A pump-driven two-phase loop air conditioning backplane cooling system for data centers

Abstract

The present invention discloses a pump-driven two-phase loop air conditioner back plate cooling system for a data center, including a working fluid pump driving part, a back plate evaporative cooling part and a gas-liquid separation heat exchange part, wherein the working fluid pump driving part includes a liquid storage tank and a working fluid pump; the back plate evaporative cooling part is a back plate evaporator; the gas-liquid separation heat exchange part includes a gas-liquid separator, a compressor-driven gas phase cooling sub-part and a liquid phase cooling sub-part; the working fluid pump can be arranged in parallel with a one-way valve, and the compressor can be arranged in parallel with a one-way valve. The present invention has high operational reliability and low cost; gas-liquid separation can be achieved through the gas-liquid separation part, and stable gas-liquid separation can be achieved under the condition of fluctuating dryness of the cooling working fluid through the self-adaptation of the working fluid liquid level height; and accurate condensation of the gas phase working fluid can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of air conditioning, and in particular to a pump-driven two-phase loop air conditioning back plate heat dissipation system for a data center. Background Art

[0002] In recent years, with the continuous progress and iteration of computing science and technology such as 5G, Internet of Things, artificial intelligence, and autonomous driving, the scale, quantity, technology, and industry of my country's data centers have maintained rapid growth. At the same time, the rapid development of data centers and the continuous expansion of their number and scale have also brought huge energy consumption. The energy consumption of traditional heat dissipation equipment in data centers is the largest energy consumption factor besides the energy consumption of IT equipment. Making full use of natural cold sources is currently one of the most effective means to reduce the heat dissipation energy consumption of data centers, and has attracted the attention of a large number of scholars and technicians. Among them, the heat pipe cooling system with good heat dissipation effect and simple structure is one of the research focuses. The heat pipe cooling system includes gravity separation heat pipe, liquid pump driven separation heat pipe, air pump driven separation heat pipe, capillary heat pipe and other forms. However, the heat pipe cooling system cannot work in the high temperature environment in summer, and the heat pipe cooling system must be combined with the air conditioning cooling system.

[0003] Invention patent ZL201610425330.4 proposes a composite computer room air conditioning system and its control method. The refrigeration unit and heat pipe unit of the system are coupled at the low-pressure liquid storage tank, and the valve switching is controlled according to the outdoor ambient temperature to respectively operate the refrigeration cycle, the composite cycle and the heat pipe cycle. Compared with this scheme, this scheme has the following disadvantages and shortcomings: 1. This scheme adopts an electric three-way valve to switch the operation mode, the system is complex, and the electric valve has the hidden danger of leakage during long-term operation. 2. The refrigeration unit and the heat pipe unit of this scheme cannot be redundant with each other: when the pump of the heat pipe unit fails, even if the compressor can work normally, the entire heat dissipation system cannot work. 3. This scheme does not propose how to achieve gas-liquid separation at the back plate evaporator outlet and dissipate heat to the gas circuit and liquid circuit separately, and the heat dissipation efficiency is low.

[0004] Invention patent ZL201910498291.4 proposes an air conditioning system with natural cooling and its control system. The solution includes indoor and outdoor modules. Compared with this solution, this solution has the following disadvantages and shortcomings: 1. The system operation mode is switched through the bypass valve of the compressor, the system is complex, and the electric valve has the risk of leakage in long-term operation, and the reliability is low. 2. The solution does not propose how to achieve gas-liquid separation at the back plate evaporator outlet and dissipate heat for the gas and liquid circuits respectively, and the heat dissipation efficiency is low.

[0005] Invention patent ZL201910497418.0 discloses a composite air-conditioning system for a data center and its control method. Compared with this solution, this solution has the following disadvantages and shortcomings: 1. This solution adopts a valve switching system operation mode, the system has many components and the switching is complicated, the electric valve has the hidden danger of leakage during long-term operation, and the reliability is low. 2. The refrigeration unit and the heat pipe unit of this solution cannot be redundant with each other: when the working fluid pump fails, even if the compressor can work normally, the entire cooling system cannot work. 3. The circuit of the working fluid pump in this solution cannot participate in condensation heat dissipation, and there is a separate heat pipe condensation circuit, which makes the system structure and piping complicated, and the long-term operation reliability cannot be guaranteed.

[0006] Invention patent ZL201610174000.2 relates to a heat pipe composite air conditioning system and its control method. Compared with this solution, this solution has the following disadvantages and shortcomings: the form of this solution is the same as the vapor compression cycle, and only the air pump heat pipe mode can be used, and the heat dissipation efficiency of the air pump heat pipe is much lower than that of the liquid pump heat pipe. Summary of the invention

[0007] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a pump-driven two-phase loop air conditioner back panel cooling system for a data center.

[0008] According to the technical solution provided in the embodiment of the present application, a pump-driven two-phase loop air-conditioning backplate cooling system for a data center is provided, which is provided with a working fluid pump driving part, a backplate evaporative cooling part and a gas-liquid separation heat exchange part, wherein the working fluid pump driving part includes a liquid storage tank, one or more working fluid pumps and a one-way valve, and the one-way valve and the working fluid pump are connected in parallel.

[0009] Gas-liquid separation heat exchange part: It includes a gas-liquid separator, a compressor-driven gas-phase heat sink part and a liquid-phase heat sink part. The gas-liquid separator can separate the gas-liquid two-phase working medium to be dissipated into a single gas and a single liquid phase and flow them into the compressor-driven gas-phase heat sink part and the liquid-phase heat sink part respectively. The compressor-driven gas-phase heat sink part condenses and dissipates the gas-phase working medium, and the liquid-phase heat sink part condenses and dissipates the liquid-phase working medium.

[0010] The compressor-driven gas phase heat dissipation sub-part includes one or more compressors, a gas phase condenser, an electronic expansion valve and a one-way valve, and the one-way valve is connected in parallel with the compressor; the liquid phase heat dissipation sub-part includes a regulating valve and a liquid phase cooler. The liquid phase cooler may not be installed depending on the heat dissipation conditions.

[0011] The liquid working fluid pump driving part, the back plate evaporation heat dissipation part and the gas-liquid separation heat exchange part are connected in series; the compressor drives the gas phase heat dissipation sub-part and the liquid phase heat dissipation sub-part in parallel. This allows the system to work in liquid pump heat pipe mode, air pump heat pipe mode, mixed mode and vapor compression refrigeration mode. Among them, the liquid pump heat pipe mode, air pump heat pipe mode and vapor compression refrigeration mode are redundant.

[0012] In summary, the beneficial effects of this application are:

[0013] 1. The system has high operational reliability and low cost: the compressor, a power component in the system, can be used as a backup for the working fluid pump. When the working fluid pump is damaged, the system can operate in a high-efficiency air pump heat pipe cooling mode or a vapor compression refrigeration mode, reducing the redundant cost of multiple working fluid pumps. The system mode switching can be completed only by starting and stopping the working fluid pump and the compressor, without the need to use various manual and electric valves, thus reducing the moving parts and control components of the system, improving system reliability, and reducing the cost of electric valves and control components.

[0014] 2. The system can achieve gas-liquid separation through the gas-liquid separation part, and achieve stable separation of gas and liquid under fluctuating conditions through self-adaptation of the working fluid liquid level height.

[0015] 3. Realize accurate condensation of gas phase working fluid, which can reduce the pipeline resistance of the cooling part by 80% and improve the efficiency of the cooling part by 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0017] Figure 1 It is a connection structure diagram of the overall device of the present invention;

[0018] Figure 2 This is a structural diagram of the device connection of the present invention without using a liquid phase cooler;

[0019] Figure 3 This is a structural diagram of the device connection of multiple refrigeration back plates working in coordination with each other according to the present invention.

[0020] Numbers in the figure: 1-liquid storage tank; 2-working fluid pump; 3-check valve; 4-back plate evaporator; 5-gas-liquid separator; 6-compressor; 7-check valve; 8-gas phase condenser; 9-electronic expansion valve; 10-valve; 11-check valve; 12-liquid phase cooler. DETAILED DESCRIPTION

[0021] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0022] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] like Figure 1 As shown, the working fluid pump 2 may be one or more, and the working fluid pump 2 may be arranged in parallel with the one-way valve 3. The inlet of the working fluid pump 2 is connected to the inlet of the one-way valve, and the outlet of the working fluid pump 2 is connected to the outlet of the one-way valve 3. When the working fluid pump is shut down or fails, the working fluid may automatically bypass the one-way valve 3 and flow into the back plate evaporator 5.

[0024] The compressor 6 may be one or more, and the compressor 6 may be arranged in parallel with the one-way valve 7. The air inlet of the compressor 6 is connected to the inlet of the one-way valve 7, and the exhaust port of the compressor 6 is connected to the outlet of the one-way valve 7. When the compressor stops, the gas phase working medium can automatically bypass the one-way valve 7 and flow into the gas phase condenser 8.

[0025] A valve 10 may be installed between the liquid phase cooler 12 and the one-way valve 11. The valve 10 may be a manual valve, an electronic expansion valve, an electric valve, etc. The valve 10 is used to set the initial pressure drop of the liquid phase pipeline. During the initial debugging of the system, the pressure drops of the gas phase and the liquid phase may be adjusted by the valve 10 and the electronic expansion valve 9, respectively, so that the gas-liquid separator 5 can meet the gas-liquid separation in the initial state.

[0026] like Figure 2 As shown, because the liquid phase outlet of the gas-liquid separator 5 is a pure liquid phase working medium, the liquid phase cooler 12 may not be installed, and the liquid phase outlet of the gas-liquid separator 5 is directly connected to the inlet of the single-phase valve 11.

[0027] The gas-liquid separator 5 is in a tall and thin form with an aspect ratio greater than 1. When the operating conditions change, the adaptive ability of the liquid level change of the working fluid in the gas-liquid separator is utilized to automatically achieve gas-liquid separation and pressure drop matching.

[0028] The refrigeration unit, the gas phase condenser 8 and the liquid phase cooler 12, can be equipped with auxiliary components commonly used in refrigeration systems such as oil separators, sight glasses, and dry filters according to needs; the oil separator is installed between the exhaust port of the compressor 6 and the gas phase condenser 8. The sight glass is installed between the outlet of the throttling device and the inlet of the refrigeration back plate evaporator 4, and the dry filter is installed between the outlet of the gas phase condenser 8 and the inlet of the throttling device. The sight glass can be installed in the gas phase area and the liquid phase area of ​​the working medium gas-liquid two-phase, respectively, and the dry filter can be installed at the outlet of the working medium pump 2.

[0029] The gas phase condenser 8 can be a common condenser such as a plate heat exchanger, a plate fin heat exchanger, a shell and tube heat exchanger, etc. The liquid phase cooler 12 can be a common cooler such as a plate heat exchanger, a plate fin heat exchanger, a shell and tube heat exchanger, etc. The cooling medium for the cold end of the gas phase condenser 8 and the liquid phase cooler can be a common cooling medium such as air, cooling water, antifreeze, working fluid, refrigeration oil, etc.

[0030] like Figure 3 As shown, the back plate evaporator 4 can be used to dissipate heat for one or more cabinets. When multiple back plate evaporators are used, a liquid separation device is provided at the inlet of each back plate evaporator. The back plate evaporator 4 can be a common evaporator such as a parallel flow heat exchanger and a fin tube heat exchanger.

[0031] In order to prevent cavitation in the working fluid pump, it is necessary to increase the subcooling of the liquid at the inlet of the liquid pump. This can be done by, but is not limited to, one of the following methods: 1. Based on the cavitation characteristics of the working fluid pump, the position of the liquid storage tank is higher than the working fluid pump; 2. A subcooler is installed between the outlet of the liquid storage tank and the working fluid pump; 3. The outlet of the single-phase valve 11 is directly connected to the outlet of the liquid storage tank 1 and the inlet of the working fluid pump 2 to increase the subcooling of the working fluid at the pump inlet.

[0032] The present invention controls the operation mode of the system according to the temperature of the current cooling medium and the system operation state. The system operation mode can be divided into a liquid pump driven heat dissipation mode, a compressor driven heat dissipation mode, a mixed heat dissipation mode and a vapor compression refrigeration mode. When the temperature of the cooling medium is higher than the temperature of the gas phase and the liquid phase working medium, only the compressor is turned on, and the system operates in the vapor compression refrigeration mode. When the temperature of the cooling medium is slightly lower than the temperature of the gas phase and the liquid phase working medium, the system turns on the compressor and the working medium pump at the same time, and the system operates in the mixed mode. When the temperature of the cooling medium is much lower than the temperature of the gas phase and the liquid phase working medium, only the working medium pump is turned on at this time, and the system operates in the liquid pump heat pipe heat dissipation mode. Further, when the working medium pump fails and the temperature of the cooling medium is much lower than the temperature of the gas phase and the liquid phase working medium, only the compressor is turned on, and the electronic expansion valve is fully opened, and the system operates in the gas pump heat dissipation mode. When the working medium pump fails and the temperature of the cooling medium is slightly lower than the temperature of the gas phase and the liquid phase working medium, only the compressor is turned on, and the system operates in the vapor compression refrigeration mode.

[0033] The gas phase working medium and liquid phase working medium separated by the gas-liquid separator 5 flow through the gas phase heat sink part and the liquid phase heat sink part respectively, ensuring that the working medium after heat dissipation by the gas phase condenser 8 and the liquid phase cooler 12 is in a supercooled state and has a certain required degree of supercooling after mixing. The installation height of the liquid storage tank 1 should be higher than the working medium pump 2 to further improve the degree of supercooling of the liquid working medium.

[0034] When the working fluid pump 2 is damaged or cannot meet the heat dissipation demand, the working fluid pump 2 does not work, and the gas phase heat dissipation sub-part and the liquid phase heat dissipation sub-part can be driven by the compressor to work in a separate cycle.

[0035] The working fluid pump 2 and the compressor drive the gas phase heat sink sub-part and the liquid phase heat sink sub-part to work in a cycle independently and can run in parallel, backing up each other and improving system reliability.

[0036] The tank body of the liquid storage tank adopts a vertical or horizontal single-layer or double-layer structure, and is filled with insulation materials according to user requirements. The inner tank is polished to Ra0.45μm, and the exterior is insulated with mirror panels or frosted panels. The top is opened with water inlet, reflux port, disinfection port, cleaning port, manhole and a 0.45μm air respirator.

[0037] The working fluid pump described in this patent refers to a refrigerant pump or a Freon pump or a refrigerant pump (refrigerant is a working fluid). Its function is to pump liquid refrigerant. The working fluid delivered by a water pump is water, and the working fluid delivered by a refrigerant pump is refrigerant.

[0038] A one-way valve is a valve that allows fluid to flow only along the inlet, but the medium at the outlet cannot flow back. It is commonly known as a one-way valve. A one-way valve is also called a check valve or a non-return valve. It is used in hydraulic systems to prevent oil from flowing in the opposite direction, or in pneumatic systems to prevent compressed air from flowing in the opposite direction. There are two types of one-way valves: straight-through and right-angle. Straight-through one-way valves are installed on the pipeline with threaded connections.

[0039] The back plate evaporator described in this patent is an air-cooled evaporator, which is a type of heat exchanger. The hot air exchanges heat with the liquid refrigerant, the hot air releases heat and cools down, and the liquid refrigerant absorbs heat and evaporates into a gas phase. Because the refrigerant has an evaporation process (a phase change process), it is called an evaporator. The installation position is on the back of the cabinet, so it is called a back plate evaporator.

[0040] The gas-liquid separator adopts the principle of centrifugal separation and wire mesh filtration to achieve liquid removal. It is mainly composed of cylinder, cyclone separator, high-efficiency foam breaking net, drain valve and other main components.

[0041] The compressor used in this patent is a driven fluid machine that lifts low-pressure gas to high-pressure gas, and is the heart of the refrigeration system. It inhales low-temperature, low-pressure refrigerant gas from the suction pipe, compresses it by driving the piston through the operation of the motor, and then discharges high-temperature, high-pressure refrigerant gas to the exhaust pipe, providing power for the refrigeration cycle. Thus, the refrigeration cycle of compression → condensation (heat release) → expansion → evaporation (heat absorption) is realized. Compressors are divided into piston compressors, screw compressors, centrifugal compressors, linear compressors, etc.

[0042] Gas condenser is gas cooling, and the heat exchange process is completed by sensible heat. At this time, the high-pressure heat exchanger is called a gas cooler. The heat exchange process is completed by sensible heat. At this time, the high-pressure heat exchanger is called a gas cooler. This is also the most popular circulation method in research. This not only avoids the excessively high temperature of the heat source under subcritical circulation conditions, which causes the system performance to decline, but also because of the special physical properties of the fluid under supercritical conditions, it has great advantages in flow and heat exchange.

[0043] The electronic expansion valve uses the electrical signal generated by the adjusted parameter to control the voltage or current applied to the expansion valve, thereby achieving the purpose of adjusting the liquid supply. The stepless variable capacity refrigeration system has a wide range of refrigeration liquid supply adjustment and requires a fast adjustment response. Traditional throttling devices (such as thermal expansion valves) are difficult to perform well, but electronic expansion valves can meet the requirements well.

[0044] The condenser is a component of the refrigeration system and a type of heat exchanger. It can convert gas or steam into liquid and transfer the heat in the pipe to the air near the pipe in a very fast way. The working process of the condenser is an exothermic process, so the condenser temperature is relatively high. Power plants use many condensers to condense the steam discharged from the turbine. Condensers are used in refrigeration plants to condense refrigeration vapors such as ammonia and Freon. Condensers are used in the petrochemical industry to condense hydrocarbons and other chemical vapors. In the distillation process, the device that converts vapor into liquid is also called a condenser. All condensers operate by taking away the heat of gas or vapor.

[0045] The liquid phase cooler described in this patent is a liquid subcooling device, that is, a subcooler is added after the condenser of the refrigerator system to cool the refrigerant liquid before the throttling mechanism to a temperature lower than the condensation temperature, which is called liquid subcooling. In the subcooler, the temperature drop of the refrigerant liquid is called the subcooling degree, and its value depends on the condensation temperature and the temperature of the cooling medium.

[0046] Condensers and coolers are both heat exchangers. They are used to cool the refrigerant, but the cooling objects and physical processes are different.

[0047] There is a phase change process in the gas phase condenser (the gas phase refrigerant releases heat and condenses into liquid phase refrigerant)

[0048] There is no phase change process in the liquid phase cooler (liquid phase refrigerant releases heat or remains in liquid phase).

[0049] Cooling the gas and liquid phases separately is more efficient than cooling the two phases together.

[0050] The above description is only an explanation of the preferred embodiments of the present application and the technical principles and other schemes used. At the same time, the scope of the invention involved in the present application is not limited to the technical scheme formed by a specific combination of the above technical features, but also should cover other technical schemes formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) by each other to form a technical scheme.

Claims

1. A pump-driven two-phase loop air conditioner backplane cooling system for a data center, characterized by: It includes the working fluid pump drive part, the back plate evaporation heat dissipation part and the gas-liquid separation heat exchange part. The working fluid pump driving part comprises a liquid storage tank (1) and a working fluid pump (2); The back plate evaporation heat dissipation part is a back plate evaporator (4); The gas-liquid separation heat exchange part comprises a gas-liquid separator (5), a compressor driven gas phase heat dissipation sub-part and a liquid phase heat dissipation sub-part; The compressor-driven gas phase heat dissipation sub-part includes a compressor (6), a gas phase condenser (8) and an electronic expansion valve (9), and the liquid phase heat dissipation sub-part includes a one-way valve (11) and a liquid phase cooler (12); The outlet of the liquid storage tank (1) is connected to the inlet of the working fluid pump (2), the outlet of the working fluid pump (2) is connected to the inlet of the back plate evaporator (4), and the outlet of the back plate evaporator (4) is connected to the inlet of the gas-liquid separator (5); The gas-liquid separator (5) has a liquid phase outlet and a gas phase outlet, wherein the liquid phase outlet of the gas-liquid separator (5) is connected to the inlet of the liquid phase cooler (12), and the outlet of the liquid phase cooler (12) is connected to the inlet of the one-way valve (11); the gas phase outlet of the gas-liquid separator (5) is connected to the air intake of the compressor (6), and the air outlet of the compressor (6) is connected to the inlet of the gas phase condenser (8), and the outlet of the gas phase condenser (8) is connected to the inlet of the electronic expansion valve (9), and the outlet of the electronic expansion valve (9) is connected to the outlet of the one-way valve (11) and together connected to the inlet of the liquid storage tank (1); The working fluid pump (2) is arranged in parallel with the one-way valve, and the compressor (6) is arranged in parallel with the one-way valve; The liquid storage tank (1) is installed higher than the working fluid pump (2); The gas phase heat sink part and the liquid phase heat sink part driven by the compressor can work in a cycle independently; The gas-liquid separator (5) is designed with a length-to-diameter ratio greater than 1.

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