Recovery system of heat conducting medium and control method thereof
The closed-loop negative pressure circulation recovery system solves the problem of high losses during the heat transfer medium recovery process, achieving efficient and safe medium recovery and reducing equipment operating costs and safety risks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUXI GUANYA REFRIGERATION TECH
- Filing Date
- 2026-03-31
- Publication Date
- 2026-05-29
AI Technical Summary
In existing technologies, heat transfer medium recovery processes suffer significant losses and pose safety risks due to high-pressure operation. Traditional purging methods result in severe medium loss, making it difficult to meet economic requirements.
A closed-loop negative pressure circulation recovery system is adopted, including a negative pressure recovery circuit, a refrigeration circuit, and a temperature control circuit. Through components such as vacuum pumps, gas-liquid separators, and heaters, multi-stage recovery and temperature control of the medium are achieved, reducing medium loss and minimizing the risk of equipment pressure.
It effectively reduces heat transfer medium loss, improves recovery rate, reduces pressure risk to equipment components, and enhances recovery efficiency and safety.
Smart Images
Figure CN121932776B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of media recovery technology, and in particular to a system for recovering heat-conducting media and its control method. Background Technology
[0002] High and low temperature control equipment has wide applications in cutting-edge technology fields such as semiconductor manufacturing, data center cooling, precision instrument maintenance, and pharmaceuticals and chemicals. These devices typically use heat transfer media such as fluorinated liquids, antifreeze, and heat transfer oils to achieve heat transfer. Because these heat transfer media are expensive, effective recovery of residual media during use can reduce operating costs.
[0003] Currently, heat transfer medium recovery is mostly achieved through dry gas purging. However, traditional purging methods typically employ high purging pressures, leading to significant heat transfer medium leakage with the gas flow. This results in substantial heat transfer medium loss and a low recovery rate, failing to meet the economic requirements of precision temperature control equipment for medium recovery. Furthermore, conventional purging systems are often open-loop systems, which not only result in high heat transfer medium loss but also expose system components to prolonged high-pressure operation, posing certain pressure safety risks. Summary of the Invention
[0004] Therefore, the purpose of this invention is to overcome the problem that when high-pressure gas is used to purge and recover the heat transfer medium in the prior art, the heat transfer medium is easily overflowed with the gas, resulting in large losses. The invention proposes a heat transfer medium recovery system and its control method. Through closed negative pressure circulation, the loss of heat transfer medium during the recovery process can be reduced, and the pressure risk of the target equipment components can be reduced.
[0005] To address the aforementioned technical problems, this invention provides a heat transfer medium recovery system, characterized in that it comprises: a negative pressure recovery circuit, the negative pressure recovery circuit comprising, in sequence: a first branch, the input end of the first branch being connected to one end of the target device, and the output end of the first branch being connected to a first gas-liquid separator; a second branch, the input end of the second branch being connected to the top of the first gas-liquid separator, and a vacuum pump being provided on the second branch; a third branch, the upstream of the third branch being connected to a refrigeration circuit through a heat exchange, and the downstream of the third branch being provided with a second gas-liquid separator; and a fourth branch, the input end of the fourth branch being connected to the top of the second gas-liquid separator, the fourth branch being provided with a heater, and the output end of the fourth branch being connected to the other end of the target device.
[0006] Preferably, the refrigeration circuit includes a first pipeline; the upstream of the first pipeline is connected to a first-side heat exchange channel of an evaporator, and the second-side heat exchange channel of the evaporator is connected to the upstream of the third branch; a compressor is provided on the first pipeline, and the compressor is located downstream of the first-side heat exchange channel of the evaporator; the downstream of the first pipeline is connected to a first-side heat exchange channel of a first radiator, and the second-side heat exchange channel of the first radiator is connected to the fourth branch, and the second-side heat exchange channel of the first radiator is located upstream of the heater; an expansion valve is provided on the first pipeline, and the expansion valve is located downstream of the first-side heat exchange channel of the first radiator.
[0007] Preferably, the heat transfer medium recovery system further includes: a temperature control circuit, the temperature control circuit being connected to the first side heat exchange channel of the second radiator, the second side heat exchange channel of the second radiator being connected to the second branch, and the second side heat exchange channel of the second radiator being located downstream of the vacuum pump.
[0008] Preferably, the heat transfer medium recovery system further includes: a first liquid level sensor for detecting the liquid level at the output end of the second branch; if the detected liquid level at the output end of the second branch is greater than 0, or if the detected liquid level at the output end of the second branch remains 0 for less than a first duration, then coarse medium recovery is performed: the input end of the first branch is connected to the medium discharge port of the target device, and the output end of the fourth branch is connected to the medium filling port of the target device; otherwise, fine medium recovery is performed: the input end of the first branch is connected to the medium filling port of the target device, and the output end of the fourth branch is connected to the medium discharge port of the target device; wherein, the number of the medium filling ports is one or more, and the medium filling ports are located at the top and / or upper part of the target device; the number of the medium discharge ports is one or more, and the medium discharge ports are located at the bottom and / or lower part of the target device.
[0009] Preferably, the heat transfer medium recovery system further includes: a second liquid level sensor for detecting the liquid level at the inlet of the second gas-liquid separator; after entering the fine recovery of the medium, if the detected liquid level at the inlet of the second gas-liquid separator is greater than 0, or the time during which the detected liquid level at the inlet of the second gas-liquid separator remains at 0 is less than a second duration, a pulse heating program is executed cyclically; otherwise, the heater is turned off; wherein, the pulse heating program includes: a first heating stage: controlling the output power of the heater to make the temperature at the medium discharge port greater than the boiling point of the medium, and continuing for a third duration; a second heating stage: controlling the output power of the heater to make the temperature at the medium discharge port less than the boiling point of the medium, and continuing for a fourth duration.
[0010] On the other hand, the present invention provides a control method for a heat-conducting medium recovery system, comprising: performing coarse recovery when the liquid level detection value in the second branch is greater than 0, or when the liquid level detection value in the second branch remains at 0 for less than a first duration: connecting the input end of the first branch to the medium discharge port of the target device and connecting the output end of the fourth branch to the medium filling port of the target device; otherwise, performing fine recovery of the medium: connecting the input end of the first branch to the medium filling port of the target device and connecting the output end of the fourth branch to the medium discharge port of the target device.
[0011] Preferably, during coarse recovery: the vacuum pump and compressor are started; the heater output power is controlled to adjust the medium filling port temperature and make the medium discharge port temperature approach the gas-liquid two-phase equilibrium temperature of the heat-conducting medium; according to the temperature difference between the vacuum pump outlet temperature and the first target temperature, the opening of the first regulating valve of the temperature control circuit is adjusted so that the temperature at the output end of the second branch approaches the first target temperature.
[0012] Preferably, the adjustment of the medium filling port temperature includes: increasing the heater output power when the medium discharge port temperature is lower than the gas-liquid two-phase equilibrium temperature of the heat-conducting medium during the first duration; and decreasing the heater output power when the medium discharge port temperature is higher than the gas-liquid two-phase equilibrium temperature of the heat-conducting medium during the first duration; the adjustment of the opening degree of the first regulating valve of the temperature control circuit according to the temperature difference between the vacuum pump outlet temperature and the first target temperature includes: when the vacuum pump outlet temperature is greater than the upper limit of the first target temperature or less than the lower limit of the first target temperature, the greater the temperature difference between the vacuum pump outlet temperature and the first target temperature, the greater the opening degree of the first regulating valve; and closing the first regulating valve when the vacuum pump outlet temperature is less than or equal to the upper limit of the first target temperature and greater than or equal to the lower limit of the first target temperature; wherein the first target temperature is 20°C to 25°C, and the cooling water temperature in the temperature control circuit is 20°C to 25°C.
[0013] Preferably, the medium filling port temperature is determined based on the medium boiling point, the target equipment reference superheat, the medium residual factor, and the heat transfer efficiency factor; the medium filling port temperature satisfies the following: the medium filling port temperature is greater than or equal to the medium boiling point and less than min[thermal decomposition temperature of the heat transfer medium, material tolerance temperature of the target equipment, and maximum operating temperature of the heater]; wherein, the target equipment reference superheat is determined based on the type of heat transfer medium; the medium residual factor is determined based on the liquid level detection value in the second branch; and the heat transfer efficiency factor is determined based on the relationship between the medium discharge port temperature, the medium boiling point, and the gas-liquid two-phase equilibrium temperature of the heat transfer medium.
[0014] Preferably, during the media fine recovery process: the refrigeration circuit and the temperature control circuit are shut down; the heater is started, and the pulse heating program is executed cyclically until the liquid level detection value at the inlet of the second gas-liquid separator remains at 0 for a second duration, at which point the heater is shut down; wherein, the pulse heating program includes: a first heating stage: controlling the output power of the heater to make the temperature at the media outlet greater than the boiling point of the media, and continuing for a third duration; a second heating stage: controlling the output power of the heater to make the temperature at the media outlet less than the boiling point of the media, and continuing for a fourth duration.
[0015] The beneficial effects of the above-mentioned technical solution of the present invention compared with the prior art include at least the following: The heat transfer medium recovery system of the present invention, through the closed negative pressure cycle of the negative pressure recovery loop, can recover heat transfer media with different boiling points by controlling the negative pressure and heating temperature, which can reduce the loss of heat transfer media in the recovery process and reduce the pressure risk of the target equipment components.
[0016] Specifically, by setting up a negative pressure recovery loop consisting of a first branch, a second branch, a third branch, and a fourth branch connected in sequence, the heat transfer medium circulates in a closed system. The medium vapor is condensed and returned to the target equipment, preventing the heat transfer medium from escaping into the external environment and significantly reducing the loss of heat transfer medium during the recovery process.
[0017] By installing a vacuum pump in the negative pressure recovery loop, the recovery system is kept under negative pressure during the recovery process. This not only eliminates the pressure risk caused by high-pressure operation, but also lowers the operating temperature of the system by reducing the boiling point of the medium, thereby extending the service life of the equipment.
[0018] In addition, by setting up a first gas-liquid separator and a second gas-liquid separator, multi-stage recovery of the heat transfer medium is achieved, which improves the recovery efficiency.
[0019] The control method of the heat-conducting medium recovery system of the present invention improves the medium recovery efficiency and recovery rate by determining the recovery stage and switching the recovery flow direction based on the liquid level detection value in the second branch.
[0020] Specifically, when the recovery system is determined to be in the coarse recovery stage, there is a large amount of residual medium inside the target equipment. A forward flow direction is adopted, with gaseous medium entering from the top medium filling port and exiting from the bottom medium discharge port. As the high-temperature gas flows downwards, it directly sweeps away the liquid film adhering to the inner wall and component surfaces of the target equipment, and simultaneously impacts the bottom liquid layer, promoting the evaporation of the heat-conducting medium. At the same time, the liquid medium naturally gathers to the bottom under gravity, making it easier for the airflow to carry it out, thus improving the coarse recovery efficiency.
[0021] When the recovery system is determined to have entered the fine recovery stage, the residual media is mainly distributed in hard-to-reach areas such as the top dead corners, the inner wall adsorption layer, and pipe connections. A reverse flow method is adopted, where gaseous media enters from the bottom media discharge port and exits from the top media filling port. The high-temperature gas flows from bottom to top, directly flushing the top dead corners and the surface of upper components, stripping away and carrying away residual media that are difficult to reach with conventional flow, effectively solving the problem of residual media in equipment dead corners and improving the recovery rate. Attached Figure Description
[0022] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.
[0023] Figure 1 This is a schematic diagram of a heat transfer medium recovery system in an embodiment of the present invention.
[0024] Figure 2 This is a schematic diagram of a temperature control circuit in an embodiment of the present invention.
[0025] Figure 3 This is a schematic diagram of another structure of the heat transfer medium recovery system in an embodiment of the present invention.
[0026] Figure 4 This is a schematic flowchart of a control method for a heat transfer medium recovery system in an embodiment of the present invention.
[0027] Explanation of reference numerals in the accompanying drawings: 101, Target equipment; 102, First gas-liquid separator; 103, Vacuum pump; 104, Second gas-liquid separator; 105, Heater; 106, First drain valve; 107, Second drain valve; 111, First branch; 112, Second branch; 113, Third branch; 114, Fourth branch; 121, Second regulating valve; 122, Pressure sensor; 123, First liquid level sensor; 124, Second liquid level sensor; 125, First temperature sensor; 126, Second temperature sensor; 127, Third temperature sensor; 128, Fourth temperature sensor; 129, Fifth temperature sensor; 21, First pipeline; 22, Evaporator; 23, Compressor; 24, First radiator; 25, Expansion valve; 31, Second radiator; 32, First regulating valve; 33, Second pipeline. Detailed Implementation
[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.
[0029] Example 1: This example introduces a heat transfer medium recovery system.
[0030] The heat transfer medium recovery system of this embodiment includes a negative pressure recovery circuit. Further, the recovery system also includes a refrigeration circuit, which is heat-exchange connected to the negative pressure recovery circuit to provide a cold source for the negative pressure recovery circuit. Even further, the recovery system also includes a temperature control circuit, which is heat-exchange connected to the negative pressure recovery circuit to regulate the temperature in the negative pressure recovery circuit before heat exchange occurs between the negative pressure recovery circuit and the refrigeration circuit.
[0031] When applying, refer to Figure 1 The negative pressure recovery circuit is connected to the target device 101, and a vacuum pump 103 is installed on the negative pressure recovery circuit. Under the action of the vacuum pump 103, a negative pressure is formed in the internal space of the target device 101 to reduce the boiling point of the medium inside the target device 101, that is, the vaporization temperature of the heat-conducting medium inside the target device 101.
[0032] In practical applications, based on the negative pressure value inside the target device 101, the boiling point of the medium in the internal environment of the target device 101 is determined through the pressure-temperature conversion relationship. Specifically, the pressure-temperature conversion relationship includes: P(T) = A × T 4 -B×T 3 +C×T 2 -D×T+E, where P(T) is the pressure, T is the boiling point temperature, and A, B, C, D, and E are fitting coefficients. For example, when the heat transfer medium is water, A=0.0000012136, B=0.0001043992, C=0.0108137083, D=0.2908714719, and E=5.3000714286.
[0033] The negative pressure recovery circuit of this embodiment includes the following sequentially connected branches: first branch 111, second branch 112, third branch 113, and fourth branch 114, as shown in the reference. Figure 1 That is, the output terminal of the first branch 111 is connected to the input terminal of the second branch 112, the output terminal of the second branch 112 is connected to the input terminal of the third branch 113, and the output terminal of the third branch 113 is connected to the input terminal of the fourth branch 114.
[0034] refer to Figure 3 The first branch 111 has its input terminal connected to one end of the target device 101, and the fourth branch 114 has its output terminal connected to the other end of the target device 101. Furthermore, the fourth branch 114 is equipped with a heater 105 for heating the heat-conducting medium before it enters the target device 101.
[0035] In application, during coarse media recovery: the input terminal of the first branch 111 is connected to the media discharge port of the target device 101, and the output terminal of the fourth branch 114 is connected to the media filling port of the target device 101. During fine media recovery: the input terminal of the first branch 111 is connected to the media filling port of the target device 101, and the output terminal of the fourth branch 114 is connected to the media discharge port of the target device 101. The number of media filling ports is one or more, and the media filling ports are located at the top and / or upper part of the target device 101. The number of media discharge ports is one or more, and the media discharge ports are located at the bottom and / or lower part of the target device 101.
[0036] In practical applications, the target device 101 has a third temperature sensor 127 at its medium filling port, which is used to detect the temperature of the medium filling port of the target device 101. The target device 101 also has a fourth temperature sensor 128 at its medium discharge port, which is used to detect the temperature of the medium discharge port of the target device 101. Finally, the target device 101 has a fifth temperature sensor 129 inside, which is used to detect the internal temperature of the target device 101.
[0037] refer to Figure 1 The first branch 111 output is connected to the first gas-liquid separator 102, and the second branch 112 input is connected to the top of the first gas-liquid separator 102. Furthermore, the first branch 111 output is connected to the upper part of the first gas-liquid separator 102. During coarse or fine media recovery: under negative pressure, the heat-conducting medium in the target device 101 vaporizes, and the vaporized heat-conducting medium, carrying the unvaporized liquid heat-conducting medium, enters the first gas-liquid separator 102. In the first gas-liquid separator 102, the heat-conducting medium undergoes gas-liquid separation; the gaseous heat-conducting medium enters the second branch 112, while the liquid heat-conducting medium remains in the first gas-liquid separator 102. Further, the bottom of the first gas-liquid separator 102 is provided with a first drain valve 106, which is connected to a collector to recover the liquid heat-conducting medium in the first gas-liquid separator 102. In this embodiment, the drain valve can be a ball valve.
[0038] refer to Figure 1 A vacuum pump 103 is installed on the second branch 112. By adjusting the opening of the vacuum pump 103, the negative pressure inside the target device 101 is made to be -80 kPa. It is worth noting that a pressure sensor 122 is installed at the medium discharge port of the target device 101, and the pressure sensor 122 is used to detect the pressure at the medium discharge port. Furthermore, the second branch 112 is connected to the temperature control circuit for heat exchange.
[0039] In application, the temperature control circuit includes a second pipe 33, a second radiator 31, and a first regulating valve 32. The second pipe 33 is a loop and contains cooling water. (Reference) Figure 2 A first regulating valve 32 is provided on the second pipe 33 for regulating the cooling water flow rate within the second pipe 33 of the temperature control circuit. The first side heat exchange channel of the second radiator 31 is connected to the second pipe 33 of the temperature control circuit, and the second side heat exchange channel of the second radiator 31 is connected to the second branch 112 to achieve heat exchange between the second branch 112 and the temperature control circuit. It is worth noting that the second side heat exchange channel of the second radiator 31 is located downstream of the vacuum pump 103. The regulating valve in this embodiment can be a proportional regulating valve.
[0040] When the outlet temperature of vacuum pump 103 is greater than the upper limit of the first target temperature, or when the outlet temperature of vacuum pump 103 is less than the upper limit of the first target temperature: the first regulating valve 32 is opened, and the opening degree of the first regulating valve 32 is adjusted according to the difference between the outlet temperature of vacuum pump 103 and the upper limit of the first target temperature, so that the temperature at the output end of the second branch 112 approaches the first target temperature. When the outlet temperature of vacuum pump 103 is within the range of the first target temperature, the first regulating valve 32 is closed. In some embodiments, the first target temperature can be 20°C to 25°C, and the temperature of the cooling water in the second pipeline 33 can be 20°C to 25°C.
[0041] In practical applications, the second branch 112 is equipped with a second regulating valve 121 and a second temperature sensor 126, with the second temperature sensor 126 and the second regulating valve 121 located between the vacuum pump 103 and the second side heat exchange channel of the first radiator 24. The second regulating valve 121 is used to regulate the flow rate of the medium flowing through the second side heat exchange channel of the first radiator 24; the second temperature sensor 126 is used to detect the outlet temperature of the vacuum pump 103. Furthermore, the output end of the second branch 112 is equipped with a first liquid level sensor 123 and a first temperature sensor 125. The first liquid level sensor 123 is used to detect the liquid level at the output end of the second branch 112; the first temperature sensor 125 is used to detect the temperature at the output end of the second branch 112.
[0042] In actual implementation, if the liquid level detection value at the output end of the second branch 112 is greater than 0, or if the liquid level detection value at the output end of the second branch 112 remains at 0 for less than a first duration, then coarse media recovery is performed: the input end of the first branch 111 is connected to the media discharge port of the target device 101, and the output end of the fourth branch 114 is connected to the media filling port of the target device 101; otherwise, fine media recovery is performed: the input end of the first branch 111 is connected to the media filling port of the target device 101, and the output end of the fourth branch 114 is connected to the media discharge port of the target device 101. The number of media filling ports is one or more, and the media filling ports are located at the top and / or upper part of the target device 101; the number of media discharge ports is one or more, and the media discharge ports are located at the bottom and / or lower part of the target device 101.
[0043] The upstream heat exchanger of the third branch 113 connects to the refrigeration circuit, and the downstream of the third branch 113 is equipped with a second gas-liquid separator 104. The input end of the fourth branch 114 is connected to the top of the second gas-liquid separator 104. Specifically, the output end of the third branch 113 is connected to the upper part of the second gas-liquid separator 104. After the heat transfer medium entering the third branch 113 exchanges heat with the refrigeration circuit and is cooled, it enters the second gas-liquid separator 104. In the second gas-liquid separator 104, the heat transfer medium undergoes gas-liquid separation; the gaseous heat transfer medium enters the fourth branch 114, while the liquid heat transfer medium remains in the second gas-liquid separator 104. Furthermore, the bottom of the second gas-liquid separator 104 is equipped with a second drain valve 107, which is connected to a collector to recover the liquid heat transfer medium in the second gas-liquid separator 104.
[0044] In application, a second liquid level sensor 124 is provided on the third branch 113. The second liquid level sensor 124 is used to detect the liquid level at the inlet of the second gas-liquid separator 104.
[0045] In practical applications, after the medium enters the fine recovery stage, if the liquid level detection value at the inlet of the second gas-liquid separator 104 is greater than 0, or if the liquid level detection value at the inlet of the second gas-liquid separator 104 remains at 0 for less than a second duration, the pulse heating program is executed cyclically; otherwise, the heater 105 is shut down. The pulse heating program includes a first heating stage and a second heating stage. In the first heating stage, the output power of the heater 105 is controlled to make the temperature at the medium discharge port greater than the boiling point of the medium, and this continues for a third duration. In the second heating stage, the output power of the heater 105 is controlled to make the temperature at the medium discharge port less than the boiling point of the medium, and this continues for a fourth duration.
[0046] refer to Figure 3The refrigeration circuit of this embodiment includes a first pipe 21, which is a loop, and an evaporator 22, a compressor 23, a first radiator 24 and an expansion valve 25 are sequentially arranged on the first pipe 21.
[0047] Specifically, the upstream of the first pipe 21 is connected to the first side heat exchange channel of the evaporator 22, and the second side heat exchange channel of the evaporator 22 is connected to the upstream of the third branch 113, so as to realize heat exchange between the upstream of the first pipe 21 and the upstream of the third branch 113. The refrigerant flowing through the evaporator 22 in the first pipe 21 is a low-temperature, low-pressure gaseous refrigerant with a temperature of 10°C to 15°C. At the same time, the temperature of the heat transfer medium flowing through the evaporator 22 in the third branch 113 can be 15°C to 20°C.
[0048] The compressor 23 is installed on the first pipeline 21 and is located downstream of the first heat exchange channel of the evaporator 22. It compresses the low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gaseous refrigerant, at which point the temperature can be between 80°C and 100°C. In this embodiment, the compressor 23 can be a scroll compressor, a rotary compressor, or a reciprocating compressor.
[0049] The first heat exchange channel of the first radiator 24 is connected downstream of the first pipe 21, and is located downstream of the compressor 23. Simultaneously, the second heat exchange channel of the first radiator 24 is connected to the fourth branch 114, and is located upstream of the heater 105. Through heat exchange between the downstream of the first pipe 21 and the fourth branch 114, waste heat from the refrigeration circuit is utilized; that is, the waste heat from the refrigeration circuit is used to preheat the heat transfer medium in the fourth branch 114.
[0050] When the temperature of the preheated heat transfer medium meets the temperature requirements, it is not necessary to start the heater 105 to further heat the heat transfer medium; when the temperature of the preheated heat transfer medium still does not meet the temperature requirements, it is necessary to start the heater 105 to further heat the heat transfer medium. It is worth noting that the refrigerant flowing through the first radiator 24 can be a liquid refrigerant with a temperature of 40°C to 50°C. The temperature of the heat transfer medium flowing through the first radiator 24 can be 50°C to 60°C.
[0051] The expansion valve 25 can be an electronic expansion valve. Furthermore, the expansion valve 25 is disposed on the first pipeline 21, and the expansion valve 25 is located downstream of the first side heat exchange channel of the first radiator 24. Even further, the refrigerant flow rate through the evaporator 22 can be adjusted by controlling the opening degree of the expansion valve 25. It is worth noting that the refrigerant flowing through the expansion valve 25 is a low-pressure gas-liquid mixture, and the refrigerant temperature can be from 5°C to 10°C.
[0052] It is worth noting that the heat transfer medium recovery system in this embodiment can regulate the temperature of the heat transfer medium before it enters the evaporator 22 by setting a temperature control loop. This can prevent the heat transfer medium temperature from being too low, which would reduce the heat exchange efficiency of the evaporator 22 in the refrigeration system and result in an insufficient degree of vaporization of the refrigerant flowing through the evaporator 22; and it can also prevent the heat transfer medium temperature from being too high, exceeding the preset load of the refrigeration system and causing the refrigerant temperature entering the compressor 23 to be too high, which would lead to an excessively high discharge temperature of the compressor 23, thereby ensuring the stable and efficient operation of the refrigeration cycle.
[0053] Example 2: This example describes a control method for a heat transfer medium recovery system. The heat transfer medium recovery system can be the same as the one described in Example 1.
[0054] The control method of the heat transfer medium recovery system in this embodiment includes: system startup stage, coarse recovery stage and fine recovery stage.
[0055] The system startup phase includes steps SS11 to SS15.
[0056] Step SS11: Connect the input terminal of the first branch 111 to the media discharge port of the target device 101, and connect the output terminal of the fourth branch 114 to the media filling port of the target device 101.
[0057] Step SS12: Start vacuum pump 103 to create a negative pressure environment inside the target device 101. For example, set the negative pressure to -80 kPa to lower the boiling point of the medium and the gas-liquid two-phase equilibrium temperature of the heat-conducting medium.
[0058] Step SS13: Start compressor 23 and open expansion valve 25.
[0059] Step SS14: Start the circulation pump and open the first regulating valve 32.
[0060] Step SS15: Control the output power of heater 105 to adjust the temperature of the medium filling port and make the temperature of the medium discharge port approach the gas-liquid two-phase equilibrium temperature of the heat transfer medium.
[0061] Once the system is running stably, the liquid level in the second branch 112 is detected, specifically the liquid level at the output end of the second branch 112. Based on the detected liquid level value in the second branch 112, the coarse recovery stage or the fine recovery stage of the medium is determined.
[0062] refer to Figure 4 When the liquid level detection value in the second branch 112 is greater than 0, or when the liquid level detection value in the second branch 112 remains at 0 for less than the first duration, the coarse recovery stage is entered; otherwise, the fine recovery stage is entered.
[0063] In application, to prevent misjudgments caused by brief splashing of droplets or momentary interference from the sensor, the first duration is determined based on the sampling period of the liquid level detection value in the second branch 112. Specifically, the first duration is 30 seconds to 120 seconds. Preferably, the first duration is 120 seconds.
[0064] When the coarse recovery stage is performed, the coarse recovery includes steps SS21 to SS24.
[0065] Step SS21: Connect the input terminal of the first branch 111 to the media discharge port of the target device 101, and connect the output terminal of the fourth branch 114 to the media filling port of the target device 101.
[0066] In application, the input terminal of the first branch 111 is connected to the media discharge port of the target device 101, and the output terminal of the fourth branch 114 is connected to the media filling port of the target device 101. The gaseous medium enters from the top and exits from the bottom, utilizing gravity to improve purging efficiency.
[0067] In actual implementation, in order to adapt to different equipment structures and enhance versatility, the number of media filling ports is one or more, and the media filling ports are opened at the top and / or upper part of the target equipment 101; the number of media discharge ports is one or more, and the media discharge ports are opened at the bottom and / or lower part of the target equipment 101.
[0068] Step SS22: Start vacuum pump 103 and compressor 23.
[0069] When using it, keep the vacuum pump 103 and compressor 23 running.
[0070] Step SS23: Control the output power of heater 105 to adjust the temperature of the medium filling port and make the temperature of the medium discharge port approach the gas-liquid two-phase equilibrium temperature of the heat transfer medium.
[0071] In application, the medium filling port temperature is determined based on the medium's boiling point, the target equipment's reference superheat, the medium's residual factor, and the heat transfer efficiency factor. Furthermore, the medium filling port temperature must also satisfy the following conditions: the medium filling port temperature is greater than or equal to the medium's boiling point and less than min[thermal decomposition temperature of the thermally conductive medium, material tolerance temperature of the target equipment 101, and maximum operating temperature of the heater 105]. Wherein, the thermal decomposition temperature of the thermally conductive medium is determined based on the properties of the thermally conductive medium, the material tolerance temperature of the target equipment 101 is determined based on the upper limit of the temperature resistance of the material least resistant to high temperatures in the equipment, and the maximum operating temperature of the heater 105 is generally 300℃.
[0072] In practical applications, the temperature at the medium filling port includes In the formula, Temperature at the medium filling port; The boiling point of the medium under negative pressure conditions inside the target equipment; The target equipment reference superheat; This refers to the residual factor of the medium. This is the heat exchange efficiency factor.
[0073] Furthermore, the boiling point of the medium The boiling point of the heat transfer medium under the current negative pressure can be calculated in real time based on the value detected by pressure sensor 122. Target equipment reference superheat. Determined based on the type of heat-conducting medium. Medium residual factor. Determined based on the liquid level detection value in the second branch 112. Heat transfer efficiency factor. The value is determined based on the relationship between the temperature at the medium discharge port, the boiling point of the medium, and the gas-liquid two-phase equilibrium temperature of the heat-conducting medium.
[0074] In practical implementation, negative pressure lowers the boiling point of the medium, requiring only a lower temperature to maintain the same evaporation driving force. This means the target equipment's reference superheat is lower in a negative pressure environment compared to an atmospheric pressure environment, resulting in both energy savings and safety. Furthermore, the lower the boiling point of the medium, the better. The smaller the value, the greater the latent heat of vaporization of the medium. The larger the viscosity, the greater the viscosity of the medium. The larger the viscosity, the better. Furthermore, since high-viscosity media are prone to residue, the viscosity can be appropriately increased. For example, at -80 kPa: the boiling point of the fluorinated liquid is 10°C to 30°C. The temperature range is 25°C to 40°C; the boiling point of water is 60°C to 65°C. The boiling point is 50℃ to 70℃; the boiling point of polydimethylsiloxane is 200℃ to 250℃. The temperature ranges from 60°C to 90°C.
[0075] Media residual factors include: In the formula, This refers to the residual factor of the medium. This represents the average value of the liquid level detection in the second branch within the first time period; This is the historical maximum value of the liquid level detection value in the second branch.
[0076] The heat transfer efficiency factor is 1 or 0. When hour, ;when hour, In the formula, This is the heat exchange efficiency factor; Temperature at the medium discharge port; The boiling point of the medium under negative pressure conditions inside the target equipment; The gas-liquid two-phase equilibrium temperature of the heat-conducting medium under negative pressure environment inside the target equipment.
[0077] In some embodiments, step SS23 of this embodiment includes steps SS231 to SS232.
[0078] Step SS231: When the temperature at the medium discharge port is lower than the gas-liquid two-phase equilibrium temperature of the heat transfer medium during the first duration, increase the output power of heater 105.
[0079] In application, in order to filter temperature fluctuations and prevent the heater 105 from frequently operating due to instantaneous temperature spikes, the first duration is 5 to 20 seconds.
[0080] In practical applications, the output power of heater 105 can be determined based on the PID algorithm, according to the current temperature difference at the medium discharge port, the historical temperature difference between the actual temperature at the medium discharge port and the second target temperature at the medium discharge port, and the temperature difference trend. This will not be elaborated here.
[0081] Step SS232: When the temperature at the medium discharge port is greater than the gas-liquid two-phase equilibrium temperature of the heat-conducting medium during the first duration, reduce the output power of heater 105.
[0082] In application, the output power of heater 105 can be determined based on the PID algorithm, according to the current temperature difference at the medium discharge port, the historical temperature difference between the actual temperature at the medium discharge port and the second target temperature at the medium discharge port, and the temperature difference trend. This will not be elaborated here.
[0083] Step SS24: Based on the temperature difference between the outlet temperature of vacuum pump 103 and the first target temperature, adjust the opening of the first regulating valve 32 of the temperature control circuit so that the temperature at the output end of the second branch 112 approaches the first target temperature.
[0084] In application, to ensure that the temperature of the heat transfer medium in the fourth branch 114 is 50°C to 60°C after flowing through the first radiator 24, and that the temperature of the refrigerant in the first pipe 21 (5°C to 10°C) is 10°C to 15°C after flowing through the evaporator 22, the first target temperature of the heat transfer medium before entering the evaporator 22, i.e., the output temperature of the second branch 112, is set to 20°C to 25°C. Furthermore, to stabilize the output temperature of the second branch 112 within the first target temperature range, the cooling water temperature in the temperature control circuit is set to 20°C to 25°C.
[0085] In practical applications, when the outlet temperature of vacuum pump 103 is less than or equal to the upper limit of the first target temperature and greater than or equal to the lower limit of the first target temperature, the first regulating valve 32 is closed. When the outlet temperature of vacuum pump 103 is greater than the upper limit of the first target temperature or less than the lower limit of the first target temperature, the greater the temperature difference between the outlet temperature of vacuum pump 103 and the first target temperature, the greater the opening degree of the first regulating valve 32. Specifically, the opening degree of the first regulating valve 32 can be determined based on the current temperature difference at the outlet of vacuum pump 103, the historical temperature difference between the actual outlet temperature of vacuum pump 103 and the first target temperature, and the temperature difference trend. This will not be elaborated further here.
[0086] When performing the media fine recovery stage, the media fine recovery includes steps SS31 to SS35.
[0087] Step SS31: Shut down the refrigeration circuit and the temperature control circuit. Specifically, shut down the compressor 23 and the expansion valve 25; shut down the circulation pump and the first regulating valve 32.
[0088] Step SS32: Turn off heater 105 and vacuum pump 103.
[0089] Step SS33: Connect the input terminal of the first branch 111 to the medium filling port of the target device 101, and connect the output terminal of the fourth branch 114 to the medium discharge port of the target device 101. The gaseous medium enters from the bottom and exits from the top, which can purge the dead corners at the top and the accumulated liquid at the bottom, thereby improving the recovery rate.
[0090] Step SS34: Turn on vacuum pump 103 to create a negative pressure environment inside target device 101.
[0091] Step SS35: Start heater 105 and cycle through the pulse heating program until the liquid level detection value at the inlet of the second gas-liquid separator 104 remains at 0 for the second duration, then turn off heater 105.
[0092] In application, very little residual medium remains during the fine recovery stage, and the output of the second branch 112 may be completely empty, failing to reflect the residual situation. However, the inlet of the first gas-liquid separator 102 is located downstream of the evaporator 22. If there is still liquid level here, it indicates that there is still condensed medium remaining on the inner wall or in the pipes of the evaporator 22 that has not been recovered. Detecting the liquid level here is a better indicator of the actual effect of the fine recovery of the medium.
[0093] During the media fine recovery stage, there is no longer a large amount of heat-conducting medium evaporating in the target equipment 101, and no large amount of condensation is required. Therefore, the refrigeration circuit is shut down during this stage. Opening the refrigeration circuit may cause the evaporator 22 to become too cold, causing trace amounts of vapor to condense on the inner wall of the pipe before reaching the second gas-liquid separator 104, forming a liquid film that is difficult to recover.
[0094] At the same time, closing the temperature control circuit can prevent excessive cooling and help the high-temperature steam generated by heating to fully diffuse into the dead areas of the recovery system, such as the inner wall of the evaporator 22.
[0095] In practical applications, the second duration is greater than or equal to 120 seconds. Preferably, the second duration is 3 to 5 minutes.
[0096] In actual implementation, the pulse heating program includes a first heating stage and a second heating stage.
[0097] First heating stage: Control the output power of heater 105 to make the temperature of the medium discharge port greater than the boiling point of the medium, and continue for a third duration.
[0098] In application, in order to protect the system and avoid damage to components and decomposition of the heat transfer medium due to excessively high temperature in the negative pressure recovery circuit, the temperature of the medium discharge port in the first heating stage of the fine recovery stage must also meet the temperature limit of the medium discharge port in the coarse recovery stage, that is, less than min[thermal decomposition temperature of heat transfer medium, material tolerance temperature of target device 101, maximum operating temperature of heater 105].
[0099] Furthermore, the temperature at the medium discharge port during the first heating stage equals the boiling point of the medium plus a first temperature threshold. To provide effective thermal driving force, the first temperature threshold is between 10°C and 30°C.
[0100] In practical applications, to ensure that heat is transferred to the inner wall and dead corners of the target device 101, and to the inner wall of the evaporator 22, so that the residual medium is fully heated, the third duration can be determined based on the airflow circulation cycle of the negative pressure recovery circuit. Specifically, the third duration is between 30 and 120 seconds.
[0101] In the second heating stage, the output power of heater 105 is controlled to make the temperature of the medium discharge port lower than the boiling point of the medium, and this continues for a fourth duration.
[0102] In application, in order to ensure that the steam generated by the high-temperature pulse in the first heating stage is fully condensed in the first gas-liquid separator 102 and the second gas-liquid separator 104, the temperature of the medium discharge port in the second heating stage is lower than the boiling point of the medium.
[0103] Furthermore, at this point, heater 105 can be turned off, allowing the heat transfer medium to cool naturally and convert to a liquid phase.
[0104] In practical applications, to allow sufficient time for the steam generated by the high-temperature pulse in the first heating stage to condense and prepare for the next pulse cycle, while avoiding excessive cooling that could affect the efficiency of subsequent cycles, the fourth duration can be greater than or equal to 120 seconds. Preferably, the fourth duration is 3 to 5 minutes.
[0105] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A system for recovering a heat-conducting medium, characterized in that, include: Negative pressure recovery circuit, the negative pressure recovery circuit comprising sequentially connected: The first branch has its input end connected to one end of the target device and its output end connected to the first gas-liquid separator. The second branch has its input end connected to the top of the first gas-liquid separator, and a vacuum pump is installed on the second branch. The third branch has an upstream heat exchange connection to a refrigeration circuit and a downstream second gas-liquid separator. The fourth branch has an input end connected to the top of the second gas-liquid separator, a heater is provided on the fourth branch, and the output end of the fourth branch is connected to the other end of the target device; The first liquid level sensor is used to detect the liquid level at the output end of the second branch; If the liquid level detection value at the output end of the second branch is greater than 0, or if the liquid level detection value at the output end of the second branch remains at 0 for less than the first duration, then coarse media recovery is performed: the input end of the first branch is connected to the media discharge port of the target device, and the output end of the fourth branch is connected to the media filling port of the target device. Otherwise, perform media fine recovery: the first branch input end is connected to the media filling port of the target device, and the fourth branch output end is connected to the media discharge port of the target device; The number of media filling ports is one or more, and the media filling ports are located at the top and / or upper part of the target device; the number of media discharge ports is one or more, and the media discharge ports are located at the bottom and / or lower part of the target device.
2. The heat transfer medium recovery system according to claim 1, characterized in that, The refrigeration circuit includes a first pipeline; The upstream of the first pipeline is connected to the first heat exchange channel of the evaporator, and the second heat exchange channel of the evaporator is connected to the upstream of the third branch. A compressor is installed on the first pipeline, and the compressor is located downstream of the first heat exchange channel of the evaporator; The first pipeline is connected downstream to the first side heat exchange channel of the first radiator, the second side heat exchange channel of the first radiator is connected to the fourth branch, and the second side heat exchange channel of the first radiator is located upstream of the heater. An expansion valve is provided on the first pipeline, and the expansion valve is located downstream of the first side heat exchange channel of the first radiator.
3. The heat transfer medium recovery system according to claim 2, characterized in that, Also includes: A temperature control circuit is provided, wherein the temperature control circuit is connected to the first side heat exchange channel of the second radiator, the second side heat exchange channel of the second radiator is connected to the second branch, and the second side heat exchange channel of the second radiator is located downstream of the vacuum pump.
4. The heat transfer medium recovery system according to claim 1, characterized in that, Also includes: The second liquid level sensor is used to detect the liquid level at the inlet of the second gas-liquid separator; After entering the medium fine recovery, if the liquid level detection value at the inlet of the second gas-liquid separator is greater than 0, or if the liquid level detection value at the inlet of the second gas-liquid separator remains at 0 for less than the second duration, the pulse heating program is executed cyclically. Otherwise, turn off the heater; The pulse heating program includes: First heating stage: Control the output power of the heater to make the temperature at the medium discharge port greater than the boiling point of the medium, and continue for a third duration; Second heating stage: Control the output power of the heater to make the temperature at the medium discharge port lower than the boiling point of the medium, and continue for a fourth time.
5. A control method for a heat transfer medium recovery system as described in any one of claims 1 to 4, characterized in that, include: When the liquid level detection value in the second branch is greater than 0, or when the liquid level detection value in the second branch remains at 0 for less than the first duration, coarse recovery is performed: connect the input end of the first branch to the medium discharge port of the target device, and connect the output end of the fourth branch to the medium filling port of the target device. Otherwise, perform media fine recovery: connect the input end of the first branch to the media filling port of the target device, and connect the output end of the fourth branch to the media discharge port of the target device.
6. The control method for the heat transfer medium recovery system according to claim 5, characterized in that, When performing coarse recycling: Start the vacuum pump and compressor; Control the heater output power to adjust the medium filling port temperature and make the medium discharge port temperature approach the gas-liquid two-phase equilibrium temperature of the heat transfer medium. Based on the temperature difference between the vacuum pump outlet temperature and the first target temperature, adjust the opening of the first regulating valve in the temperature control circuit so that the temperature at the output end of the second branch approaches the first target temperature.
7. The control method for the heat transfer medium recovery system according to claim 6, characterized in that, The adjustment of the medium filling port temperature includes: When the temperature at the medium discharge port is lower than the gas-liquid two-phase equilibrium temperature of the heat transfer medium during the first duration, increase the output power of the heater. When the temperature at the medium discharge port is greater than the gas-liquid two-phase equilibrium temperature of the heat transfer medium during the first duration, reduce the heater output power. The step of adjusting the opening degree of the first regulating valve in the temperature control circuit based on the temperature difference between the vacuum pump outlet temperature and the first target temperature includes: When the vacuum pump outlet temperature is greater than the upper limit of the first target temperature or less than the lower limit of the first target temperature, the greater the temperature difference between the vacuum pump outlet temperature and the first target temperature, the greater the opening of the first regulating valve. When the vacuum pump outlet temperature is less than or equal to the upper limit of the first target temperature and greater than or equal to the lower limit of the first target temperature, the first regulating valve is closed. The first target temperature is 20℃ to 25℃, and the cooling water temperature in the temperature control circuit is 20℃ to 25℃.
8. The control method for the heat transfer medium recovery system according to claim 6, characterized in that, The temperature of the medium filling port is determined based on the boiling point of the medium, the reference superheat of the target equipment, the medium residual factor, and the heat exchange efficiency factor. The medium filling port temperature satisfies the following conditions: the medium filling port temperature is greater than or equal to the boiling point of the medium and less than min[thermal decomposition temperature of the thermally conductive medium, material tolerance temperature of the target equipment, and maximum operating temperature of the heater]. Among them, the target equipment reference superheat is determined according to the type of heat transfer medium; the medium residual factor is determined according to the liquid level detection value in the second branch; and the heat exchange efficiency factor is determined according to the relationship between the medium discharge port temperature, the medium boiling point and the gas-liquid two-phase equilibrium temperature of the heat transfer medium.
9. The control method for the heat transfer medium recovery system according to claim 5, characterized in that, During the media fine recovery process: Shut down the refrigeration circuit and the temperature control circuit; Start the heater and cycle through the pulse heating program until the liquid level detection value at the inlet of the second gas-liquid separator remains at 0 for the second duration, then turn off the heater; The pulse heating program includes: First heating stage: Control the output power of the heater to make the temperature at the medium discharge port greater than the boiling point of the medium, and continue for a third duration; Second heating stage: Control the output power of the heater to make the temperature at the medium discharge port lower than the boiling point of the medium, and continue for a fourth time.