JP2016211773A - Loop heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a loop heat pipe which is smooth in stop of a heat transport function while preventing deterioration of heat exchange efficiency and can prevent deformation and breakage of an evaporation part when restarting the heat transport function.SOLUTION: A loop heat pipe has an evaporation part, a condensation part, a steam flow passage in which working fluid of a gas phase flows from the evaporation part to the condensation part, and a liquid flow passage in which the working fluid of a liquid phase flows from the condensation part to the evaporation part. The liquid flow passage has a liquid reservoir part in which the working fluid of the liquid phase flowing from the condensation part to the evaporation part is retained, and a flow rate regulation part which regulates the flow rate of the working fluid of the liquid phase. A wick is provided from the liquid reservoir part to the inside of the evaporation part.SELECTED DRAWING: Figure 1

Description

  The present invention has a closed loop structure, and can efficiently transport heat from the evaporation section side to the condensation section side using the latent heat of the working fluid circulating in the loop structure in one direction, and smoothly. The present invention relates to a loop heat pipe capable of stopping heat transport.

  In a loop heat pipe, a pipe in which a working fluid is sealed in an internal space forms a closed loop structure, and the working fluid is evaporated by receiving heat from the external environment at an evaporation section disposed in a relatively high temperature external environment. This is a heat pipe in which the vapor of the working fluid is led from the evaporating unit to the condensing unit arranged in a relatively low temperature external environment and condensed, and the condensed working fluid circulates from the condensing unit to the evaporating unit. As a conventional loop heat pipe, in order to prevent the heat exchange from being hindered by condensation on the outer surface of the evaporation section, the higher temperature fluid or its components are cooled by the evaporation section and become a solid phase on the outer surface of the evaporation section. A loop heat pipe having a valve that can stop the circulation of hydraulic fluid has been proposed (Patent Document 1).

  That is, in patent document 1, the heat | fever transport function of a loop heat pipe is stopped by closing the valve | bulb provided in the pipe and stopping the circulation of a hydraulic fluid. As a result, the condensation on the outer surface of the evaporation unit is not cooled from the inside of the evaporation unit, and the condensation on the outer surface of the evaporation unit is naturally melted and removed by the warm atmosphere surrounding the evaporation unit, resulting in no energy input. Restore heat exchangeable state.

  Then, when the loop heat pipe is restored to a heat exchangeable state, the valve is opened again to restart the heat transport function.

  However, in patent document 1, there existed a problem that efficient heat transport could not be performed depending on the relationship between the height of an evaporation part and a condensation part. That is, in the so-called top heat type in which the condensing part is lower than the evaporating part, it is necessary to increase the working fluid so that the evaporating part does not dry out during operation of the heat pipe. There is a problem that the working fluid is filled with the working fluid and the condensing efficiency of the working fluid is extremely deteriorated. Furthermore, in Patent Document 1, when the heat transport function of the loop heat pipe is restarted by opening the valve, a low-temperature working fluid is added to the evaporation section that has become hot while the heat transport function of the loop heat pipe is stopped. However, there is a problem that deformation or breakage may occur in the evaporation section.

JP-A-8-14775

  The present invention has been made in view of the above-described problems of the prior art. The heat transfer function can be smoothly stopped while preventing the heat exchange efficiency from being lowered. An object of the present invention is to provide a loop heat pipe that can prevent deformation and breakage.

  The aspect of the present invention includes an evaporation unit, a condensing unit, a vapor channel through which the gas phase working fluid flows from the evaporation unit to the condensing unit, and the liquid phase working fluid from the condensing unit to the evaporating unit. A liquid heat flow path, wherein the liquid flow path is a liquid reservoir that holds the liquid-phase working fluid flowing from the condensing part to the evaporation part, and A loop heat pipe having a flow rate adjusting unit that adjusts the flow rate of the liquid-phase working fluid and having a wick from the liquid reservoir to the inside of the evaporation unit.

  In this aspect, a liquid reservoir exists in the liquid flow path of the loop heat pipe, and the flow rate adjuster is disposed in the liquid reservoir. When the loop heat pipe is in operation, the flow rate adjusting unit is open in the liquid reservoir. The liquid-phase working fluid that has flowed out of the condensing part once stays in the liquid reservoir part before being introduced into the evaporation part. In addition, since the flow rate adjusting unit is disposed in the liquid reservoir, both the condensing unit side and the evaporation unit side of the open flow rate adjusting unit are filled with the liquid-phase working fluid.

  Further, since the wick extends from the liquid reservoir portion to the inside of the evaporation portion, the working fluid staying in the liquid reservoir portion is transported to the inside of the evaporation portion by the capillary force of the wick. On the other hand, by closing the flow rate adjusting unit, the supply of the liquid-phase working fluid from the condensing unit to the evaporation unit is shut off, and the heat transport function of the root heat pipe is stopped.

  An aspect of the present invention is a loop heat pipe in which the flow rate adjusting unit is a valve.

  An aspect of the present invention is a loop heat pipe in which the valve is a thermostat.

  An aspect of the present invention is a loop heat pipe in which the wick is a porous body or a powder sintered body.

  An aspect of the present invention is a loop heat pipe in which a heat insulating material is provided on the outer surface of the steam channel.

  According to the aspect of the present invention, the liquid-phase working fluid is supplied from the liquid flow path to the evaporation unit by the wick extending from the liquid reservoir to the inside of the evaporation unit. Therefore, when the flow adjustment unit is opened and the heat transport function of the loop heat pipe is restarted or started, a low-temperature working fluid is added to the evaporation part that has become hot while the heat transport function of the loop heat pipe is stopped. Since the gas gradually flows in accordance with the capillary force, the evaporation part can be prevented from being deformed or damaged. Further, according to the aspect of the present invention, since the wick extends from the liquid reservoir portion to the inside of the evaporation portion, the working fluid is reliably and continuously evaporated regardless of the height relationship between the condensation portion and the evaporation portion. Can be supplied to the department. In particular, the working fluid can be reliably supplied from the condensing unit to the evaporating unit even if the evaporating unit is disposed at a position higher than the condensing unit. Furthermore, according to the aspect of the present invention, the flow rate of the liquid-phase working fluid supplied to the evaporation unit can be controlled by the wick's capillary force and / or the flow rate adjusting unit, thereby preventing excessive cooling of the evaporation unit. It is possible to prevent a decrease in heat exchange efficiency of the loop heat pipe.

  Further, according to the aspect of the present invention, since the flow rate adjusting unit is disposed in the liquid phase working fluid reservoir, the heat transfer function of the root heat pipe can be reliably and quickly performed by closing the flow rate adjusting unit. In addition, the heat transport function of the root heat pipe can be restarted reliably and promptly by opening the flow rate adjusting unit.

  According to the aspect of the present invention, since the flow rate of the liquid-phase working fluid can be adjusted by the valve, it is easy to adjust the amount of heat transfer from the evaporation part to the condensation part of the root heat pipe. Further, since the flow rate adjusting unit is a valve, the heat transport function of the root heat pipe can be stopped and restarted more smoothly.

  According to the aspect of the present invention, since the valve is a thermostat, the opening and closing of the valve can be selected and adjusted according to the temperature of the liquid-phase working fluid, so the amount of heat transfer from the evaporation section to the condensation section can be adjusted. It can be adjusted according to the temperature.

  According to the aspect of the present invention, since the wick is a porous body or a powder sintered body, the flow rate of the liquid-phase working fluid supplied to the evaporation section can be easily controlled.

It is explanatory drawing at the time of the action | operation of the loop heat pipe which concerns on the example of embodiment of this invention. It is explanatory drawing at the time of the stop of the loop heat pipe which concerns on the example of embodiment of this invention.

  Hereinafter, a loop heat pipe according to an embodiment of the present invention will be described with reference to the drawings. First, a heat transport system for a loop heat pipe according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, a loop heat pipe 1 according to an embodiment of the present invention includes an evaporation unit 2 that changes a liquid-phase working fluid L to a gas phase by heat input from a first external environment, and evaporation. A condensing unit that introduces a gas-phase working fluid G from the unit 2 and changes the phase of the gas-phase working fluid G to a liquid-phase working fluid L by releasing heat from the gas-phase working fluid G to the second external environment. 3, one end communicates with the evaporation unit 2, the other end communicates with the condensation unit 3, a steam channel 4 that is a tubular body, one end communicates with the condensation unit 3, and the other The liquid flow path 5 which is a tubular body and whose end is in communication with the evaporation section 2. The vapor-phase working fluid G flows from the evaporation section 2 to the condensation section 3 in the vapor flow path 4. In the liquid flow path 5, the liquid-phase working fluid L flows from the condensation unit 3 to the evaporation unit 2.

  The container of the loop heat pipe 1 is a closed circulation path composed of a loop pipe, and the working fluid is sealed inside the circulation path in a depressurized (degassed) state. As described above, the working fluid circulates in one direction (counterclockwise in FIG. 1) while repeating the phase change.

  The fluid F2 in the second external environment in which the condensing unit 3 is disposed has a lower temperature than the fluid F1 in the first external environment in which the evaporation unit 2 is disposed. Accordingly, in the evaporation unit 2, the liquid-phase working fluid L receives heat from the fluid F1 having a relatively higher temperature than the fluid F2, evaporates, and changes into a gas-phase working fluid G. The working fluid G in the gas phase is transported from the evaporation unit 2 to the condensation unit 3 through the vapor flow path 4 that connects the evaporation unit 2 and the condensation unit 3 using a pressure difference. In the condensing unit 3, the gas-phase working fluid G dissipates heat to the fluid F <b> 2 having a relatively lower temperature than the fluid F <b> 1, and is condensed into a liquid-phase working fluid L.

  Due to the above action, the loop heat pipe 1 transports heat from the evaporator 2 to the condenser 3. That is, the loop heat pipe 1 transports the heat of the first external environment having a relatively high temperature to the second external environment having a relatively low temperature. The liquid-phase working fluid L condensed in the condensing unit 3 is refluxed from the condensing unit 3 to the evaporating unit 2 via the liquid flow path 5 connecting the condensing unit 3 and the evaporating unit 2.

  As shown in FIG. 1, the loop heat pipe 1 temporarily stays in the liquid flow path 5 before the liquid-phase working fluid L flowing back from the condensing unit 3 to the evaporation unit 2 is introduced into the evaporation unit 2. It has a liquid reservoir 6 to be used. In the liquid reservoir 6, the inside of the pipe of the liquid flow path 5 is filled with a liquid-phase working fluid L. For example, in the loop heat pipe 1, the pipe of the liquid flow path 5 has a substantially U shape in a side view, and of the substantially U shape, the entire bottom portion formed in the horizontal direction and the two formed in the vertical direction. A portion of the side portion excluding the vicinity of the evaporation portion 2 and the vicinity of the condensation portion 3 is a liquid reservoir portion 6 filled with a liquid-phase working fluid L. Therefore, in the liquid flow path 5, between the evaporation part side end surface 9 of the liquid reservoir 6 and the evaporation part 2 side end of the liquid flow path 5 and the condensation part side end face 10 of the liquid storage part 6 and the liquid flow path 5. Since the liquid-phase working fluid L does not stay between the two end portions on the condensing unit 3 side, a space is formed.

  Further, in the liquid flow path 5, a valve 7 is provided as a flow rate adjusting unit at the center of the liquid reservoir 6 in the flow of the liquid-phase working fluid L. Therefore, the valve 7 is closed by the liquid-phase working fluid L that has accumulated in the liquid reservoir 6 on both the evaporation section 2 side and the condensation section 3 side.

  Further, a long wick 8 is installed in a region from the bottom side of the pipe of the liquid flow path 5 to the inside of the evaporation unit 2 with respect to the evaporation unit side end surface 9 of the liquid reservoir 6. That is, in a state where the valve 7 is opened and the loop heat pipe 1 is operating, the liquid pool 6 side end of the wick 8 is immersed in the liquid phase working fluid L including the tip 11 thereof. ing. Further, the central portion of the wick 8 is located in the space formed between the evaporation portion side end face 9 and the evaporation portion 2 side end portion of the liquid flow path 5. Accordingly, the portion of the wick 8 located in the space portion of the liquid flow path 5 is exposed in the space portion. Furthermore, the evaporation unit 2 side end of the wick 8 is located in the evaporation unit 2.

  In FIG. 1, the wick 8 has a smaller cross-sectional area (cross-sectional area in the direction orthogonal to the longitudinal direction) than the cross-sectional area in the radial direction of the liquid flow path 5. Due to the capillary force of the wick 8, the liquid-phase working fluid L is transported from the vicinity of the evaporation portion side end face 9 of the liquid reservoir portion 6 into the evaporation portion 2. Therefore, the liquid-phase working fluid L can be reliably and continuously supplied from the liquid reservoir 6 to the evaporator 2 regardless of the difference in height between the condenser 3 and the evaporator 2.

  Further, the flow rate of the liquid-phase working fluid L transported to the evaporation unit 2 can be adjusted by the strength of the capillary force of the wick 8. Further, by supplying the liquid-phase working fluid L to the evaporation unit 2 by the wick 8, the liquid-phase working fluid L is supplied to the evaporation unit 2 even when the evaporation unit 2 is located higher than the condensing unit 3. It can supply reliably and can carry out heat transport efficiently.

  As shown in FIG. 1, by opening the valve 7, the liquid-phase working fluid L condensed in the condensing unit 3 is refluxed from the condensing unit 3 to the evaporating unit 2 through the liquid channel 5. The heat transport function from the evaporation section 2 to the condensation section 3 of the loop heat pipe 1 is continuously operated. When the valve 7 is in the open state, the condensing part side end face 10 and the evaporation part side end face 9 of the liquid pool part 6 are substantially the same height.

  Next, the stop of the heat transport function of the loop heat pipe 1 will be described with reference to FIG.

  As shown in FIG. 2, by closing the valve 7, the liquid-phase working fluid L condensed in the condensing unit 3 cannot be recirculated from the condensing unit 3 to the evaporation unit 2. Therefore, the liquid-phase working fluid L condensed in the condensing unit 3 is stored between the condensing unit side end surface 10 of the liquid reservoir 6 and the condensing unit 3 side end of the liquid channel 5. That is, when the valve 7 is closed, the position of the condensing part side end face 10 of the liquid pool part 6 rises while the heat transport function from the evaporation part 2 to the condensing part 3 of the loop heat pipe 1 is still operating. Then, the position of the end surface 9 on the evaporation portion side of the liquid pool portion 6 is lowered. As the condensing unit side end surface 10 rises and the evaporation unit side end surface 9 descends, the tip 11 on the liquid reservoir 6 side of the wick 8 is exposed from the liquid reservoir 6 at a certain point.

  When the tip 11 on the liquid reservoir 6 side of the wick 8 is exposed from the liquid reservoir 6, the supply of the liquid-phase working fluid L to the evaporator 2 is inhibited, and the heat transport function of the loop heat pipe 1 is stopped. The

  Thus, in the root heat pipe 1, the heat transport function can be stopped reliably and quickly by closing the valve 7. Further, by adjusting the position of the tip 11 of the wick 8 with respect to the evaporation portion side end surface 9 of the liquid reservoir 6, the time between the closing operation of the valve 7 and the stop of the heat transport function can be adjusted.

  On the other hand, by closing the valve 7 in the closed state, the position of the condensing portion side end face 10 of the liquid reservoir 6 that has been raised when the valve 7 is closed is lowered, and the evaporation of the liquid reservoir 6 that has been lowered is lowered. The position of the part side end face 9 rises, and the condensation part side end face 10 and the evaporation part side end face 9 return to the same height. Then, the liquid reservoir 6 side end portion of the wick 8 returns to the state of being immersed in the liquid reservoir portion 6 including the tip 11, and therefore the evaporation portion side end surface 9 of the liquid reservoir portion 6 by the capillary force of the wick 8. The liquid-phase working fluid L is transported again from the vicinity into the evaporation unit 2. Therefore, by opening the valve 7 in the closed state, the liquid-phase working fluid L can be recirculated from the condensing unit 3 to the evaporating unit 2, and the heat transport function of the root heat pipe 1 can be reactivated. it can.

  Even while the heat transport function of the loop heat pipe 1 is stopped, the evaporation unit 2 receives heat from the fluid F1, so that the temperature in the evaporation unit 2 is increased and is in a high temperature state. As described above, when the heat transport function of the root heat pipe 1 is reactivated, the low-temperature liquid-phase working fluid L slowly flows into the high-temperature evaporation unit 2 according to the capillary force of the wick 8. Therefore, it is possible to prevent the evaporation unit 2 from being deformed or damaged.

  The material of the container of the loop heat pipe 1 is not specifically limited, For example, metals, such as copper, a copper alloy, and stainless steel, can be mentioned. Further, the long wick 8 is not particularly limited as long as it is a substance having a capillary structure. For example, a sintered body using a powder of metal, a porous body, a metal mesh, a metal wire, etc. Can be mentioned. Furthermore, the working fluid of the loop heat pipe 1 is not particularly limited, and examples thereof include water, alcohol, and alternative chlorofluorocarbon. Here, it is preferable that both the material of the container and the type of the working fluid are selected so as to improve the heat exchange efficiency, and the combination of the material of the container and the working fluid has an influence on each other, causing deterioration and decomposition. It is preferable to select such that denaturation or the like is prevented.

  Further, the valve is not particularly limited as long as the circulation of the liquid-phase working fluid L can be stopped. The valve may have only a function of opening and closing. It may have. Examples of the valve include a solenoid valve, a thermostat, a gate valve, a ball valve, and a needle valve. When a thermostat is used, the opening and closing of the valve can be selected and adjusted according to the temperature of the liquid-phase working fluid.

  Next, an example of how to use the loop heat pipe of the present invention will be described. The loop heat pipe of the present invention can be used as long as it can be equipped with a heat transport function. For example, the evaporation of the loop heat pipe into an exhaust pipe connected to an internal combustion engine mounted on a vehicle. It is possible to achieve energy saving of the vehicle by installing the section and thermally connecting the condensing section of the loop heat pipe with the warming device of the engine.

  Next, another embodiment of the loop heat pipe of the present invention will be described. In the above embodiment example, the wick 8 is installed, but instead of this, on the inner surface of the region of the liquid flow path 5 that is a tubular body from the vicinity of the end surface 9 of the liquid reservoir 6 to the inside of the evaporator 2. A groove having a capillary force may be formed. In the above embodiment, the wick 8 has a cross-sectional area perpendicular to the longitudinal direction that is smaller than the cross-sectional area in the radial direction of the liquid flow path 5. The cross-sectional area may be the same as the cross-sectional area in the radial direction of the channel 5 and the same cross-sectional shape as the cross-sectional shape in the radial direction of the liquid channel 5. That is, the region of the liquid flow path in which the wick is disposed may be filled with the wick. In the above embodiment, heat is directly input from the fluid F1 to the evaporation unit 2, but heat may be input via a heat sink or other heat transfer member instead. Further, in the above embodiment, heat is radiated directly from the condensing unit 3 to the fluid F2, but instead, heat may be radiated via a heat sink or other heat transfer member.

  Furthermore, in the loop heat pipe of the above embodiment, a heat insulating member may be provided on the outer surface of the steam flow path. By providing the heat insulating member on the outer surface of the steam flow path, heat can be efficiently transported from the evaporation section to the condensation section.

  The loop heat pipe of the present invention has a smooth stopping of the heat transport function, and can prevent deformation and breakage of the evaporation section when restarting the heat transport function. It is highly useful in a wide range of fields, such as the field of reusing water for cooling water and oil warming, and the field of laser oscillator and battery temperature control.

DESCRIPTION OF SYMBOLS 1 Loop heat pipe 2 Evaporating part 3 Condensing part 4 Steam flow path 5 Liquid flow path 6 Liquid accumulation part 7 Valve 8 Wick

Claims (5)

An evaporating unit, a condensing unit, a vapor channel through which the gas-phase working fluid flows from the evaporating unit to the condensing unit, and a liquid channel through which the liquid-phase working fluid flows from the condensing unit to the evaporating unit A loop heat pipe having
The liquid flow path includes a liquid reservoir that holds the liquid-phase working fluid flowing from the condensing unit to the evaporation unit, and a flow rate adjusting unit that adjusts the flow rate of the liquid-phase working fluid. A loop heat pipe provided with a wick from the liquid reservoir to the inside of the evaporator.   The loop heat pipe according to claim 1, wherein the flow rate adjusting unit is a valve.   The loop heat pipe according to claim 2, wherein the valve is a thermostat.   The loop heat pipe according to any one of claims 1 to 3, wherein the wick is a porous body or a powder sintered body. The loop heat pipe according to any one of claims 1 to 4, wherein a heat insulating material is provided on an outer surface of the steam channel.