FR3100874A1 - Heat exchanger - Google Patents

Abstract

Heat exchanger (1) comprising a radiator (5a-5e) comprising a base part (7) and fins (10) formed of a projecting rib in which a proximal end (13) of each of the fins is connected to the base portion and a distal end (14) of each of the fins extend to the heat radiating side of the base portion (7), the plurality of fins being brought into contact with the coolant and being able to radiate from the base portion (7). heat absorbed from the heat absorbing side of the base part to the refrigerant. The fins are arranged in parallel and are formed such that a distance between the fins disposed adjacent to each other on a distal end side is greater than a distance between the fins on a proximal end side. . Figure to be published with the abstract: Fig. 1

Description

Heat exchanger

In the background, the field of the present invention relates to a heat exchanger using the latent heat produced by a change in a gaseous/liquid phase of a refrigerant.

In the prior art, conventionally, a heat exchanger is known which uses the latent heat produced by a change in a gaseous/liquid phase of a refrigerant (see, for example, International Publication No. WO2014/049805).

There is a view intended to describe a typical 900 heat exchanger. shows (a) a complete perspective view of the heat exchanger 900.

As represented by , the conventional heat exchanger 900 has a radiator 905 which includes: a base portion 907 which defines a heat absorbing side (lower side) and a heat radiating side (upper side); and a plurality of fins 910 forming projecting ribs on which proximal ends are connected to the base portion 907 and distal ends extend toward the heat radiating side, the fins of the plurality of fins 910 are brought into contact with a refrigerant and radiate the heat absorbed on the heat absorption side of the base part 907 to the refrigerant. The plurality of fins 910 are arranged parallel to each other in a longitudinal direction (a direction parallel to a y-axis) of the fins 910. A distance between the fins arranged adjacent to each other others (fin distance) is set to a fixed value extending from a proximal end side to a distal end side when the fins arranged adjacent to each other are viewed along the longitudinal direction of the fins.

A heat-generating element H is disposed on the heat-absorbing side of the base part 907 such that the heat-generating element H is contacted with a back surface 907a of the base part 907. The radiator 905 is contained in a housing 6 in a liquid-tight manner. A space formed by the base part 907 of the radiator 905 and the case 6 is filled with the refrigerant such as a coolant.

When the base part 907 absorbs heat from the heat generating element H such that a temperature of the base part 907 rises to a high temperature, the temperature of the fins 910 also rises to a high temperature. high value, simultaneously with the temperature increase of the base part 907. When a surface temperature of the fins 910 exceeds a boiling point of the coolant, a part of the coolant which is contacted with surfaces of the fins 910 undergoes a gas phase change in which the refrigerant changes from a liquid to a gas (evaporation/vaporization). At this point, heat (latent heat) is transferred from the fins 910 to the cooler. The gas forms "bubbles" due to surface tension on the surfaces of the fins 910.

When the change in the gas phase is favored so that bubbles grow larger (the volumes of the bubbles being increased), the buoyancy of the bubbles increases. When the buoyancy exceeds a value sufficient to lift the bubbles, the bubbles separate from the surfaces of the fins 910 and are lifted into the liquid phase coolant and strike an upper inner wall of the casing 6. When the bubbles strike the upper inner wall of the casing 6, the heat contained in the bubbles is transferred to the housing 6. The heat transferred by the bubbles is collected via an upper surface of the housing 6a (see an arrow represented in bold line on the ). Such heat is transferred mainly to the air by a radiator or the like not shown in the drawing, and the bubbles, the temperature of which is lowered due to the aforementioned heat transfer, undergo a liquid phase change (condensation) from a gas to a liquid, and return to the refrigerant again in the liquid phase.

In this way, the conventional heat exchanger 900 can perform heat exchange using the latent heat produced by a gas/liquid phase change of a refrigerant. A heat generating element H such as a semiconductor can be cooled using such a heat exchanger 900.

In general, heat transfer performance is improved in proportion to the effective area of the heat transfer surface. In the conventional heat exchanger 900, the plurality of fins 910 are arranged parallel to each other in the longitudinal direction of the fins (so-called rib-shaped fins are formed) and therefore , the effective area of the heat transfer surface can be increased in a limited space and, therefore, a larger contact area can be ensured between the fins 910 and the coolant. Accordingly, the heat exchanger 900 presents an opportunity to exchange a large amount of heat.

However, in summary of the invention, in a typical heat exchanger 900, when the rib-like fins 910 are arranged at a narrower pitch in an attempt to increase the effective heat transfer area, bubbles are likely to coalesce. between the fins arranged adjacent to each other.

It is assumed a case where the fin distance is set to a value less than a diameter of a bubble that can rise in the liquid-phase refrigerant (a diameter of a spherical bubble having a size that allows the initiation of bubble rise). In a process in which the bubble grows gradually, when the bubble is sandwiched between a first wall of a first fin and a second wall of the other fin (the two walls being simply referred to as "one wall of a fin" or "a fin surface") such that bubble growth is limited, the only way the bubble will grow to a volume that allows the bubble to rise is for the bubble to expand in a vertical direction.

Even when the bubble grows to a volume that allows the bubble to rise or a larger volume, the larger part of the bubble is not brought into contact with the liquid phase (liquid) refrigerant and therefore , the bubble cannot receive rise pressure from the liquid. On the contrary, the bubble is brought into close contact with the walls of the fins, so that the bubble is sandwiched between the walls and, therefore, given a resisting force between a bubble main body and the walls of the fins , it is difficult for the bubble main body to separate from the walls of the fins so that the elevation of the entire bubble main body cannot be secured easily. Then, the bubble main body grows to a state in which a space between the fins 910 is filled with gas from the proximal end side to the distal end side of the fins 910 thus leading to a state in which the walls fins which form heat transfer surfaces are almost entirely covered by the bubble main body.

In such a case, for example, when there is an impulse such that the buoyancy of the bubble main body greatly exceeds the resistance effort mentioned above or an impulse such that the bubble main body receives an external effort such as vibration or stirring, a small bubble is gradually separated from the bubble main body such that a part of the bubble main body is separated from an upper side of the bubble main body. However, even when the separated bubble is separated from the bubble main body, new gas is rapidly generated due to gas phase change of the remaining refrigerant, and the bubble main body swells again.

In this way, on the conventional heat exchanger 900, a bubble is likely to chronically cluster between the fins arranged adjacent to each other and, therefore, when the heat exchanger 900 is actually in use, a period during which the bubbles are brought into contact with the surfaces of the fins is extended.

During a period that the fin surfaces are in contact with the bubbles (gas), a small amount of "sensible heat" is transferred from the fin surfaces to the gas. However, compared to "latent heat" transfer from the fin surfaces to the liquid, significant heat transfer cannot be provided by sensible heat transfer. That is, during a period in which the fin surfaces are kept in contact with the bubbles, it is difficult to extract heat from the fin surfaces. Consequently, a temperature of the surfaces of the fins eventually becomes substantially equal to a temperature of the bubbles (gas) and becomes equal to a temperature which greatly exceeds a boiling point or a temperature obtained by superheating (for example, 120°C when the refrigerant is water). In other words, it is true to say that, to increase cooling efficiency, it is desirable that the fin surfaces be contacted with the liquid phase refrigerant for as long as possible.

As previously described, in the conventional heat exchanger 900, bubbles are liable to coalesce and therefore the period during which the fin surfaces are contacted with bubbles is prolonged. Consequently, the heat exchanger 900 cannot effectively cool the fins 910 and the base part 907, as well as, possibly, the heat generating element H.

The present invention has been made in view of the aforementioned circumstances, and it is an object of the present invention to provide a heat exchanger which exhibits higher cooling efficiency than a conventional heat exchanger.

According to a first aspect of the present invention, there is provided a heat exchanger which utilizes latent heat produced by a change on a gas/liquid phase of a refrigerant, the heat exchanger comprising a radiator, wherein the radiator comprises: a base portion configured to define a heat absorbing side and a heat radiating side; and a plurality of fins, each being formed of a protruding rib in which a proximal end of each of the fins is connected to the base portion and a distal end of each of the fins extends toward the heat radiating side , the plurality of fins being brought into contact with the coolant and capable of radiating absorbed heat from the heat absorbing side of the base part to the coolant, wherein the fins of the plurality of fins are arranged parallel in a longitudinal direction of the plurality of fins, and in a state in which the fins disposed adjacent to each other are viewed along the longitudinal direction of the fins, the fins of the plurality of fins are formed of such that a distance between the fins disposed adjacent to each other on a distal end side is greater than a distance between the fins on one side of proximal end.

In the heat exchanger according to the present invention, it is desirable that the distance between the fins disposed adjacent to each other is gradually increased from the proximal end side to the distal end side.

In the heat exchanger according to the present invention, it is desirable that the distance between the fins disposed adjacent to each other is monotonically increased from the proximal end side to the distal end side.

In the heat exchanger according to the present invention, it is desirable that an inclined part be formed on at least one wall of each of the fins on the distal end side so that an angle formed between the inclined part and a a predetermined reference plane approximately parallel to a major surface of the base part is set less than an angle formed between the wall on the proximal end side and the reference plane.

In the heat exchanger according to the present invention, it is desirable that the fins arranged adjacent to each other are formed such that, by equating a distance between the fins arranged adjacent to each other at the distal end at Wt and a distance between fins disposed adjacent to each other at the proximal end at Wb, the Wt/Wb ratio is within an inclusive range of 1.5 to 5.0 .

In the heat exchanger according to the present invention, it is desirable that the fins arranged adjacent to each other are formed such that the distance between the fins arranged adjacent to each other is within an inclusive range of 0.1mm to 0.8mm.

According to the heat exchanger of the present invention, it is possible to obtain a heat exchanger which has higher cooling efficiency than conventional heat exchangers.

A brief description of the drawings will now be given.

Figs. 1A and 1B are views for describing a heat exchanger 1 according to an embodiment 1;

Figs. 2A to 2E are views for describing the working principle of the heat exchanger 1 according to Embodiment 1;

there is a view for describing the principle of operation of the heat exchanger 1 according to the embodiment 1;

there is a view for describing an evaluation result of the heat exchanger 1 according to the embodiment 1;

there is an enlarged cross-sectional view of a main part for describing a radiator 5b of an embodiment 2;

Figures 6A to 6C are enlarged cross-sectional views of a main part intended to describe radiators 5c, 5d, 5e according to an alternative; And

there is a view intended to describe a typical 900 heat exchanger.

Preferred embodiments will be described in detail.

Hereinafter, embodiments of a heat exchanger according to the present invention are described with reference to the drawings. The respective drawings are schematic views showing a first example, and do not strictly represent actual dimensions, ratios and the like. In this specification, a direction substantially parallel to a direction that acts on the gravitational acceleration (vertical line) when a heat exchanger is placed in a normal posture (-z direction) is referred to as "downward", and a direction (direction +z) opposed to "downward" is denoted by "upward".

An embodiment 1 will be described.

The configuration of a heat exchanger 1 according to Embodiment 1 is first described.

Figures 1A and 1B are views for describing a heat exchanger 1 according to an embodiment 1. Figure 1A is an overall perspective view of the heat exchanger 1. Figure 1B is an enlarged cross-sectional view of a main part taken along a plane perpendicular to a longitudinal direction of the fins 10 in a zone surrounded by a broken line D in FIG. 1A, as seen along a direction indicated by an arrow Q. FIGS. 2A to 2E, the , there and Figs. 6A to 6C described later are views corresponding to an enlarged cross-sectional view of the main part shown in Fig. 1B.

The overall configuration of the heat exchanger 1 is then described.

The heat exchanger 1 according to embodiment 1 is a so-called refrigerant boiling type heat exchanger which utilizes latent heat produced by a gas/liquid phase change of a refrigerant.

As shown in Figure 1A, the heat exchanger 1 comprises a radiator 5a having a base part 7 and a plurality of fins 10. The radiator 5a is contained in a casing 6 in a liquid-tight manner. A space formed by the base part 7 of the radiator 5a and the casing 6 is filled with a refrigerant CL such as a coolant. A heat-generating element H is disposed on a heat-absorbing side (lower side in the drawing) of the base part 7 in a state in which the heat-generating element H is brought into contact with a back surface 7a of the base part 7.

The heat generating element H can be any element which requires cooling. For example, the heat generating element H is an electronic device such as a semiconductor.

As the CL refrigerant, an agent referred to as a coolant in general which maintains a liquid state at an ambient temperature can be used. For example, an alcohol-based solvent having a boiling point of 80°C or less can be used as the LC refrigerant.

A guaranteed operating temperature of an electronic device is set to several tens of °C or less in many cases, and therefore, using the previously mentioned CL refrigerant, cooling can be set by setting a temperature less than or equal to several tens of °C as the cooling setpoint temperature. The coolant CL can be an agent having, for example, a viscosity lower than that of water. This is because the bubbles can acquire buoyancy which allows the bubbles to rise to a stage in which a diameter of the bubble is relatively small (small diameter) and therefore it is expected that as soon as the bubbles are produced, the bubbles can be successively and regularly detached from the walls of the fins (described later).

The detailed configuration of the heat exchanger 1 is then described starting with the base part 7.

As shown in Figure 1B, the base portion 7 defines a heat absorbing side and a heat radiating side. The base part 7 is made of a metal foil material.

The "heat absorbing side" is a lower side (a rear surface side 7a of the base part) on which the heat generating element H is arranged, and the "heat radiating side" is a side top (a side on which an inner lower part 7b of the base part and the fins 10 described later are arranged) on which the refrigerant CL is present. The term "defines" can also be expressed as "forms a boundary" or "is an interface".

The fins 10 are then described. The fins 10 are brought into contact with the CL cooler and radiate absorbed heat from the heat absorption side of the base part 7 of the CL cooler. As long as the fins 10 can radiate heat to the cooler CL, the fins 10 can be made of any material. However, in embodiment 1, the fins 10 are made of a metal such as aluminum, aluminum alloy, copper, copper alloy or stainless steel.

The proximal ends 13 of the fins 10 are connected to the base portion 7, and the distal ends 14 of the fins 10 form projecting ribs which extend toward a heat radiating side. In this embodiment, "connected to" means that the proximal ends 13 are connected to the base portion 7 at least from a thermal circuit point of view. In Embodiment 1, the fins 10 and the base portion 7 which is a plate member, are unitarily formed using the same material and therefore the proximal ends 13 and the base portion 7 are also physically connected to each other from a thermal circuit point of view. "Protruding ribs" means that the protruding ribs extend in a linear manner in a planar direction when the fins 10 are viewed from above along a z-axis.

The fin 10 has a first wall 11 on a first side (one side along an -x direction) extending from the proximal end 13 towards the distal end 14, and has a second wall 12 on the other side (one side along a direction +x) extending from the proximal end 13 towards the distal end 14. In the description given below, these first wall 11 and second wall 12 can also be designated collectively by "the walls of the fin". The term "fin walls 11, 12" and inner bottom portion 7b (described later) of base portion 7 are positioned as a "heat transfer surface" through which heat is transferred to the CL refrigerant. In the following description, "fin walls 11, 12" and inner bottom portion 7b of base portion 7 may also be referred to collectively as "fin surface".

Next, the relationship between fins disposed adjacent to each other will be described.

The fins of the plurality of fins 10 are arranged parallel to each other in a longitudinal direction of the fins 10 (in this embodiment, a direction along a y axis).

The first wall 11 and the second wall 12 of each fin 10 rise from the inner bottom part 7b disposed on a front surface side of the base part 7. The "slot SL1" is formed by the first wall 11 of a first fin 10 from among the fins arranged adjacent to each other, the second wall 12 of the other fin 10, and the inner lower part 7b of the base part 7 (see FIG. 1B).

In the heat exchanger according to embodiment 1, in a state in which the fins disposed adjacent to each other are viewed in the longitudinal direction of the fins, the plurality of fins 10 are formed such that a distance Wt between the fins 10 disposed adjacent to each other on a distal end side 14 is greater than a distance Wb between the fins 10 disposed adjacent to each other on a side of proximal end 13. That is, the fins 10 are formed such that the distance between the fins arranged adjacent to each other (fin distance) is small on the side of proximal end 13 and is large on the distal end 14 side. To express it in other words from a viewpoint of the slit SL1, the slit SL1 is narrow on an inner lower part 7b side. e t is wide on an open side which is the distal end side 14 of the fins 10 (see FIG. 1B).

In Embodiment 1, the distance between the fins disposed adjacent to each other (fin distance) gradually increases from the proximal end side 13 to the distal end side 14 (see Fig. 1B).

The expression "gradually increases" means a state in which the fin distance is neither increased locally on intermediate portions of the fins nor reduced locally on intermediate portions of the fins. In the configuration mentioned above, a case in which there is a part over which the same fin distance is partially continuous is also included in the term "gradually increases". The monotonic increase in fin distance and the linear increase in fin distance are also considered to be a gradual increase in fin distance as seen microscopically and, therefore, the monotonic increase and linear increase are also included in the expression "gradually increases".

As shown in Fig. 1B, equating the fin distance at the proximal end 13 to Wb, the fin distance at the distal end 14 to Wt, and the fin distance at the intermediate position between the proximal end 13 and the distal end 14 to Wm, the relation Wb≤Wm≤Wt is established. Accordingly, the fin distance gradually increases from the proximal end side 13 to the distal end side 14.

In Embodiment 1, the distance between the fins disposed adjacent to each other increases monotonically from the proximal end side 13 to the distal end side 14 (see Fig. 1B)."

The expression "increasing monotonically" can also be expressed as such that, when the distance between the fins arranged adjacent to each other is seen by scanning from the proximal end 13 towards the distal end 14, there is no part on which the same fin distance is constant (nor respectively that there is a part on which the fin walls are arranged linearly, parallel to each other). another, nor a part on which the fin walls are continuously formed maintaining the same distance although the fin walls are formed in a curved line).

In embodiment 1, the fins disposed adjacent to each other are formed such that, equating a distance between the fins disposed adjacent to each other at the distal end 14 to Wt, and a distance between the fins arranged adjacent to each other at the proximal end 13 to Wb, a value of Wt/Wb becomes a value which is within an inclusive range of 1.5 to 30, 0. In this case, it is preferable that the fins arranged adjacent to each other are formed such that the value of Wt/Wb becomes equal to a value within an inclusive range of 1.5 to 5.0 . It is more preferable that the fins arranged adjacent to each other are formed such that the value of Wt/Wb becomes equal to a value within an inclusive range of 1.5 to 3.0.

Further, in Embodiment 1, it is preferable that the fins disposed adjacent to each other are formed such that the distance Wb between the fins disposed adjacent to each other at proximal end 13 is within the inclusive range of 0.1 mm to 0.8 mm. It is more preferable that the fins arranged adjacent to each other are formed such that the distance Wb is within the range inclusive of 0.2 mm to 0.4 mm.

Next, the principle of operation and the advantageous effects of the heat exchanger 1 according to the embodiment 1 will be described.

Figs. 2A to 2E are views for describing the principle of operation of the heat exchanger 1 according to Embodiment 1.

Figures 2A to 2E sequentially and schematically depict a mode in which B bubbles are produced near the inner bottom portion 7b of the base portion, B bubbles grow, and B bubbles separate from the fin surface. . In Figs. 2A to 2E, a case is considered in which an upliftable bubble diameter (a spherical bubble diameter of a size that allows initiation of bubble uplift) is relatively large in view of of the relationship between the diameter of the rising bubble and a physical property of the CL refrigerant.

There is a view for describing the working principle of the heat exchanger 1 according to the embodiment 1. The schematically depicts the respective bubbles B1, B2, B3, B4, B5 in a mode in which the bubbles are produced and separated considering the case where the diameter of the elevating bubble is at an intermediate size in view of the relationship between the diameter of the bubble that can rise and the physical property of the CL refrigerant.

In the heat exchanger 1 according to embodiment 1, the plurality of fins 10 are formed such that the distance Wt between the fins arranged adjacent to each other at the distal end 14 is defined at a value greater than the distance Wb between the fins arranged adjacent to each other at the proximal end 13. In other words, as seen from the bubbles produced on the walls of the fins, there is no fin wall in the up direction (+z direction) and in the direction relatively close to the fin walls with respect to the up direction (a region at a relatively small angle).

Therefore, during a B-bubble growth process, B-bubbles can also be inflated in an oblique rising direction without being blocked by the fin walls in a lateral direction (a direction parallel to an x-axis), unlike heat exchangers. conventional thermal systems, while receiving one after the other an additional source of gas, not only from the inner lower part 7b of the base part, but also from the walls 11, 12 of the fins and, consequently , a large part of the diameter of the bubble B can be increased.

When the bubble B grows, given an internal pressure of a gas in the bubble B, the bubble B pushes the walls 11, 12 of the fins which are globally inclined and the internal lower part 7b, and such a force also acts as a separation force of the bubble B itself relative to the walls 11, 12 of the fins and to the inner lower part 7b.

In this way, in the heat exchanger 1 according to the embodiment 1, as soon as the bubbles B are produced, it is possible to sequentially and evenly separate the bubbles B from the fin surfaces.

In the heat exchanger 1 according to the embodiment 1, there is no fin wall in the upward direction of the bubbles and in the direction relatively close to the fin walls with respect to the upward direction, and therefore , an environment is created in which a body which shows resistance when the bubbles rise can be eliminated as much as possible.

Therefore, as shown, for example, in the , when the bubbles grow to a certain level and once they acquire sufficient buoyancy to allow the bubbles to rise, the bubbles (B1, B3, B4 and the like) can rise sequentially and smoothly.

It can also be considered a case in which the bubble on the lower side (eg, B4) grows earlier than the bubble on the upper side (eg, B2), and the bubble on the lower side separates from the surface. of the fin (the inner lower part 7b and the walls 11, 12 of the fin). In this case, the volume of the bubble on the lower side (eg B4) increases by merging with the bubble on the upper side (eg B2) and therefore the buoyancy increases further such that the separation bubble that was previously disposed above (eg, B2) relative to the fin surface is also accelerated.

As has been described so far, according to the heat exchanger 1 of embodiment 1, a period during which the bubbles are brought into contact with the fin surface can be shortened and, therefore, a period during which the fin surface is contacted with the liquid-phase CL refrigerant can be extended compared to conventional heat exchangers.

Therefore, the heat exchanger of the present invention can increase opportunities for changing the refrigerant from the liquid phase (liquid) to a phase with bubbles (gas) on the fin surfaces and, therefore, it is possible to absorb more latent heat from the fin surfaces so that the heat exchanger can exhibit high cooling efficiency compared with that of conventional heat exchangers.

When the fin distance is locally narrowed at an intermediate position of the fins, there is a possibility that the fins form a bottleneck when bubble B rises. On the contrary, when the fin distance is widened locally at an intermediate position of the fins, the rising bubbles B merge with each other or the like and, therefore, a volume of the bubble increases unexpectedly creating thus a possibility that the bubble sticks at the position where the fin distance is locally narrowed above the bubble. That is, when the fin distance is widened locally at the intermediate position of the fins, it also creates a possibility that such a structure causes the bubble to stagnate and increase in volume.

On the other hand, in the heat exchanger 1 according to the embodiment 1, the distance between the fins disposed adjacent to each other gradually increases from the proximal end portion toward the end portion distal. Therefore, there is no possibility that the previously mentioned drawbacks occur and therefore the bubbles can rise more gradually.

In the heat exchanger 1, the distance between the fins arranged adjacent to each other (fin distance) monotonically increases from the proximal end side 13 to the distal end side 14.

The heat exchanger 1 having such a configuration does not have a part in which the same fin distance is constant, and therefore the bubbles B can separate more regularly from the fin surface (the inner lower part 7b and the walls 11, 12 of the fins).

Equating the distance between the fins disposed adjacent to each other at the distal end 14 to Wt and the distance between the fins disposed adjacent to each other at the proximal end 13 to Wb, when Wt/Wb is set to a value less than 1.5, the resistance of the walls 11, 12 of the fins increases when the bubbles B rise and therefore the cooling efficiency cannot be increased contrary to expectation . Further, when Wt/Wb is set to a value larger than 30.0, it is necessary to ensure a relatively large width in order to arrange the fins 10 and, therefore, an arrangement pitch of the fins 10 is increased. so that a large space becomes necessary to arrange a large number of fins 10.

In view of the foregoing, it is desirable that the value of Wt/Wb be defined by taking an appropriate compromise in accordance with the specifications and performance of the heat exchanger 1 to be produced. In the heat exchanger 1 according to embodiment 1, the fins arranged adjacent to each other are formed such that Wt/Wb is within an inclusive range of 1.5 to 30.0. It is desirable that the fins disposed adjacent to each other be formed such that Wt/Wb is within an inclusive range of 1.5 to 5.0. It is more preferable that the fins disposed adjacent to each other are formed such that Wt/Wb is within an inclusive range of 1.5 to 3.0.

In the heat exchanger 1 according to embodiment 1, the heat exchanger 1 can provide both cooling efficiency and space saving by setting the value of Wt/Wb as described above.

The inventors of the present invention have monitored and evaluated the relationships among the distance Wb between the fins disposed adjacent to each other at the proximal end 13, the validity of an effective heat transfer surface to required specifications and the ease of bubble separation property B. The is a view for describing an evaluation result of the heat exchanger 1 according to the embodiment 1. In a table shown in Fig. , a double circle indicates that the assessment result is extremely good, a single circle indicates that the assessment result is good, and a triangle indicates that the assessment result is possible, but has some problems. As shown on the , it is confirmed that when the distance Wb between the fins arranged adjacent to each other at the proximal end 13 is within an inclusive range of 0.1 mm to 0.8 mm, the favorable result is obtained on the two evaluation criteria. It is also confirmed that when the distance Wb between fins arranged adjacent to each other at the proximal end 13 is within an inclusive range of 0.2 mm to 0.4 mm, a good compromise and a favorable results are obtained on the two evaluation criteria.

From the above, forming the heat exchanger 1 such that the distance between the fins arranged adjacent to each other at the proximal end 13 is within an inclusive range of 0.1 mm at 0.8 mm, the heat exchanger 1 makes it possible to obtain both the assurance of the ease of separation of the bubbles B and the assurance of a sufficient contact surface of the fins and of the coolant CL.

Next, a heat exchanger 2 according to an embodiment 2 is described.

There is an enlarged cross-sectional view of a main part for describing a radiator 5b of Embodiment 2. In Embodiment 2, with respect to the constitutional elements identical to the corresponding constitutional elements of Embodiment 1 on the structures of base and technical characteristics, the same reference numerals as for Embodiment 1 are used and the description of such constitutional elements is omitted.

The heat exchanger 2 according to the embodiment 2 (the indication of the reference numeral 2 in the drawings being omitted) has, in principle, substantially the same configuration as the heat exchanger 1 according to the embodiment 1. However , the heat exchanger 2 according to the embodiment 2 differs from the heat exchanger 1 according to the embodiment 1 with respect to the structure of the radiator.

That is to say, as shown in the , inclined portions 25 are formed on the radiator 5b of embodiment 2. More specifically, on the radiator 5b of embodiment 2, with respect to the walls (a first wall 21 and a second wall 22) that has a fin 20, the inclined portion 25 is formed on at least one wall (in this embodiment, the first wall 21) of the fin 20, on a distal end side 24 such that an angle formed between the inclined part 25 and a predetermined reference plane approximately parallel to a main surface of a base part 7 is defined at a value less than an angle formed between the wall (in this embodiment, the first wall 21) on one side proximal end 23 and the reference plane.

In this embodiment, the "main surface of the base part 7" is, in general, a rear surface of the base part 7 (not shown in the figure). ) and, therefore, "a predetermined reference plane approximately parallel to the major surface of base portion 7" is, for convenience, an imaginary plane which includes distal ends of the plurality of fins 20.

As shown on the , although a thickness of the fin 20 gradually decreases from the proximal end 23 side toward the distal end 24 side of the fin 20, in the example shown in , such a portion having an inclined shape may also be referred to as an inclined portion 25.

Compared to the walls that the fin 20 comprises, the other wall (in this embodiment, the second wall 22) can be made in a flat shape without having an inclined shape (see ). Needless to say, forming the inclined portion 25 on the other wall (in this embodiment, the second wall 22) is not prohibited.

In the heat exchanger 2 according to embodiment 2, when bubbles B rise, the inclined portions 25 are formed on the distal end side 24 of the fins 20, which are also called outlets of the bubbles B from of the plurality of fins 20 (the exits of the bubbles B from the slots SL2) and, therefore, the bubbles B can be more easily separated from the fins 20.

The heat exchanger 2 according to embodiment 2 has, in principle, substantially the same configuration as the heat exchanger 1 according to embodiment 1 with respect to configurations other than the radiator configuration. Therefore, the heat exchanger 2 according to the embodiment 2 directly acquires corresponding advantageous effects found among all the advantageous effects which the heat exchanger 1 according to the embodiment 1 acquires.

Variations are possible and will be described.

Although the present invention has been described based on the aforementioned embodiments, the present invention is not limited to the aforementioned embodiments. Different modes can be implemented without departing from the spirit of the present invention, and, for example, the following variants can also be envisaged.

In the aforementioned embodiments, the number of constitutional elements and the materials, shapes, positions, sizes and the like of the constitutional elements are given by way of example only and can be changed within a range in which the advantageous effects of the present invention are not degraded.

Different modes can be adopted within such a range that the structure of the radiator does not degrade the advantageous effects of the present invention. The radiator 5a of Embodiment 1 and the radiator 5b of Embodiment 2 are shown as having the shape in which the first wall and the second wall of the fin each form a straight line as a base. However, the present invention is not limited to such a form. For example, as shown in Fig. 6A, a radiator 5c can be formed to have a shape in which a first wall 31 and a second wall 32 are each formed of a curved line (variant 1). In addition to the configuration mentioned above, as shown in Fig. 6B, a radiator 5d can be formed such that a base part 7 has inclined inner lower parts 7c (variant 2). Different from the above-mentioned Variant 1 and Variant 2, as shown in Fig. 6C, a width of an inner bottom portion of the base portion 7 is substantially set to 0 (zero) (this is i.e., a fin distance at a proximal end 53 being defined substantially at 0), the "heat transfer surface" may be formed of only a first wall 51 and a second wall 52 (variant 3 ).

Figures 6A to 6C represent an enlarged cross-sectional view of a main part intended to describe the radiators 5c, 5d, 5e of the variants.

Claims (6)

A heat exchanger (1) which uses latent heat produced by a change in a gaseous/liquid phase of a refrigerant (CL), the heat exchanger comprising a radiator (5a-5e), in which
the radiator includes: a base part (7) configured to define a heat absorbing side and a heat radiating side; And
a plurality of fins (10), each being formed of a projecting rib in which a proximal end (13, 23) of each of the fins is connected to the base portion and a distal end (14, 24) of each fins (10) extends to the heat radiating side, the plurality of fins (10) being brought into contact with the coolant (CL) and capable of radiating absorbed heat from the heat absorbing side from the base part to the cooler (CL), in which
the fins (10) of the plurality of fins (10) are arranged parallel in a longitudinal direction of the plurality of fins (10), and
in a state in which the fins arranged adjacent to each other are seen along the longitudinal direction of the fins (10), the fins (10) of the plurality of fins are formed such that a distance between the fins (10) arranged adjacent to each other on a distal end side (14, 24) is greater than a distance between the fins on a proximal end side (13, 23). Heat exchanger (1) according to claim 1, wherein the distance between the fins disposed adjacent to each other gradually increases from the proximal end side (13, 23) to the distal end side ( 14, 24). A heat exchanger (1) according to claim 1 or 2, wherein the distance between the fins disposed adjacent to each other increases monotonically from the proximal end side (13, 23) towards the d distal end (14, 24). A heat exchanger (1) according to any one of claims 1 to 3, wherein an inclined portion (25) is formed on at least one wall of each of the fins on the distal end side (24) such that an angle formed between the inclined part (25) and a predetermined reference plane approximately parallel to a main surface of the base part is set to a value less than an angle formed between the wall on the proximal end side (23) and the reference plane. Heat exchanger (1) according to any one of claims 1 to 4, in which the fins arranged adjacent to each other are formed such that, by equating a distance between the fins (10) arranged adjacent to each other at the distal end (14, 24) to Wt and a distance between the fins disposed adjacent to each other at the proximal end (13, 23) to Wb, the ratio Wt/Wb is within an inclusive range of 1.5 to 5.0. A heat exchanger (1) according to any one of claims 1 to 5, wherein the fins (10) arranged adjacent to each other are shaped such that the distance between the fins (10) arranged adjacent adjacent to each other is within an inclusive range of 0.1 mm to 0.8 mm.