A gas-liquid two-phase flow cooling device with online measurement and control of liquid return dryness

Abstract

This invention discloses a gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness, belonging to the field of electronic equipment cooling technology. It includes a refrigerant pump, a first flow sensor, a two-phase flow cooling plate, a first gas-liquid separator, a first electric valve, a second flow sensor, and a storage tank, connected in a circulating sequence. It also includes a condenser and a third flow sensor. The gas phase outlet of the first gas-liquid separator is connected to the condenser inlet, the condenser outlet is connected to the third flow sensor, and the third flow sensor is connected to the storage tank. The actual return liquid dryness is calculated. By comparing the actual return liquid dryness with a set value, the frequency of the refrigerant pump is controlled. The beneficial effects of this invention are: obtaining high-precision return liquid dryness parameters, thereby achieving accurate control of the two-phase flow return liquid dryness in dryness measurement, and allowing for adjustment as needed to ensure stable operation of the two-phase flow cooling system. It has broad application prospects in gas-liquid two-phase flow cooling systems for electronic equipment.

Description

Technical Field

[0001] This invention relates to the field of electronic device cooling technology, and more particularly to a gas-liquid two-phase flow cooling device for online measurement and control of return liquid dryness. Background Technology

[0002] The reliability of electronic device components decreases as their operating temperature increases. The "10°C rule" clearly states that the reliability of semiconductor devices decreases by 50% for every 10°C increase in temperature, and this failure rate increases with increasing temperature. If the operating temperature of electronic devices reaches 70-80°C, the reliability will decrease by 10% for every 1°C increase in operating temperature. Therefore, good heat dissipation is a necessary condition for ensuring the normal operation of electronic devices.

[0003] Due to the ever-increasing demand for heat dissipation, liquid cooling technology has replaced air cooling technology as the mainstream heat dissipation technology for electronic devices. However, in recent years, with technological development and progress, the heat dissipation capacity of cooling systems has been continuously improved, while the weight, power consumption, and size of cooling systems have been continuously reduced. Therefore, liquid cooling technology is gradually approaching its performance limits. To address this issue, pump-driven gas-liquid two-phase flow cooling technology is receiving increasing attention due to its advantages over liquid cooling technology, such as lower power consumption, smaller size, higher heat dissipation capacity, and better temperature uniformity.

[0004] Compared to traditional liquid cooling systems, pump-driven two-phase flow cooling systems are influenced by factors beyond just the temperature and flow rate of the cooling medium and the structure of the cooling plates. To ensure adequate heat dissipation for the terminal electronic equipment, the return liquid dryness should generally not exceed 0.5. Furthermore, to reduce the required cooling medium flow rate, the system's return liquid dryness should not be too low, and a value less than 0.3 is generally not recommended. For equipment with a fixed heat output, a reasonable supply flow rate can be selected during the design phase to ensure the return liquid dryness meets the requirements, and monitoring the supply flow rate is sufficient during system operation. However, for electronic equipment such as radar, due to different operating modes and significant differences in heat generation between these modes, it is difficult to achieve the required return liquid dryness through pre-designed fixed flow rates. Moreover, since the actual heat output of electronic equipment generally has some error compared to the estimated values ​​given during design, the actual dryness during operation differs significantly from the theoretical dryness during design. If the return liquid dryness cannot be monitored and adjusted in real time, it will affect the system's heat dissipation capacity and operational stability.

[0005] Currently, there is a lot of research on dryness measurement of gas-liquid two-phase flow systems, including separate measurement methods, multi-sensor fusion (including differential pressure, capacitance, microwave, ultrasonic, temperature sensors, etc.), model-based calculation and simulation methods, image / optical methods, and other new technologies. Among them, separate measurement methods have high accuracy, but generally their instruments are complex, the equipment is large, the process is complicated, the cost is high, and they require dedicated personnel for maintenance. Most of the time, the measurement is done in shifts and cannot achieve continuous online measurement. CN115183827A discloses a new gas-liquid separation type gas-liquid two-phase flow measurement system and method. It obtains dryness parameters by measuring the flow rates of liquid and gas after gas-liquid separation. However, the gas outlet uses a wet gas flow meter, which has a large pressure loss during use. If integrated into the system, it will have a significant impact on the system parameters. At the same time, this test method requires keeping the internal liquid level of the gas-liquid separation constant to obtain high accuracy. During electronic equipment operation, changes in the system's working mode may make it difficult to keep the level constant, thus affecting the measurement accuracy. Although this patent improves the impact of volume changes caused by changes in the internal liquid level during gas-liquid separation, it will bring additional measurement equipment requirements and accuracy issues in actual testing.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The technical problem to be solved by this invention is: how to solve the problem of low test accuracy in current gas-liquid two-phase flow systems because the dynamic changes in the liquid level in the gas-liquid separator are not taken into account.

[0008] The present invention solves the above-mentioned technical problems through the following technical means:

[0009] A gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness includes a fluorine pump, a first flow sensor, a two-phase flow cooling plate, a first gas-liquid separator, a first electric valve, a second flow sensor, and a liquid storage tank connected in a cycle.

[0010] It also includes a condenser and a third flow sensor; the gas phase outlet of the first gas-liquid separator is connected to the condenser inlet, the condenser outlet is connected to the third flow sensor, and the third flow sensor is connected to the liquid storage tank.

[0011] The actual mass flow rate of the gas entering the first gas-liquid separator is calculated by using the gas density ρv and liquid density ρl in the first gas-liquid separator, as well as the flow rates m1, m3, and m2 measured by the first, second, and third flow sensors, respectively. The actual dryness of the returned liquid is then calculated. The frequency of the refrigerant pump is controlled by comparing the actual dryness of the returned liquid with the set value.

[0012] This invention obtains the return liquid dryness by measuring the mass flow rate of the condensed gas after gas-liquid separation and combining it with the liquid supply flow rate obtained from the liquid supply side. At the same time, the dryness is corrected by measuring the liquid phase mass of the gas-liquid separator and combining it with the liquid supply flow rate and the condensed gas phase flow rate to obtain a high-precision return liquid dryness parameter. This parameter can be adjusted as needed, thereby achieving high-precision measurement and control of return liquid dryness at a relatively low cost to ensure the stable operation of the two-phase flow cooling system. This invention has broad application prospects in gas-liquid two-phase flow cooling systems for electronic equipment.

[0013] Preferably, the first gas-liquid separator integrates a temperature sensor and a pressure sensor. The gas density ρv and liquid density ρl are calculated from the temperature and pressure measured by the temperature and pressure sensors.

[0014] At this point, the volume changes of both gas and liquid in the storage tank are (m2+m3-m1) / ρl.

[0015] The actual mass flow rate of the gas entering the gas-liquid separator is m2+(m2+m3-m1)ρv / ρl.

[0016] The actual dryness fraction of the returned liquid is α=(m2+(m2+m3-m1)ρv / ρl) / m1.

[0017] Preferably, the first gas-liquid separator integrates a liquid level measuring device. When the liquid level approaches the upper limit of the set range, the opening of the first electric valve is increased; when the liquid level approaches the lower limit of the set range, the opening of the first electric valve is decreased, so as to maintain the liquid level fluctuating within the set range.

[0018] Preferably, the set value for the dryness of the returned liquid is 0.3-0.5.

[0019] Preferably, it also includes a filter, with the outlet of the fluorine pump connected to the filter, and the outlet of the filter connected to a first flow sensor.

[0020] The filter can filter two-phase flow liquids to remove impurities and obtain more accurate measurement results. It can also prevent impurities from condensing on the two-phase flow cooling plate and affecting the cooling effect.

[0021] Preferably, there is at least one two-phase flow cooling plate; when there are multiple two-phase flow cooling plates, the multiple two-phase flow cooling plates are connected in series or in parallel.

[0022] Preferably, it further includes a second gas-liquid separator and a second electric valve. The gas phase outlet of the first gas-liquid separator is connected to the inlet of the second gas-liquid separator. The gas phase outlet of the second gas-liquid separator is connected to the inlet of the condenser. The liquid phase outlet of the second gas-liquid separator is connected to the inlet of the second electric valve. The outlet of the second electric valve is connected to the inlet of the second flow sensor.

[0023] Multiple gas-liquid separators can participate in gas-liquid separation multiple times to ensure more thorough gas-liquid separation.

[0024] Preferably, the mass flow rate measured by the second mass flow rate is the sum of the liquid phase outlet values ​​of the first gas-liquid separator and the second gas-liquid separator.

[0025] Preferably, it also includes a fourth flow sensor, the inlet of which is connected to the outlet of the second gas-liquid separator, and the outlet of which is connected to a liquid storage tank.

[0026] Preferably, the flow rate value m3 is the sum of the parameters obtained from the second mass flow rate and the parameters obtained from the fourth flow sensor.

[0027] The advantages of this invention are:

[0028] This invention obtains the return liquid dryness by measuring the mass flow rate of the condensed gas after gas-liquid separation and combining it with the liquid supply flow rate obtained from the liquid supply side. At the same time, the dryness is corrected by measuring the liquid phase mass of the gas-liquid separator and combining it with the liquid supply flow rate and the condensed gas phase flow rate to obtain a high-precision return liquid dryness parameter. This parameter can be adjusted as needed, thereby achieving high-precision measurement and control of return liquid dryness at a relatively low cost to ensure the stable operation of the two-phase flow cooling system. This invention has broad application prospects in gas-liquid two-phase flow cooling systems for electronic equipment. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness according to Embodiment 1 of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness according to Embodiment 2 of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of the gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness according to Embodiment 3 of the present invention;

[0032] Numbering on the map:

[0033] 1. Fluorine pump; 2. Filter; 3. First flow sensor; 4. Two-phase flow cooling plate; 5. First gas-liquid separator; 6. First electric valve; 7. Second flow sensor; 8. Liquid storage tank; 9. Condenser; 10. Third flow sensor; 11. Second gas-liquid separator; 12. Second electric valve; 13. Fourth flow sensor. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1:

[0036] like Figure 1 As shown, a gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness includes a fluorine pump 1, a filter 2, a first flow sensor 3, a two-phase flow cooling plate 4, a first gas-liquid separator 5, a first electric valve 6, a second flow sensor 7, a liquid storage tank 8, a condenser 9, and a third flow sensor 10.

[0037] The following components are connected in sequence to form a circulation path: 1. Fluorine pump; 2. Filter; 3. First flow sensor; 4. Two-phase flow cooling plate; 5. First gas-liquid separator; 6. First electric valve; 7. Second flow sensor; and 8. Storage tank. The liquid phase outlet of the first gas-liquid separator 5 is connected to the inlet of the first electric valve 6. The outlet of the first electric valve 6 is connected to the inlet of the second flow sensor 7. The outlet of the second flow sensor 7 is connected to the first inlet of the storage tank 8. At the same time, the gas phase outlet of the first gas-liquid separator 5 is connected to the inlet of the condenser 9. The outlet of the condenser 9 is connected to the inlet of the third flow sensor 10. The outlet of the third flow sensor 10 is connected to the second inlet of the storage tank 8.

[0038] In this embodiment, the fluorine pump 1 is a variable frequency pump, used to adjust the liquid supply flow rate as needed. There can be more than one two-phase flow cooling plate 4; the specific number and arrangement can be designed according to requirements. The working medium can be Freon or other two-phase flow cooling media. The opening degree of the first electric valve 6 can be adjusted in real time via the control system as needed; various valves meeting this requirement can be used. The filter 2 filters the working medium, preventing impurities from affecting the measurement results and preventing impurities from condensing on the two-phase flow cooling plate 4.

[0039] The first gas-liquid separator 5 integrates a temperature sensor and a pressure sensor to measure the temperature and pressure data, and obtains the gas density ρv and liquid density ρl inside the first gas-liquid separator 5 through existing calculation methods.

[0040] In this embodiment, the liquid Freon from the outlet of the Freon pump 1 is dried and filtered by the filter 2. When it flows through the first flow sensor 3, the supply liquid mass flow rate m1 is obtained. Then, the liquid Freon flows to the two-phase flow cooling plate 4 of the electronic device, where its heat is carried away. The Freon at the outlet of the two-phase flow cooling plate 4 of the electronic device becomes a two-phase state. The two-phase Freon flows to the first gas-liquid separator 5. The gas phase flows to the condenser 9 and is condensed into a liquid phase. After passing through the third flow sensor 10, the gas phase mass flow rate m2 at the outlet of the gas-liquid separator is obtained. The mass flow rate m3 at the liquid phase outlet of the first gas-liquid separator 5 is obtained by timing the flow through the second mass flow meter 7. In actual operation, the internal liquid volume of the first gas-liquid separator 5 is constantly changing. The change in mass is (m2+m3-m1). If (m2+m3-m1)>0, it indicates that the internal coolant is decreasing, and the decreased volume is filled by gas. At this time, the actual gas volume flow rate and dryness flow rate should be greater. The specific calculation method is as follows: the gas density ρv and liquid density ρl are calculated by using the temperature and pressure data measured by the internal temperature and pressure sensors of the first gas-liquid separator 5 and the physical property parameters integrated by the control system. Then, the volume change values ​​of gas and liquid in the liquid storage tank 8 are both (m2+m3-m1) / ρl. The actual mass flow rate of the gas entering the gas-liquid separator is m2+(m2+m3-m1)ρv / ρl. The actual return liquid dryness is α=(m2+(m2+m3-m1)ρv / ρl) / m1.

[0041] It should be noted that in special cases, i.e. when the system is in a complete steady state, the amount of liquid and gas inside the first gas-liquid separator 5 remains constant, i.e., m1 = m2 + m3, and α = m2 / m1.

[0042] It is important to note that in actual operation, the liquid level in the gas-liquid separator can fluctuate continuously, but it must be kept within a certain upper and lower limit range. If the liquid level is too high, it will affect the gas-liquid separation effect; if the liquid level is too low, some gas may flow directly into the liquid storage tank 8 through the liquid phase outlet, both of which will affect the measurement accuracy. Therefore, a liquid level gauge or liquid level switch is integrated inside the first gas-liquid separator 5. When the liquid level approaches the upper limit of the set range, the opening of the first electric valve 6 is increased through the automatic control program to gradually lower the liquid level. When the liquid level approaches the lower limit of the set range, the opening of the first electric valve 6 is decreased through the automatic control program to gradually raise the liquid level, thereby maintaining the liquid level fluctuation within a certain range. After obtaining the dryness of the returned liquid through the above process, if the dryness value is close to the allowable upper limit of 0.5, the liquid supply flow rate is increased by adjusting the frequency of the refrigerant pump 1 to reduce the dryness of the returned liquid back to 0.3-0.4. If the dryness of the returned liquid is lower than 0.3, the liquid supply flow rate is decreased by reducing the frequency of the refrigerant pump 1 to increase the dryness of the returned liquid back to 0.3-0.4. Through the above process, high-precision online measurement and control of the dryness of this gas-liquid two-phase flow cooling device can be achieved. The controller mentioned above can be implemented using existing software technology.

[0043] Example 2:

[0044] like Figure 2 As shown, in this embodiment, based on embodiment one, a second gas-liquid separator 11 is provided between the first gas-liquid separator 5 and the condenser 9. The gas phase outlet of the first gas-liquid separator 5 is connected to the inlet of the second gas-liquid separator 11. The gas phase outlet of the second gas-liquid separator 11 is connected to the inlet of the condenser 9. The liquid phase outlet of the second gas-liquid separator 11 is connected to the inlet of the second electric valve 12. The outlet of the second electric valve 12 is connected to the inlet of the second flow sensor 7.

[0045] In this embodiment, the second gas-liquid separator 11 further separates the gas and liquid, ensuring a more thorough gas-liquid separation.

[0046] At this time, the mass flow rate m3 obtained by the second mass flow rate 7 is the sum of the liquid phase outlets of the first gas-liquid separator 5 and the second gas-liquid separator 11.

[0047] The gas density ρv and liquid density ρl are calculated using the temperature and pressure data measured by the internal temperature and pressure sensors of the first gas-liquid separator 5 and the integrated physical property parameters of the control system. Therefore, the volume change of both gas and liquid in the storage tank 8 is (m2 + m3 - m1) / ρl. The actual mass flow rate of the gas entering the gas-liquid separator is m2 + (m2 + m3 - m1)ρv / ρl, and the actual dryness fraction of the returned liquid is α = (m2 + (m2 + m3 - m1)ρv / ρl) / m1. The control method for the fluorine pump 1 can be referenced in Example 1.

[0048] It should be noted that the gas density and liquid density in the second gas-liquid separator 11 are the same as those in the first gas-liquid separator 5. Therefore, it is only necessary to obtain the gas density and liquid density in the first gas-liquid separator 5.

[0049] Example 3:

[0050] like Figure 3 As shown, based on Embodiment 2, a fourth flow sensor 13 is provided between the second electric valve 12 and the storage tank 8. The outlet of the second electric valve 12 and the inlet of the fourth flow sensor 13 are connected, and the outlet of the fourth flow sensor 13 is connected to the second inlet of the storage tank 8.

[0051] At this time, the mass flow rate m3 is the sum of the parameters obtained by the second mass flow rate 7 and the parameters obtained by the fourth flow sensor 13.

[0052] The opening degree of the second electric valve 12 can be adjusted in real time as needed through the control system.

[0053] For other details, please refer to Example 2.

[0054] In the above embodiments, the dryness of the cooling medium return liquid is obtained by measuring the mass flow rate of the condensed gas after gas-liquid separation and combining it with the liquid supply flow rate obtained from the liquid supply side. At the same time, the dryness is corrected by measuring the liquid phase mass of the gas-liquid separator and combining it with the liquid supply flow rate and the gas phase flow rate after condensation, so as to obtain a high-precision return liquid dryness parameter. It can be adjusted as needed, thereby achieving high-precision measurement and control of return liquid dryness at a relatively low cost to ensure the stable operation of the two-phase flow cooling system. It has broad application prospects in gas-liquid two-phase flow cooling systems for electronic equipment.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness, characterized in that, It includes a fluorine pump, a first flow sensor, a two-phase flow cooling plate, a first gas-liquid separator, a first electric valve, a second flow sensor, and a liquid storage tank, which are connected in a cycle in sequence. It also includes a condenser and a third flow sensor; the gas phase outlet of the first gas-liquid separator is connected to the condenser inlet, the condenser outlet is connected to the third flow sensor, and the third flow sensor is connected to the liquid storage tank. The actual mass flow rate of the gas entering the first gas-liquid separator is calculated by using the gas density ρv and liquid density ρl in the first gas-liquid separator, as well as the flow rates m1, m3, and m2 measured by the first flow sensor, the second flow sensor, and the third flow sensor, respectively. The actual dryness of the returned liquid is then calculated. The frequency of the refrigerant pump is controlled by comparing the actual dryness of the returned liquid with the set value. The first gas-liquid separator integrates temperature and pressure sensors. The gas density ρv and liquid density ρl are calculated from the temperature and pressure readings obtained by these sensors. At this point, the volume changes of both gas and liquid in the storage tank are (m2 + m3 - m1) / ρl. The actual mass flow rate of the gas entering the gas-liquid separator is m2 + (m2 + m3 - m1)ρv / ρl. The actual dryness fraction of the returned liquid is α = (m2 + (m2 + m3 - m1)ρv / ρl) / m1; The first gas-liquid separator integrates a liquid level measuring device. When the liquid level approaches the upper limit of the set range, the opening of the first electric valve is increased; when the liquid level approaches the lower limit of the set range, the opening of the first electric valve is decreased, maintaining the liquid level fluctuating within the set range.

2. The gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness as described in claim 1, characterized in that, The set value for the dryness of the returned liquid is 0.3-0.

5.

3. The gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness as described in claim 1, characterized in that, It also includes a filter, with the outlet of the fluorine pump connected to the filter, and the outlet of the filter connected to the first flow sensor.

4. The gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness as described in claim 1, characterized in that, There is at least one two-phase flow cooling plate. When there are multiple two-phase flow cooling plates, they are connected in series or in parallel.

5. A gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness as described in claim 1, characterized in that, It also includes a second gas-liquid separator and a second electric valve. The gas phase outlet of the first gas-liquid separator is connected to the inlet of the second gas-liquid separator. The gas phase outlet of the second gas-liquid separator is connected to the inlet of the condenser. The liquid phase outlet of the second gas-liquid separator is connected to the inlet of the second electric valve. The outlet of the second electric valve is connected to the inlet of the second flow sensor.

6. A gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness as described in claim 5, characterized in that, The mass flow rate measured by the second mass flow rate is the sum of the liquid phase outlet values ​​of the first and second gas-liquid separators.

7. A gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness as described in claim 5, characterized in that, It also includes a fourth flow sensor, the inlet of which is connected to the outlet of the second gas-liquid separator, and the outlet of which is connected to the liquid storage tank.

8. A gas-liquid two-phase flow cooling device with online measurement and control of return liquid dryness as described in claim 7, characterized in that, The flow rate value m3 is the sum of the parameters obtained from the second mass flow rate sensor and the parameters obtained from the fourth flow sensor.

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