluid A flowing in the X-axis direction from the right-hand side of FIG. 2 flows through the straight flow passages 32 in the first and the third layers (counted from the bottom) and through the undulating flow passage 31 in the second layer, as shown with a dashed arrow in the drawing. In contrast, a second fluid B flowing in the Y-axis direction from the left-hand side of FIG. 2 flows through the undulating flow passages 31 in the first and the third layers (counted from the bottom) and through the straight flow passage 32 in the second layer. In other words, the structure is arranged so that both the first fluid A and the second fluid B used for performing the heat exchange process pass through the two mutually-different types of flow passages (i.e., the undulating flow passages 31 and the straight flow passages 32) at the same time. The first fluid A and the second fluid B thus perform the heat exchange process, while using the first wave-form plate members 11, the second wave-form plate members 12, and the flat-plate-like members 13 as a medium at the time of the heat exchange process. As explained above, because the flow passages that extend in the two mutually-different directions and through which the fluids used for performing the heat exchange process flow are made up of the two types of flow passages such as the undulating flow passages 31 and the straight flow passages 32 and are in mutually the same shapes, it is possible to arrange the pressure losses in both of the directions so as to be substantially equal.
FIG. 9 is a perspective view of an example of a conventional heat exchange element shown for a comparison. A heat exchange element 201 shown in FIG. 9 is configured so that partition members 213 each of which is in the form of a flat plate and spacers (i.e., corrugated fins) 211 each of which is shaped in such a manner that the cross section thereof is in the form of corrugated fins are stacked in the manner of layers so as to alternate. The layer stacking method being used can be explained as follows: A unit structuring member 220 is prepared by positioning one partition member 213 and one spacer 211 on top of each other in such a manner that the projecting parts of the wave-like forms are in contact, as shown in FIG. 9, and further fixing these members together by adhesion or the like. Unit structuring members 220 each prepared in this manner are stacked in the manner of layers so that the partition members 213 and the spacers 211 alternate and so that the directions in which the openings of the wave-like forms of the spacers 211 are oriented alternate by approximately 90 degrees. (In the example shown in FIG. 9, six unit structuring members 220 are stacked in the manner of layers.) In the heat exchange element 201, the first fluid A flowing in the X-axis direction from the right-hand side of FIG. 9 and the second fluid B flowing in the Y-axis direction from the left-hand side of FIG. 9 are arranged to flow in the directions intersecting each other in any two adjacently-positioned layers, as shown with a dashed arrow in the drawing. When the two types of fluids are configured so as to pass through the flow passages in this manner, it is possible to perform a heat exchange process between the two fluids, while using the partition members 213 as a medium.
The first wave-form plate member 11 and the second wave-form plate member 12 according to the first embodiment function as a medium during the heat exchange process and correspond to the partition members 213 in the conventional example shown in FIG. 9.
The most significant characteristic of the heat exchange element according to the first embodiment is that the material is not wasted and that the heat transfer area size of the element per unit volume is kept large because almost all the wall surfaces within the element other than the spacers serve as direct heat-transfer areas having the mutually-different heat exchanging fluids flowing on the two surfaces thereof, instead of indirect heat-transfer areas like the fins. Because the fins transfer heat by giving the heat stored therein to the direct heat-transfer area, the area size that contributes to the heat exchange process is not 100 percent of the surface areas of the fins. The fins impact the area size only on the basis of the amounts obtained from the formula “the surface areas of the fins”×“the fin efficiency” including the fin efficiency determined by the shapes of the fins and the circumstances of the surroundings. In contrast, as for the direct heat-transfer areas that are in contact with the mutually-different heat exchanging fluids on the two surfaces thereof, 100 percent of the surface areas thereof are able to contribute to the heat exchange process. For this reason, less material is wasted when the direct heat-transfer area is arranged to be as large as possible.
When the material is not wasted, it is possible not only to provide the element at a lower cost, but also to reduce the quantity of flat plates required in achieving the same level of performance because the material is used without being wasted. Accordingly, it is also possible to keep large the space volume (i.e., the volume in which the fluids are able to flow) per unit volume. In addition, because the size of the area that is in contact with the fluids is also smaller than in the example where the fins are used, it is ultimately also more advantageous in terms of the pressure losses caused while the fluids are flowing.
Each of the unit structuring members 20 according to the first embodiment is in the form of a flat plate having a substantially square shape; however, each of the unit structuring members 20 may be in the form of a flat plate having a parallelogram shape or a rectangular shape.

EXAMPLE 1

The heat exchange element 101 according to the first embodiment shown in FIG. 1 was manufactured in the following manner:
As the flat-plate-like member 13, a piece of specially-processed paper (to which a process has been applied so as to close the grain gaps in the paper with a resin or the like so that air does not leak) having a thickness of approximately 100 micrometers was prepared. As the second wave-form plate member 12, another piece of specially-processed paper having a thickness of, again, approximately 100 micrometers and having been processed into a wave-like form with folding creases, was cut into a 120-millimeter square, and was positioned over the abovementioned piece of paper. Subsequently, an aqueous vinyl-acetate resin emulsion adhesive was applied to the apexes of the folding creases of the piece of paper processed into the wave-like form by using a roll coater or the like so as to adhere the pieces of paper together.
In this situation, by appropriately devising tools being used or the like, the height of the wave-like form was arranged so as to be 1.7 millimeters, whereas the distance between any two adjacently-positioned apexes of the wave-like form was arranged so as to be 11.5 millimeters. After that, the spacers 14 were cut out from thick paper having a thickness of approximately 1.2 millimeters so as to fit the shape of the surface of the wave-like form of the second wave-form plate member 12. The spacers 14 were positioned over the second wave-form plate member 12 at the end portions thereof. By applying the aqueous vinyl-acetate resin emulsion adhesive described above with the use of a brush, the spacers 14 were adhered to the two sides of the second wave-form plate member 12 extending parallel to the developing direction of the wave-like form.
After that, after an adhesive is applied to an upper edge of the spacers 14, another piece of the specially-processed paper that is the same as the one used for the second wave-form plate member 12 and that has a thickness of approximately 100 micrometers was pasted onto the spacers 14 so as to fit the wave-like form thereof, as the first wave-form plate member 11. The height (i.e., the width) of the spacers 14 were determined in such a manner that the distance between the first wave-form plate member 11 and the second wave-form plate member 12 in the layer stacking direction was approximately 1.5 millimeters.
The unit structuring member 20 was thus produced. A plurality of unit structuring members 20 were prepared in this manner and stacked in the manner of layers while being turned by 90 degrees for each of the layers. The heat exchange element 101 shown in FIG. 1 was thus obtained.

COMPARISON EXAMPLE

In contrast, to make a comparison with the heat exchange element 101 according to the first embodiment, the conventional heat exchange element 201 shown in FIG. 9 was produced. In this situation, the wave-like form of the spacers (i.e., the corrugated fins) 211 were shaped so as to be the same as the wave-like forms of the first wave-form plate members 11 and the second wave-form plate members 12 according to the first embodiment. In other words, the height of the wave-like form of the spacers 211 was arranged so as to be 1.7 millimeters, whereas the distance between any two adjacently-positioned apexes of the wave-like form was arranged so as to be 11.5 millimeters.
<Comparison>
The table shown below indicates results of comparing the direct heat-transfer area sizes when an equal number of layers are stacked for Example 1 and for Comparison Example. In the conventional example, the direct heat-transfer area size is represented only by the areas of the partition members 213 each of which is in the form of a flat plate. In contrast, in the configuration of Example 1, the direct heat-transfer area size is represented by the areas of the flat-plate-like members and the wave-form plate members. Thus, the heat exchange element 101 according to the first embodiment has an extremely larger direct heat-transfer area size per the same volume.

	TABLE 1

	Direct heat-transfer area size (values
	expressed with comparison example being 1.0)

Example 1	1.37
Comparison example	1.0
(corrugated fins)

When the heat exchange element 101 according to the first embodiment is produced, it should be noted that, even if the heat exchange element 101 has a structure with a seemingly large direct heat-transfer area size, there is a possibility that the actual heat transfer area size may have become smaller depending on how the fluids flow in the flow passages and there is a possibility that the expected advantageous effect may not be achieved. These possibilities are significantly higher especially when the undulating flow passages are shaped so as to have a rectangular cross section. For example, if the height of the undulating flow passages is configured to be too high, a phenomenon occurs where, as shown in FIG. 3, the fluid flows only in a straight flow path formed between the upper wave forms and the lower wave forms. In that situation, in actuality, the effect of the heat transfer areas is not realized because the heat is blocked by dead water regions D1 having circling flows, which occur between the wall surface and the fluid (most of which is flowing in the straight flow path) that is supposed to be exchanging the heat. To prevent this situation, it is desirable to configure the distance between the undulating flow passages so as to be smaller than the height of the wave-like forms of the wave-form plate members, because the apexes of the upper wave-form plate members and the apexes of the lower wave-form plate members fit one another in such a manner that no straight flow path is formed, and it is therefore possible to inhibit the dead water regions from occurring.
Further, in some situations, dead water regions may occur even in curved portions of the undulating flow passages, if any part of the flow gets separated, depending on the flow rates and the shapes of the wave-like forms. FIG. 4 is a drawing of a cross-sectional view of an undulating flow passage having a rectangular cross section in which the apexes formed by the wave-form plate member are sharp. FIG. 5 is a drawing of a cross-sectional view of an undulating flow passage having a rectangular cross section in which each of the apexes formed by the wave-form plate member is shaped with a curvature. FIGS. 4 and 5 depict results of simulations performed by allowing a fluid (i.e., air in the present example) to flow in each of these flow passages at mutually the same flow rate. In the example shown in FIG. 4, fluid circling regions (i.e., dead water regions D2) occur on the downstream-side wall surfaces of the apexes due to a part of the flow that has been separated. As a result, although the wall surfaces that are in contact with the dead water regions D2 are seemingly direct heat-transfer areas, these wall surfaces hardly contribute to the heat transfer in actuality. When the dead water regions D2 occur in this manner, undesirable impacts are made such as a decrease in the heat exchange amount and an increase in the pressure loss.
As a means for improving this situation, it is possible to adopt a method by which, as shown in FIG. 5, each of the curved portions of the undulating flow passages (i.e., the bending parts including the apexes of the wave-form plate members) is shaped in an arched form having an appropriate curvature, instead of being in a form obtained by folding a plane as explained in the description of the first embodiment.
Further, the wave-like form of the wave-form plate members may be in any shape as long as the wave-like form is realized; however, it is desirable if the wave-like form is shaped with a sinusoidal curve or is a triangular wave. Alternatively, the wave-like form may be a rectangular wave; however, when the wave-like form is a rectangular wave, there is a possibility that the level of performance may become lower because the areas in which the flat-plate-like members and the wave-form plate members are in contact with each other are larger. In addition, because the fluids passing through the undulating flow passages flow so as to collide with a rising portion of the rectangular wave, an increase in the pressure loss is also anticipated.
Furthermore, when each of the apexes of the wave-like form is shaped with a curvature, it is possible to provide a heat exchange element having a smaller pressure loss. By reducing the pressure loss, it is possible to reduce the input of the fluid power device included in the apparatus into which the heat exchange element is to be assembled, and also, it is thereby possible to contribute to energy saving of the apparatus.

Second Embodiment

FIG. 6 is a perspective view of a heat exchange element according to a second embodiment of the present invention. A heat exchange element 102 according to the second embodiment is configured so that each of the bending parts near the apexes of the first wave-form plate members 11 and the second wave-form plate members 12 is shaped, as shown in FIG. 5, in a smooth arched form having a predetermined curvature so that no dead water region occurs while the fluids are flowing. Also, in the heat exchange element 102 according to the second embodiment, a plurality of partition walls 24 are provided between the first wave-form plate members 11 and the second wave-form plate members 12 so as to divide each of the undulating flow passages 31 into a plurality of sections with respect to the width direction thereof and so as to enable the first and the second wave- form plate members 11, 12 to support each other. The other configurations are the same as those in the first embodiment.
According to the second embodiment, because the plurality of partition walls 24 are provided, the first wave-form plate members 11 and the second wave-form plate members 12 support each other at small intervals. As a result, the number of points in which the first and the second wave- form plate members 11, 12 are held is larger, which enhances the structural strengths of the unit structuring members 20 during the manufacturing process and of the entire heat exchange element 102. It is therefore possible to improve workability and handleability of the element. Furthermore, the configuration contributes to preventing the two fluids used for the heat exchange process from leaking into each other.
Further, as an advantageous effect during the manufacture, by designing, in advance, the element with a large exterior dimension that is partitioned by the plurality of partition walls 24, it is possible to obtain heat exchange elements each having an arbitrary exterior dimension by cutting the large elements into similarly-shaped elements of arbitrary sizes. As a result, it is possible to change the exterior dimension of the elements without the need to change the mold or the like. This characteristic significantly contributes to improvement of the productivity and enhancement of the degree of freedom in designing the product.

Third Embodiment

FIG. 7 is a perspective view of a heat exchange element according to a third embodiment of the present invention. A heat exchange element 103 according to the third embodiment is configured so that partition walls that are provided in the undulating flow passages 31 so as to divide each of the undulating flow passages 31 into a plurality of sections with respect to the width direction thereof are arranged in such a manner that the thickness of the partition wall with respect to the width direction of the flow passage gets larger for one partition wall in every predetermined number of partition walls. In other words, partition walls 24 b having the smaller thickness and partition walls 24 a having the larger thickness are arranged in a predetermined order. According to the third embodiment, the partition walls 24 b having the smaller thickness and the partition walls 24 a having the larger thickness are provided so as to alternate. Other configurations are the same as those in the second embodiment.
In the example according to the second embodiment, although it is possible to obtain elements each having an arbitrary exterior dimension by cutting the large elements into elements of arbitrary sizes, there is a possibility that a large part of the end portions of the obtained elements may be wasted depending on the relationship between the positions of the partition walls and the cutting positions. To cope with this situation, it would be necessary to combine the element with another structure that is able to close a wider portion than that in the conventional example, for the purpose of preventing the fluid from flowing into the end portions of the elements and from leaking into the flow passage of the other fluid. In that situation, it would be difficult to design and prepare the combined structure because it would not be possible to determine the width thereof until the cutting positions of the element are determined. For this reason, although the cutting positions will be limited, by cutting the centers of the thick portions of the partition walls, it is possible to obtain similarly-shaped elements, while ensuring that the elements resulting from the cutting have no wasted part even in the end portions thereof.

INDUSTRIAL APPLICABILITY

As explained above, the heat exchange element according to an aspect of the present invention is suitable for an application to a cross-flow type heat exchange element that performs a heat exchange process between two fluids having mutually different temperatures and in which plate members are stacked in the manner of layers. In particular, the heat exchange element according to an aspect of the present invention is optimal for an application to a cross-flow type heat exchange element to be assembled into a ventilation apparatus or into an air conditioning apparatus so as to perform an air-versus-air heat exchange process.

Claims

1. A heat exchange element in which a first fluid and a second fluid are respectively caused to flow through a first flow passage and a second flow passage that are formed between plate members stacked in a manner of layers so as to extend in directions intersecting each other, so that a heat exchange process is performed between the first fluid and the second fluid, wherein

the first flow passage is an undulating flow passage that has a rectangular cross section and is formed by positioning, a first wave-form plate member that is shaped in a form of a wave undulating in a layer stacking direction toward a traveling direction of the fluid and a second wave-form plate member that is shaped in a form of a wave undulating substantially in a same cycle as the first wave-form plate member on top of each other and with a predetermined interval therebetween, and further causing spacers to hermetically close two lateral portions with respect to the traveling direction of the fluid, and

the second flow passage is a straight flow passage that has a substantially triangular cross section and is formed between a flat-plate-like member and one of the first and the second wave-form plate members, when the flat-plate-like member is positioned on a wave-like form of the one of the first and the second wave-form plate members so as to be in close contact therewith, and wherein

the heat exchange element comprises a plurality of unit structuring members stacked in a manner of layers while being turned by 90 degrees for each of the layers, each of the unit structuring members being configured with a set made up of the first wave-form plate member, the second wave-form plate member, and the flat-plate-like member.

2. (canceled)

3. The heat exchange element according to claim 1, wherein a difference between a height of a wave-like form of the first wave-form plate member and a height of a wave-like form of the second wave-form plate member is larger than a layer-stacking-direction distance between the first wave-form plate member and the second wave-form plate member.

4. The heat exchange element according to claim 1, wherein each of bending parts at apexes of wave-like forms of the first wave-form plate member and the second wave-form plate member is shaped so as to be in an arched form having a curvature so that no dead water region occurs while the first fluid and the second fluid are flowing.

5. The heat exchange element according to claim 1, wherein at least one partition wall that divides the undulating flow passage having the rectangular cross section into a plurality of sections with respect to a width direction thereof and that enables the first and the second wave-form plate members to support each other is provided between the first wave-form plate member and the second wave-form plate member.

6. The heat exchange element according to claim 5, wherein

a plurality of partition walls are provided, and

at least one of the partition walls provided in a predetermined position is configured so as to have a larger thickness with respect to the width direction of the flow passage than thicknesses of other partition walls provided in other positions.