KR20220010880A - Cryogenic Loop Heat Pipe and Controlling the temperature of a primary evaporator thereof - Google Patents

Abstract

The present invention relates to a method capable of dynamically adjusting the temperature of the primary evaporator of a cryogenic loop heat pipe. The method comprises the steps of: considering the pressure (P_tank) of a gas buffer tank as the internal saturation pressure (P_1.sat) of a compensation chamber; confirming the internal saturation temperature (T_1.sat) of the compensation chamber from the known saturation property table; calculating the saturation pressure (P_2.sat) of space by calculating the pressure drop in each section in which a working fluid discharged from the space returns to the compensation chamber; confirming the saturation temperature (T_2.sat) of the space in the known saturation property table; obtaining the surface temperature (T_pe) of the primary evaporator from the pressure (P_tank) of the gas buffer tank by applying the experimental data correction formula between the saturation temperature (T_2.sat) of the space and the surface temperature (T_pe) of the primary evaporator; and adjusting the pressure of the gas buffer tank by selectively opening or closing a pressure supply valve and an exhaust valve.

Description

Cryogenic Loop Heat Pipe and Controlling the Temperature of a Primary Evaporator thereof

The present invention relates to a cryogenic loop heat pipe, and more particularly, to a method for actively controlling the temperature of the main evaporator.

The universe is a harsh environment in which the influence of gravity is very small and high vacuum, and high temperature and cryogenic temperature are repeated due to solar radiation. Therefore, before launching a satellite, it must be sufficiently tested on the ground to see if it works well in a space environment that is significantly different from that of Earth. To this end, the space environment is simulated using a thermal vacuum chamber device on the ground, and a test is performed to confirm that the satellite works well in the extreme environment of space, such as high temperature, low temperature, and vacuum.

As one of the devices used in a space environment where the influence of gravity is very small, as shown in FIG. 1 , a cryogenic loop heat pipe is used.

In this conventional cryogenic loop heat pipe, as shown in FIG. 3 , the temperature of the primary evaporator 101 is passive by the heat inflow of the primary evaporator 101 and the cooling capacity of the condenser 102 . It corresponds to a passive heat transfer device that is fixed to That is, it is impossible to actively control the temperature of the main evaporator 101, and even if the performance is reduced due to the decrease in the working fluid inside the loop heat pipe due to leakage, there is a problem that cannot be supplemented. For reference, in FIG. 1, reference numeral 102 denotes a secondary evaporator, and reference numeral 104 denotes a gas buffer tank. The auxiliary evaporator 102 serves to send the working fluid liquefied in the condenser 102 to the main evaporator. The gas buffer tank 104 serves to prevent excessively high pressure inside the cryogenic loop heat pipe at room temperature.

Korean Patent Publication No. 10-2076016 (2020.02.05.)

SUMMARY OF THE INVENTION The present invention is to solve the problems of the prior art as described above, and an object of the present invention is to provide a cryogenic loop heat pipe capable of actively controlling an evaporator temperature.

In order to achieve the above object, a cryogenic loop heat pipe used in a space environment according to an embodiment of the present invention includes a main evaporator for absorbing heat by vaporizing a working fluid, and condensing the working fluid flowing from the main evaporator. A condenser for dissipating heat, and a high-pressure working fluid storage for selectively supplying a high-pressure working fluid to the main evaporator in order to adjust the pressure of the main evaporator.

In addition, a gas buffer tank is further provided, and the high-pressure working fluid reservoir selectively supplies a high-pressure working fluid to the main evaporator through the gas buffer tank, and the high-pressure working fluid reservoir and the A pressure supply valve is provided between one side of the gas buffer tank, and an exhaust valve is provided at the other side of the gas buffer tank.

In addition, the main evaporator includes a compensation chamber (CC) in which a liquid working fluid and a vapor working fluid (vapor) coexist, and a main evaporator wick located at one side thereof, and the main evaporator A space is formed between the wick and the inner wall of the main evaporator.

As a method of controlling the surface temperature of the main evaporator of the cryogenic loop heat pipe described above, the step of considering _{the pressure (P tank} ) of the gas buffer tank as the internal saturation pressure (P _{1.sat ) of the compensation chamber, known saturation Checking the internal saturation temperature (T 1.sat} ) of the compensation chamber in the physical property table, the saturation pressure (P _2.sat ) of the space in each section in which the working fluid discharged from the space returns to the compensation chamber _{Calculating the pressure drop of these, confirming the saturation temperature (T 2.sat} ) of the space in a known table of saturation properties, the saturation temperature of the space (T _2.sat ) and the surface temperature of the main evaporator (T _pe ) by applying an experimental data correction _{formula between, obtaining the surface temperature (T pe} ) of the main evaporator from the _{pressure (P tank} ) of the gas buffer tank, and selectively opening or It characterized in that it comprises the step of adjusting the pressure of the gas buffer tank by closing.

In addition, the experimental data correction equation is characterized in that T _pe = 132.73998 - 1.42102 × T _1.sat + 0.0115 × T _1.sat ^2.

In addition, each section in which the working fluid discharged from the space returns to the compensation chamber is a tube section between the evaporator and the condenser, and the condenser section.

According to the cryogenic loop heat pipe according to the embodiment of the present invention having the above-described configuration, it is possible to actively control the surface temperature of the main evaporator of the cryogenic loop heat pipe.

In addition, when the evaporator temperature rises, the pressure supply valve is opened to increase the target pressure, and when the temperature is lowered, the exhaust valve is opened to lower the target pressure to the correct target temperature.

On the other hand, although not explicitly described, the present invention also includes other effects that can be expected from the above-described configuration.

1 is a schematic diagram showing the main configuration of a cryogenic loop heat pipe according to an embodiment of the present invention.
FIG. 2 shows a detailed configuration of the main evaporator of the cryogenic loop heat pipe of FIG. 1 .
3 is an example of a conventional cryogenic loop heat pipe.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can practice. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

1 is a schematic diagram of a cryogenic loop heat pipe according to an embodiment of the present invention, and FIG. 2 shows a detailed structure inside the main evaporator in the cryogenic loop heat pipe of FIG. 1 .

1, the cryogenic loop heat pipe according to the present invention is a cryogenic loop heat pipe that can be used in a space environment where the influence of gravity is very small. (primary evaporator) (1), a condenser (2) condensing the working fluid flowing in from the main evaporator (1) and dissipating heat, and to control the pressure of the main evaporator (1), the main evaporator ( 1) includes a high pressure working fluid reservoir (high pressure tank) that selectively supplies a high pressure working fluid.

In addition, a gas buffer tank 6 is further provided, and a high-pressure working fluid reservoir 3 selectively supplies a high-pressure working fluid to the main evaporator 1 through the gas buffer tank 6 . . And a pressure-increase valve 4 is provided between the high-pressure working fluid reservoir 3 and one side of the gas buffer tank 6 , and the other side of the gas buffer tank 6 has a vent valve ) (5) is provided. And it is preferable that a pressure sensor 8 for measuring the pressure of the gas buffer tank 6 is provided.

On the other hand, the main evaporator 1, as shown in FIG. 2, a compensation chamber (CC) 11 in which a liquid working fluid and a gaseous working fluid (vapor) coexist, and located on one side A main evaporator wick (wick) 12 is included, and an empty space (13) is formed between the main evaporator wick (12) and the inner wall of the main evaporator. For reference, the main evaporator wick 12 not only serves as a pump to move the condensed working fluid from the cooling unit to the heat source using capillary pressure, but also maximizes the surface area to increase heat transfer efficiency.

는 보상챔버에서 보조증발기로 토출되는 작동유체의 질량 유량,

는 주증발기에서 응축기로 토출되는 작동유체의 질량 유량, ΔP_wick는 작동유체가 주증발기 윅(wick)을 통과하며 겪는 압력 강하, T_pe는 주증발기의 표면 온도, Q_pe는 주증발기에 부과되는 열, H_pe는 주증발기 내부 공간에서의 열전달계수, SE는 보조증발기를 각각 가리킨다. _{Through this configuration, the present invention can actively control the surface temperature (T pe} ) of the primary evaporator of the cryogenic loop heat pipe. Hereinafter, referring to FIGS. 1 and 2 , the cryogenic loop according to the present invention The operation of the heat pipe will be described. For reference, in this specification and drawings, T _1.sat is the saturation temperature of the working fluid in the compensation chamber, P _1.sat is the saturation pressure of the working fluid in the _{compensation chamber, and T 1a} is the main evaporator wick in the compensation chamber. The temperature of the working fluid after passing, P _1a is the pressure of the working fluid after passing through the wick of the main evaporator in the compensation chamber, T _2.sat is the saturation temperature of the working fluid in the _{main evaporator, P 2.sat} is the main evaporator the saturation pressure of the working fluid in the

is the mass flow rate of the working fluid discharged from the compensation chamber to the auxiliary evaporator,

is the mass flow rate of the working fluid discharged from the main evaporator to the condenser, ΔP _wick is the pressure drop experienced by the working fluid passing through the wick of the main evaporator _{, T pe is the surface temperature of the main evaporator, and Q pe} is the pressure applied to the main evaporator. Heat, H _pe is the heat transfer coefficient in the interior space of the main evaporator, SE is the auxiliary evaporator, respectively.

During normal operation, the inside of the main evaporator compensation chamber 11 of the cryogenic loop heat pipe is maintained in a saturated state in which the liquid is filled in a certain ratio. Therefore, the internal temperature (T ₁ ) of the compensation chamber ( 11 ) is determined as a corresponding saturation temperature according to the internal pressure (P _{1 ). Therefore, if the pressure P tank} of the external gas buffer tank 6 connected to the main evaporator compensation chamber 11 is changed, the pressure P ₁ inside the compensation chamber 11 can be changed, and eventually the compensation chamber 11 ) The internal temperature (T ₁ ) can also be changed to the saturation temperature accordingly.

The inside of the main evaporator compensation chamber 11 is also maintained in a saturated state, but the space 13 (T ₂ , P ₂ ) between the main evaporator wick 12 and the main evaporator case 14 is also saturated because the liquid evaporation occurs. remain in the state _{Here, the relationship between the internal pressure P 1} of the compensation chamber 11 and the pressure P ₂ of the space 13 is the working fluid for each section from the space 13 in the cryogenic loop heat pipe to the compensation chamber 11 . It can be obtained as the sum of the pressure drop calculations, and the value depends on the specifications of the cryogenic loop heat pipe components and the state value of the working fluid.

_{That is, the relationship between the internal pressure P 1} of the compensation chamber 11 and the pressure P _{2 of the} space 13 is obtained by the pressure drop calculation, and the saturation temperature at the _{pressure P 2 of the space 13} By checking (T _2,sat ), the temperature (T ₂ ) of the space 13 can be obtained.

Therefore, if the correlation between the compensation chamber temperature (T ₁ ) and the main evaporator surface temperature (T _pe ) is experimentally obtained, the pressure (P ₁ ) of the compensation chamber 11 is changed according to this correlation equation to It can be created by accurately predicting the temperature of the evaporator surface (T _{pe ).} According to the correlation equation, when the temperature of the evaporator 1 needs to rise, the pressure supply valve 4 is opened to increase the target pressure, and when the temperature of the evaporator 1 needs to be lowered, the exhaust valve 5 is opened to lower the target pressure to the exact target pressure. temperature can be adjusted.

_{That is, the pressure P tank} of the gas buffer tank 6 is a value known by measuring it using the pressure sensor 8 , and the surface temperature T _pe of the main evaporator 1 is a desired value.

Pressure (P _tank) of the gas buffer tank 6, a pressure (P _tank), so the difference between the internal vapor pressure of the compensating chamber (11) (P _1.sat) minimal, gas buffer tank (6) of the compensation chamber It can be seen as substantially the same as the internal saturation pressure (P _{1.sat ) in (11).} Therefore, since the internal saturation pressure (P _1.sat ) of the compensation chamber 11 is known, it is possible to check _{the internal saturation temperature (T 1.sat} ) of the compensation chamber 11 from a known table of saturation properties.

The internal saturation pressure (P _1.sat ) of the compensation chamber 11 and the internal saturation temperature (T _1.sat ) of the compensation chamber 11 were known, and the saturation pressure (P _2.sat ) of the space 13 is shown in FIG. It can be obtained by calculating the pressure drop in each section in which the working fluid is discharged to the right side of the space 13 in 2 and returns to the compensation chamber 11 again. At this time, the section through which the working fluid passes is the tubes 9 and the condenser 2 between the evaporator 1 and the condenser 2 of FIG. 1 .

Since the saturation pressure (P _2.sat ) of the space 13 is _known , the value of the saturation temperature (T 2.sat) of the space 13 can be finally confirmed.

Applying the experimental data correction _equation between the saturation temperature (T 2.sat ) of the space 13 and the surface temperature (T _{pe ) of the main evaporator 1, the pressure (P tank} ) of the gas buffer tank 6 is The surface temperature (T _pe ) of (1) can be obtained.

As an example, the experimental data correction equation obtained through the experimental results is as follows.

T _pe = 132.73998 - 1.42102 × T _1.sat + 0.0115 × T _1.sat ^2 ....[Equation 1]

(P _1.sat is confirmed in the table of saturation properties, P _1.sat = P _tank )

As described above, according to the cryogenic loop heat pipe according to the embodiment of the present invention, it is possible to actively control the surface temperature of the main evaporator of the cryogenic loop heat pipe.

Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

1....primary evaporator
2...Condenser
3....high pressure tank
4...pressure-increase valve
5...vent valve
6...gas buffer tank
7...Auxiliary evaporator
8...pressure sensor
11...Compensation Chamber (CC)
12...main evaporator wick
13...space between the main evaporator wick and the inner wall of the main evaporator

Claims (6)

In the cryogenic loop heat pipe used in the space environment,
The main evaporator that absorbs heat by vaporizing the working fluid,
A condenser condensing the working fluid flowing in from the main evaporator to emit heat, and
In order to control the pressure of the main evaporator, a high-pressure working fluid storage for selectively supplying a high-pressure working fluid to the main evaporator.
containing
Cryogenic loop heat pipe. In claim 1,
A gas buffer tank is further provided, and the high-pressure working fluid reservoir selectively supplies a high-pressure working fluid to the main evaporator through the gas buffer tank,
A pressure supply valve is provided between the high-pressure working fluid storage and one side of the gas buffer tank, and an exhaust valve is provided at the other side of the gas buffer tank.
Cryogenic loop heat pipe. In claim 2,
The main evaporator
A compensation chamber (CC) in which a liquid working fluid and a vapor working fluid (vapor) coexist, and a main evaporator wick located at one side thereof, the main evaporator wick and the inner wall of the main evaporator space is formed between
Cryogenic loop heat pipe. A method of controlling the surface temperature of the main evaporator of the cryogenic loop heat pipe according to claim 3,
_{Considering the pressure (P tank} ) of the gas buffer tank as the internal saturation pressure (P 1.sat ) of the compensation chamber;
Checking _{the internal saturation temperature (T 1.sat} ) of the compensation chamber in the known saturation physical property table,
_obtaining the saturation pressure (P 2.sat) of the space by calculating the pressure drop of each section in which the working fluid discharged from the space returns to the compensation chamber;
_{Checking the saturation temperature (T 2.sat} ) of the space in the known saturation physical property table,
By applying the experimental data correction _formula between the saturation temperature (T 2.sat ) of the space and the surface temperature (T _pe ) of the main evaporator, the surface temperature (T) of the main evaporator from the _{pressure (P tank ) of the gas buffer tank pe} ), and
adjusting the pressure of the gas buffer tank by selectively opening or closing the pressure supply valve and the exhaust valve;
containing
A method for controlling the surface temperature of the main evaporator of a cryogenic loop heat pipe. In claim 4,
The experimental data correction formula
T _pe = 132.73998 - 1.42102 × T _1.sat + 0.0115 × T _1.sat ^2
A method for controlling the surface temperature of the main evaporator of a cryogenic loop heat pipe. In claim 5,
Each section in which the working fluid discharged from the space returns to the compensation chamber is a tube section between the evaporator and the condenser, and the condenser section, A method for controlling the surface temperature of the main evaporator of a cryogenic loop heat pipe.

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