Heat recovery system suitable for direct expansion type air conditioner data center and control method of heat recovery system

Abstract

The invention provides a heat recovery system suitable for a direct expansion type air conditioner data center and a control method thereof.The heat recovery system suitable for the direct expansion type air conditioner data center comprises a double-pipe heat exchanger, and an inner pipe and an outer pipe are arranged in the double-pipe heat exchanger; the inner pipe is connected with a heat dissipation loop, and the outer pipe is connected with a heat recovery loop. A liquid storage tank, a second switch valve, a fluorine pump, an expansion valve, an evaporator, a first switch valve, a compressor and a second switch valve are sequentially connected to the heat dissipation loop, a first branch is connected to the fluorine pump in parallel, and a second branch is connected to the first switch valve and the compressor in parallel; the heat recovery loop is connected with a first water pump and a water source heat pump, and the water source heat pump is connected with a heat load loop; the thermal load loop is connected with a second water pump; according to the invention, the condenser of the small and medium-sized data center air-cooled refrigeration system is changed into the double-pipe heat exchanger, so that the problem of investment increase caused by addition of a heat recovery condenser or an independent heat recovery system is solved, and the problem of energy consumption increase caused by resistance increase of a series system is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of heating, ventilation and air conditioning, and particularly relates to a heat recovery system applicable to a direct expansion air-conditioning data center and a control method thereof. Background Art

[0002] With the booming development of the digital economy, the data center, as the foundation of the data economy, has entered a rapid development stage. Due to the large power density of the data center, the rapid growth of the data center scale has brought huge energy-saving pressure to the industry. The data center has a high load density and continuous operation, and its power consumption is ultimately converted into a large amount of waste heat. Therefore, the waste heat recovery technology of the data center has attracted the attention of the industry. At present, the ways of using waste heat in the data center include absorption refrigeration, organic Rankine cycle power generation, seawater purification, district heating and building heating, etc. Among them, the use of waste heat for district heating and building heating has good energy-saving, environmental and economic benefits, and is currently the most potential and main utilization method.

[0003] At present, the waste heat recovery system of the data center is often combined with the water-cooled refrigeration system of large data centers, and it is rarely possible to directly recover heat in the refrigerant system of small and medium-sized data centers. On the one hand, large data centers are often far from cities, and their own heating loads are extremely small. It is necessary to invest in long-distance transmission pipelines to supply heat to heating users. On the other hand, small and medium-sized data centers use air-cooled refrigerant refrigeration systems, and the existing technology for recovering heat from air-conditioning water is difficult to be directly applied in the refrigerant system.

[0004] For the heat recovery of small and medium-sized data centers, the current measures are to set heat recovery coils in the hot channels of small and medium-sized data centers, and directly recover the heat of the data center through a separate heat recovery system independent of the refrigeration system; develop a small refrigeration system with multiple condensers, and recover the heat of the data center in the newly added condenser under the heat recovery condition; adopt a double-coil system, use the cooling tower for natural cooling in winter, and the heat recovery system recovers heat from the cooling water of the data center.

[0005] However, these methods still have some deficiencies:

[0006] 1) High investment. Separately setting up a heat recovery system independent of the refrigeration system, custom-developing a refrigeration system with multiple condensers, and a double-coil system will all increase the system investment;

[0007] 2) Low energy efficiency. If parallel systems or components are added, one for refrigeration and the other for heat recovery, it is very difficult to achieve seamless switching control between the two systems or components. There may be a situation where the heat in the data center is dissipated into the atmosphere by the refrigeration system, resulting in a low heat recovery rate. If series systems or components are added, it will increase the system resistance and the energy consumption of pumps or compressors. When controlling the system, the energy consumption of the data center cooling system is mainly considered, and the energy consumption of the data center cooling and heating systems is not considered as a whole.

[0008] 3) Risk of thermal downtime. Similarly, the control of the above two parallel systems or components is complex and cannot be seamlessly connected. There may be a situation where the heat recovery component or system cannot meet the refrigeration demand, while the refrigeration component or system is not started, resulting in an increase in the temperature of the computer room and a risk of downtime.

[0009] Therefore, it is necessary to design a heat recovery system and its control method for a direct expansion air-conditioning data center that can reduce investment costs, improve energy utilization efficiency, and reduce the risk of thermal downtime to solve the current technical problems. Summary of the Invention

[0010] In view of the deficiencies in the prior art, the present invention provides a heat recovery system and its control method for a direct expansion air-conditioning data center that can reduce investment costs, improve energy utilization efficiency, and reduce the risk of thermal downtime.

[0011] The technical solution of the present invention is as follows: A heat recovery system applicable to a direct expansion air-conditioning data center includes a double-pipe heat exchanger, and the double-pipe heat exchanger has an inner pipe and an outer pipe;

[0012] A heat dissipation circuit is connected to the inner pipe, and a heat recovery circuit is connected to the outer pipe;

[0013] A liquid storage tank, a second switching valve, a fluorine pump, an expansion valve, an evaporator, a first switching valve, and a compressor are sequentially connected to the heat dissipation circuit. A first branch is connected in parallel to the second switching valve and the fluorine pump. A second branch is connected in parallel to the first switching valve and the compressor;

[0014] A first water pump and a water source heat pump are connected to the heat recovery circuit, and a heat load circuit is connected to the water source heat pump;

[0015] A second water pump is connected to the heat load circuit.

[0016] Further, a third check valve is connected to the output end of the fluorine pump. The third check valve, the fluorine pump, and the second switching valve are connected in series and then connected in parallel to the first branch;

[0017] A first check valve is connected to the output end of the compressor. The first check valve, the compressor, and the first switching valve are connected in series and then connected in parallel to the second branch;

[0018] Further, a fourth check valve is connected to the first branch, and a second check valve is connected to the second branch.

[0019] Further, heat exchange fins are arranged on the outer side of the outer pipe.

[0020] Further, the shell-and-tube heat exchanger and the evaporator are both equipped with variable-frequency cooling fans, and the compressor and the fluorine pump are both driven by variable-frequency motors.

[0021] A control method for a heat recovery system applicable to a direct expansion air-conditioning data center includes the following steps:

[0022] Adopt the heat recovery system applicable to the direct expansion air-conditioning data center as described in any one of the above;

[0023] When there is no heat load demand, the system operates in a non-heat recovery mode;

[0024] When the condensation heat of the data center cannot be fully utilized, the system operates in a partial heat recovery mode;

[0025] When the condensation heat of the data center is fully utilized, the system operates in a full heat recovery mode;

[0026] In the non-heat recovery mode, heat exchange does not occur between the heat recovery loop and the heat load loop. When the outdoor air dry-bulb temperature T o satisfies T o > T 2 , the heat dissipation loop operates in the compressor refrigeration mode; when the outdoor air dry-bulb temperature T o satisfies T 1 ≤ T o ≤ T 2 , the heat dissipation loop operates in the combined operation mode of the compressor and the fluorine pump; when the outdoor air dry-bulb temperature T o satisfies T o < T 1 , the heat dissipation loop operates in the fluorine pump natural cooling mode;

[0027] In the partial heat recovery mode, heat exchange occurs between the heat recovery loop and the heat load loop. When the outdoor air dry-bulb temperature T o satisfies T o ≥ T 3 , the heat dissipation loop operates in the compressor refrigeration mode, and heat exchange occurs between the heat recovery loop and the heat load loop; when the outdoor air dry-bulb temperature T o satisfies T o < T 3 , the heat dissipation loop operates in the fluorine pump natural cooling mode;

[0028] In the full heat recovery mode, heat exchange occurs between the heat recovery circuit and the heat load circuit, and the heat dissipation circuit operates in the natural cooling mode of the fluorine pump.

[0029] Further, in the compression refrigeration mode, the fluorine pump stops running, the compressor runs, the second switching valve closes, and the first switching valve opens.

[0030] Further, in the combined operation mode of the compressor and the fluorine pump, the compressor and the fluorine pump run, and the second switching valve and the first switching valve open.

[0031] Further, in the natural cooling mode of the fluorine pump, the compressor stops running, the fluorine pump runs, the second switching valve opens, and the first switching valve closes.

[0032] Further, when heat exchange occurs between the heat recovery circuit and the heat load circuit, the first water pump, the water source heat pump, and the second water pump run; when heat exchange does not occur between the heat recovery circuit and the heat load circuit, the first water pump, the water source heat pump, and the second water pump stop running.

[0033] Further, the first water pump, the second water pump, the water source heat pump, the compressor, the fluorine pump, the shell-and-tube heat exchanger, and the variable-frequency cooling fan in the evaporator all adopt variable-frequency control.

[0034] Advantages of the present invention:

[0035] (1) In the present invention, by changing the condenser of the air-cooled refrigeration system of a medium and small data center into a shell-and-tube heat exchanger, the problems of increased investment caused by adding a heat recovery condenser or a separate heat recovery system are solved, and the problem of increased energy consumption caused by increased resistance in a series system is solved;

[0036] (2) By combining the shell-and-tube heat exchanger to improve the control of the system, there is no need to switch the system or components, and problems such as complex control system, low energy utilization efficiency, and heat downtime risk are solved;

[0037] (3) By setting a fluorine pump in the system, the compressor 2 does not need to run during heat recovery, further improving the operation efficiency and reliability of the system. Description of the Drawings

[0038] Figure 1 It is a schematic structural diagram of the heat recovery system applicable to a direct expansion air-conditioning data center in the present invention. Detailed Embodiments

[0039] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and in no way limits the present invention and its application or use. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present invention thorough and complete, and to fully convey the scope of the present invention to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, the composition of materials, numerical expressions and values set forth in these embodiments should be construed as merely exemplary and not as limitations.

[0040] The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different parts. Words such as "comprising" or "including" mean that the elements before the word cover the elements listed after the word, and do not exclude the possibility of also covering other elements. "Upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0041] As Figure 1 shown, a heat recovery system applicable to a direct expansion air-conditioning data center includes a shell-and-tube heat exchanger 1, and the shell-and-tube heat exchanger 1 has an inner tube 12 and an outer tube 13; a heat dissipation circuit is connected to the inner tube 12, and a heat recovery circuit is connected to the outer tube 13; a liquid storage tank 6, a second switching valve 51, a fluorine pump 5, an expansion valve 4, an evaporator 3, a first switching valve 21, and a compressor 2 are sequentially connected to the heat dissipation circuit, and a first branch is connected in parallel to the second switching valve 21 and the fluorine pump 5, and a second branch is connected in parallel to the first switching valve 21 and the compressor 2; a first water pump 7 and a water source heat pump 8 are connected to the heat recovery circuit, and a heat load circuit is connected to the water source heat pump 7; a second water pump 9 is connected to the heat load circuit; in this embodiment, by changing the condenser of the air-cooled refrigeration system of a small and medium-sized data center to a shell-and-tube heat exchanger 1, the problem of increased investment caused by adding a heat recovery condenser or a separate heat recovery system is solved, and the problem of increased energy consumption caused by increased resistance in a series system is solved; by combining the shell-and-tube heat exchanger 1 to perform perfect control on the system, there is no need to switch the system or components, and problems such as complex control system, low energy utilization efficiency, and risk of thermal shutdown are solved; by providing a fluorine pump 5 in the system, the compressor 2 does not need to operate during heat recovery, further improving the operating efficiency and reliability of the system.

[0042] In some embodiments, a third check valve 52 is connected to the output end of the fluorine pump 5. The third check valve 52, the fluorine pump 5, and the second switching valve 51 are connected in series and then in parallel with the first branch; a first check valve 22 is connected to the output end of the compressor 2. The first check valve 22, the compressor 2, and the first switching valve 21 are connected in series and then in parallel with the second branch; a fourth check valve 53 is connected to the first branch, and a second check valve 23 is connected to the second branch; the first check valve 22, the second check valve 23, the third check valve 52, and the fourth check valve 53 are used to prevent the fluid in the corresponding circuit from flowing back, protecting the fluorine pump 5 and the compressor 2, and at the same time ensuring the stable operation of the system.

[0043] In some embodiments, heat exchange fins 14 are provided on the outer side of the outer tube 13. Through the heat exchange fins 14, the heat exchange area between the outer tube 13 and the external air can be increased, and the heat exchange efficiency can be improved.

[0044] In some embodiments, the shell-and-tube heat exchanger 1 and the evaporator 3 both have variable-frequency cooling fans 11. By adjusting the operating frequency of the variable-frequency cooling fan 11 of the shell-and-tube heat exchanger 1, the refrigerant condensation pressure in the shell-and-tube heat exchanger 1 is adjusted to minimize the total power consumption of the refrigeration and heating system; the compressor 2 and the fluorine pump 5 are both driven by variable-frequency motors, and the controller adjusts the operating frequencies of the compressor 2 and the fluorine pump 5 to adjust the system refrigeration capacity in the corresponding mode.

[0045] In some embodiments, a control method for a heat recovery system applicable to a direct expansion air-conditioning data center is disclosed, including the following steps:

[0046] Adopt the heat recovery system applicable to the direct expansion air-conditioning data center as described in any one of claims 1 to 4;

[0047] When there is no heat load demand, the system operates in the no heat recovery mode;

[0048] When the condensation heat of the data center cannot be fully utilized, the system operates in the partial heat recovery mode;

[0049] When the condensation heat of the data center is fully utilized, the system operates in the full heat recovery mode;

[0050] In the no heat recovery mode, no heat exchange occurs between the heat recovery circuit and the heat load circuit. When the outdoor air dry-bulb temperature T o satisfies T o > T 2 , the heat dissipation circuit operates in the compressor refrigeration mode; when the outdoor air dry-bulb temperature T o satisfies T 1 ≤T o ≤T 2When the outdoor air dry-bulb temperature T o satisfies T o <T 1 the heat dissipation circuit operates in the combined operation mode of the compressor and the fluorine pump; when the outdoor air dry-bulb temperature T 1 <T 2 ;

[0051] In the partial heat recovery mode, heat exchange occurs between the heat recovery circuit and the heat load circuit. When the outdoor air dry-bulb temperature T o satisfies T o ≥T 3 the heat dissipation circuit operates in the compression refrigeration mode, and heat exchange occurs between the heat recovery circuit and the heat load circuit; when the outdoor air dry-bulb temperature T o satisfies T o <T 3 the heat dissipation circuit operates in the natural cooling mode of the fluorine pump;

[0052] In the full heat recovery mode, heat exchange occurs between the heat recovery circuit and the heat load circuit, and the heat dissipation circuit operates in the natural cooling mode of the fluorine pump.

[0053] In the above embodiment, as a specific implementation manner of the compression refrigeration mode, in the compression refrigeration mode, the fluorine pump 5 stops running, the compressor 2 runs, the second switching valve 51 is closed, and the first switching valve 21 is opened; the compressor 2 absorbs the superheated refrigerant vapor discharged from the evaporator 3, and after compression, outputs the high-temperature and high-pressure superheated refrigerant vapor into the shell-and-tube heat exchanger 1; in the non-heat recovery mode, the variable-frequency cooling fan 11 of the shell-and-tube heat exchanger 1 runs to discharge the heat of the high-temperature refrigerant vapor into the air; in the partial heat recovery mode, the first water pump 7 in the heat recovery circuit starts to extract the required heat from the shell-and-tube heat exchanger 1, and at the same time, the variable-frequency cooling fan 11 of the shell-and-tube heat exchanger 1 runs to discharge the remaining heat of the refrigerant in the shell-and-tube heat exchanger 1 into the air; in the full heat recovery mode, the first water pump 7 in the heat recovery circuit starts to extract the heat from the shell-and-tube heat exchanger 1; the refrigerant vapor is cooled to a high-pressure refrigerant liquid in the space between the outer tube 13 and the inner tube 12 of the shell-and-tube heat exchanger 1, the refrigerant liquid flows into the liquid storage tank 6 under the drive of pressure, and then passes through the expansion valve 4 to reduce the pressure, and finally enters the evaporator 3 to absorb the heat of the return air of the data center and becomes refrigerant superheated vapor, completing a cycle; further, the controller adjusts the system refrigeration capacity by adjusting the operating frequency of the compressor 2; by adjusting the operating frequency of the variable-frequency cooling fan 11 of the shell-and-tube heat exchanger 1, the refrigerant condensation pressure in the shell-and-tube heat exchanger 1 is adjusted, and the refrigerant evaporation pressure in the evaporator 3 is controlled by the opening degree of the expansion valve 4.

[0054] In the above embodiment, as a specific implementation manner of the combined operation mode of the compressor and the fluorine pump, in the combined operation mode of the compressor and the fluorine pump, the compressor 2 and the fluorine pump 5 operate, and the second switching valve 51 and the first switching valve 21 are opened; the compressor 2 absorbs the superheated refrigerant vapor discharged from the evaporator 3, and after compression, outputs high-temperature and high-pressure superheated refrigerant vapor into the shell-and-tube heat exchanger 1; in the non-heat recovery mode, the variable-frequency cooling fan 11 of the shell-and-tube heat exchanger 1 operates to discharge the heat of the high-temperature refrigerant vapor into the air; in the partial heat recovery mode, the first water pump 7 in the heat recovery loop starts to extract the required heat from the shell-and-tube heat exchanger 1, and at the same time, the variable-frequency cooling fan 11 of the shell-and-tube heat exchanger 1 operates to discharge the remaining heat of the refrigerant in the shell-and-tube heat exchanger 1 that needs to be discharged into the air; in the full heat recovery mode, the first water pump 7 in the heat recovery loop starts to extract the heat from the shell-and-tube heat exchanger 1; the refrigerant vapor is cooled into high-pressure refrigerant liquid in the space between the outer tube 13 and the inner tube 12 of the shell-and-tube heat exchanger 1, and the refrigerant liquid flows into the liquid storage tank 6 under the drive of pressure, then is transported by the fluorine pump 5, then is depressurized by the expansion valve 4, and finally enters the evaporator 3 to absorb the heat of the return air in the data center and becomes refrigerant superheated vapor, completing a cycle; further, the controller adjusts the system refrigerating capacity by coordinately controlling the operating frequencies of the compressor 2 and the fluorine pump 4; utilizes the fluorine pump 4 to assist the evaporator in liquid inlet under the low pressure ratio condition to save the operating energy consumption; adjusts the refrigerant condensation pressure in the shell-and-tube heat exchanger 1 by adjusting the operating frequency of the variable-frequency cooling fan 11 of the shell-and-tube heat exchanger 1, and controls the refrigerant evaporation pressure in the evaporator 3 by the opening degree of the expansion valve 4.

[0055] In the above embodiment, in the natural cooling mode of the fluorine pump 5, the compressor stops operating, the fluorine pump 5 operates, the second switching valve 51 is opened, and the first switching valve 21 is closed; further, the controller adjusts the system refrigerating capacity by coordinately controlling the operating frequencies of the compressor 2 and the fluorine pump 4; utilizes the fluorine pump 4 to assist the evaporator 3 in liquid inlet under the low pressure ratio condition to save the operating energy consumption; adjusts the refrigerant condensation pressure in the shell-and-tube heat exchanger 1 by adjusting the operating frequency of the variable-frequency cooling fan 11 of the shell-and-tube heat exchanger 1, and controls the refrigerant evaporation pressure in the evaporator 3 by the opening degree of the expansion valve 4.

[0056] In the above embodiments, when heat exchange occurs between the heat recovery circuit and the heat load circuit, the first water pump 7, the water source heat pump 8, and the second water pump 9 operate. The water flow driven by the frequency-variable water pump 7 flows through the inner pipe 12 of the shell-and-tube heat exchanger 1, absorbs heat and its temperature rises, and is sent to the water source heat pump 8. The water source heat pump 8 operates with frequency conversion to further raise the heat temperature to the temperature required by the user. The user-side water pump 9 operates with frequency conversion to meet the user's heat demand. Further, a relationship table between the supply air temperature, refrigerating capacity, condensing pressure, and power consumption of the heat dissipation circuit provided by the equipment manufacturer is input into the controller in advance; at the same time, the relationship between the evaporator outlet water temperature, condenser outlet water temperature, heating capacity, and power consumption provided by the manufacturer of the water source heat pump 8 is input. The controller adjusts the operating frequency of the compressor 2 to adjust the system refrigerating capacity; by adjusting the operating frequency of the frequency-variable cooling fan 11 of the shell-and-tube heat exchanger 1, the refrigerant condensing pressure in the shell-and-tube heat exchanger 1 is adjusted to minimize the total power consumption of the heat dissipation circuit, the heat recovery circuit, and the heat load circuit; the evaporator supply air temperature of the heat dissipation circuit, the refrigerating capacity of the heat dissipation circuit, the heating capacity of the water source heat pump, the evaporator outlet water temperature of the water source heat pump, the condenser outlet water temperature of the water source heat pump, etc. are input to the controller. Assuming that the evaporator outlet water temperature of the water source heat pump is higher than the condensing temperature of the refrigeration system by ΔT 1 , the controller gives the condensing pressure of the refrigeration system that minimizes the total power consumption of the refrigeration and heating systems in real time; the evaporation pressure of the refrigerant in the evaporator 3 is controlled by the opening degree of the expansion valve 4; by controlling the operating frequency of the water pump 7, the water temperature difference passing through the evaporator of the heat pump 8 is made constant; by adjusting the operating frequency of the heat pump 8, the heating capacity of the heat pump 8 is adjusted to meet the user's needs; by maintaining the constant pressure difference at the user end, the operating frequency of the water pump 9 is adjusted; when no heat exchange occurs between the heat recovery circuit and the heat load circuit, the first water pump 7, the water source heat pump 8, and the second water pump 9 stop running.

[0057] In the above embodiments, the first water pump 7, the second water pump 9, the water source heat pump 8, the compressor 2, the fluorine pump 5, the shell-and-tube heat exchanger 1, and the frequency-variable cooling fan 11 in the evaporator 3 all adopt frequency conversion control.

[0058] In some embodiments, in the no-heat-recovery mode, no heat exchange occurs between the heat recovery circuit and the heat load circuit, T 1 = 15 °C, T 2 = 25 °C, T 3 = 15 °C. When the outdoor air dry-bulb temperature T o satisfies T o > 25 °C, the heat dissipation circuit operates in the compressor refrigeration mode; when the outdoor air dry-bulb temperature T o satisfies 15 °C ≤ T o ≤ 25 °C, the heat dissipation circuit operates in the combined operation mode of the compressor and the fluorine pump; when the outdoor air dry-bulb temperature T o satisfies T oWhen the temperature is below 15°C, the heat dissipation circuit operates in the natural cooling mode of the fluorine pump. In some embodiments, in the partial heat recovery mode, heat exchange occurs between the heat recovery circuit and the heat load circuit. When the outdoor air dry-bulb temperature T o satisfies T o ≥15°C, the heat dissipation circuit operates in the compression refrigeration mode, and heat exchange occurs between the heat recovery circuit and the heat load circuit; when the outdoor air dry-bulb temperature T o satisfies T o <15°C, the heat dissipation circuit operates in the natural cooling mode of the fluorine pump.

[0059] So far, the embodiments of the present invention have been described in detail. In order to avoid obscuring the concept of the present invention, some details well known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0060] The above-described embodiments only represent some implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A heat recovery system suitable for a direct expansion air conditioning data center, characterized in that: It comprises a shell and tube heat exchanger, wherein the shell and tube heat exchanger has an inner tube and an outer tube; The inner tube is connected to a heat dissipation circuit, and the outer tube is connected to a heat recovery circuit; The heat dissipation circuit is connected in sequence with a liquid storage tank, a second switch valve, a fluorine pump, an expansion valve, an evaporator, a first switch valve, and a compressor; the second switch valve and the fluorine pump are connected in parallel with a first branch; the first switch valve and the compressor are connected in parallel with a second branch; The heat recovery circuit is connected to a first water pump and a water source heat pump, and the water source heat pump is connected to a heat load circuit; The heat load circuit is connected with a second water pump.

2. The heat recovery system for a direct expansion air conditioning data center according to claim 1, characterized in that: The output end of the fluorine pump is connected to a third check valve, and the third check valve, the fluorine pump, and the second switch valve are connected in series and in parallel with the first branch; The output end of the compressor is connected to a first check valve, and the first check valve, the compressor, and the first switch valve are connected in series and in parallel with the second branch; The first branch is connected to a fourth check valve, and the second branch is connected to a second check valve.

3. The heat recovery system for a direct expansion air conditioning data center according to claim 1, characterized in that: Heat exchange fins are arranged on the outer side of the outer tube.

4. The heat recovery system for a direct expansion air conditioning data center according to claim 1, characterized in that: The shell and tube heat exchanger and the evaporator are both provided with variable frequency cooling fans, and the compressor and the fluorine pump are both driven by variable frequency motors.

5. A control method for a heat recovery system of a direct expansion air conditioning data center, characterized in that: The following steps are involved: A heat recovery system suitable for a direct expansion air conditioning data center as described in any one of claims 1 to 4 is used; When there is no heat load demand, the system operates in a no-heat-recovery mode; When the condensation heat of the data center cannot be fully utilized, the system operates in partial heat recovery mode; When the condensation heat of the data center is fully utilized, the system operates in full heat recovery mode; In the non-heat recovery mode, there is no heat exchange between the heat recovery loop and the heat load loop. When the outdoor air dry bulb temperature T o Meet T o >T2, the heat dissipation circuit operates in the compressor cooling mode; when the outdoor air dry bulb temperature T o Satisfy T1≤T o ≤T2, the heat dissipation circuit operates in the combined operation mode of the compressor and the fluorine pump; when the outdoor air dry bulb temperature T o Meet T o When <T1, the heat dissipation circuit operates in the natural cooling mode of the fluorine pump; In the partial heat recovery mode, heat is exchanged between the heat recovery circuit and the heat load circuit. When the outdoor air dry bulb temperature T o Meet T o ≥T3, the heat dissipation circuit operates in the compressor cooling mode, and the heat recovery circuit exchanges heat with the heat load circuit; when the outdoor air dry bulb temperature T o Meet T o When <T3, the heat dissipation circuit operates in the natural cooling mode of the fluorine pump; In the full heat recovery mode, heat is exchanged between the heat recovery circuit and the heat load circuit, and the heat dissipation circuit operates in the fluorine pump natural cooling mode.

6. The control method for a heat recovery system for a direct expansion air conditioning data center according to claim 5, characterized in that: In the compressor refrigeration mode, the fluorine pump stops running, the compressor runs, the second switch valve is closed, and the first switch valve is opened.

7. The control method for a heat recovery system for a direct expansion air conditioning data center according to claim 5, characterized in that: In the combined operation mode of the compressor and the fluorine pump, the compressor and the fluorine pump are in operation, and the second switch valve and the first switch valve are opened.

8. The control method for a heat recovery system for a direct expansion air conditioning data center according to claim 5, characterized in that: In the natural cooling mode of the fluorine pump, the compressor stops running, the fluorine pump runs, the second switch valve is opened, and the first switch valve is closed.

9. The control method for a heat recovery system for a direct expansion air conditioning data center according to claim 5, characterized in that: When the heat recovery circuit and the heat load circuit are in heat exchange state, the first water pump, the water source heat pump and the second water pump are in operation; when the heat recovery circuit and the heat load circuit are not in heat exchange state, the first water pump, the water source heat pump and the second water pump are stopped.

10. The control method of the heat recovery system applicable to the direct expansion air conditioning data center according to claim 5, characterized in that: The first water pump, the second water pump, the water source heat pump, the compressor, the fluorine pump, the shell and tube heat exchanger and the variable frequency cooling fan in the evaporator are all controlled by variable frequency.

Images