CN111811303B

CN111811303B - Loop heat pipe

Info

Publication number: CN111811303B
Application number: CN201910288364.7A
Authority: CN
Inventors: 郭春生; 李言伟; 李佳航; 辛稀龙; 徐怡平; 张欣哲; 姜鲲; 纪文睿; 张茜卓
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2019-04-11
Filing date: 2019-04-11
Publication date: 2021-06-29
Anticipated expiration: 2039-04-11
Also published as: CN111811303A

Abstract

The invention provides a loop heat pipe which comprises an evaporator, a condenser and a heat accumulator, wherein the evaporator and the condenser form a circulating pipeline through a first pipeline and a second pipeline, fluid absorbs heat in the evaporator and evaporates, then the condenser releases heat through the first pipeline, then the fluid circulates from the condenser to the evaporator through the second pipeline, and the heat accumulator is arranged in the second pipeline; the heat pipe further comprises a first three-way valve and a second three-way valve, the first three-way valve is arranged on the first pipeline, the second three-way valve is arranged on the second pipeline between the heat accumulator and the evaporator, one end of the third pipeline is connected with the second three-way valve, the other end of the third pipeline is connected to the first pipeline between the first three-way valve and the evaporator, one end of the fourth pipeline is connected with the first three-way valve, and the other end of the fourth pipeline is connected to the second pipeline between the heat accumulator and the condenser. The invention designs the loop heat pipe with a novel structure, which makes full use of the heat source of the loop heat pipe and reduces the energy consumption.

Description

Loop heat pipe

Technical Field

The invention belongs to the field of heat pipes, and particularly relates to a loop heat pipe.

Background

The heat pipe technology is a heat transfer element called a heat pipe invented by george geover grover (Los Alamos) national laboratory in Los Alamos (1963), which makes full use of the heat conduction principle and the rapid heat transfer property of a phase change medium, and the heat of a heating object is rapidly transferred to the outside of a heat source through the heat pipe, and the heat conduction capability of the heat transfer element exceeds the heat conduction capability of any known metal.

The heat pipe technology is widely applied to the industries of aerospace, military industry and the like, and since the heat pipe technology is introduced into the radiator manufacturing industry, the design idea of the traditional radiator is changed for people, the single heat radiation mode that a high-air-volume motor is used for obtaining a better heat radiation effect is avoided, the heat pipe technology is adopted for enabling the radiator to obtain a satisfactory heat exchange effect, and a new place in the heat radiation industry is opened up. At present, the heat pipe is widely applied to various heat exchange devices, including the field of nuclear power, such as the utilization of waste heat of nuclear power.

Aiming at the problems, the invention is improved on the basis of the prior invention, and provides a new heat pipe structure, which makes full use of the heat source of the loop heat pipe and reduces the energy consumption.

Disclosure of Invention

The invention aims to provide a novel loop heat pipe, which can improve the heat exchange efficiency of the heat pipe and reduce the energy consumption.

In order to achieve the purpose, the technical scheme of the invention is as follows: a loop heat pipe comprises an evaporator, a condenser and a heat accumulator, wherein the evaporator and the condenser form a circulation pipeline through a first pipeline and a second pipeline, fluid absorbs heat in the evaporator and evaporates, then the condenser releases heat through the first pipeline, then the fluid circulates from the condenser back to the evaporator through the second pipeline, and the heat accumulator is arranged in the second pipeline; the heat pipe further comprises a first three-way valve and a second three-way valve, the first three-way valve is arranged on the first pipeline, the second three-way valve is arranged on the second pipeline between the heat accumulator and the evaporator, one end of the third pipeline is connected with the second three-way valve, the other end of the third pipeline is connected to the first pipeline between the first three-way valve and the evaporator, one end of the fourth pipeline is connected with the first three-way valve, and the other end of the fourth pipeline is connected to the second pipeline between the heat accumulator and the condenser.

Preferably, a phase change heat storage medium is arranged in the heat accumulator.

Preferably, the evaporator is of a flat plate construction.

A solar energy system comprising the loop heat pipe as described above, said evaporator being a solar collector.

Preferably, the evaporator absorbs solar energy to form a solar heat collector, the evaporator is of a flat plate structure and comprises a heat collection area, the heat collection area comprises a transparent cover plate, a support plate, a capillary component, a first space and a second space, the transparent cover plate is arranged on the upper portion, the first space is formed between the support plate and the lower wall face of the evaporator, the second space is formed between the support component and the transparent cover plate, a through hole communicated with the first space and the second space is formed in the support component, the capillary component is arranged in the through hole, the first space is a liquid space, the transparent cover plate corresponding to the through hole is provided with a lens, and the through hole is located at the focus of the lens.

Preferably, the through holes are provided in a plurality, each through hole is provided with a lens on the corresponding transparent cover plate, and the through holes are located at the focus of the corresponding lens.

Preferably, the evaporator further comprises a liquid storage area, the liquid storage area is of a flat plate structure, the bottom of the liquid storage area is communicated with the liquid channel, and the height of the upper wall surface of the liquid storage area is higher than that of the capillary component.

Preferably, the heat collecting region has a circular cross-section, and the capillary members include a central capillary member disposed at a center of the circle and a peripheral capillary member disposed around the center.

Preferably, the capillary force of the central capillary element is greater than the capillary force of the surrounding capillary elements.

Preferably, the peripheral capillary components are of a one-layer structure, the radius of the inner wall of the heat collection region is K, the center of the central capillary component is arranged at the center of the heat collection region, the distance between the center of the peripheral capillary component and the center of the heat collection region is M, the centers of adjacent peripheral capillary components are respectively connected with the center of the heat collection region, an included angle formed by the two connecting lines is a, the capillary force of a single peripheral capillary component is F1, and the capillary force of a single central capillary component is F2, so that the following requirements are met:

L2/L1 ═ a-b ═ Ln (K/M); ln is a logarithmic function;

a, b are coefficients, wherein 1.5599< a <1.5605,0.4358< b < 0.4364;

1.23<K/M<2.05；

1.2<F2/F1<1.5。

wherein 40 ° < a <100 °.

Preferably, the number of the four sides is 4-8; preferably 4-5.

Preferably, K is 1500-; m is 756-1260 mm, preferably 800 mm.

More preferably, a is 1.5602 and b is 0.4361.

Preferably, the wall surface of the lower part of the heat collection area is provided with an auxiliary heating device, a flow meter is arranged on a pipeline of the evaporator flowing to the condenser to test the steam flow, and the auxiliary heating device adjusts the electric heating device to heat according to the tested steam flow.

Preferably, the auxiliary heating device automatically starts heating if the tested flow rate is lower than a certain value, and stops heating if the tested flow rate is higher than a certain value.

Compared with the prior art, the invention has the following advantages:

1) the invention provides a novel loop heat pipe structure, which can realize the heat storage of a heat accumulator, the heat dissipation of a condenser and the heat supply operation of the condenser of a heat accumulator box by setting the opening and closing of a three-way valve.

2) The invention provides a novel loop heat pipe soil treatment system which can purify soil by heating.

3) According to the invention, the capillary components are arranged at selective partial positions in the heat collection area, and heat collection is carried out through the corresponding lenses, so that the area where important liquid appears is selectively selected for heating, the cost of the capillary structure is reduced, the cost is integrally reduced, and the utilization rate of heat energy is improved.

4) According to the invention, the liquid storage area is arranged in the heat collector, the liquid storage area is communicated with the liquid channel of the heat collection area, and the water level is obviously higher than the height of the capillary component of the heat collection area, so that the liquid absorption capacity of the capillary component can be increased, and the drying of the heat collector can be avoided.

5) According to the invention, a novel distribution structure of the capillary component in the heater is designed, an optimal capillary force optimization result in the optimal distribution structure is obtained through multiple tests and numerical simulation, and the test verifies, so that the accuracy of the result is proved.

6) The invention is provided with the auxiliary heating device which is arranged on the tube wall below the capillary component, and the liquid in the liquid channel is heated, so that on one hand, the heat absorption capacity of the capillary can be improved, and on the other hand, the situation that the solar heat collection capacity is insufficient under special conditions (such as at night or low illumination intensity) can be avoided.

Drawings

FIG. 1 is a schematic diagram of a loop heat pipe configuration;

FIG. 2 is a schematic diagram of a loop heat pipe solar collector system

FIG. 3 is a schematic view of a loop heat pipe solar collector in a top view

FIG. 4 is a schematic cross-sectional view of the solar collector of FIG. 3

Fig. 5 is a schematic diagram of a capillary element distribution structure according to the present invention.

Fig. 6 is a schematic condenser distribution.

FIG. 7 is a schematic diagram of a loop heat pipe solar collector system.

The reference numbers are as follows:

solar collector system reference numerals: evaporator 1, evaporator 2, heat collecting area 1011, transparent cover plate 21, support plate 103, capillary component 24, first space 104, second space 105, through hole 106, lens 107,

pressure gauges

109, 110, heat accumulator 3, first pipeline 4, second pipeline 5, second three-way valve 6, first three-way valve 7, third pipeline 8, fourth pipeline 9

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

As shown in fig. 1, a loop heat pipe includes an evaporator 1, a condenser 2, and a heat accumulator 3, the evaporator 1 and the condenser 2 form a circulation line through a first line 4 and a second line 5, the fluid absorbs heat and evaporates in the evaporator, then enters the condenser 2 through the first line 5 to release heat, and then circulates from the condenser 2 back to the evaporator 1 through the second line 5, and the heat accumulator 3 is disposed in the second line. Through the heat accumulator, redundant heat can be stored in the heat accumulator, and therefore the heat can be better utilized.

Preferably, the heat pipe further includes a first three-way valve 7 and a second three-way valve 6, the first three-way valve 7 being disposed on the first pipe 4, the second three-way valve 6 being disposed on the second pipe 5 between the regenerator 3 and the evaporator 1, a third pipe 8 having one end connected to the second three-way valve 6 and the other end connected to the first pipe 4 between the first three-way valve 7 and the evaporator 1, and a fourth pipe 9 having one end connected to the first three-way valve 7 and the other end connected to the second pipe 5 between the regenerator 3 and the condenser 2.

The loop heat pipe structure can realize the following functions: 1) storing the waste heat in a heat accumulator; 2) the heat accumulator or the evaporator supplies heat to the condenser by setting the opening and closing of the three-

way valves

6 and 7. For example, the heat accumulator can supply heat to the condenser by closing the line between the evaporator and the heat accumulator by the three-way valve 6, closing the fourth line by the three-way valve 7, closing the first line by the three-way valve 7, and opening the second line by the three-way valve 6.

Preferably, the evaporator is of a flat plate construction.

The invention also provides a method for controlling the three-

way valves

6 and 7 to be opened and closed according to the requirement, thereby realizing the heat storage and heat supply functions of intelligent control.

The heat pipe also comprises a controller which is in data connection with the three-

way valves

6 and 7. The controller can control the open and close states of the three-

way valves

6, 7.

Preferably, when the evaporator supplies insufficient heat (for example, as a solar heat collector, the light is not strong or at night), the controller controls the three-way valve 6 to close the communication between the heat accumulator and the evaporator, opens the communication between the heat accumulator and the third pipeline 8, controls the three-way valve 7 to close the communication between the first pipeline and the fourth pipeline, opens the communication of the first pipeline, and forms a circulation loop with the heat accumulator and the condensation end, so that the heat accumulator supplies heat to the condenser.

As a preference, when the condenser 5 does not need heat (for example, the condenser is placed in the soil, the soil temperature is too high), the controller controls the three-way valve 7 to close the communication between the first line and the fourth line, close the communication between the evaporator and the condenser, the three-way valve 6 to open the communication between the heat accumulator 3 and the evaporator, and close the communication between the second line and the third line, so that the evaporator only supplies heat to the heat accumulator.

Preferably, the condenser is arranged in soil and used for repairing the soil. The condensation end conducts heat to the surrounding soil.

The invention provides a soil remediation system of a loop heat pipe with a novel structure, and the loop heat pipe is used as a high-efficiency heat transfer tool, so that the principle is simple, the structure is compact, and the cooling efficiency is obviously improved.

Preferably, the condensing end is a coil structure arranged on a plane, as shown in fig. 6. The hot fluid flows from the outside to the center, dissipating heat into the soil.

Preferably, the coiled tube structure extends from the center of the circular structure, extends the outer end of the circular structure, and then coils toward the center of the circular structure, as shown in fig. 6. Through so setting up, can make the heat begin the heat dissipation from the outer end of circular structure earlier, then inwards gradually. Because the pipe diameter of the coil pipe at the outer end is large, more heat is needed. Through the arrangement, the soil can be uniformly heated on the whole.

Preferably, the distribution density of the coils is increased (the spacing between adjacent coils is increased and decreased) in the radial direction along the center of the circular structure. The main reason is that by so arranging, heat can be dissipated from the outer end of the circular structure first and then gradually inwards. Because the pipe diameter of the coil pipe of outer end is big, need more heats for whole heat dissipation is even, strengthens soil remediation effect. So that the overall repair is uniform.

Further preferably, the distribution density of the coils increases to a greater and greater extent, preferably in the radial direction along the centre of the circular structure. Numerical simulation and experiments show that the uniformity of soil heating can be further improved through the structure.

Preferably, the diameter of the coil increases to a radial direction along the center of the circular structure. The main reason is that by so arranging, heat can be dissipated from the outer end of the circular structure first and then gradually inwards. Because the pipe diameter of the coil pipe of outer end is big, need more heats for whole heat dissipation is even, strengthens soil remediation effect. So that the overall repair is uniform.

Further preferably, the diameter of the coil increases to a greater and greater extent in the radial direction along the center of the circular structure. Numerical simulation and experiments show that the uniformity of soil heating can be further improved through the structure. The soil restoration effect is enhanced, and the overall restoration is uniform.

Preferably, a power device is arranged between the condenser and the evaporator. Preferably, the power means may be a capillary structure or a circulation pump.

Preferably, the loop heat pipe solar collector system comprises a loop heat pipe, and the loop heat pipe is the loop heat pipe in fig. 1.

The solar energy and the loop heat pipe are used for soil treatment, so that the device can be directly heated by using the heat of sunlight when the sunlight is sufficient, and the solar energy can be stored in a heat storage medium in the heat storage device. When no illumination is available, the device is heated by utilizing the stored energy, so that the purpose of heating the soil without inputting energy is achieved.

The loop heat pipe condenser is fully contacted with external soil in a coiling mode, and the heat exchange efficiency is improved.

The invention can store the redundant heat in the heat storage medium while raising the temperature of the soil, and can be used for other purposes. And other external energy is not needed to be input, and the energy utilization efficiency is high. Can work in different weather, and because this soil purification device adopts microbial degradation can not produce secondary pollutant, reduced environmental pollution.

Preferably, a temperature sensor is arranged in the soil and used for detecting the temperature of the soil, and the controller is in data connection with the temperature sensor. The controller controls the opening and closing of the three-way valve according to the detected soil temperature.

When the detected soil temperature is too high, the controller controls the three-way valve 7 to open the communication between the first pipeline and the fourth pipeline and close the communication between the evaporator and the condenser, the three-way valve 6 opens the communication between the heat accumulator 3 and the evaporator and closes the communication between the second pipeline and the third pipeline, and therefore the evaporator only supplies heat to the heat accumulator.

When the detected soil temperature is too low, the controller controls the three-way valve 7 to close the communication between the first pipeline and the fourth pipeline, close the communication between the evaporator and the condenser, close the communication between the heat accumulator 3 and the evaporator by the three-way valve 6, and open the communication between the second pipeline and the third pipeline, so that the evaporator only supplies heat to the heat accumulator.

As shown in fig. 2, the loop heat pipe solar collector system using fig. 1 is shown, the evaporator 1 absorbs solar energy to form a solar collector 101, as shown in fig. 2 and 3, the evaporator 1 is a flat plate structure and includes a heat collecting area 1011, the heat collecting area 1011 includes a transparent cover plate 21, a support plate 103, a capillary component 24, a first space 104 and a second space 105, the transparent cover plate 21 is disposed at an upper portion, the first space 104 is formed between the support component 103 and a lower wall surface of the evaporator 1, the support component 103 is preferably a support plate, the second space 105 is formed between the support component 103 and the transparent cover plate 21, the support component 103 is provided with a through hole 106 communicating the first space 104 and the second space 105, the capillary component 24 is disposed in the through hole 106, the first space 105 is a liquid space, the transparent cover plate 21 corresponding to the through hole 106 is provided with a lens 107, the through hole 106 is located at the focal point of the lens 107.

According to the invention, the capillary parts are arranged at selective partial positions in the heat collection area, namely, the capillary parts are arranged at the heat collection part and heat collection is carried out through the corresponding lenses arranged on the transparent cover plate, so that the area where important liquid appears is selectively selected for heating, the area of the capillary parts arranged in the structure is small, the cost of the capillary structure is reduced, the cost is integrally reduced, and the utilization rate of heat energy is improved.

The support structure can play a role of supporting the capillary component, and can avoid the capillary component from sinking and keep good liquid absorption capacity compared with the situation that only the capillary component is arranged.

Preferably, the capillary members occupy 60-80% of the cross-sectional area of the heat collecting region 1011.

Preferably, the capillary member is a porous material.

Preferably, as shown in fig. 2 to 3, the through holes 106 are provided in a plurality, each through hole 106 is provided with a lens 107 on the corresponding transparent cover plate 21, and the through hole 106 is located at the focal point of the corresponding lens 107. By providing a plurality of capillary members and corresponding lenses, multipoint heating can be performed, and the heating capability can be further improved.

Preferably, as shown in fig. 3, the evaporator further includes a liquid storage area 28, the liquid storage area 28 is a flat plate structure, the bottom of the liquid storage area 28 is communicated with the liquid space 105, and the height of the upper wall surface of the liquid storage area 28 is higher than that of the capillary component 24.

Preferably, the height of the upper wall surface of the liquid storage region 28 is 5mm higher than that of the capillary member.

Preferably, the water is driven into the liquid storage area by a power plant.

The liquid storage area is arranged in the heat collector, the liquid storage area is communicated with the liquid channel of the heat collection area, and the water level is obviously higher than the height of the capillary component of the heat collection area, so that the water level is obviously higher than the upper part of the capillary component, the liquid absorption capacity of the capillary component can be increased through the pressure difference of the water level height, and the drying of the heat collector can be avoided.

Preferably, the cross-section of the heat collecting region 1011 is circular, and the capillary member 24 includes a central capillary member disposed at the center of the circle and a peripheral capillary member disposed around the center. The invention designs a novel distribution structure of the capillary component in the heater, can further promote the liquid absorption capacity of the capillary component, avoids the defect of the liquid absorption capacity of the capillary at different positions, and aims at the targeted arrangement and reasonable layout of the capillary component at different positions.

Preferably, the capillary force of the central capillary element is greater than the capillary force of the surrounding capillary elements. Because the central fluid is distributed towards the periphery, the influence range is wide, the peripheral capillary components only radiate the periphery, and the overall radiation cannot be realized, so that the absorbed liquid can flow towards the periphery through the middle part by arranging the central capillary component with large capillary capacity, the uneven distribution of the fluid is ensured, meanwhile, the central heat collection capacity is large under normal conditions, the liquid heating capacity is strong, the heat collection capacity is ensured, and the solar energy is fully utilized.

Preferably, in the second space, the fluid is heated uniformly to avoid uneven distribution of heat exchange, which leads to drying of partial areas, because the central fluid radiates to the periphery, which can affect the whole situation, while the peripheral fluid affects only the peripheral areas. It is therefore desirable to achieve uniform distribution of internal heat transfer by reasonably distributing the amount of capillary capacity of the different capillary members. Through experiments, the capillary capacity of the central capillary element and the peripheral capillary elements is related to two key factors, wherein one factor is related to the distance between the peripheral capillary elements and the circle center of the heat collecting area and the diameter of the heat collecting area. The invention thus optimizes the optimal proportional distribution of capillary forces according to a large number of numerical simulations and experiments.

F2/F1 ═ a-b ═ Ln (K/M); ln is a logarithmic function;

a, b are coefficients, wherein 1.5599< a <1.5605,0.4358< b < 0.4364;

preferably, 1.23< K/M < 2.05;

preferably, 1.2< F2/F1< 1.5.

Wherein 40 ° < a <100 °.

Preferably, the number of the four sides is 4-8; preferably 4-5.

Preferably, K is 1500-; m is 756-1260 mm, preferably 800 mm.

More preferably, a is 1.5602 and b is 0.4361.

Preferably, the auxiliary heating device 23 is arranged on the lower wall surface of the heat collection area, the flow meter is arranged on the pipeline of the evaporator flowing to the condenser to test the steam flow, and the auxiliary heating device adjusts the auxiliary heating device to heat according to the tested steam flow. Through setting up auxiliary heating device, set up it on capillary part below pipe wall, the liquid in the liquid heating channel, can improve capillary heat absorption ability on the one hand, on the other hand also can avoid the not enough condition of solar energy collection ability under the special circumstances (for example evening or illumination intensity is little).

Preferably, the heating means is activated to heat when the wicking capacity of the capillary element is insufficient, for example, the capillary liquid has a working capacity exceeding a rated working life, or in the case of sufficient sunlight, the vapor flow is significantly insufficient.

The working capacity of the capillary element can be indirectly improved by heating so that the temperature of the liquid in the liquid space is increased.

Preferably, the condenser is disposed in the water tank.

Preferably, the inlet and the outlet of the heat collector are provided with pressure sensors for detecting the pressure of the inlet and the pressure of the outlet.

Preferably, the upper wall of the liquid storage region and the support member are of an integral structure, as shown in fig. 4.

Although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A loop heat pipe comprises an evaporator, a condenser and a heat accumulator, wherein the evaporator and the condenser form a circulation pipeline through a first pipeline and a second pipeline, fluid absorbs heat in the evaporator and evaporates, then the condenser releases heat through the first pipeline, then the fluid circulates from the condenser back to the evaporator through the second pipeline, and the heat accumulator is arranged in the second pipeline; the heat pipe also comprises a first three-way valve and a second three-way valve, wherein the first three-way valve is arranged on a first pipeline, the second three-way valve is arranged on a second pipeline between the heat accumulator and the evaporator, one end of a third pipeline is connected with the second three-way valve, the other end of the third pipeline is connected to the first pipeline between the first three-way valve and the evaporator, one end of a fourth pipeline is connected with the first three-way valve, and the other end of the fourth pipeline is connected to the second pipeline between the heat accumulator and the condenser; the evaporator absorbs solar energy to form a solar heat collector, the evaporator is of a flat plate structure and comprises a heat collection area, the heat collection area comprises a transparent cover plate, a support plate, a capillary component, a first space and a second space, the transparent cover plate is arranged at the upper part, the first space is formed between the support plate and the lower wall surface of the evaporator, the second space is formed between the support component and the transparent cover plate, a through hole for communicating the first space with the second space is formed in the support component, the capillary component is arranged in the through hole, the first space is a liquid space, the transparent cover plate corresponding to the through hole is provided with a lens, and the through hole is positioned on the focus of the lens; the through holes are arranged in a plurality of numbers, each through hole is provided with a lens on the corresponding transparent cover plate correspondingly, and the through holes are positioned on the focus of the corresponding lens.

2. A loop heat pipe as claimed in claim 1 wherein a phase change heat storage medium is provided in said heat accumulator.

3. A loop heat pipe as claimed in claim 1 wherein said evaporator is of flat plate construction.

4. A solar energy system comprising the loop heat pipe of any one of claims 1-3, the evaporator being a solar collector.