A sub-loop partially coupled low-temperature loop heat pipe

Abstract

The present invention provides a secondary circuit partially coupled low-temperature loop heat pipe, including a main circuit, a secondary circuit and a condenser, the main circuit including a main evaporator, a main steam pipeline, a main condensing pipeline, a main liquid pipeline, a main liquid reservoir and a main gas reservoir, the secondary circuit including a secondary evaporator, a secondary steam pipeline, a secondary condensing pipeline, a secondary liquid pipeline, a secondary liquid reservoir and a secondary gas reservoir, the main circuit and the secondary circuit are two independent circuits, the secondary liquid pipeline includes a coil, the coil is coupled with the main liquid reservoir, the main condensing pipeline and the secondary condensing pipeline are fixed on the condenser through the coil structure, and the secondary liquid reservoir is connected to the condenser. The beneficial effects of the present invention are: the main circuit and the secondary circuit are two independent two-phase circuits with a simple structure; the working fluid filling amount of the independent circuit is simple to design, and the system is more stable when running; the two independent circuits have their own gas reservoirs, and the volume of the gas reservoir is small; the test can be carried out at room temperature, and the test cost is low; the applicable temperature range is large through the selection of different working fluids.

Description

Technical Field

[0001] The invention relates to the technical field of loop heat pipe design, and in particular to a sub-loop partially coupled low-temperature loop heat pipe. Background Art

[0002] The loop heat pipe (LHP) is a passive gas-liquid two-phase heat transfer device. It is widely used in aerospace thermal control systems due to its advantages such as high heat transfer efficiency, long-distance heat transfer capability, low system thermal resistance, and high reliability. With the increasing demand in the field of earth exploration and deep space exploration, infrared remote sensing detection systems are widely used in various satellites. When infrared detectors work in low temperature conditions, the response time is shortened, the sensitivity is improved, the response wavelength is broadened, and the limited background noise is reduced. Therefore, it is particularly important to develop a passive low-temperature heat transfer device that can be transmitted remotely.

[0003] The normal temperature loop heat pipe is composed of an evaporator, a condenser, a liquid reservoir, a steam pipeline and a liquid pipeline. The working fluid of the normal temperature loop heat pipe is usually in a two-phase saturated state before startup. The capillary wick in the evaporator should be able to be infiltrated by the liquid working fluid provided by the liquid reservoir, that is, the liquid level of the liquid reservoir should be above the central hole of the capillary wick. When the evaporator receives external heat, the liquid evaporates on the outer surface of the capillary wick through capillary force, and the steam is collected from the circumferential groove to the axial groove and then enters the steam pipeline. The steam is condensed into liquid by the condenser and transported to the liquid storage tank through the liquid pipeline, finally forming a self-circulating two-phase loop.

[0004] Compared with normal temperature loop heat pipes, the working fluid of low temperature loop heat pipes is usually in an overheated state at normal temperature, and is a gas with a supercritical temperature lower than normal temperature. If the working fluid is directly filled into the loop heat pipe, the pressure in the system will be very high, reaching 30-40MPa. At this time, the wall thickness of the pipeline, evaporator, liquid reservoir, etc. needs to be increased to achieve the strength to withstand the pressure, which will increase the processing cost and increase the weight of the equipment exponentially, which is not conducive to the installation of the loop heat pipe. At this time, the above problem can be solved by adding a gas reservoir.

[0005] Compared with normal temperature loop heat pipes, low temperature loop heat pipes mainly face the following technical difficulties: 1) Starting the low temperature loop heat pipe (CLHP) from the supercritical state; 2) There is a huge temperature difference between the medium in the pipeline and the ambient temperature, and the heat leakage of the pipeline is quite serious.

[0006] Foreign researchers have invented a low-temperature loop heat pipe (patent number: US6810946B2), which adds a secondary evaporator and gas reservoir on the basis of the normal temperature loop heat pipe, which can effectively solve the problem of pipeline heat leakage and the difficulty of starting the loop from the initial supercritical state. However, the main loop and the secondary loop of the invention are fully coupled, and its disadvantages are complex structure, large operation fluctuations, difficult design of working fluid filling volume, large gas reservoir volume and high testing cost. Chinese patent CN107144160A discloses a dual-loop cryogenic loop heat pipe adapted to the working temperature range of 160K to 220K, including a set of ethane working fluid loop heat pipes and a set of propylene working fluid loop heat pipes, wherein the ethane working fluid loop heat pipe is provided with an external liquid reservoir, the evaporators of the two sets of loop heat pipes are coupled together through a heat collecting seat and fit with the heat source to absorb heat, and the condensers of the two sets of loop heat pipes are thermally coupled together and fit with the heat sink to release heat. However, during supercritical startup, the inability to establish superheat between the liquid reservoir and the evaporator may lead to supercritical startup failure; during operation, the external liquid reservoir is connected to the liquid reservoir, which will cause large temperature fluctuations and affect the stable operation of the loop heat pipe; at the same time, the applicable temperature range of the system is small. Summary of the invention

[0007] In order to solve the above technical problems, the present invention discloses a secondary circuit partially coupled low-temperature loop heat pipe with simple structure, stable operation, simple design of gas reservoir working fluid filling amount, small gas reservoir volume, low testing cost, and wide applicable temperature range through selection of different working fluids. The technical solution of the present invention is implemented as follows:

[0008] A secondary loop partially coupled low-temperature loop heat pipe, comprising a main loop, a secondary loop and a condenser, wherein the main loop and the secondary loop are both connected to the condenser; the main loop comprises a main evaporator, a main steam pipeline, a main condensing pipeline, a main liquid pipeline, a main liquid reservoir and a main gas reservoir, the main evaporator is connected to the main liquid reservoir, the main steam pipeline connects the main evaporator and the main condensing pipeline, the main liquid pipeline connects the main condensing pipeline and the main liquid reservoir, and the main gas reservoir is connected to the main steam pipeline; the secondary loop comprises a secondary evaporator, a secondary steam pipeline, a secondary condensing pipeline, a secondary liquid pipeline, a secondary liquid reservoir and a secondary gas reservoir, the secondary evaporator is connected to the secondary liquid reservoir, the secondary steam pipeline connects the secondary evaporator and the secondary condensing pipeline, the secondary liquid pipeline connects the secondary condensing pipeline and the secondary liquid reservoir, the secondary gas reservoir is connected to the secondary liquid pipeline, and the secondary liquid pipeline comprises a coil, which is coupled to the main liquid reservoir.

[0009] Preferably, the working fluids in the primary loop and the secondary loop are respectively selected from any one of helium, hydrogen, neon, nitrogen, methane and ethylene.

[0010] Preferably, the main condensing pipeline and the secondary condensing pipeline are both fixed on the condenser through a coil structure.

[0011] Preferably, the secondary liquid reservoir is connected to the condenser.

[0012] The technical solution of the present invention can solve the technical problems in the prior art that supercritical startup is difficult, loop heat pipes are unstable under low temperature conditions, and the system filling volume is difficult to adapt to the large temperature difference span; the technical solution of the present invention is implemented by adopting two completely independent main circuits and secondary circuits, the main liquid reservoir of the main circuit and the coil part of the secondary liquid pipeline of the secondary circuit are coupled, and the main circuit and the secondary circuit are separately provided with gas reservoirs, which can achieve the following technical effects:

[0013] 1. The main circuit and the secondary circuit are two independent two-phase circuits with simple structure;

[0014] 2. The design of the working fluid filling quantity of the independent circuit is simple, and the system is more stable during operation;

[0015] 3. Independent circuits have their own gas reservoirs, and the volume of the gas reservoirs is small;

[0016] 4. The test can be carried out at room temperature, and the test cost is low;

[0017] 5. The applicable temperature range is wide through the selection of different working fluids. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] The same parts are denoted by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "bottom" and "top", "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0020] Figure 1 It is a schematic diagram of the structure of the secondary loop partially coupled low-temperature loop heat pipe;

[0021] Figure 2 This is the main circuit structure diagram;

[0022] Figure 3 This is a schematic diagram of the secondary loop structure.

[0023] In the above drawings, the figure numbers represent:

[0024] 1 Main circuit

[0025] 1-1 Main evaporator

[0026] 1-2 Main steam pipeline

[0027] 1-3 Main condensation pipeline

[0028] 1-4 Main liquid pipeline

[0029] 1-5 main reservoir

[0030] 1-6 Main gas reservoir

[0031] Secondary circuit

[0032] 2-1 Evaporator

[0033] 2-2 steam pipeline

[0034] 2-3 condensation lines

[0035] 2-4 secondary liquid pipeline

[0036] 2-5 coils

[0037] 2-6 times reservoir

[0038] 2-7 gas storage

[0039] 3 Condenser DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example

[0042] In a preferred embodiment, Figure 1 As shown, a sub-loop partially coupled low-temperature loop heat pipe includes a main loop 1, a sub-loop 2 and a condenser 3. The main loop 1 and the sub-loop 2 are two independent loops. Therefore, the filling amount of the working fluid can be calculated based on the filling amounts of the main loop 1 and the sub-loop 2, respectively, which can simplify the calculation of the working fluid filling of the loop heat pipe. The main loop 1 and the sub-loop 2 are connected in a partially coupled manner, and both the main loop 1 and the sub-loop 2 are connected to the condenser 3. The main loop 1 includes a main evaporator 1-1, a main steam pipeline 1-2, a main condensing pipeline 1-3, a main liquid pipeline 1-4, a main liquid reservoir 1-5 and a main gas reservoir 1-6, as shown in FIG. Figure 2As shown, the main evaporator 1-1 is connected to the main liquid reservoir 1-5, the main steam pipeline 1-2 connects the main evaporator 1-1 and the main condensing pipeline 1-3, the main liquid pipeline 1-4 connects the main liquid reservoir 1-5 and the main condensing pipeline 1-3, and the main gas reservoir 1-6 is connected to the main steam pipeline 1-2. The secondary circuit 2 includes the secondary evaporator 2-1, the secondary steam pipeline 2-2, the secondary condensing pipeline 2-3, the secondary liquid pipeline 2-4, the secondary liquid reservoir 2-6 and the secondary gas reservoir 2-7, as shown in FIG. Figure 3 As shown, the secondary evaporator 2-1 is connected to the secondary liquid reservoir 2-6, the secondary steam pipeline 2-2 connects the secondary evaporator 2-1 and the secondary condensation pipeline 2-3, the secondary liquid pipeline 2-4 connects the secondary liquid reservoir 2-6 and the secondary condensation pipeline 2-3, the secondary gas reservoir 2-7 is connected to the secondary liquid pipeline 2-4, the secondary liquid pipeline 2-4 includes a coil 2-5, and the coil 2-5 is coupled to the main liquid reservoir 1-5. The main condensation pipeline 1-3 and the secondary condensation pipeline 2-3 are fixed on the condenser 3 by setting a coil structure. The secondary liquid reservoir 2-6 is connected to the condenser 3. The secondary liquid pipeline 2-4 is coupled in the main liquid reservoir 1-5 through the coil 2-5, so that the working medium in the secondary liquid pipeline 2-4 and the working medium in the main liquid reservoir 1-5 can fully exchange heat.

[0043] Before the system is started, the working fluid in the low-temperature loop heat pipe is in a high-pressure state. When the condenser 3 is turned on, the working fluid in the secondary liquid reservoir 2-6 connected to the condenser 3 begins to cool down continuously, and the pressure in the secondary liquid reservoir 2-6 also decreases. The high-pressure gas in the secondary gas reservoir 2-7 enters the secondary liquid reservoir 2-6 due to the pressure difference and begins to condense and liquefy. When the liquid level in the secondary liquid reservoir 2-6 is above the central hole position of the secondary capillary core in the secondary evaporator 2-1, the evaporator 2-1 receives external After the heat is absorbed, the liquid evaporates on the outer surface of the secondary capillary core by capillary force, and the steam enters the secondary steam pipeline 2-2. After the steam is cooled by the secondary condensation pipeline 2-3 connected to the condenser 3, it is condensed into liquid. The liquid working medium is transported to the coil 2-5 coupled to the main liquid reservoir 1-5 through the secondary liquid pipeline 2-4. The liquid in the coil 2-5 fully exchanges heat with the working medium in the main liquid reservoir 1-5 and returns to the secondary liquid reservoir 2-6, finally forming a self-circulating two-phase secondary loop, and the secondary loop is successfully started.

[0044] The working fluid in the main condensing pipeline 1-3 is cooled by the condenser 3 and then enters the main liquid reservoir 1-5 through the main liquid pipeline 1-4. After heat exchange with the low-temperature working fluid in the coil 2-5, the temperature continues to drop, and the pressure in the main liquid reservoir 1-5 also decreases accordingly. The high-pressure gas in the main gas reservoir 1-6 enters the main liquid reservoir 1-5 due to the pressure difference and begins to condense and liquefy. When the liquid level in the main liquid reservoir 1-5 is above the central hole position of the main capillary core in the main evaporator 1-1, after the main evaporator 1-1 receives external heat, the liquid evaporates on the outer surface of the main capillary core by capillary force, and the steam enters the main steam pipeline 1-2. After the steam is cooled by the main condensing pipeline 1-3 connected to the condenser 3, it is condensed into liquid. The liquid working fluid is transported to the main liquid reservoir 1-5 through the main liquid pipeline 1-4, and finally a self-circulating two-phase main loop is formed, and the main loop is successfully started.

[0045] According to different working temperature zones, the working fluids of the primary loop 1 and the secondary loop 2 of the low-temperature loop heat pipe can be selected as any one of helium (2.7-4.4K), hydrogen (20-30K), neon (28-44K), nitrogen (75-100K), methane (100-180K), and ethylene (150-250K).

[0046] It should be pointed out that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A secondary loop partially coupled low temperature loop heat pipe, characterized in that: The main circuit comprises a main circuit, a secondary circuit and a condenser, wherein the main circuit and the secondary circuit are both connected to the condenser; the main circuit comprises a main evaporator, a main steam pipeline, a main condensing pipeline, a main liquid pipeline, a main liquid reservoir and a main gas reservoir, the main evaporator is connected to the main liquid reservoir, the main steam pipeline connects the main evaporator and the main condensing pipeline, the main liquid pipeline connects the main condensing pipeline and the main liquid reservoir, and the main gas reservoir is connected to the main steam pipeline; the secondary circuit comprises a secondary evaporator, a secondary steam pipeline, a secondary condensing pipeline, a secondary liquid pipeline The secondary vaporizer is connected to the secondary vaporizer, the secondary vapor pipeline connects the secondary vaporizer and the secondary condenser, the secondary liquid pipeline connects the secondary condenser and the secondary liquid reservoir, the secondary gas reservoir is connected to the secondary liquid pipeline, the secondary liquid pipeline includes a coil, and the coil is coupled to the main liquid reservoir; the working fluids in the main loop and the secondary loop are respectively selected from any one of helium, hydrogen, neon, nitrogen, methane and ethylene; the main loop and the secondary loop are two independent two-phase loops.

2. The secondary loop partially coupled low temperature loop heat pipe according to claim 1, characterized in that: The main condensing pipeline and the secondary condensing pipeline are both fixed on the condenser through a coil structure.

3. The secondary loop partially coupled low temperature loop heat pipe according to claim 2, characterized in that: The secondary liquid reservoir is connected to the condenser.

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