HEAT EXCHANGER

TECHNICAL FIELD

The technique disclosed herein relates to heat exchangers, and more particularly relates to the structure of a heat exchanger that includes a core as a heat transfer part and can reduce uneven flow of fluid passing through the core.

BACKGROUND ART

An uneven flow phenomenon has been conventionally known. In the uneven flow phenomenon, for example, the shapes and layout of header tanks, nozzles, and other elements of a heat exchanger cause the flow rate distribution of fluid passing through a core of the heat exchanger to be uneven. For example, Patent Document 1 describes a plate fin heat exchanger including a core and a long and thin header tank extending from an opening of an inflow nozzle in a direction of flow of fluid through the inflow nozzle. This header tank shape causes the flow rate of fluid passing through a back part of the core remote from the opening of the nozzle to be higher than that of fluid passing through a front part of the core near the opening of the nozzle. Patent Document 1 shows that a baffle plate (a flow director) is placed in the header tank of the plate fin heat exchanger. Fluid flowing through the nozzle into the header tank interferes with the baffle plate to reduce the flow of fluid toward the back of the header tank, thereby reducing uneven flow of fluid passing through the core.

Likewise, Patent Document 2 describes a plate fin heat exchanger including a header tank. The header tank extends vertically downward from the upper end of the header tank having an opening of an inflow nozzle. Patent Document 2 describes a technique in which the plate fin heat exchanger includes a cylindrical flow director protruding upwardly from the bottom of the header tank. The provision of the cylindrical flow director reduces the cross-sectional area of a portion of a channel near the inside bottom of the header tank to reduce the downward flow of fluid through an inlet into the header tank toward the bottom of the header tank. This reduces uneven flow of fluid passing through the core.

By contrast, Patent Documents 3 and 4 each describe a multitubular heat exchanger. The multitubular heat exchanger includes a core and a header tank, and the header tank has a central part having an opening of an inflow nozzle. The width of the header tank gradually increases from the opening of the inflow nozzle to the core. These Patent Documents each describe a technique in which the multitubular heat exchanger includes a flow director disposed near the opening of the nozzle to allow the flow of fluid through the nozzle into the heat exchanger to collide with the flow director. This collision allows the flow of the fluid to be spread outwardly, thereby reducing uneven flow of fluid passing through the core.

CITATION LIST
Patent Document

PATENT DOCUMENT 1: Japanese Unexamined Patent Publication No. 2002-310593

PATENT DOCUMENT 2: Japanese Unexamined Patent Publication No. 2007-71434

PATENT DOCUMENT 3: Japanese Unexamined Patent Publication No. S50-139454

PATENT DOCUMENT 4: Japanese Unexamined Patent Publication No. 2001-248980

SUMMARY OF THE INVENTION
Technical Problem

Reducing such uneven flow of fluid passing through a core as described above increases the heat exchange efficiency of the core, and helps, for example, downsize heat exchangers. Here, a possible uneven flow of fluid in the heat exchanger described in each of Patent Documents 1-4 described above results from an uneven distribution of dynamic pressure of fluid that has yet to flow into the core to an inflow surface of the core through which the fluid flows into the core and which has many inlets. The flow director described in each Patent Document reduces high dynamic pressures to allow the distribution of dynamic pressure of the fluid to the inflow surface of the core to be as even as possible.

Studies of the inventors of this application show that different channel resistances of many channels forming a core also cause uneven flow of fluid passing through the core. For example, in a core of a plate fin heat exchanger, channels are defined by a corrugated fin placed in a passage, and a distributor fin is placed in the passage to change the direction of flow of fluid, thereby causing the channels from their inlets to their outlets to have different lengths. Such differences in length among the channels cause the channels to have different channel resistances. A core of a multitubular heat exchanger includes pipes corresponding to channels. The pipes are bent in a U shape to cause the pipes to have different channel lengths. Such differences in channel length among the pipes cause the channels to have different channel resistances. In the core of the plate fin heat exchanger or the core of the multitubular heat exchanger, the differences in channel resistance among the channels cause the flow rates of fluid passing through some of the channels having relatively low channel resistances to be relatively high while causing the flow rates of fluid passing through the other channels having relatively high channel resistances to be relatively low. This results in uneven flow of fluid passing through the core. The direction of deviation of the fluid flow arising from the differences in channel resistance among the channels forming the core may be different from that of deviation of the fluid flow arising from the above-described distribution of dynamic pressure of fluid to the inflow surface. The provision of such a flow director as described in any one of Patent Documents 1-4 could not eliminate uneven flow of the fluid.

It is therefore an object of the technique disclosed herein to reduce uneven flow of fluid passing through a core of a heat exchanger.

Solution to the Problem

The inventors of this application decided to reduce uneven flow of fluid passing through a core by providing two types of flow-directing members having different configurations to address the two causes of the uneven flow, i.e., the distribution of the dynamic pressure of fluid to the inflow surface and the differences in channel resistance among the channels forming the core.

Specifically, the technique disclosed herein relates to a heat exchanger comprising: a core having at least a plurality of first passages through which a first fluid flows and a plurality of second passages through which a second fluid flows and at least exchanging heat between the first fluid and the second fluid.

The core has an inflow surface through which the first fluid flows into the core and an outflow surface through which the first fluid flows out of the core. At least the first passages each include a plurality of channels that each connect an inlet formed in the inflow surface and an outlet formed in the outflow surface together. The channels have different channel resistances.

The heat exchanger further includes: a flow-directing member of a first type disposed to a side of the core where the inflow surface is located to provide a uniform distribution of a dynamic pressure of the first fluid flowing into the core to the inflow surface; and a flow-directing member of a second type reducing a difference between flow rates of the first fluid through the channels arising from a difference in channel resistance between the channels forming each first passage of the core.

Here, the “channels” include, in addition to channels separated from each other, channels substantially along which fluid flows without completely separating the channels from each other.

With such a configuration, in the heat exchanger in which the distribution of dynamic pressure of the first fluid to the inflow surface of the core is not uniform due to, for example, the configuration of an inflow header tank connected to the core or an inflow nozzle placed on the header tank, the flow-directing member of the first type is disposed to the side of the core where the inflow surface is located to provide a uniform distribution of dynamic pressure of the first fluid. The flow-directing member of the first type can be, for example, such a baffle that interferes with the flow of the first fluid flowing through the inflow nozzle into the header tank to reduce the dynamic pressure.

On the other hand, in a heat exchanger which includes a core having first passages and in which a plurality of channels forming the first passages have different channel resistances due to, for example, different channel lengths and different channel diameters, the flow-directing member of the second type is provided independently of the flow-directing member of the first type. The flow-directing member of the second type reduces the differences among the flow rates of fluid through the channels arising from the differences in channel resistance among the channels. Specifically, the flow-directing member of the second type restricts the flow rates of the first fluid flowing into at least some of the channels having relatively low channel resistances or restricts the flow rates of the first fluid flowing out of at least the some of the channels having relatively low channel resistances to reduce the differences among the flow rates of the first fluid through the channels independently of the differences in channel resistance among the channels.

As such, the provision of the flow-directing members of two types, i.e., the flow-directing member of the first type and the flow-directing member of the second type, can effectively reduce both uneven flow of fluid arising from the distribution of dynamic pressure of fluid to the inflow surface of the core and uneven flow of fluid arising from the differences in channel resistance among the channels of the core. This can enhance the heat exchange efficiency of the heat exchanger. This helps, for example, downsize heat exchangers.

The core does not always need to exchange heat between two types of fluid, i.e., the first fluid and the second fluid, and may exchange heat among three or more types of fluid.

The flow-directing member of the second type may be disposed to a side of the core where the outflow surface is located. As described above, the flow-directing member of the second type can adjust the flow rates of the first fluid flowing into the channels toward inlets of the first passages or adjust the flow rates of the first fluid flowing out of the channels toward outlets of the first passages to reduce the differences among the flow rates of the first fluid through the channels. The flow-directing member of the second type can be disposed to the side of the core where either the inflow surface or outflow surface is located.

However, the flow-directing member of the first type is disposed to the side of the core where the inflow surface is located, and for this reason, when an attempt is made to dispose the flow-directing member of the second type to the side of the core where the inflow surface is located, it may be difficult to dispose the flow-directing members of the two types to the side of the core where the inflow surface is located due to, for example, limitations of placement space.

Here, the flow-directing member of the second type can be a plate-like member having many holes passing therethrough and arranged in a predetermined pattern as described below. The diameter of each hole passing through the flow-directing member of the second type, the number of the holes, and/or the spacing between each adjacent pair of the holes are appropriately varied to allow the distribution of the aperture ratio of the flow-directing member of the second type (the total area of holes per unit area) to be uneven. On the other hand, the channel resistance distribution across the inflow surface of the core in which the inlets of the channels are uniformly spaced or the outflow surface of the core in which the outlets of the channels are uniformly spaced is determined to correspond to the channel resistances of the channels. Thus, the flow-directing member of the second type faces the inflow surface or the outflow surface such that the distribution of the aperture ratio of the flow-directing member of the second type corresponds to the channel resistance distribution across the inflow surface or the outflow surface. In other words, if a portion of the flow-directing member of the second type having low aperture ratios faces a portion of the inflow surface or the outflow surface corresponding to the corresponding ones of the inlets and the outlets of some of the channels having low channel resistances, the flow rates of the first fluid flowing into or out of at least some of the channels having relatively low channel resistances are restricted.

If the flow-directing member of the second type configured as above is disposed to the side of the core where the inflow surface is located, and is apart from the inflow surface, the differences among the flow rates of the first fluid caused by the passage of the first fluid through the flow-directing member of the second type and corresponding to the distribution of the aperture ratio of the flow-directing member of the second type are less effective before the first fluid reaches the inflow surface. This prevents the flow-directing member of the second type from functioning. Thus, the flow-directing member of the second type is preferably close to the inflow surface.

By contrast, the steep velocity gradient of fluid between portions of the flow-directing member of the second type corresponding to the through holes (i.e., openings) and the other portion thereof (i.e., a portion thereof except the openings) occurs downstream of the flow-directing member of the second type. Thus, if the flow-directing member of the second type is excessively close to the inflow surface, the velocity gradient affects the flow of the first fluid through the inlets of the channels formed in the inflow surface of the core into the channels. Specifically, while the flow rates of the first fluid into some of the channels having the inlets facing the through holes increase, the first fluid hardly flows into the other ones of the channels having the inlets that do not face the through holes. This not only prevents the flow-directing member of the second type from functioning, but also may increase the differences among the flow rates of the first fluid through the channels. For this reason, if the flow-directing member of the second type is disposed to the side of the core where the inflow surface is located, the flow-directing member of the second type is often difficult to position.

On the other hand, when the flow-directing member of the second type is disposed to the side of the core where the outflow surface is located, the flow-directing member of the first type and the flow-directing member of the second type are respectively disposed to the side of the core where the inflow surface is located and the side of the core where the outflow surface is located. This facilitates ensuring space for placing each of the flow-directing members of the first and second types. When the flow-directing member of the second type having the many through holes faces the outflow surface, the flow-directing member of the second type closer to the outflow surface more easily functions, whereas unlike when the flow-directing member of the second type is disposed to the side of the core where the inflow surface is located, the velocity gradient downstream of the flow-directing member of the second type does not need to be considered. Thus, the flexibility in positioning the flow-directing member of the second type is relatively high.

In view of the foregoing, the flow-directing member of the second type is advantageously disposed to the side of the core where the outflow surface is located. This allows the flow-directing member of the second type to be relatively flexibly positioned while reliably ensuring the function of the flow-directing member of the second type.

While the outlets of the channels may be uniformly spaced from each other in the outflow surface of the core, a flow rate distribution of the first fluid through the outflow surface of the core may be equivalent to a predetermined channel resistance distribution corresponding to channel resistances of the channels. The flow-directing member of the second type may be a plate-like member facing at least a portion of the outflow surface, and may have a plurality of holes passing through the flow-directing member of the second type along a thickness of the flow-directing member of the second type. An aperture ratio of the flow-directing member of the second type defined by the holes may be determined such that a distribution of the aperture ratio corresponds to the channel resistance distribution equivalent to the flow rate distribution of the first fluid through the outflow surface of the core.

Here, the distribution of the aperture ratio of the flow-directing member of the second type is equivalent to the channel resistance distribution corresponding to the distribution of the flow rate of fluid flowing through the outflow surface. The aperture ratio of a portion of the flow-directing member of the second type facing some of the channels having high channel resistances is increased to allow the fluid to easily pass through the some of the channels, whereas the aperture ratio of the other portion of the flow-directing member of the second type facing the other ones of the channels having low channel resistances is decreased to make it difficult for the fluid to pass through the other ones of the channels. This allows the flow-directing member of the second type to adjust the flow rates of the first fluid through the channels even with differences in channel resistance among the channels, thereby reducing the differences among the flow rates of the first fluid through the channels. In other words, uneven flow of fluid arising from the differences in channel resistance among the channels is reduced.

The core may be a plate fin core including the first and second passages that are alternately stacked, and at least the first passages may each include a distributor fin configured to change a direction of flow of fluid through the first passage.

In other words, placing the distributor fin in each first passage of the plate fin core causes the channels to have different lengths, resulting in different channel resistances. However, the above-described flow-directing member of the second type reduces the differences among the flow rates of the fluid through the channels arising from the differences in channel resistance among the channels. This reduces uneven flow of the fluid through the core.

Advantages of the Invention

As described above, according to the heat exchanger, the flow-directing member of the first type and the flow-directing member of the second type are individually provided. The flow-directing member of the first type reduces uneven flow of fluid arising from the distribution of dynamic pressure of fluid to the inflow surface of the core. The flow-directing member of the second type reduces uneven flow of fluid arising from the differences in channel resistance among the channels of the core. The individual provision of the flow-directing members of the first and second types can effectively reduce uneven flow of fluid through the heat exchanger. This helps enhance the heat exchange efficiency and downsize heat exchangers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a partially fragmented, schematic front view of the configuration of a heat exchanger, and FIG. 1B is a partially fragmented, schematic side view of the configuration of the heat exchanger.

FIG. 2 is a front view of a flow-directing member of a first type.

FIG. 3 is a front view of a flow-directing member of a second type.

FIG. 4 is a front view of another flow-directing member of the second type having a shape different from the shape of the flow-directing member of the second type in FIG. 3.

FIGS. 5A and 5B illustrate a heat exchanger having a configuration different from that of the heat exchanger in FIG. 1 and including still another flow-directing member of the second type, and correspond to FIGS. 1A and 1B, respectively.

FIGS. 6A and 6B illustrate a heat exchanger including yet another flow-directing member of the second type placed upstream of first passages, and correspond to FIGS. 1A and 1B, respectively.

FIGS. 7A and 7B illustrate a heat exchanger omitting the flow-directing member of the first type, and correspond to FIGS. 1A and 1B, respectively.

DESCRIPTION OF EMBODIMENTS

An embodiment of a heat exchanger will now be described with reference to the drawings. The following preferred embodiment will be described merely as an example. FIGS. 1A and 1B schematically illustrate the configuration of a heat exchanger 1 according to an embodiment. FIG. 1A is a front view of the heat exchanger 1, and FIG. 1B is a side view of the heat exchanger 1. For convenience of explanation, the upward and downward directions of the drawing sheet of FIG. 1A are referred to as X directions, the rightward and leftward directions of the drawing sheet of FIG. 1A are referred to as Y directions, and the rightward and leftward directions of the drawing sheet of FIG. 1B are referred to as Z directions.

The heat exchanger 1 includes a plate fin core 2 exchanging heat between a first fluid and a second fluid. As illustrated in FIG. 1A, the core 2 includes first passages 21 through which the first fluid flows, and second passages 22 through which the second fluid flows. The first passages 21 and the second passages 22 are alternately stacked along the Y directions with a tube plate 23 interposed between each adjacent pair of the first and second passages 21 and 22. In the illustrated example, the core 2 has a box-like shape. The length of the box-like shape in the Z direction illustrated in FIG. 1B is shorter than that of the box-like shape in each of the X direction and the Y direction illustrated in FIG. 1A. The shape of the core 2 should not be limited to the box-like shape, and can be selected from among various shapes.

As indicated by solid arrows in FIGS. 1A and 1B, the first fluid flows through an upper end surface of the core 2 into the first passages 21, flows through the core 2 downwardly, and then flows out of the core 2 through a side surface of a lower end portion of the core 2 in one of the Z directions. As indicated by hollow arrows in FIGS. 1A and 1B, the second fluid flows through a lower end surface of the core 2 into the second passages 22, flows through the core 2 upwardly, and then flows out of the core 2 through a side surface of an upper end portion of the core 2 in the other one of the Z directions. As such, the core 2 is a so-called counter-flow core through which the first fluid and the second fluid flow in opposite directions. Note that the core 2 should not be limited to the counter-flow core, and may be a parallel-flow core designed such that the first fluid and the second fluid flow through the core in the same direction, or a cross-flow core through which the first fluid and the second fluid flow in directions orthogonal to each other.

As schematically illustrated in FIG. 1B, the first passages 21 of the core 2 each include a corrugated fin 211. The corrugated fin 211 partitions the corresponding one of the first passages 21 into a plurality of channels arranged in the Z direction. Any one of various types of corrugated fins 211, such as plain fins or perforated fins, can be used as the corrugated fin 211. Although not shown, the second passages 22 each include a corrugated fin, and the corrugated fin also partitions the corresponding one of the second passages into a plurality of channels arranged in the Z direction. Furthermore, although not shown, the first and/or second passages 21, 22 may each include, for example, a serrated fin. In this case, while the channels are not completely separated from one another, fluid flows along the fin principally in the X directions. The provision of the serrated fin is, therefore, substantially equivalent to the partitioning of the corresponding one of the first and second passages 21 and 22 into a plurality of channels.

A portion of each first passage 21 near an outlet thereof corresponds to a lower end portion of the core 2, and includes a distributor fin 212, which changes the direction of flow of fluid through the corresponding first passage 21 from one of the X directions, i.e., the downward direction, to one of the Z directions, i.e., a horizontal direction (the leftward direction of the drawing sheet of FIG. 1B). A portion of each second passage 22 near an outlet thereof corresponds to an upper end portion of the core 2, and also includes a distributor fin 222, which changes the direction of flow of fluid through the corresponding second passage 22 from one of the X directions, i.e., the upward direction, to one of the Z directions, i.e., a horizontal direction (the rightward direction of the drawing sheet of FIG. 1B).

As such, the upper end surface of the box-like core 2 forms an inflow surface 31 thereof through which the first fluid flows into the core 2, and the side surface of the lower end portion of the core 2 forms an outflow surface 32 thereof through which the first fluid flows out of the core 2. The lower end surface of the core 2 forms an inflow surface 33 thereof through which the second fluid flows into the core 2, and the side surface of the upper end portion of the core 2 forms an outflow surface 34 thereof through which the second fluid flows out of the core 2.

The core 2 configured as above has the inflow surface 31 through which the first fluid flows into the core 2 and on which an inflow header tank 41 is placed to distribute the first fluid into the channels of each first passage 21. The inflow header tank 41 has a shape corresponding to that of the inflow surface 31 through which the first fluid flows, is long and thin, and extends along the Y direction. An inflow nozzle 411 through which the first fluid flows into the inflow header tank 41 is placed on a central portion of the inflow header tank 41 in the Y direction. By contrast, the core 2 has the outflow surface 32 through which the first fluid flows out of the core 2 and on which an outflow header tank 42 is placed to collect the first fluid that has passed through the channels of each first passage and to allow the collected first fluid to flow out of the outflow header tank 42. The outflow header tank 42 is also long and thin, and also extends along the Y direction. An outflow nozzle 421 through which the first fluid flows out of the outflow header tank 42 is placed on a central portion of the outflow header tank 42 in the Y direction. An inflow header tank 43 is placed on the inflow surface 33 through which the second fluid flows, and an outflow header tank 44 is placed on the outflow surface 34 through which the second fluid flows. The configurations of the inflow header tank 43 and the outflow header tank 44 both for the second fluid are respectively identical to those of the inflow header tank 41 and the outflow header tank 42 both for the first fluid. An inflow nozzle 431 and an outflow nozzle 441 are respectively placed on central portions of the inflow header tank 43 and the outflow header tank 44 in the Y direction.

The heat exchanger 1 includes two types of flow-directing members, i.e., a flow-directing member 51 of a first type and a flow-directing member 52 of a second type, for the first passages 21 through which the first fluid flows, and two types of flow-directing members, i.e., another flow-directing member 51 of the first type and another flow-directing member 52 of the second type, for the second passages 22 through which the second fluid flows. The flow-directing members 51 of the first type are each placed in one of the inflow header tanks 41 and 43. The flow-directing members 51 of the first type each enable a uniform distribution of dynamic pressure of fluid to the corresponding one of the inflow surface 31 through which the first fluid flows and the inflow surface 33 through which the second fluid flows. In other words, while the core 2 and the inflow header tanks 41 and 43 are all long and thin, and all extend along the Y direction, the inflow nozzles 411 and 431 are each placed on the central portion of the corresponding one of the inflow header tanks 41 and 43 in the Y direction. Furthermore, the inflow header tanks 41 and 43 each have a relatively short length in the X direction. As a result, fluid that has flowed into the inflow header tanks 41 and 43 is difficult to spread in the Y and Z directions. This tendency is accelerated, in particular, when the velocity of flow of fluid through each inflow nozzle 411, 431 is high. This causes the distribution of dynamic pressure of fluid to each inflow surface 31, 33 to be uneven. For example, in the uneven distribution, while the dynamic pressure of fluid to a region of each inflow surface 31, 33 onto which an opening of the corresponding one of the inflow nozzles 411 and 431 is projected and its surrounding region is extremely high, the dynamic pressure of fluid to a region of each inflow surface 31, 33 outside the region of each inflow surface 31, 33 onto which the opening of the corresponding one of the inflow nozzles 411 and 431 is projected and its surrounding region is relatively low, and the dynamic pressure of fluid to a peripheral portion of each inflow surface 31, 33 is lower. Such an uneven distribution of dynamic pressure causes uneven flow of fluid. The uneven flow of fluid corresponds to a situation where while the flow rates of fluid through central ones of the passages in the Y direction are high, the flow rates of fluid through the other ones of the passages located outwardly along the Y directions are low. In the illustrated core 2, uneven flow of fluid arising from an uneven distribution of dynamic pressure of the fluid corresponds to variations in the flow rate of fluid among different portions of the core 2 aligned in a direction in which the first and second passages 21 and 22 are stacked.

The flow-directing members 51 of the first type each enable a uniform distribution of dynamic pressure of fluid to the corresponding one of the inflow surfaces 31 and 33. Specifically, the illustrated flow-directing members 51 of the first type are plate-like baffles. The plate-like baffles are each disposed in the vicinity of the opening of the corresponding one of the inflow nozzles 411 and 431 placed on the central portion of the corresponding one of the inflow header tanks 41 and 43. As illustrated in the enlarged view in FIG. 2, each flow-directing member 51 of the first type has a plurality of through holes 511 penetrating the flow-directing member 51 along the thickness thereof. The through holes 511 have the same diameter, and are spaced substantially uniformly.

The length of each flow-directing member 51 of the first type in the Y direction is slightly greater than the diameter of the corresponding one of the inflow nozzles 411 and 431. Each flow-directing member 51 of the first type crosses the flow of fluid through the corresponding one of the inflow nozzles 411 and 431 into the corresponding one of the inflow header tanks 41 and 43, and is fixed to the inner wall of the corresponding one of the inflow header tanks 41 and 43 by, for example, welding as illustrated in FIG. 1B.

Each flow-directing member 51 of the first type configured as above interferes with the flow of fluid having flowed through the corresponding one of the inflow nozzles 411 and 431 into the corresponding one of the inflow header tanks 41 and 43. Part of the fluid flows through the through holes 511 of the flow-directing members 51 of the first type in the X directions without changing the directions of flow of the fluid, whereas the direction of flow of the remaining fluid is changed as indicated by the solid arrows in FIG. 1A such that the remaining fluid bypasses the flow-directing members 51 of the first type, thereby allowing the remaining fluid to flow while spreading in the Y directions. This enables a uniform distribution of dynamic pressure of fluid to each inflow surface 31, 33, and reduces variations in the flow rate of fluid into the core 2 among different portions of the core 2 aligned in the direction in which the first and second passages 21 and 22 are stacked. In other words, the flow rates of fluid into the first passages 21 are equalized, and the flow rates of fluid into the second passages 22 are equalized. This helps enhance the heat exchange efficiency of the heat exchanger 1.

Here, each flow-directing member 51 of the first type that is closer to the opening of the corresponding one of the inflow nozzles 411 and 431 than to the corresponding one of the inflow surfaces 31 and 33 of the core 2 enhances the dispersibility of fluid flowing through the corresponding one of the inflow nozzles 411 and 431 into the corresponding one of the inflow header tanks 41 and 43, and helps prevent variations in the flow rate of fluid through the core 2 among different portions of the core 2 aligned in the direction in which the first and second passages 21 and 22 are stacked. Note that the distribution of dynamic pressure of fluid to each inflow surface 31, 33 varies depending on, for example, the size of each inflow surface 31, 33, the shape of the corresponding one of the inflow header tanks 41 and 43, the shape and placement of the corresponding one of the inflow nozzles 411 and 431, and the velocity of flow of fluid. The size of each flow-directing member 51 of the first type, the sizes, number, and placement of the through holes 511, and the placement of each flow-directing member 51 of the first type merely need to be appropriately determined depending on the distribution of dynamic pressure of fluid to the corresponding one of the inflow surfaces 31 and 33. If necessary, the through holes may be omitted. A plurality of baffles may be placed in each header tank 41, 43.

By contrast, unlike the flow-directing members 51 of the first type, the flow-directing members 52 of the second type each reduce the differences among the flow rates of fluid through the channels of the corresponding ones of the first passages 21 and the second passages 22 due to different channel resistances of the channels. In other words, the first passages 21 and the second passages 22 of the core 2 each include the corresponding one of the distributor fins 212 and 222 as described above, and the channels defined by the corrugated fin 211 and the distributor fin 212 in each first passage 21 and the channels defined by the corrugated fin 211 and the distributor fin 222 in each second passage 22 have different lengths from their inlets to their outlets. In the example illustrated in FIG. 1B, in each first passage 21, some of the channels each having the outlet formed in a relatively upper portion of the outflow surface 32 have relatively short lengths, and the other ones of the channels each having the outlet formed in a relatively lower portion of the outflow surface 32 have relatively long lengths. The differences in length among the channels cause the differences in channel resistance among the channels, and the differences in channel resistance among the channels cause the differences among the flow rates of fluid through the channels. In other words, in the illustrated example, in each first passage 21, the flow rates of fluid through the some of the channels each having the outlet formed in the relatively upper portion of the outflow surface 32 are relatively high, and the flow rates of fluid through the other ones of the channels each having the outlet formed in the relatively lower portion of the outflow surface 32 are relatively low. Although not shown, in each second passage 22, some of the channels each having the outlet formed in a relatively upper portion of the outflow surface 34 have relatively long lengths, and the flow rates of fluid through the some of the channels are, therefore, relatively low, whereas the other ones of the channels each having the outlet formed in a relatively lower portion of the outflow surface 34 have relatively short lengths, and the flow rates of fluid through the other ones of the channels are, therefore, relatively high. The flow rate distribution of fluid flowing through each outflow surface 32, 34 is equivalent to the channel resistance distribution corresponding to the resistances of the channels. The uneven flow of fluid through the illustrated core 2 due to the differences in channel resistance among the channels corresponds to variations in the flow rate of fluid among different portions of the core 2 aligned in the Z direction (along the width of the core 2).

The flow-directing members 52 of the second type, which reduce the uneven flow of fluid arising from the differences in channel resistance among the channels, are each placed in the corresponding one of the outflow header tanks 42 and 44 unlike the flow-directing members 51 of the first type. Specifically, the flow-directing members 52 of the second type are plate-like members, and are each placed in a portion of the interior of the corresponding one of the outflow header tanks 42 and 44 near the corresponding one of the outflow surface 32 and 34 to face the corresponding one of the outflow surfaces 32 and 34. The flow-directing members 52 of the second type are also each fixed to the inner wall of the corresponding one of the outflow header tanks 42 and 44 by, for example, welding.

As illustrated in FIG. 3, the flow-directing members 52 of the second type also each have a plurality of same-diameter through holes 521 similar to those of the flow-directing members 51 of the first type. The through holes 521 penetrate the corresponding one of the flow-directing members 52 of the second type along the thickness thereof. In contrast to the flow-directing members 51 of the first type, the through holes 521 of each flow-directing member 52 of the second type are not spaced uniformly. Upper ones of the through holes 521 in the drawing sheet of FIG. 3 are spaced relatively widely, and lower ones of the through holes 521 in the drawing sheet of FIG. 3 are spaced relatively narrowly. Thus, the aperture ratio (the total area of holes per unit area) of an upper portion of each flow-directing member 52 of the second type is relatively low, and the aperture ratio of a lower portion thereof is relatively high. Such flow-directing members 52 of the second type are each positioned in response to the above-described channel resistance distribution corresponding to the flow rate distribution of fluid flowing through the corresponding one of the outflow surfaces 32 and 34. Specifically, a portion of each flow-directing member 52 of the second type having low aperture ratios faces the outlets of some of the channels having relatively low channel resistances in the corresponding one of the outflow surfaces 32 and 34, and a portion of each flow-directing member 52 of the second type having high aperture ratios faces the outlets of the other ones of the channels having relatively high channel resistances in the corresponding one of the outflow surfaces 32 and 34. Specifically, as illustrated in FIG. 3, one of the flow-directing members 52 of the second type faces the outflow surface 32 through which the first fluid flows such that the portion of the one of the flow-directing members 52 of the second type having low aperture ratios is above the portion of the one of the flow-directing members 52 of the second type having high aperture ratios. By contrast, the other one of the flow-directing members 52 of the second type faces the outflow surface 34 through which the second fluid flows such that the flow-directing member 52 illustrated in FIG. 3 is turned upside down, i.e., such that the portion of the other one of the flow-directing members 52 of the second type having high aperture ratios is above the portion of the other one of the flow-directing members 52 of the second type having low aperture ratios. Thus, since the portion of each flow-directing member 52 of the second type having low aperture ratios faces the outlets of the some of the channels having relatively low channel resistances, fluid is less likely to flow out of the some of the channels, whereas since the portion of each flow-directing member 52 of the second type having high aperture ratios faces the outlets of the other ones of the channels having relatively high channel resistances, fluid easily flows out of the other ones of the channels. This reduces the differences among the flow rates of fluid through the channels independently of the differences in channel resistance among the channels. In other words, the flow-directing members 52 of the second type reduce the uneven flow of fluid arising from the differences in channel resistance among the channels. This helps enhance the heat exchange efficiency of the heat exchanger 1.

If the flow-directing members 52 of the second type are relatively close to the corresponding outflow surfaces 32 and 34, the differences among the flow rates of fluid through the channels due to the differences in channel resistance among the channels are highly effectively reduced. If the flow-directing members 52 of the second type are away from the corresponding outflow surfaces 32 and 34, the portion of each flow-directing member 52 of the second type having low aperture ratios less effectively restricts the flow rates of fluid through the corresponding channels.

As such, the provision of the flow-directing members of two types, i.e., the flow-directing members 51 of the first type and the flow-directing members 52 of the second type, can reduce both the uneven flow of fluid arising from the dynamic pressure distribution of fluid to each inflow surface 31, 33 of the core 2 (in the illustrated example, variations in the flow rate of fluid among different portions of the core 2 aligned in the direction in which the first and second passages 21 and 22 are stacked) and the uneven flow of fluid arising from the differences in channel resistance among the channels of the core 2 (in the illustrated example, variations in the flow rate of fluid among different portions of the core 2 aligned along the width of the core 2). In other words, two types of uneven flows of fluid with different mechanisms for flow generation are each reduced by the corresponding ones of the two types of the flow-directing members, i.e., the flow-directing members 51 of the first type and the flow-directing members 52 of the second type, to accurately reduce the two types of even flows, thereby enhancing the heat exchange efficiency of the heat exchanger 1.

Here, the spacing between each adjacent pair of the same-diameter through holes 521 of the flow-directing member 52 of the second type illustrated in FIG. 3 is varied to vary the aperture ratio. In contrast to this, the diameter of through holes spaced uniformly may be varied to vary the aperture ratio. Alternatively, both the diameter of through holes and the spacing between each adjacent pair of the through holes may be varied to vary the aperture ratio of the flow-directing member 52 of the second type.

The through holes of the flow-directing members 52 of the second type should not be limited to such circular holes as illustrated in FIG. 3, and may be, for example, such elongated through holes 531 as illustrated in FIG. 4. In the example illustrated in FIG. 4, the size of each elongated through hole 531 and the spacing between each adjacent pair of the elongated through holes 531 are both varied. Only either the size of each elongated through hole 531 or the spacing between each adjacent pair of the elongated through holes 531 may be varied to vary the aperture ratio.

The aperture ratio of each flow-directing member 52 of the second type may be successively varied along the X direction as illustrated in FIG. 3, or may be varied in stages along the X direction as illustrated in FIG. 4.

One of the flow-directing members 52 of the second type may be positioned to face at least a portion of the outflow surface 32 as illustrated in, for example, FIG. 5 instead of positioning the flow-directing members 52 of the second type to face the corresponding entire outflow surfaces 32 and 34. FIGS. 5A and 5B illustrate an example in which one of the flow-directing members 52 of the second type for the first passages 21 faces a portion of the outflow surface 32 that is about half the size of the outflow surface 32. A portion of the outflow surface 32 that does not face the one of the flow-directing members 52 of the second type is equivalent to a portion of the outflow surface 32 facing a portion of a flow-directing member 52 of the second type having higher aperture ratios.

Furthermore, one of the flow-directing members 52 of the second type may be placed in the inflow header tank 41 instead of in the outflow header tank 42. FIGS. 6A and 6B illustrate an example in which one of the flow-directing members 52 of the second type for the first passages 21 is placed in the inflow header tank 41. The one of the flow-directing members 52 of the second type is also a plate-like member having different aperture ratios as illustrated in FIGS. 3 and 4. The one of the flow-directing members 52 of the second type is positioned to face the inflow surface 31 such that the aperture ratio distribution of the one of the flow-directing members 52 of the second type corresponds to the channel resistance distribution across the inflow surface 31. This allows the flow rates of fluid into the channels to be adjusted in response to the channel resistances, thereby reducing the differences among the flow rates of fluid passing through the channels.

Here, also in the case where the one of the flow-directing members 52 of the second type is positioned to face the inflow surface 31, the one of the flow-directing members 52 of the second type is preferably close to the inflow surface 31 to adequately reduce the uneven flow of fluid. Specifically, the one of the flow-directing members 52 of the second type placed in the inflow header tank 41 has different aperture ratios, which cause the flow rates of fluid through the one of the flow-directing members 52 of the second type and thus the flow rates of fluid through the inflow surface 31 into the core 2 to be different. This reduces the differences among the flow rates of fluid through the channels. For this reason, if the one of the flow-directing members 52 of the second type is away from the inflow surface 31, the differences among the flow rates of fluid through the channels, which are provided by passing fluid through the one of the flow-directing members 52 of the second type, are less effective before the fluid reaches the inflow surface 31. By contrast, if the one of the flow-directing members 52 of the second type is excessively close to the inflow surface 31, the velocity gradient of fluid between portions of the one of the flow-directing members 52 of the second type corresponding to the through holes 521 (i.e., openings) and the other portion thereof (i.e., a portion thereof except the openings) affects the flow of fluid through the inflow surface 31 into the channels. Specifically, while the flow rate of fluid into some of the inlets facing the openings increases, fluid hardly flows into the other ones of the inlets facing the portion of the one of the flow-directing members 52 of the second type except the openings. This not only prevents the one of the flow-directing members 52 of the second type from functioning to reduce the differences among the flow rates of fluid through the channels, but also may increase the differences. When, as such, the one of the flow-directing members 52 of the second type is placed in the inflow header tank 41, the one of the flow-directing members 52 of the second type may be difficult to position. By contrast, when the one of the flow-directing members 52 of the second type is placed in the outflow header tank 42 as illustrated in, for example, FIG. 1, the velocity gradient of fluid that has passed through the one of the flow-directing members 52 of the second type does not need to be considered. This increases the flexibility in positioning the flow-directing member 52 of the second type, and can effectively reduce the uneven flow of fluid arising from the differences in channel resistance among the channels.

One of the flow-directing members 51 of the first type is placed in the inflow header tank 41. Thus, when the one of the flow-directing members 52 of the second type is placed in the inflow header tank 41, the two types of flow-directing members, i.e., the one of the flow-directing members 51 and the one of the flow-directing members 52, are placed in the inflow header tank 41. For this reason, the configuration of the inflow header tank 41 and the configuration of the inflow nozzle 411 may make it difficult for the two types of flow-directing members, i.e., the one of the flow-directing members 51 and the one of the flow-directing members 52, to be each positioned to adequately function. Placing one of the flow-directing members 52 of the second type in the outflow header tank 42 means that the one of the flow-directing members 51 of the first type and the one of the flow-directing members 52 of the second type are respectively placed to sides of the core 2 where the inflow surface 31 and the outflow surface 32 are located. This helps suitably position the flow-directing members 51 and 52 of the first and second types.

A heat exchanger 10 providing a substantially uniform distribution of dynamic pressure of fluid to an inflow surface 31 of a core 2 as illustrated in, for example, FIGS. 7A and 7B may fail to include a flow-directing member of the first type facing the inflow surface 31. In other words, in FIGS. 7A and 7B, ducts 44 and 45 form a passage of a first fluid. This allows the distribution of dynamic pressure of the first fluid to the inflow surface 31 of the core 2 to be substantially uniform. This eliminates the need for one of the flow-directing members of the first type. By contrast, first passages 21 of the core 2 each include at least a distributor fin 212 as described above, resulting in differences in channel resistance among the channels. To address this problem, in the heat exchanger 10 illustrated in FIGS. 7A and 7B, a flow-directing member 52 of the second type is positioned to face an outflow surface 32 of the core 2. This can prevent variations in the flow rate of the first fluid among different portions of the core 2 aligned along the width of the core 2. The variations may be caused by the differences in channel resistance among the channels. In the example illustrated in FIGS. 7A and 7B, a flow-directing member 52 of the second type may be placed to the side of the core 2 where the inflow surface 31 is located.

Depending on the configuration of a heat exchanger, only either channels for the first fluid or channels for the second fluid may be provided with the flow-directing members of the first and second types or the flow-directing member of the first or second type.

The flow-directing members of the first type reducing uneven flow of fluid caused by the distribution of dynamic pressure should not be limited to baffles, and the configuration of the flow-directing members of the first type may be selected from various known configurations, depending on the configurations of the corresponding inflow header tanks and the configurations and placement of the corresponding inflow nozzles.

Here, the heat exchanger 1, 10 including the plate fin core 2 is used as an example to describe the flow-directing members of the first and second types. Flow-directing members of the first and second types can be used for a multitubular heat exchanger. A multitubular heat exchanger including, for example, pipes bent in a U shape causes channels to have different channel resistances. This may cause uneven flow of fluid. The flow-directing members of the second type help reduce the uneven flow of fluid also in such a multitubular heat exchanger.

In either the plate fin heat exchanger or the multitubular heat exchanger, the differences in channel resistance among the channels may be caused not only by the differences in length among the channels but also by the differences in cross-sectional area among the channels or both the differences in length among the channels and the differences in cross-sectional area among the channels. In either of the cases, the flow-directing members of the second type can reduce the differences among the flow rates of fluid through the channels arising from the differences in channel resistance among the channels.

INDUSTRIAL APPLICABILITY

As described above, the heat exchanger disclosed herein includes the flow-directing members of the first type and the flow-directing members of the second type. The flow-directing members of the first type each provide a uniform distribution of dynamic pressure of fluid to the corresponding one of the inflow surfaces. The flow-directing members of the second type reduce the differences among the flow rates of fluid through the corresponding channels arising from the differences in channel resistance among the corresponding channels. The flow-directing members of the first and second types can reduce the uneven flow of fluid. This helps enhance the heat exchange efficiencies of various heat exchangers. The flow rates of fluid through the channels are equalized, thereby helping improve the reaction efficiency and thus performance of a heat exchanger (i.e., a catalytic reactor) that has channels each including a catalyst support and is used, for example, to cause the fluid passing through the channels to react.

DESCRIPTION OF REFERENCE CHARACTERS

1 Heat Exchanger

10 Heat Exchanger

2 Core

21 First Passage

22 Second Passage

211 Corrugated Fin

212, 222 Distributor Fin

31, 33 Inflow Surface

32, 34 Outflow Surface

51 Flow-Directing Member Of First Type

52 Flow-Directing Member Of Second Type

521, 531 Through Hole

HEAT EXCHANGER

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CPC

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Abstract

Description

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