JP5163548B2 - Boiling cooler - Google Patents

Description

  The present invention relates to a boiling cooling device, and more particularly to improvement of cooling performance in a cooling device using boiling / two-phase flow (gas-liquid two-phase flow).

  Conventionally, a cooling device using boiling / two-phase flow under forced convection has been developed and applied to an inverter cooling system of a hybrid vehicle.

  Patent Document 1 is composed of a cooling base body having a coolant channel and a plurality of power semiconductors mounted thereon, optimally determining the mounting position of the power semiconductor element to optimize the temperature rise of the coolant, and cooling A power semiconductor module with improved efficiency is disclosed.

  Patent Document 2 discloses a boiling cooling device that prevents a decrease in heat dissipation performance in the upper part (downstream area) of the module in boiling cooling. In the lower part (upstream area) of the module due to heat transfer from the power semiconductor. It is disclosed that a generated partition prevents the generated steam from entering the upper part (downstream area) of the module.

JP 2007-12722 A JP-A-9-23081

  The cooling device using boiling / two-phase flow is a high-efficiency heat transfer method that utilizes latent heat transport by phase change, and the saturation temperature depends on the pressure along the vapor pressure curve, so the liquid temperature control is within a certain range. It is possible to adjust the temperature difference with the cooling surface temperature, and there is an effect such as having an advantage in the ability to follow load fluctuations.However, in order to further improve the cooling performance, the generated steam is transferred to the cooling fins. It is necessary to quickly leave the root. In other words, the heat flow distribution of the cooling fin is highest at the root in contact with the heating element, and decreases as it moves away from the root and toward the tip of the cooling fin. Not only can latent heat not be used, reducing heat transfer efficiency, but also burnout due to liquid depletion.

  An object of the present invention is to provide a boiling cooling device capable of quickly discharging generated steam to prevent the filling of steam and maintaining or improving cooling performance.

The present invention relates to a boiling cooling device, a refrigerant flow path, a cooling fin that cools a heating element by the refrigerant supplied from the refrigerant flow path, and a vapor discharge flow that discharges steam generated in the cooling fin to the outside The cooling fin is formed with an elevation angle from the fin base toward the tip, and the device is vertically placed in which the refrigerant is supplied from vertically downward to vertically upward of the device, Of the fin surfaces of the cooling fins, both the vertically upper surface and the vertically lower surface are formed with the elevation angle, and further, a collision plate disposed along the vapor discharge flow path, and gravity from the collision plate And a condensate discharged from the discharge port is returned to a loop for circulating the refrigerant .

In one embodiment of the present invention, the collision plate is characterized in that its surface shape is corrugated or serrated .

  According to the present invention, the generated steam can be quickly discharged to prevent the steam from being filled, and the cooling performance can be maintained or improved.

It is a top view of the device in an embodiment. It is a bottom view of the device in an embodiment. It is AA sectional drawing of FIG. It is sectional drawing of other embodiment. It is a top view of the device in other embodiments. It is a top view in other embodiments. FIG. 7 is a partially enlarged view of FIG. 6. It is a partial enlarged view of other embodiment. It is a partial enlarged view of other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a front view of a boiling cooling device 1 using boiling / two-phase flow in this embodiment, and FIG. 2 shows a bottom view. The boiling cooling device 1 includes a cooling fin, a refrigerant flow path, and a vapor discharge flow path in a casing made up of a bottom plate and a top plate. The boiling cooling device 1 in the present embodiment is vertically placed, and is used as, for example, a component of a system that cools a power element unit (IGBT module) of a hybrid vehicle. The figure shows a front view when the boiling cooling device 1 is placed vertically, and the direction of gravity is indicated by an arrow g. When the apparatus is placed vertically, the refrigerant is supplied from below vertically. Coolant, which is a refrigerant, is forced to convection by a circulation pump of the cooling system. The refrigerant flows vertically upward in the refrigerant flow paths 10 provided on the left and right along the longitudinal direction of the apparatus, and is supplied to the cooling fins 12. The cooling fins 12 are divided into left and right parts, the right cooling fins 12 are supplied with refrigerant from the right refrigerant flow path 10, and the left cooling fins 12 are supplied with refrigerant from the left refrigerant flow path 10. . The cooling fins 12 increase the heat transfer area, and the gaps between the fins are configured as narrow flow paths for three-side heating of both side surfaces and the bottom surface. The refrigerant passes through the inter-fin flow path, flattenes the bubbles generated by the narrow inter-fin flow path, and promotes thin liquid film evaporation by the passing flat bubbles to obtain a high heat transfer coefficient. Further, by supplying the coolant directly to the cooling surface, burnout due to liquid depletion can be prevented, and the critical heat flow rate that becomes the heat removal limit of nucleate boiling can be increased. Further, a steam discharge channel 14 is provided in the center of the apparatus along the longitudinal direction of the apparatus. Bubbles (steam) generated in the narrow fin passage are collected in the steam discharge passage 14 and discharged to the outside through a steam outlet provided vertically above. The discharged steam is circulated to the apparatus as a cooling liquid through a gas-liquid separator and a condenser.

  The cooling fin 12 extends in the horizontal direction as shown in the front view of FIG. 1, but the fin surface does not exist in a horizontal plane, but is inclined at a predetermined angle from the base of the fin toward the tip, that is, from the base. It is formed with a predetermined elevation angle toward the tip.

  FIG. 3 shows an AA cross section of FIG. The fin surface of the cooling fin 12 protrudes from the fin base 12a that contacts the heating element 16 such as a power element unit, but the fin surface does not protrude in the horizontal direction but is inclined at a predetermined angle vertically upward. Protruding. The predetermined angle is, for example, 15 to 60 degrees with respect to the horizontal direction. The coolant as the refrigerant 11 is supplied from the direction perpendicular to the paper surface in the figure. The root of the cooling fin 12 has the highest heat flow rate, and the refrigerant boils in the vicinity of the root to generate bubbles (steam). Assuming that the fin surface of the cooling fin 12 protrudes in the horizontal direction from the root, the generated steam 18 stops at the root and fills up. When the steam 18 is filled, the transfer surface including the fins is dried, so that heat transfer is deteriorated, and burnout may occur. On the other hand, when the fin surface of the cooling fin 12 is inclined as shown in FIG. 3, the steam 18 is detached from the root, so that the root with a high heat flow rate is prevented from being filled with steam, and the heat transfer coefficient is improved. be able to. Further, since the vapor 18 is easily removed by buoyancy, the pump load for forced convection of the refrigerant can also be reduced. One of the advantages of vertical installation is that the steam 18 can be easily discharged by buoyancy.

  In FIG. 4, the structure of the cooling fin 12 of other embodiment is shown. The fin surface of the cooling fin 12 protrudes from the fin base portion 12a. If the fin surface of the cooling fin 12 is a vertically upper surface 12b and a vertically lower surface 12c, the vertically upper surface 12b is horizontal. On the other hand, the surface 12c on the vertically lower side of the cooling fin 12 protrudes obliquely from the root toward the vertically upper side.

  As described above, even if the shapes of the one surface and the other surface of the cooling fin 12 are different and only the vertically lower surface 12c is inclined, the same effect as in FIG. 3 is obtained. That is, it is possible to increase the heat transfer efficiency by separating the steam generated at the root of the fin from the root. Further, the steam 18 is easily removed by buoyancy. The angle of the inclined surface is the same as that in FIG. 3, and is preferably 15 to 60 degrees with respect to the horizontal direction.

  In the present embodiment, the cooling fins 12 are formed so as to be inclined from the root. However, the cooling fins 12 may be tilted without being inclined from the root or inclined from the root and viewed from the front.

  In FIG. 5, the front view of the boiling cooling device 1 in other embodiment is shown. It is a structural example in the case of inclining the cooling fin 12 seeing from the front. Similar to the boiling cooling apparatus 1 shown in FIG. 1, the apparatus is placed vertically, and refrigerant is supplied from vertically below. The refrigerant is forcedly convected by a pump or the like. The refrigerant flows in the refrigerant flow path 10 provided on the left and right sides vertically upward, and is supplied to the cooling fins 12 from the left and right toward the center. A steam discharge passage 14 is provided at the center of the boiling cooling device 1, and the generated steam is collected in the steam discharge passage 14 and discharged to the outside through a discharge port provided vertically above.

  The cooling fins 12 are formed to be inclined at a predetermined angle. That is, when viewed from the refrigerant flow path 10, it is formed so as to be inclined vertically upward toward the downstream side rather than the upstream side close to the refrigerant flow path 10. In other words, the cooling fins 12 located on the right side of the steam discharge flow path 14 are formed to be inclined vertically upward toward the steam discharge flow path 14, and the cooling fins 12 located on the left side of the steam discharge flow path 14 are also Since it forms inclining vertically upwards as it goes to the vapor | steam discharge flow path 14, it arrange | positions so that the cooling fin 12 may become a square shape seeing from the front. By inclining the cooling fins 12 in this way, it becomes easy to discharge the steam 18 generated and grown in the narrow fin flow path, and the retention of the steam 18 can be prevented and the heat transfer efficiency can be improved.

  In the present embodiment, the steam 18 discharged from the cooling fins 12 is discharged to the outside from the steam discharge flow path 14, but since it is a boiling / liquid two-phase flow, a mechanism for collecting excess condensate is provided inside the apparatus. It is also suitable.

  In FIG. 6, the front view of the boiling cooling device 1 in other embodiment is shown. A collision plate 20 is disposed in the steam discharge path 14. FIG. 7 shows an enlarged view of a portion P in FIG. By disposing the collision plate 20 along the vapor discharge path 14, the flow of the steam 18 generated by the left and right cooling fins 12 collides with the collision plate 20 as shown in FIG. And flows downward vertically by gravity, and is discharged from a drain (discharge port) provided in the lower part of the apparatus 1. The condensate discharged from the drain is returned to the loop for circulating the coolant.

  In this way, by disposing the collision plate 20 inside the apparatus and collecting the excess condensate 22, there is no need to separately provide a gas-liquid separator in the circulation loop outside the apparatus, and the cost of the system can be reduced. it can. Moreover, since the excess condensate 22 does not enter the condenser in the circulation loop, the condensation performance is improved. This is because if the condensate enters the condenser together with the steam 18, the area where the condenser wall surface comes into contact with the steam is reduced, so that it is difficult to obtain condensed heat transfer with a high heat transfer coefficient. Furthermore, when the refrigerant accumulates, corrosion products in the refrigerant accumulate and corrosion of the material can be prevented.

  Although the surface shape of the collision plate 20 is a flat plate in FIG. 6, the shape is not limited to this, and the surface shape of the collision plate 20 can be uneven, corrugated, sawtooth, or the like. Further, the surface of the collision plate 20 may exist discretely instead of a continuous surface. 8 and 9 show an example of the collision plate 20. FIG. 8 shows a case of a waveform or sawtooth shape, and FIG. 9 shows a case of discrete existence.

  DESCRIPTION OF SYMBOLS 1 Boiling cooler, 10 Refrigerant flow path, 12 Cooling fin, 14 Steam discharge flow path, 16 Heat generating body, 18 Steam, 20 Collision plate, 22 Excess condensate.

Claims (2)

A boiling cooling device,
A refrigerant flow path;
Cooling fins for cooling the heating element by the refrigerant supplied from the refrigerant flow path;
A steam discharge passage for discharging the steam generated in the cooling fin to the outside;
The cooling fin is formed with an elevation angle from the fin base toward the tip ,
The apparatus is a vertical installation in which the refrigerant is supplied from vertically downward to vertically upward of the apparatus,
Of the fin surfaces of the cooling fins, both the vertically upper surface and the vertically lower surface are formed with the elevation angle, and
A collision plate disposed along the vapor discharge flow path;
A discharge port for discharging the condensate falling from the collision plate by gravity;
And the condensate discharged from the discharge port is returned to a loop for circulating the refrigerant . The apparatus of claim 1.
The impingement plate has a corrugated surface or a sawtooth shape, and is a boiling cooling device .

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