A TEC coupled loop heat pipe and a temperature control method thereof

Abstract

The application discloses a kind of using TEC coupling loop heat pipe and its temperature control method, including reservoir, evaporator, first semiconductor refrigerator, second semiconductor refrigerator, heat source plate and copper bar;The reservoir is set on the upper surface of the evaporator, and the evaporator is set on the upper surface of the heat source plate;The first semiconductor refrigerator and the second semiconductor refrigerator are respectively installed on the two sides of evaporator, and the first semiconductor refrigerator and the second semiconductor refrigerator are both provided with two connecting ends: one connecting end is installed on the heat source plate close to the side of evaporator, and the other connecting end is connected to the top cover of reservoir by copper bar;The first semiconductor refrigerator and the second semiconductor refrigerator are connected in series;The power and polarity of TEC can be controlled by changing the voltage size and polarity applied on TEC refrigerator.Both the rapid start of loop heat pipe can be realized, and the operating efficiency of loop heat pipe can be further improved, and the working temperature of loop heat pipe system can be further reduced.

Description

Technical Field

[0001] This invention relates to the field of aerospace thermal design, and in particular to a TEC coupled loop heat pipe and its temperature control method. Background Technology

[0002] A thermoelectric cooler (TEC) is a device that generates cooling by utilizing the thermoelectric effect of semiconductors; it is also known as a thermoelectric cooler. When two different metals are connected by a conductor and a direct current is applied, the temperature at one junction decreases, while the temperature at the other junction increases.

[0003] A loop heat pipe (LHP) is a highly efficient and reliable two-phase heat transfer device that utilizes the vapor-liquid phase change of the working fluid in the evaporator and condenser for efficient heat transfer. Compared with traditional heat pipes, LHPs offer advantages such as longer heat transfer distances, flexible installation, high temperature control accuracy, and resistance to overload acceleration. Over the past thirty years, LHPs have been widely used in aerospace and electronics cooling fields.

[0004] Capillary pumps are the core component of loop heat pipes, providing the capillary force to drive the circulation of the working fluid. Capillary pumps are classified into cylindrical capillary pumps and flat capillary pumps based on their configuration. Cylindrical capillary pumps, as the earliest and most traditional configuration, possess advantages such as good structural stability, low back-side heat leakage, and stable start-up and operation. Currently, cylindrical capillary pump technology is relatively mature and has been widely used in the aerospace field. However, due to their cylindrical shape, an adapter saddle is required when installing with the heat source, significantly increasing installation thermal resistance, and the structure is difficult to miniaturize, making them unsuitable for scenarios with high weight and volume requirements. Flat capillary pumps, with their excellent mechanical and thermal interface and the advantage of being miniaturizable and lightweight, have always been a key research focus for scholars worldwide.

[0005] Loop heat pipes are typically controlled by attaching electric heaters to the evaporator or receiver, using heating to regulate the heat pipe. Heating the evaporator promotes heat pipe startup, while heating the receiver inhibits flow and raises receiver temperature. However, traditional heater control methods suffer from drawbacks such as difficulty starting large heat capacity systems, slow heat pipe response, low heat pipe efficiency, and an inability to further reduce the operating temperature of the heat pipe system. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method using a TEC-coupled loop heat pipe and its temperature control, which can achieve rapid start-up of the loop heat pipe, further improve the operating efficiency of the loop heat pipe, and further reduce the operating temperature of the loop heat pipe system.

[0007] The technical solution of the present invention is: a TEC coupled loop heat pipe, comprising a liquid receiver, an evaporator, a first semiconductor cooler, a second semiconductor cooler, a heat source plate, and copper strips;

[0008] The liquid reservoir is disposed on the upper surface of the evaporator. The liquid reservoir is provided with a subcooled liquid inlet, and the evaporator is provided with a superheated steam outlet. The superheated steam flowing out of the superheated steam outlet flows to the external cold plate.

[0009] The evaporator is disposed on the upper surface of the heat source plate;

[0010] The first semiconductor cooler and the second semiconductor cooler are respectively installed on both sides of the evaporator. Both the first semiconductor cooler and the second semiconductor cooler have two connection ends: one connection end is installed on the heat source plate close to the side of the evaporator, and the other connection end is connected to the top cover of the liquid receiver through a copper strip.

[0011] The first and second semiconductor coolers are connected in series; the power and polarity of the TEC are controlled by changing the magnitude and polarity of the voltage applied to the TEC cooler.

[0012] The bottom of the heat source plate is an external heat source.

[0013] Furthermore, a thermally conductive pad is filled between the copper strip and the top cover of the reservoir.

[0014] Furthermore, the heat source plate is an aluminum plate.

[0015] This invention also provides a TEC coupled loop thermal control temperature management method, including the following two control modes:

[0016] Control Mode 1: The first and second semiconductor coolers are powered from the front. Specifically, the hot ends of the first and second semiconductor coolers are mounted on a heat source plate close to the evaporator, and the cold ends are connected to the top cover of the liquid receiver via copper strips. The first and second semiconductor coolers absorb heat from the liquid receiver, creating a cooling effect, and transfer this absorbed heat to the heat source plate connected to the hot ends. Simultaneously, the first and second semiconductor coolers themselves generate heat loss, which is also transferred to the heat source plate. Ultimately, the cooling capacity of the first and second semiconductor coolers, their own heat loss, and the heat from the external heat source are all absorbed by the vaporized gas in the evaporator, thus forming a loop heat pipe and completing the system's heat dissipation task.

[0017] Control Mode 2: The first and second semiconductor coolers are powered in reverse. That is, the cold ends of the first and second semiconductor coolers are installed on the heat source plate close to the evaporator, and the hot ends are connected to the top cover of the liquid receiver through copper strips. The heating function of the first and second semiconductor coolers is used to control the temperature of the liquid receiver. In this mode, the amount of heat received by the loop heat pipe liquid receiver is the sum of the heat consumption of the first and second semiconductor coolers themselves and the cooling capacity of the first and second semiconductor coolers.

[0018] Furthermore, the specific steps of the TEC coupled loop thermal control temperature management method are as follows:

[0019] Step 1: Read the external heat source temperature and cold plate temperature. If the heat source temperature is greater than the upper limit of the temperature control point, proceed to Step 2; if the heat source temperature is less than or equal to the upper limit of the temperature control point, proceed to Step 3.

[0020] Step 2: When the minimum temperature of the cold plate is less than the reference minimum temperature and the maximum temperature of the cold plate is less than the reference maximum temperature, start control mode 1 and supply positive power to the first and second semiconductor coolers.

[0021] Step 3: When the heat source temperature is lower than the lower limit of the temperature control point, disconnect the power to the first and second semiconductor coolers or reverse the power supply; when the minimum temperature of the cold plate is greater than or equal to the reference minimum temperature and the maximum temperature of the cold plate is greater than or equal to the reference maximum temperature, disconnect the power to the first and second semiconductor coolers or reverse the power supply.

[0022] The beneficial effects of the present invention are as follows: The present invention provides a TEC coupled loop heat pipe and its temperature control method. The cold and hot ends of the TEC are respectively connected to the liquid receiver and the evaporator. By adjusting the power of the TEC and the forward and reverse power supply, the start-up speed of the loop heat pipe is accelerated, the operating efficiency is improved, and the controllable range of the heat pipe system's operating temperature is expanded.

[0023] These advantages can further expand the application scenarios of loop heat pipes in engineering, and greatly improve the ease of use and controllability of loop heat pipes in engineering. Attached Figure Description

[0024] To further illustrate the above and other advantages and features of the various embodiments of the present invention, a more specific description of the various embodiments of the present invention will be presented with reference to the accompanying drawings. It is to be understood that these drawings depict only typical embodiments of the invention and are therefore not intended to limit its scope. In the drawings, identical or corresponding parts will be indicated by identical or similar reference numerals for clarity.

[0025] Figure 1 This is a schematic diagram of the operation of the loop heat pipe in this invention;

[0026] Figure 2 This is a schematic diagram of the forward operation of the TEC coupling loop heat pipe in this invention;

[0027] Figure 3 This is a schematic diagram of the reverse operation of the TEC coupling loop heat pipe in this invention;

[0028] Figure 4 This is a schematic diagram of the start-up of the loop heat pipe heater in this invention;

[0029] Figure 5 This is a schematic diagram of the TEC startup process using a loop heat pipe.

[0030] Figure 6 This is the control logic diagram of the TEC coupling loop heat pipe in this invention.

[0031] In the diagram: 1 is the liquid receiver, 2 is the evaporator, 3 is the first semiconductor cooler, 4 is the second semiconductor cooler, 5 is the copper strip, 6 is the subcooled liquid inlet, 7 is the superheated steam outlet, 8 is the heat source plate, 9 is the external heat source, 10 is the capillary wick, and 11 is the steam channel. Detailed Implementation

[0032] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings and embodiments.

[0033] like Figure 1-3 As shown, a TEC coupled loop heat pipe includes a liquid receiver 1, an evaporator 2, a first thermoelectric cooler 3, a second thermoelectric cooler 4, a heat source plate 8, and a copper strip 5. The liquid receiver 1 is disposed on the upper surface of the evaporator 2, and has a subcooled liquid inlet 6. The evaporator 2 has a superheated steam outlet 7, and the superheated steam flowing out of the superheated steam outlet 7 flows to an external cold plate. The evaporator 2 is disposed on the upper surface of the heat source plate 8. The first thermoelectric cooler 3 and the second thermoelectric cooler 4 are respectively installed on both sides of the evaporator 2. Both the first thermoelectric cooler 3 and the second thermoelectric cooler 4 have two connection ends: one connection end is installed on the heat source plate 8 close to the side of the evaporator 2, and the other connection end is connected to the top cover of the liquid receiver 1 via the copper strip 5. A thermally conductive pad is filled between the copper strip 5 and the top cover of the liquid receiver 1. The first thermoelectric cooler 3 and the second thermoelectric cooler 4 are connected in series. The power and polarity of the TEC are controlled by changing the voltage applied to the TEC cooler. The bottom of the heat source plate 8 is an external heat source 9.

[0034] The flat-plate loop heat pipe used in this embodiment is a longitudinal design, meaning the liquid receiver is located above the evaporator. The working fluid in the heat pipe travels longitudinally from the liquid receiver through the capillary wick to the evaporator. Although this type of flat-plate loop heat pipe is not as thick as a transversely arranged flat-plate heat pipe, this longitudinal arrangement allows more working fluid to contact the capillary wick and shortens the path the working fluid takes through the capillary wick, thus accommodating larger heat loads.

[0035] The startup problem of loop heat pipes is a significant factor limiting their widespread use in the aerospace field. In practical engineering, issues such as failure to start, slow startup, and excessively high startup temperatures frequently arise. Especially under low-power loads, the liquid in the vapor channels of the loop heat pipe vaporizes slowly, making it even more difficult to create the pressure differential needed to drive the heat pipe.

[0036] The conventional startup method for loop heat pipes is to raise the evaporator temperature by applying a heat load, creating a certain degree of superheat relative to the receiver, thereby starting the heat pipe. However, using TEC to start the heat pipe can similarly create superheat by cooling the receiver, thus driving the heat pipe to operate.

[0037] A thermoelectric cooler (TEC) mainly consists of thermoelectric elements, flow guides, and a ceramic substrate. N-type and P-type thermoelectric elements are connected by copper flow guides, and high-purity alumina ceramic substrates are used for coupling with the external environment on the cold and hot sides. The flat-plate loop heat pipe used in this paper employs two TEC coolers, each consisting of 127 pairs of PN junctions. Utilizing the Peltier effect, when energized, one end absorbs heat while the other releases heat; the heat absorption or release at the junction depends on the direction of the current.

[0038] When used in conjunction with a flat-plate loop heat pipe, two TECs are installed on opposite sides of the evaporator in series. One end of the TEC is mounted on the heat source plate, close to the evaporator, while the other end is connected to the top cover of the reservoir via a thermally conductive copper strip. A thermally conductive pad is placed between the copper strip and the reservoir. Special attention must be paid to heat insulation and vibration damping when installing and securing the copper strip. Heat insulation ensures the efficiency of the TEC, while vibration damping prevents damage during the rocket's active phase.

[0039] A heat source plate is designed at the bottom of the evaporator to ensure liquid supply even under extreme conditions. The evaporator is mounted on the heat source plate, with the heat source at the bottom and TECs (heat exchangers) on both sides. The TECs are fixed above the aluminum heat source plate by copper strips, and their heat can be transferred to the liquid reservoir through thermal bridges made of copper strips with good thermal conductivity. During the experiment, two TECs are connected in series, and the power and polarity of the TECs are controlled by changing the voltage applied to them.

[0040] To improve the start-up speed, operating efficiency, and temperature control range of a loop heat pipe, this invention proposes a temperature control method for a TEC-coupled loop heat pipe.

[0041] Figure 1 The diagram shows a loop heat pipe involved in this invention. The subcooled liquid enters the reservoir 1 through the subcooled liquid inlet 6. Under the capillary force of the capillary wick 10, the working fluid passes through the capillary wick and enters the evaporator. After absorbing heat and vaporizing, the working fluid enters the steam channel 11 and finally forms superheated steam, which leaves the loop heat pipe pump body through the superheated steam outlet 7.

[0042] Figure 2 This is a schematic diagram of the TEC coupled loop heat pipe installation in this invention. The hot end of the TEC shares a mounting surface with the evaporator, and the cold end of the TEC is connected to the liquid receiver via a thermally conductive copper strip. The TEC is powered in the forward direction and absorbs heat from the liquid receiver, creating a cooling effect on the receiver and transferring the absorbed heat to the mounting plate of the hot end of the TEC. Simultaneously, the TEC itself generates heat loss during operation, which is also transferred to the mounting plate of the hot end. Ultimately, the cooling capacity of the TEC, its own heat loss, and the heat from the heat load are all absorbed by the vaporized gas in the evaporator, thus forming the loop heat pipe and completing the system's heat dissipation task.

[0043] Figure 3 This diagram illustrates the TEC (Transfer Regulator) coupled to a loop heat pipe operating in reverse power. In this state, the TEC is powered in reverse, making the end of the TEC closest to the evaporator the cold end, and the end of the TEC connected to the receiver via a thermally conductive copper strip the hot end. The TEC's heating function is used to control the receiver temperature. In this mode, the amount of heat received by the loop heat pipe receiver is the sum of the TEC's own heat loss and its cooling capacity. Compared to the traditional method of using a heater to control the receiver temperature, the reverse TEC method saves energy and achieves more efficient temperature control.

[0044] Figure 4 This is a schematic diagram of the start-up of a loop heat pipe heater. Traditional loop heat pipe start-up involves applying a heat source to the evaporator, causing the evaporator temperature to gradually rise and create a temperature difference with the liquid receiver. This, in turn, creates a pressure difference between the evaporator and the liquid receiver, driving the loop heat pipe to operate.

[0045] Figure 5 This is a schematic diagram of the TEC (Transmission Controlled Heat Pipe) startup process. Utilizing the TEC's cooling function, the cooling capacity is transferred to the receiver, causing it to cool down. This creates a temperature difference between the evaporator and the receiver, which in turn generates a pressure difference that drives the loop heat pipe.

[0046] Figure 6This is a detailed control logic diagram of the TEC-coupled loop heat pipe in this invention. When the loop heat pipe enters the TEC temperature control mode, it first reads the external heat source temperature and the cold plate temperature. When the heat source plate temperature is detected to be higher than the upper limit of the temperature control point, the minimum temperature of the cold plate is used to determine whether the cold plate has heat dissipation capacity. When both the high temperature of the heat source and the low temperature of the cold plate are met, forward power is supplied to the TEC, causing the loop heat pipe to start. In this TEC control mode, if the heat source temperature is lower than the lower limit of the temperature control point, the TEC is powered off or reversed; if the minimum and maximum temperatures of the cold plate are higher than the reference temperature limits, the TEC is also powered off or reversed.

[0047] Although various embodiments of the invention have been described above, it should be understood that they are presented by way of example only and not as limitations. It will be apparent to those skilled in the art that various combinations, modifications, and alterations can be made without departing from the spirit and scope of the invention. Therefore, the breadth and scope of the invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined solely by the appended claims and their equivalents.

Claims

1. A TEC-coupled loop heat pipe, characterized in that: It includes a liquid receiver (1), an evaporator (2), a first semiconductor cooler (3), a second semiconductor cooler (4), a heat source plate (8), and a copper strip (5); The liquid reservoir (1) is disposed on the upper surface of the evaporator (2). The liquid reservoir (1) is provided with a supercooled liquid inlet (6). The evaporator (2) is provided with a superheated steam outlet (7). The superheated steam flowing out of the superheated steam outlet (7) flows to the external cold plate. The evaporator (2) is disposed on the upper surface of the heat source plate (8); The first semiconductor cooler (3) and the second semiconductor cooler (4) are respectively installed on both sides of the evaporator (2). The first semiconductor cooler (3) and the second semiconductor cooler (4) each have two connection ends: one connection end is installed on the heat source plate (8) close to the side of the evaporator (2), and the other connection end is connected to the top cover of the liquid storage tank (1) through a copper strip (5). The first semiconductor cooler (3) and the second semiconductor cooler (4) are connected in series; The bottom of the heat source plate (8) is an external heat source.

2. The TEC coupled loop heat pipe according to claim 1, characterized in that: A thermally conductive pad is filled between the copper strip (5) and the top cover of the liquid reservoir (1).

3. A TEC-coupled loop heat pipe according to claim 1, characterized in that: The heat source plate (8) is an aluminum plate.

4. A method for temperature control of a TEC-coupled loop heat pipe implemented according to any one of claims 1-3, characterized in that, It includes the following two control modes: Control Mode 1: The first and second semiconductor coolers are powered from the front. Specifically, the hot ends of the first and second semiconductor coolers are mounted on a heat source plate close to the evaporator, and the cold ends are connected to the top cover of the liquid receiver via copper strips. The first and second semiconductor coolers absorb heat from the liquid receiver, creating a cooling effect, and transfer this absorbed heat to the heat source plate connected to the hot ends. Simultaneously, the first and second semiconductor coolers themselves generate heat loss, which is also transferred to the heat source plate. Ultimately, the cooling capacity of the first and second semiconductor coolers, their own heat loss, and the heat from the external heat source are all absorbed by the vaporized gas in the evaporator, thus forming a loop heat pipe and completing the system's heat dissipation task. Control Mode 2: The first and second semiconductor coolers are powered in reverse. That is, the cold ends of the first and second semiconductor coolers are installed on the heat source plate close to the evaporator, and the hot ends are connected to the top cover of the liquid receiver through copper strips. The heating function of the first and second semiconductor coolers is used to control the temperature of the liquid receiver. In this mode, the amount of heat received by the loop heat pipe liquid receiver is the sum of the heat consumption of the first and second semiconductor coolers themselves and the cooling capacity of the first and second semiconductor coolers.

5. The TEC coupling loop thermal control temperature management method according to claim 4, characterized in that, The specific steps are as follows: Step 1: Read the external heat source temperature and cold plate temperature. If the heat source temperature is greater than the upper limit of the temperature control point, proceed to Step 2; if the heat source temperature is less than or equal to the upper limit of the temperature control point, proceed to Step 3. Step 2: When the minimum temperature of the cold plate is less than the reference minimum temperature and the maximum temperature of the cold plate is less than the reference maximum temperature, start control mode 1 and supply positive power to the first and second semiconductor coolers. Step 3: When the heat source temperature is lower than the lower limit of the temperature control point, disconnect the power to the first and second semiconductor coolers or reverse the power supply; when the minimum temperature of the cold plate is greater than or equal to the reference minimum temperature and the maximum temperature of the cold plate is greater than or equal to the reference maximum temperature, disconnect the power to the first and second semiconductor coolers or reverse the power supply.

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