Liquid cooling system and control method

Abstract

The present application relates to a kind of liquid cooling system and control method, it includes: heat exchanger, one side of heat exchanger is communicated with primary side pipeline, the other side is communicated with secondary side pipeline, cooling medium in secondary side pipeline is exchanged heat with cooling medium in primary side pipeline by heat exchanger;First pump and second pump are provided with parallel on secondary side pipeline, the maximum flow of first pump is greater than the maximum flow of second pump, first pump and second pump are communicated with secondary side pipeline;Secondary side pipeline is also connected with bypass pipeline, bypass pipeline is communicated with secondary side pipeline, and bypass pipeline is provided with pressure difference balance valve, pressure difference balance valve is parallel with first pump, second pump, so that liquid cooling system forms at least three kinds of working mode, at least three kinds of working mode include first pump working mode, second pump working mode and second pump and pressure difference balance valve mixed working mode. By controlling the switching of different working mode, precision control flow can be realized, and it can adapt to the use scene of lower load rate.

Description

Technical Field

[0001] This invention relates to the field of liquid cooling technology for data centers, and particularly to a liquid cooling system and control method. Background Technology

[0002] As the power of server central processing units gradually increases, the power consumption of individual servers is getting higher and higher, causing the power density of a single rack to exceed 20kW or even higher. Traditional air cooling methods cannot meet the heat dissipation of such high power density, and other more efficient heat dissipation methods are needed to solve the problem. Data centers usually consider adopting liquid cooling solutions.

[0003] When data centers are initially planned and constructed, factors such as server expansion and business growth needs are taken into account. Generally, the number of servers actually put into use accounts for about 50% of the planned servers, or even less.

[0004] In related technologies, coolant distribution units (CDUs) provide cooling media to multiple server racks to cool them; depending on the actual rack occupancy rate of the servers, the coolant distribution units need to provide different coolant flow rates.

[0005] Water pumps operate at different speeds, corresponding to different water flow rates. However, the pump speed cannot decrease indefinitely. When the speed drops to a certain value, the magnetic flux decreases, the motor output torque decreases, and in order to match the load torque, the current increases, causing the frequency converter to overheat and eventually generate an alarm.

[0006] Therefore, it is necessary to design a new liquid cooling system and control method to overcome the above problems. Summary of the Invention

[0007] This invention provides a liquid cooling system and control method to solve the problem in related technologies where, when the speed of a water pump drops to a certain value, the magnetic flux decreases, the motor output torque decreases, which in turn causes the frequency converter to overheat severely and eventually generate an alarm.

[0008] In a first aspect, a liquid cooling system is provided, comprising: a heat exchanger, one side of which is connected to a primary side pipeline and the other side to a secondary side pipeline, wherein a cooling medium in the secondary side pipeline exchanges heat with the cooling medium in the primary side pipeline through the heat exchanger; a first pump and a second pump connected in parallel on the secondary side pipeline, wherein the maximum flow rate of the first pump is greater than the maximum flow rate of the second pump, and both the first pump and the second pump are connected to the secondary side pipeline; a bypass pipeline is also connected to the secondary side pipeline, the bypass pipeline is connected to the secondary side pipeline, and the bypass pipeline is equipped with a differential pressure balancing valve, the differential pressure balancing valve being connected in parallel with the first pump and the second pump, thereby enabling the liquid cooling system to form at least three operating modes, including a first pump operating mode, a second pump operating mode, and a mixed operating mode of the second pump and the differential pressure balancing valve.

[0009] In some embodiments, the first pump is connected in series with a first solenoid valve, and the second pump is connected in series with a second solenoid valve. The first and second solenoid valves control the on / off state of the first and second pumps. A primary-side electric valve is connected in series on the primary-side pipeline. The primary-side electric valve is configured to control the flow rate of the cooling medium in the primary-side pipeline by adjusting its opening. At the same time, a primary-side temperature sensor and a primary-side pressure sensor are also provided on the primary-side pipeline.

[0010] In some embodiments, a safety valve is connected in series on the secondary side pipeline, the safety valve being used to control the internal pressure of the liquid cooling system within a preset range; an expansion tank and an exhaust valve are also connected in series on the secondary side pipeline, the expansion tank being located between the heat exchanger and the first pump, and the exhaust valve being located at the highest point of the liquid cooling system; simultaneously, an outlet water temperature sensor, an inlet water temperature sensor, an outlet water pressure sensor, an inlet water pressure sensor, a pump pre-pressure sensor, and a flow sensor are also installed on the secondary side pipeline.

[0011] Secondly, a control method for the aforementioned liquid cooling system is provided, comprising the following steps: controlling the first pump to start while maintaining the differential pressure balancing valve in a closed state; determining whether the inlet and outlet pressure difference of the secondary side pipeline and the actual speed of the first pump meet a first preset condition; if yes, controlling the second pump to start and controlling the first pump to stop, while maintaining the differential pressure balancing valve in a closed state; otherwise, maintaining the operation of the first pump until the first preset condition is met; determining whether the inlet and outlet pressure difference of the secondary side pipeline and the actual speed of the second pump meet a second preset condition; if yes, controlling the differential pressure balancing valve to open and controlling the second pump to maintain a minimum speed; otherwise, maintaining the operation of the second pump until the second preset condition is met.

[0012] In some embodiments, determining whether the inlet and outlet pressure difference of the secondary side pipeline and the actual speed of the first pump meet the first preset condition includes: determining whether the inlet and outlet pressure difference of the secondary side pipeline is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone; if so, determining whether the actual speed of the first pump is maintained at the minimum speed for a preset time; if the inlet and outlet pressure difference of the secondary side pipeline is not greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone, then maintaining the operation of the first pump until the inlet and outlet pressure difference of the secondary side pipeline is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone; if the actual speed of the first pump is maintained at the minimum speed for a preset time, then controlling the second pump to start and controlling the first pump to stop, while maintaining the closed state of the pressure difference balance valve; otherwise, maintaining the operation of the first pump until the actual speed of the first pump is maintained at the minimum speed for a preset time.

[0013] In some embodiments, after determining that the inlet and outlet pressure difference of the secondary side pipeline is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the dead zone of the secondary side inlet and outlet water pressure difference, the method further includes: controlling the actual speed of the first pump to decrease.

[0014] In some embodiments, after determining that the inlet and outlet pressure difference of the secondary side pipeline is not greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone, the following steps are included: determining whether the inlet and outlet pressure difference of the secondary side pipeline is greater than or equal to the difference between the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone, and less than or equal to the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone; if so, then control the first pump to maintain the current speed; otherwise, control the actual speed of the first pump to increase.

[0015] In some embodiments, determining whether the inlet and outlet pressure difference of the secondary side pipeline and the actual speed of the second pump meet the second preset condition includes: determining whether the inlet and outlet pressure difference of the secondary side pipeline is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone; if so, determining whether the actual speed of the second pump has been maintained at the minimum speed for a preset time and whether the pressure difference balancing valve is closed; if the inlet and outlet pressure difference of the secondary side pipeline is not greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone, then maintaining the operation of the second pump until the inlet and outlet pressure difference of the secondary side pipeline is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone; if the actual speed of the second pump has been maintained at the minimum speed for a preset time and the pressure difference balancing valve is closed, then controlling the pressure difference balancing valve to open and controlling the second pump to maintain the minimum speed, otherwise maintaining the operation of the second pump until the actual speed of the second pump has been maintained at the minimum speed for a preset time and the pressure difference balancing valve is closed.

[0016] In some embodiments, after determining that the inlet and outlet pressure difference of the secondary side pipeline is not greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone, the following steps are included: determining whether the inlet and outlet pressure difference of the secondary side pipeline is greater than or equal to the difference between the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone, and less than or equal to the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone; if so, then control the second pump to maintain the current speed operation; otherwise, control the actual speed of the second pump to increase. The system operates under pressure and determines whether the actual speed of the second pump remains at its maximum speed for a preset time, and whether the differential pressure balancing valve is closed. If the actual speed of the second pump remains at its maximum speed for a preset time, and the differential pressure balancing valve is closed, then the system controls the first pump to start and the second pump to stop, and controls the differential pressure balancing valve to remain closed. Otherwise, the system continues to operate the second pump until the differential pressure between the inlet and outlet of the secondary side pipeline is greater than the sum of the setpoint value of the differential pressure between the secondary side inlet and outlet and the setpoint value of the differential pressure dead zone between the secondary side inlet and outlet.

[0017] In some embodiments, after controlling the differential pressure balancing valve to open and controlling the second pump to maintain a minimum speed, the method further includes: determining whether the difference between the inlet and outlet pressures of the secondary side pipeline is less than the sum of the set point value of the differential pressure difference between the secondary side inlet and outlet and the set point value of the dead zone of the differential pressure difference between the secondary side inlet and outlet for a preset time; if so, closing the differential pressure balancing valve; otherwise, continuing to keep the differential pressure balancing valve open and controlling the second pump to maintain a minimum speed.

[0018] The beneficial effects of the technical solution provided by this invention include:

[0019] This invention provides a liquid cooling system and control method. Because a first pump and a second pump are connected in parallel on the secondary side pipeline, with different maximum flow rates, and a differential pressure balancing valve is also connected in parallel, the liquid cooling system can operate in at least three modes: a first pump mode, a second pump mode, and a mixed mode of the second pump and the differential pressure balancing valve. When the heat load demand is high, the system can operate in the first pump mode; when the heat load demand is low, it can operate in the second pump mode; and when the heat load is particularly low, operating the second pump alone may not be sufficient, so the system can operate in the mixed mode of the second pump and the differential pressure balancing valve. Therefore, by controlling the switching between different operating modes, precise flow control can be achieved, adapting to low-load usage scenarios, reducing the energy consumption of the liquid cooling system, and lowering the overall PUE in the computer room. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a liquid cooling system provided in an embodiment of the present invention;

[0022] Figure 2 A flowchart of a control method for a liquid cooling system provided in an embodiment of the present invention;

[0023] Figure 3 A flowchart of another control method provided in an embodiment of the present invention.

[0024] In the picture:

[0025] 1. Heat exchanger;

[0026] 2. Primary side piping; 21. Primary side electric valve; 22. Primary side temperature sensor; 23. Primary side pressure sensor;

[0027] 3. Secondary side piping; 31. Safety valve; 32. Expansion tank; 33. Air vent valve; 34. Outlet water temperature sensor; 35. Inlet water temperature sensor; 36. Outlet water pressure sensor; 37. Inlet water pressure sensor; 38. Pump inlet pressure sensor; 39. Flow sensor;

[0028] 4. First pump; 41. First solenoid valve; 5. Second pump; 51. Second solenoid valve;

[0029] 6. Bypass pipeline; 61. Differential pressure balancing valve. Detailed Implementation

[0030] 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 with reference to the accompanying drawings. 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.

[0031] This invention provides a liquid cooling system and control method that can solve the problem in related technologies where the pump speed drops to a certain value, causing a reduction in magnetic flux and motor output torque, which in turn leads to severe overheating of the frequency converter and ultimately generates an alarm.

[0032] See Figure 1 As shown, an embodiment of the present invention provides a liquid cooling system, which may include: a heat exchanger 1, one side of which is connected to a primary side pipe 2, and the other side of which is connected to a secondary side pipe 3. The cooling medium in the secondary side pipe 3 exchanges heat with the cooling medium in the primary side pipe 2 through the heat exchanger 1. In this embodiment, the heat exchanger 1 is preferably a plate heat exchanger 1. Of course, other types of heat exchangers 1 can also be used, as long as heat exchange can be achieved. A first pump 4 and a second pump 5 connected in parallel can be provided on the secondary side pipe 3. The maximum flow rate of the first pump 4 is greater than the maximum flow rate of the second pump 5, that is, the first pump 4 is a large pump and the second pump 5 is a small pump. The second pump 5 is connected to the secondary side pipeline 3. A bypass pipeline 6 can also be connected to the secondary side pipeline 3. The bypass pipeline 6 is connected to the secondary side pipeline 3 and is equipped with a differential pressure balancing valve 61. The differential pressure balancing valve 61 is connected in parallel with the first pump 4 and the second pump 5. The differential pressure balancing valve 61 can bypass part of the water flow in the secondary side pipeline 3, so that the liquid cooling system can form at least three working modes. The at least three working modes include the working mode of the first pump 4, the working mode of the second pump 5, and the mixed working mode of the second pump 5 and the differential pressure balancing valve 61. That is, the bypass pipeline 6 where the differential pressure balancing valve 61 is located is connected in parallel with the pipelines where the first pump 4 and the second pump 5 are located.

[0033] In the above technical solution, a cold source can be supplied from the outside to the liquid cooling primary side pipeline 2, and after heat exchange through heat exchanger 1, the high-grade cooling medium returns to the external chiller unit or cooling tower. The low-grade cooling medium after heat exchange through heat exchanger 1 is powered by the first pump 4 or the second pump 5 to be transported to the heat source in the machine room. After heat exchange, the high-grade cooling medium returns to heat exchanger 1 and can continue to exchange heat through the primary side pipeline 2.

[0034] In this embodiment, since a first pump 4 and a second pump 5 are connected in parallel on the secondary side pipeline 3, and the maximum flow rates of the first pump 4 and the second pump 5 are different, that is, they are divided into large pumps and small pumps, and a differential pressure balancing valve 61 is also connected in parallel, the liquid cooling system can form at least three working modes, namely the first pump 4 working mode, the second pump 5 working mode, and the mixed working mode of the second pump 5 and the differential pressure balancing valve 61. When the heat load demand is high, the first pump 4 working mode can be entered. When the heat load demand is low, the second pump 5 working mode can be entered. When the heat load is particularly low, the second pump 5 alone may not be able to meet the demand. At this time, the mixed working mode of the second pump 5 and the differential pressure balancing valve 61 can be entered.

[0035] This embodiment uses a combination of large and small pumps, where the first pump 4 is the large pump and the second pump 5 is the small pump. Generally, the small pump can have the same head as the large pump, and the maximum flow rate of the small pump can be 30% to 50% of that of the large pump. This allows for stepless adjustment from 5% to 100%, which is more energy-efficient than a direct bypass control strategy. By controlling the switching between dual pumps of different sizes, flow rate can be precisely controlled. Considering the current realities of data centers, especially in the initial stages of operation when server rack occupancy is very low, the inability of servers to be unloaded to very low load rates leads to frequent start-ups and shutdowns or prolonged low-speed operation, shortening the lifespan of some components. Furthermore, some cooling capacity is bypassed, resulting in energy waste. This invention enables stepless load adjustment from 5% to 100%, effectively mitigating these adverse effects. Therefore, by controlling the switching between different operating modes, precise flow rate control can be achieved, adapting to low-load scenarios, reducing liquid cooling system energy consumption, and lowering the overall PUE within the data center. This effectively addresses scenarios with single-rack power densities exceeding 20kW, while also increasing the lifespan of components. PUE is an indicator of data center energy efficiency, calculated as the ratio of all energy consumed by the data center to the energy consumed by the IT load. PUE = Total Data Center Energy Consumption / IT Equipment Energy Consumption.

[0036] In some embodiments, see Figure 1As shown, the first pump 4 can be connected in series with a first solenoid valve 41, and the second pump 5 can be connected in series with a second solenoid valve 51. The first solenoid valve 41 and the second solenoid valve 51 can control the on / off state of the first pump 4 and the second pump 5. The first solenoid valve 41 and the second solenoid valve 51 can be equivalent to an electric switch. Each pump is equipped with a corresponding solenoid valve, and the switching between different sizes of dual pumps can be automatically controlled by the solenoid valve. A primary side electric valve 21 can also be connected in series on the primary side pipeline 2. In this embodiment, the primary side electric valve 21 is preferably a primary side electric two-way valve. Of course, other types of electric valves can also be selected. The primary side electric valve 21 is configured to control the flow rate of the cooling medium in the primary side pipeline 2 by adjusting its opening degree. At the same time, a primary side temperature sensor 22 and a primary side pressure sensor 23 are also provided on the primary side pipeline 2. Two primary side pressure sensors 23 can be connected to the primary side pipeline 2 to detect the primary side inlet and outlet water pressure values, and the primary side temperature sensor 22 can detect the primary side inlet water temperature value. Of course, in other embodiments, individual switches can be set on each pump to control the start and stop of each pump by manually turning them on or off.

[0037] Furthermore, in some optional embodiments, see [link to documentation]. Figure 1 As shown, a safety valve 31 can be connected in series on the secondary side pipeline 3. The safety valve 31 is used to control the internal pressure of the liquid cooling system within a preset range. The secondary side pipeline 3 can have an outlet and an inlet. The outlet allows the cooling medium in the secondary side pipeline 3 to flow out to the heat source in the machine room. After heat exchange, the cooling medium from the heat source in the machine room returns to the secondary side pipeline 3 through the inlet. The safety valve 31 can be located at the outlet of the secondary side pipeline 3. An expansion tank 32 and an exhaust valve 33 can also be connected in series on the secondary side pipeline 3. The expansion tank 32 is located between the heat exchanger 1 and the first pump 4. At the same time, the expansion tank 32 is also located between the heat exchanger 1 and the second pump 5. The expansion tank 32 can be used for both the first pump 4 and the second pump 5. The second pump 5 provides a stable inlet water pressure. The exhaust valve 33 is located at the highest point of the liquid cooling system to remove air from the system. At the same time, the secondary side pipeline 3 is also equipped with an outlet water temperature sensor 34, an inlet water temperature sensor 35, an outlet water pressure sensor 36, an inlet water pressure sensor 37, a pump inlet pressure sensor 38, and a flow sensor 39. That is, the secondary side pipeline 3 is equipped with three pressure sensors to detect the secondary side outlet water pressure, the secondary side inlet water pressure, and the secondary side pump inlet pressure, respectively. The secondary side pipeline 3 is equipped with two temperature sensors to detect the secondary side outlet water temperature and the secondary side inlet water temperature, respectively. The secondary side pipeline 3 is equipped with one flow sensor 39 to detect the secondary side flow rate.

[0038] The liquid cooling system provided in this invention can achieve precise flow control under different loads. In particular, when the server rack rate is low, precise water flow control can be achieved by changing the operating mode of different secondary side pumps.

[0039] See Figure 2 As shown, a control method for a liquid cooling system provided in an embodiment of the present invention may include the following steps:

[0040] S1: Control the first pump 4 to start while keeping the differential pressure balancing valve 61 closed (in this embodiment, only the first pump 4 is working). Before step S1, the liquid cooling system is initially in a shutdown state. It can be determined whether the liquid cooling system (i.e., CDU) needs to be turned on. If there is a need, proceed to step S1; otherwise, the liquid cooling system remains in a shutdown state. Preferably, the first pump 4 can be connected in series with a first solenoid valve 41. In this embodiment, the first solenoid valve 41 can be opened first to start the first pump 4, and the actual speed of the first pump 4 when it starts can be controlled to be Speed_1 = 50% of the rated speed.

[0041] S2: Determine whether the inlet and outlet pressure difference of the secondary side pipeline 3 and the actual speed of the first pump 4 meet the first preset condition. Further, before determining the inlet and outlet pressure difference of the secondary side pipeline 3, the inlet and outlet pressures Pso1 and Psi1 of the secondary side can be collected first.

[0042] S3: If yes, then control the second pump 5 to start and control the first pump 4 to stop, while maintaining the differential pressure balance valve 61 in the closed state (in this embodiment, only the second pump 5 is working); otherwise, maintain the first pump 4 working until the first preset condition is met. In this embodiment, if the inlet and outlet pressure difference of the secondary side pipeline 3 and the actual speed of the first pump 4 meet the first preset condition, it means that such a large cooling flow is not needed at this time, and the second pump 5 needs to be turned on, while the first pump 4 can be turned off.

[0043] S4: Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline 3 and the actual speed of the second pump 5 meet the second preset condition.

[0044] S5: If yes, then control the differential pressure balancing valve 61 to open and control the second pump 5 to maintain minimum speed (in this embodiment, the second pump 5 and the differential pressure balancing valve 61 work together). Otherwise, maintain the operation of the second pump 5 until the second preset condition is met. In this embodiment, if the inlet and outlet pressure difference of the secondary side pipeline 3 and the actual speed of the second pump 5 meet the second preset condition, it means that a smaller cooling flow rate is required. At this time, it is necessary to open the differential pressure balancing valve 61 to bypass part of the water flow, while keeping the second pump 5 at minimum speed.

[0045] This invention embodiment uses an adaptive control method to first determine the operating status of the first pump 4, the second pump 5, and the pressure balancing valve. Through the coupled control of the two pumps and the pressure balancing valve, it can effectively avoid the variable frequency water pump failing to meet the actual machine room usage requirements when the speed is at its lower limit. The pressure balancing valve can further adjust the load on the one hand, and on the other hand, it can be manually opened when the end load and resistance are severely uneven, thus playing a role in hydraulic balancing.

[0046] Further, see Figure 3 As shown, in some embodiments, determining whether the pressure difference between the inlet and outlet of the secondary side pipeline 3 and the actual rotational speed of the first pump 4 meet the first preset condition may include the following steps:

[0047] Determine whether the inlet and outlet pressure difference of secondary side pipeline 3 is greater than the sum of the setpoint value of the secondary side inlet and outlet pressure difference and the setpoint value of the secondary side inlet and outlet pressure difference dead zone, i.e., Pso1-Psi1>P_set+P_dead; before this step, the setpoint value of the secondary side inlet and outlet pressure difference P_set, the secondary side inlet and outlet pressure difference dead zone P_dead, and the minimum speed of the secondary side pump Speed_min can be collected. The three values ​​of the setpoint value of the secondary side inlet and outlet pressure difference P_set, the secondary side inlet and outlet pressure difference dead zone P_dead, and the minimum speed of the secondary side pump Speed_min (the minimum speed of the first pump 4 and the minimum speed of the second pump 5 are the same by default) can be preset.

[0048] If so, it is determined whether the actual speed of the first pump 4 has been maintained at the minimum speed (i.e., Speed_1 = Speed_min) for a preset time. In this embodiment, the preset time is preferably set to 2 minutes. Of course, the preset time can also be adjusted according to the actual situation, and no restriction is imposed here.

[0049] If the pressure difference between the inlet and outlet of the secondary side pipeline 3 is not greater than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the dead zone of the pressure difference between the secondary side inlet and outlet, then the first pump 4 shall continue to operate until the pressure difference between the inlet and outlet of the secondary side pipeline 3 is greater than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the dead zone of the pressure difference between the secondary side inlet and outlet.

[0050] If the actual speed of the first pump 4 remains at the minimum speed for a preset time, then the second pump 5 is started and the first pump 4 is stopped, while the differential pressure balance valve 61 remains closed. Otherwise, the first pump 4 continues to operate until its actual speed remains at the minimum speed for a preset time. Preferably, the second pump 5 can be connected in series with a second solenoid valve 51. In this embodiment, the second solenoid valve 51 can be opened first to start the second pump 5, and its actual speed Speed_2 = 100% of the rated speed can be controlled when the second pump 5 starts. In this embodiment, by judging the two conditions "Pso1-Psi1>P_set+P_dead and whether the actual speed of the first pump 4 remains at the minimum speed for a preset time?", it can be confirmed whether the liquid cooling system meets the conditions for starting the second pump 5, preventing the second pump 5 from being incorrectly started due to parameter jumps or system instability.

[0051] In some embodiments, after determining that the inlet and outlet pressure difference of the secondary side pipeline 3 is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the dead zone of the secondary side inlet and outlet water pressure difference, the method may further include: controlling the actual speed of the first pump 4 to decrease. That is, the speed of the first pump 4 can be reduced before determining whether the actual speed of the first pump 4 remains at the minimum speed for a preset time. In this embodiment, the pump can adopt a fast incremental speed control, and the following formula is fitted by the deviation value of the pressure difference between the secondary side inlet and outlet water to obtain:

[0052] ▲Speed ​​= ROUND(a*(Pso1-Psi1-P_set)^2+b*(Pso1-Psi1-P_set)+c), which is more suitable for data center temperature control products, enabling the computer room temperature to reach the target temperature faster. That is, when the actual speed of the first pump 4 is controlled to decrease, its actual speed Speed_1 = Speed_1-ROUND(a*(Pso1-Psi1-P_set)^2+b*(Pso1-Psi1-P_set)+c).

[0053] Furthermore, in some embodiments, after determining that the inlet and outlet pressure difference of the secondary side pipeline 3 is not greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone, the following steps may be included:

[0054] Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline 3 is greater than or equal to the difference between the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side, and is less than or equal to the sum of the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side, that is, P_set-P_dead≤Pso1-Psi1≤P_set+P_dead;

[0055] If so, then control the first pump 4 to maintain the current speed, that is, Speed_1 = Speed_1;

[0056] Otherwise, the actual speed of the first pump 4 is controlled to increase.

[0057] Specifically, when the actual speed of the first pump 4 is controlled to increase, its actual speed...

[0058] Speed_1=Speed_1+ROUND(a*(Pso1-Psi1-P_set)^2+b*(Pso1-Psi1-P_set)+c).

[0059] In some optional embodiments, determining whether the pressure difference between the inlet and outlet of the secondary side pipeline 3 and the actual rotational speed of the second pump 5 meet the second preset condition may include:

[0060] Determine whether the inlet and outlet pressure difference of secondary side pipeline 3 is greater than the sum of the set point value of the secondary side inlet and outlet pressure difference and the set point value of the secondary side inlet and outlet pressure difference dead zone, that is, Pso1-Psi1>P_set+P_dead; where, before this determination step, the inlet and outlet pressures Pso1, Psi1, the set point value of the secondary side inlet and outlet pressure difference P_set, the dead zone value of the secondary side inlet and outlet pressure difference P_dead, and the minimum speed of the secondary side pump Speed_min of secondary side pipeline 3 can be collected first;

[0061] If so, it is determined whether the actual speed of the second pump 5 has been maintained at the minimum speed (i.e., Speed_2 = Speed_min) for a preset time and whether the differential pressure balance valve 61 is in the closed state. Before this determination step, the actual speed of the second pump 5 can be controlled to run in a decreasing trend, that is, it can be Speed_2 = Speed_2 - 1% of the rated speed. In this embodiment, the preset time is preferably set to 2 minutes. Of course, the preset time can also be adjusted according to the actual situation, which is not limited here.

[0062] If the pressure difference between the inlet and outlet of the secondary side pipeline 3 is not greater than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the dead zone of the pressure difference between the secondary side inlet and outlet, then the second pump 5 shall continue to operate until the pressure difference between the inlet and outlet of the secondary side pipeline 3 is greater than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the dead zone of the pressure difference between the secondary side inlet and outlet.

[0063] If the actual speed of the second pump 5 is maintained at the minimum speed for a preset time and the differential pressure balance valve 61 is closed, then the differential pressure balance valve 61 is opened and the second pump 5 is maintained at the minimum speed. Otherwise, the second pump 5 is kept running until the actual speed of the second pump 5 is maintained at the minimum speed for a preset time and the differential pressure balance valve 61 is closed.

[0064] Furthermore, based on the above technical solution, after determining that the inlet and outlet pressure difference of the secondary side pipeline 3 is not greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the dead zone of the secondary side inlet and outlet water pressure difference, the following steps may be included:

[0065] Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline 3 is greater than or equal to the difference between the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side, and is less than or equal to the sum of the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side, that is, P_set-P_dead≤Pso1-Psi1≤P_set+P_dead;

[0066] If so, then control the second pump 5 to maintain the current speed, that is, Speed_2 = Speed_2;

[0067] Otherwise, the actual speed of the second pump 5 is controlled to increase, and it is determined whether the actual speed of the second pump 5 is maintained at the maximum speed (i.e., the actual speed of the second pump 5 is Speed_2 = 100% of the rated speed) for a preset time, and whether the differential pressure balance valve 61 is in the closed state; wherein, controlling the actual speed of the second pump 5 to increase can be Speed_2 = Speed_2 + 1% of the rated speed; in this embodiment, the preset time is preferably set to 2 minutes, of course, the preset time can also be adjusted according to the actual situation, and there is no limitation here;

[0068] If the actual speed of the second pump 5 is maintained at the maximum speed for a preset time, and the differential pressure balancing valve 61 is in the closed state, then the first pump 4 is controlled to start and the second pump 5 is controlled to stop, and the differential pressure balancing valve 61 is controlled to remain in the closed state. At this time, the actual speed of the first pump 4 can be controlled to Speed_1 = 50% of the rated speed, and the process returns to step S1; otherwise, the second pump 5 is kept working until the inlet and outlet pressure difference of the secondary side pipeline 3 is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone.

[0069] In some alternative embodiments, after controlling the differential pressure balancing valve 61 to open and controlling the second pump 5 to maintain a minimum speed, the method may further include:

[0070] Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline 3 is less than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the dead zone of the pressure difference between the secondary side inlet and outlet (i.e., Pso1-Psi1<P_set+P_dead) has reached a preset time. In this embodiment, the preset time is preferably set to 2 minutes. Of course, the preset time can also be adjusted according to the actual situation, and no restriction is imposed here.

[0071] If so, the differential pressure balancing valve 61 is closed; otherwise, the differential pressure balancing valve 61 remains open, and the second pump 5 is controlled to maintain a minimum speed.

[0072] This invention can adaptively determine the operating status of the dual pumps and pressure balancing valve by detecting the actual operating changes of the internal parameters of the liquid cooling system. Fuzzy control or PID regulation can be used to control the speed of the secondary side dual pumps. When the pressure balancing valve is opened, the pressure of the secondary side inlet and outlet water can be controlled by the internal algorithm of the pressure balancing valve.

[0073] To prevent oscillations in the liquid cooling system, the maximum speed change rate of the first pump 4 and the second pump 5 is set at 10% / s, and the minimum is set at 1% / s. Adjustments can be made according to actual conditions.

[0074] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0075] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0076] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A control method for a liquid cooling system, characterized in that, The liquid cooling system includes: A heat exchanger (1) is connected to a primary side pipe (2) on one side and to a secondary side pipe (3) on the other side. The cooling medium in the secondary side pipe (3) exchanges heat with the cooling medium in the primary side pipe (2) through the heat exchanger (1). The secondary side pipeline (3) is equipped with a first pump (4) and a second pump (5) connected in parallel. The maximum flow rate of the first pump (4) is greater than the maximum flow rate of the second pump (5). Both the first pump (4) and the second pump (5) are connected to the secondary side pipeline (3). A bypass pipeline (6) is also connected to the secondary side pipeline (3). The bypass pipeline (6) is connected to the secondary side pipeline (3), and the bypass pipeline (6) is equipped with a differential pressure balancing valve (61). The differential pressure balancing valve (61) is connected in parallel with the first pump (4) and the second pump (5), so that the liquid cooling system forms at least three working modes. The at least three working modes include the working mode of the first pump (4), the working mode of the second pump (5), and the mixed working mode of the second pump (5) and the differential pressure balancing valve (61). The control methods include: controlling the first pump (4) to start and keeping the differential pressure balancing valve (61) closed; Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline (3) and the actual speed of the first pump (4) meet the first preset condition; If so, control the second pump (5) to start and control the first pump (4) to stop, while maintaining the differential pressure balance valve (61) in the closed state; otherwise, maintain the first pump (4) working until the first preset condition is met. Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline (3) and the actual speed of the second pump (5) meet the second preset condition; If so, control the differential pressure balance valve (61) to open and control the second pump (5) to maintain the minimum speed; otherwise, keep the second pump (5) working until the second preset condition is met. Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline (3) is less than the sum of the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side for a preset time. If so, then close the differential pressure balancing valve (61); otherwise, keep the differential pressure balancing valve (61) open and control the second pump (5) to maintain the minimum speed. The determination of whether the inlet and outlet pressure difference of the secondary side pipeline (3) and the actual speed of the first pump (4) meet the first preset condition includes: Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline (3) is greater than the sum of the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side; If so, determine whether the actual rotational speed of the first pump (4) has been maintained at the minimum rotational speed for a preset time; If the pressure difference between the inlet and outlet of the secondary side pipeline (3) is not greater than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the dead zone of the pressure difference between the secondary side inlet and outlet, then the first pump (4) will continue to operate until the pressure difference between the inlet and outlet of the secondary side pipeline (3) is greater than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the dead zone of the pressure difference between the secondary side inlet and outlet. If the actual speed of the first pump (4) is maintained at the minimum speed for a preset time, the second pump (5) is controlled to start and the first pump (4) is controlled to stop, while the differential pressure balance valve (61) is kept closed. Otherwise, the first pump (4) is kept working until the actual speed of the first pump (4) is maintained at the minimum speed for a preset time. The determination of whether the inlet and outlet pressure difference of the secondary side pipeline (3) and the actual speed of the second pump (5) meet the second preset condition includes: Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline (3) is greater than the sum of the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side; If so, determine whether the actual speed of the second pump (5) has been maintained at the minimum speed for a preset time and whether the differential pressure balance valve (61) is in the closed state; If the pressure difference between the inlet and outlet of the secondary side pipeline (3) is not greater than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the pressure difference dead zone of the secondary side inlet and outlet, then the second pump (5) will continue to operate until the pressure difference between the inlet and outlet of the secondary side pipeline (3) is greater than the sum of the set point value of the pressure difference between the secondary side inlet and outlet and the set point value of the pressure difference dead zone of the secondary side inlet and outlet. If the actual speed of the second pump (5) is maintained at the minimum speed for a preset time and the differential pressure balance valve (61) is closed, then the differential pressure balance valve (61) is controlled to open and the second pump (5) is controlled to maintain the minimum speed. Otherwise, the second pump (5) is kept working until the actual speed of the second pump (5) is maintained at the minimum speed for a preset time and the differential pressure balance valve (61) is closed.

2. The control method as described in claim 1, characterized in that: The first pump (4) is connected in series with a first solenoid valve (41), and the second pump (5) is connected in series with a second solenoid valve (51). The first solenoid valve (41) and the second solenoid valve (51) control the on / off state of the first pump (4) and the second pump (5). A primary side electric valve (21) is connected in series on the primary side pipeline (2). The primary side electric valve (21) is configured to control the flow rate of the cooling medium in the primary side pipeline (2) by adjusting its opening degree. At the same time, a primary side temperature sensor (22) and a primary side pressure sensor (23) are also provided on the primary side pipeline (2).

3. The control method as described in claim 1, characterized in that: A safety valve (31) is connected in series on the secondary side pipeline (3). The safety valve (31) is used to control the internal pressure of the liquid cooling system within a preset range. An expansion tank (32) and an exhaust valve (33) are connected in series on the secondary side pipeline (3). The expansion tank (32) is located between the heat exchanger (1) and the first pump (4), and the exhaust valve (33) is located at the highest point of the liquid cooling system. Meanwhile, the secondary side pipeline (3) is also equipped with an outlet water temperature sensor (34), an inlet water temperature sensor (35), an outlet water pressure sensor (36), an inlet water pressure sensor (37), a pump inlet pressure sensor (38), and a flow sensor (39).

4. The control method as described in claim 1, characterized in that, After determining that the inlet and outlet pressure difference of the secondary side pipeline (3) is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the dead zone of the secondary side inlet and outlet water pressure difference, the following is also included: The actual speed of the first pump (4) is controlled to decrease.

5. The control method as described in claim 1, characterized in that, After determining that the inlet and outlet pressure difference of the secondary side pipeline (3) is not greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the dead zone of the secondary side inlet and outlet water pressure difference, the following steps are included: Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline (3) is greater than or equal to the difference between the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side, and is less than or equal to the sum of the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side. If so, then control the first pump (4) to maintain the current speed. Otherwise, the actual speed of the first pump (4) is controlled to increase.

6. The control method as described in claim 1, characterized in that, After determining that the inlet and outlet pressure difference of the secondary side pipeline (3) is not greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the dead zone of the secondary side inlet and outlet water pressure difference, the following steps are included: Determine whether the pressure difference between the inlet and outlet of the secondary side pipeline (3) is greater than or equal to the difference between the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side, and is less than or equal to the sum of the set point value of the pressure difference between the inlet and outlet of the secondary side and the set point value of the dead zone of the pressure difference between the inlet and outlet of the secondary side. If so, control the second pump (5) to maintain the current speed; Otherwise, the actual speed of the second pump (5) is controlled to increase, and it is determined whether the actual speed of the second pump (5) is maintained at the maximum speed for a preset time, and whether the differential pressure balance valve (61) is closed. If the actual speed of the second pump (5) is maintained at the maximum speed for a preset time, and the differential pressure balancing valve (61) is in the closed state, then the first pump (4) is controlled to start and the second pump (5) is controlled to stop, and the differential pressure balancing valve (61) is controlled to remain in the closed state; otherwise, the second pump (5) is kept working until the inlet and outlet pressure difference of the secondary side pipeline (3) is greater than the sum of the set point value of the secondary side inlet and outlet water pressure difference and the set point value of the secondary side inlet and outlet water pressure difference dead zone.

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