Magnetic suspension centrifugal water chiller based on thermosyphon cooling and control method

Abstract

The present application relates to a magnetic suspension centrifugal water chiller based on thermosyphon cooling and a control method, in the present application, the refrigerant evaporates in turn through the evaporator, is compressed by the magnetic suspension refrigeration compressor, is condensed by the evaporative condenser, and then flows into the thermosyphon tank from the evaporative condenser, when the liquid refrigerant in the thermosyphon tank exceeds the set liquid level, the liquid refrigerant flows through the liquid accumulator, the first expansion valve and the evaporator in turn, and circulates reciprocally to complete the main refrigeration cycle of the magnetic suspension centrifugal water chiller. The first cooling channel is arranged for the magnetic suspension refrigeration compressor, the no-power dissipation of the magnetic suspension refrigeration compressor is realized by using the thermosyphon effect of the refrigerant, compared with the conventional heat dissipation scheme, the refrigeration capacity loss of the main refrigeration cycle in the water chiller is reduced, the energy efficiency of the magnetic suspension water chiller is improved, and the thermosyphon cycle cooling is automatically carried out without interruption, and the heat dissipation effect is stable and reliable. The second cooling channel is arranged to ensure the cooling effect of the magnetic suspension refrigeration compressor under special circumstances.

Description

TECHNICAL FIELD

[0001] The application relates to a magnetic suspension centrifugal water chiller based on thermosyphon cooling and a control method, and belongs to the technical field of magnetic suspension centrifugal water chiller heat dissipation. BACKGROUND

[0002] The magnetic suspension centrifugal water chiller is an oil-free system, and a refrigerant is used to cool the motor of the magnetic suspension refrigeration compressor. A conventional motor cooling scheme is to use the refrigerant flowing out of the condenser or the high-pressure liquid accumulator, which is adjusted and controlled through solenoid valves and throttling valves, to enter the motor cooling channel of the magnetic suspension refrigeration compressor. The refrigerant absorbs heat of the motor and then vaporizes, and then enters the suction end of the magnetic suspension refrigeration compressor or the evaporator. After being sucked and compressed by the magnetic suspension refrigeration compressor, the refrigerant performs a subsequent refrigeration cycle. The refrigerant used for heat dissipation of the magnetic suspension refrigeration compressor cannot provide refrigerating capacity for users, and needs to consume compression power, so the energy efficiency of the magnetic suspension centrifugal water chiller is reduced.

[0003] How to reduce the effective refrigerating capacity and power consumption consumed by cooling the magnetic suspension refrigeration compressor, and at the same time improve the cooling effect of the magnetic suspension refrigeration compressor and the stability of the motor temperature, is of great significance to improve the refrigeration energy efficiency of the magnetic suspension centrifugal water chiller and ensure the safe operation of the motor. SUMMARY

[0004] In view of the deficiencies of the prior art, the application provides a magnetic suspension centrifugal water chiller based on thermosyphon cooling and a control method. A first cooling channel is arranged in the magnetic suspension centrifugal water chiller to cool the magnetic suspension refrigeration compressor. The first cooling channel uses the thermosyphon effect of the refrigerant to realize non-power dissipation, and does not pass through the suction compression of the magnetic suspension refrigeration compressor. Compared with the conventional cooling scheme, the magnetic suspension centrifugal water chiller reduces the refrigeration capacity loss and compressor power consumption.

[0005] The technical scheme of the application is as follows:

[0006] The magnetic suspension centrifugal water chiller based on thermosyphon cooling comprises a magnetic suspension refrigeration compressor, an evaporative condenser, a thermosyphon tank, a liquid accumulator, a first expansion valve and an evaporator which are connected in sequence.

[0007] In the main refrigeration cycle of the magnetic suspension centrifugal water chiller, the gaseous refrigerant output from the evaporator is compressed by the magnetic suspension refrigeration compressor and is condensed into liquid refrigerant by the evaporative condenser. The liquid refrigerant then flows into the thermosyphon tank from the evaporative condenser. When the liquid refrigerant in the thermosyphon tank exceeds a set liquid level, the liquid refrigerant flows through the liquid accumulator, the first expansion valve and the evaporator in sequence, and circulates back and forth to complete the main refrigeration cycle of the magnetic suspension centrifugal water chiller.

[0008] The first cooling channel is arranged between the thermosyphon tank and the magnetic suspension refrigeration compressor, and the refrigerant in the magnetic suspension refrigeration compressor is circulated and flows between the thermosyphon tank and the magnetic suspension refrigeration compressor by using the thermosyphon effect, so that the magnetic suspension refrigeration compressor is cooled.

[0009] According to the application, the first liquid outlet pipe and the first return pipe are arranged between the thermosyphon tank and the magnetic suspension refrigeration compressor, the first liquid outlet pipe and the first return pipe are respectively connected to the inlet of the first refrigerant channel and the outlet of the first refrigerant channel in the magnetic suspension refrigeration compressor, and the thermosyphon tank, the first liquid outlet pipe, the magnetic suspension refrigeration compressor and the first return pipe are connected to form the first cooling channel.

[0010] According to the application, the first liquid inlet pipe is arranged between the evaporative condenser and the thermosyphon tank, the exhaust pipe is arranged between the magnetic suspension refrigeration compressor and the evaporative condenser, and the thermosyphon tank is connected to the exhaust pipe through the exhaust bypass pipe.

[0011] According to the application, the magnetic suspension centrifugal water chiller further comprises a second cooling channel, the second liquid outlet pipe is arranged between the liquid accumulator and the magnetic suspension refrigeration compressor, the electromagnetic valve and the second expansion valve are arranged on the second liquid outlet pipe, the second return pipe is arranged between the magnetic suspension refrigeration compressor and the evaporator, and the liquid accumulator, the second liquid outlet pipe, the magnetic suspension refrigeration compressor, the second return pipe and the evaporator form the second cooling channel.

[0012] According to the application, the liquid discharge pipe is arranged between the thermosyphon tank and the liquid accumulator, the liquid return pipe is arranged between the liquid accumulator and the evaporator, and the first expansion valve is arranged on the liquid return pipe.

[0013] According to the application, the installation position of the evaporative condenser is higher than that of the thermosyphon tank, and the installation position of the thermosyphon tank is higher than that of the liquid accumulator.

[0014] According to the application, the installation position of the thermosyphon tank is higher than that of the magnetic suspension refrigeration compressor, and the pipe resistance in the first cooling channel is smaller than the driving force generated by the thermosyphon effect.

[0015] The control method of the magnetic suspension centrifugal water chiller based on the thermosyphon cooling comprises the following steps:

[0016] The liquid refrigerant flowing out of the thermosyphon tank is vaporized to form a gas-liquid mixed state after absorbing heat of the magnetic suspension refrigeration compressor under the heat siphon effect, and then returns to the thermosyphon tank, and circulates between the magnetic suspension refrigeration compressor and the thermosyphon tank, so that the magnetic suspension refrigeration compressor is cooled; the gaseous refrigerant returning to the thermosyphon tank enters the evaporative condenser under the pressure difference and is condensed into liquid refrigerant, and the liquid refrigerant in the evaporative condenser is transported to the thermosyphon tank again under the action of gravity;

[0017] When the liquid level of the liquid refrigerant in the thermosyphon tank exceeds the set height, the liquid refrigerant is transported to the liquid accumulator, and the main refrigeration cycle of the magnetic suspension centrifugal water chiller continues.

[0018] According to the application, the second liquid outlet pipe is further provided with an electromagnetic valve, and the control method further comprises:

[0019] The motor temperature T of the magnetic suspension refrigeration compressor is monitored in real time, and when T is greater than or equal to a first set threshold T1, the electromagnetic valve and the expansion valve on the second liquid outlet pipe are opened to connect the second cooling channel;

[0020] When T is less than T2 and T2 is less than T1, the electromagnetic valve and the expansion valve on the second liquid outlet pipe are closed, and the second cooling channel stops running, and T2 represents a second set threshold, which is set based on the lower limit of the temperature for stable operation of the magnetic suspension centrifugal water chiller.

[0021] The application has the following beneficial effects:

[0022] In the application, the first cooling channel of the magnetic suspension refrigeration compressor realizes non-waste heat dissipation by using the heat siphon effect, and reduces the loss of cold energy of the main refrigeration cycle of the magnetic suspension centrifugal water chiller. The heat siphon cooling capacity is positively correlated with the heat generation of the magnetic suspension refrigeration compressor, that is, when the heat generation of the magnetic suspension refrigeration compressor is large, the heat siphon cycle cooling capacity is strong, and when the heat generation of the magnetic suspension refrigeration compressor is small, the heat siphon cycle cooling capacity is weak. Cooling the magnetic suspension refrigeration compressor by using the heat siphon effect of the refrigerant is conducive to automatically keeping the motor temperature within a normal range when the magnetic suspension centrifugal water chiller operates at different powers. In addition, the temperature of the refrigerant entering the first cooling channel is generally between 20-36℃, and the temperature fluctuation is small. When the temperature of the magnetic suspension refrigeration compressor is higher than the temperature of the refrigerant in the first cooling channel, the heat siphon cycle cooling is automatically performed without interruption, and the heat dissipation effect is stable and reliable.

[0023] The second cooling channel is only used when necessary to avoid additional energy consumption and ensure the overall energy efficiency of the unit. The first cooling channel uses the heat siphon effect as the main cooling cycle to realize non-interrupted and non-waste heat dissipation; the second cooling channel serves as an auxiliary cooling cycle and has an intelligent opening and closing function to realize efficient heat dissipation of the magnetic suspension refrigeration compressor while reducing system energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Structure diagram of the magnetic suspension centrifugal water chiller based on thermosyphon cooling provided by the present application.

[0025] 1, magnetic suspension refrigeration compressor, 2, evaporative condenser, 3, liquid accumulator, 4, evaporator, 5, thermosyphon tank, 6, first liquid outlet pipe, 7, first return pipe, 8, second liquid outlet pipe, 9, second return pipe, 10, exhaust bypass pipe, 11, first liquid inlet pipe, 12, liquid return pipe, 13, electromagnetic valve, 14, first expansion valve, 15, liquid discharge pipe, 16, exhaust pipe, 17, second expansion valve. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described below in the drawings to clearly and completely describe several embodiments of the present application, which form a part of the present application. The drawings are used to provide further understanding of the present application, and the illustrative embodiments and descriptions are used to explain the present application and do not constitute an improper limitation on the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0027] It should be noted that, unless otherwise defined or limited, the up, down, left, right, and the like directions referred to in the present application are based on the up, down, left, right, and the like directions shown in the embodiments of the present application. If the specific posture changes, the directional indications also change accordingly. The terms "first", "second", and the like used in the present application do not represent any order, quantity, or importance, but are only used to distinguish different components. In addition, in various embodiments of the present application, the same or similar reference numerals represent the same or similar components. Figure 1

[0028] In the present application, unless otherwise defined or limited, the terms "connection", "fixation", and the like should be understood broadly, for example, "connection" can be fixed connection, or detachable connection, or integral, unless otherwise defined or limited. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present application according to the specific circumstances.

[0029] In addition, the technical solutions of various embodiments of the present application can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can realize it. When the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection of the present application.

[0030] Example 1

[0031] ​The embodiment provides a magnetic suspension centrifugal water chiller based on thermosyphon cooling, which comprises, as shown in the figure, a magnetic suspension refrigeration compressor 1, an evaporative condenser 2, a thermosyphon tank 5, a liquid accumulator 3, a first expansion valve 14 and an evaporator 4 connected in sequence. Figure 1

[0032] In the main refrigeration cycle of the magnetic suspension centrifugal water chiller, gaseous refrigerant output from the evaporator 4 is compressed by the magnetic suspension refrigeration compressor 1, condensed into liquid refrigerant by the evaporative condenser 2, and then flows from the evaporative condenser 2 into the thermosyphon tank 5; when the liquid refrigerant in the thermosyphon tank 5 exceeds a set liquid level, the liquid refrigerant flows through the liquid accumulator 3, the first expansion valve 14 and the evaporator 4 in sequence, and the cycle is repeated to complete the main refrigeration cycle of the magnetic suspension centrifugal water chiller.

[0033] The first cooling channel is further arranged between the thermosyphon tank 5 and the magnetic suspension refrigeration compressor 1, and the refrigerant in the magnetic suspension refrigeration compressor 1 is circulated and flows between the thermosyphon tank 5 and the magnetic suspension refrigeration compressor 1 by using the thermosyphon effect, so that the magnetic suspension refrigeration compressor 1 is cooled.

[0034] The liquid refrigerant at the bottom of the thermosyphon tank 5 enters the first cooling channel of the magnetic suspension refrigeration compressor 1 through the first liquid outlet pipe 6, the heat generated by the magnetic suspension refrigeration compressor 1 exchanges with the liquid refrigerant, part of the liquid refrigerant absorbs heat and vaporizes into gaseous refrigerant, the density of the first reflux pipe 7 is reduced, the thermosyphon driving force is formed under the action of the density difference, the circulation of the refrigerant is promoted, the heat-absorbed gaseous-liquid mixed refrigerant returns to the thermosyphon tank 5, and the cooling cycle in the first cooling channel of the magnetic suspension refrigeration compressor 1 is completed.

[0035] The magnetic suspension refrigeration compressor 1 is cooled by using the thermosyphon effect of the refrigerant, which is equivalent to releasing the heat of the magnetic suspension refrigeration compressor 1 to the outdoor environment through the circulation of the refrigerant, does not consume the refrigeration capacity of the magnetic suspension centrifugal water chiller itself and the power consumption of the magnetic suspension refrigeration compressor 1, and helps to improve the refrigeration energy efficiency of the magnetic suspension centrifugal water chiller.

[0036] Embodiment 2

[0037] The embodiment provides a magnetic suspension centrifugal water chiller based on thermosyphon cooling, which is different from the embodiment 1 in that:

[0038] As shown in the figure, Figure 1 ​As shown, a first liquid outlet pipe 6 and a first return pipe 7 are respectively installed between the thermosiphon tank 5 and the magnetic levitation refrigeration compressor 1. The first liquid outlet pipe 6 and the first return pipe 7 are connected to the inlet and outlet of the first refrigerant channel in the magnetic levitation refrigeration compressor 1, respectively. The thermosiphon tank 5, the first liquid outlet pipe 6, the magnetic levitation refrigeration compressor 1, and the first return pipe 7 are connected to form a first cooling channel. The first cooling channel plays a major role in cooling the magnetic levitation refrigeration compressor 1. The refrigerant entering the first cooling channel only flows within the first cooling channel and is not connected to the cavity of the magnetic levitation refrigeration compressor 1. The first refrigerant channel is not marked in the attached drawing.

[0039] Example 3

[0040] This embodiment provides a magnetic levitation centrifugal chiller unit based on thermosiphon cooling, which differs from Embodiment 2 in that:

[0041] A first inlet pipe 11 is provided between the evaporative condenser 2 and the thermosiphon tank 5, and an exhaust pipe 16 is provided between the magnetic levitation refrigeration compressor 1 and the evaporative condenser 2. The thermosiphon tank 5 is also connected to the exhaust pipe 16 via an exhaust bypass pipe 10. Driven by the pressure difference, the gaseous refrigerant in the thermosiphon tank 5 passes through the exhaust bypass pipe 10 and the exhaust pipe 16, and then enters the evaporative condenser 2 for condensation. After condensing into liquid refrigerant, it flows back into the thermosiphon tank 5 through the first inlet pipe 11, and the cycle repeats continuously. The exhaust bypass pipe 10 is used to guide the gaseous refrigerant in the thermosiphon tank 5 into the exhaust pipe 16 to maintain a stable pressure inside the thermosiphon tank 5.

[0042] Example 4

[0043] This embodiment provides a magnetic levitation centrifugal chiller unit based on thermosiphon cooling, which differs from Embodiment 2 in that:

[0044] like Figure 1 As shown, the magnetic levitation centrifugal chiller unit is also equipped with a second cooling channel. A second liquid outlet pipe 8 is provided between the liquid receiver 3 and the magnetic levitation refrigeration compressor 1. A solenoid valve 13 and a second expansion valve 17 are provided on the second liquid outlet pipe 8. A second return pipe 9 is provided between the magnetic levitation refrigeration compressor 1 and the evaporator 4. The second liquid outlet pipe 8 and the second return pipe 9 are respectively connected to the inlet and outlet of the second refrigerant channel in the magnetic levitation refrigeration compressor 1. The liquid receiver 3, the second liquid outlet pipe 8, the magnetic levitation refrigeration compressor 1, the second return pipe 9 and the evaporator 4 form the second cooling channel.

[0045] The liquid refrigerant output by the liquid accumulator 3 enters the second liquid outlet pipe 8, is throttled by the second expansion valve 17, and then enters the inlet of the second refrigerant passage of the magnetic suspension refrigeration compressor 1. The refrigerant absorbs heat in the second refrigerant passage, flows out from the outlet of the second refrigerant passage, and then flows back to the evaporator 4 through the second return pipe 9. The gaseous refrigerant output by the evaporator 4 enters the inlet of the magnetic suspension refrigeration compressor 1 to be compressed, and enters the path of the main refrigeration cycle.

[0046] The second cooling passage cools the magnetic suspension refrigeration compressor 1, and ensures the cooling effect of the magnetic suspension refrigeration compressor 1. The second refrigerant passage is not marked in the drawings.

[0047] Embodiment 5

[0048] The embodiment provides a magnetic suspension centrifugal water chiller based on thermosyphon cooling, which is different from the embodiment 4 in that:

[0049] As shown in Figure 1 , the liquid discharge pipe 15 is arranged between the thermosyphon tank 5 and the liquid accumulator 3; the liquid return pipe 12 is arranged between the liquid accumulator 3 and the evaporator 4, and the first expansion valve 14 is arranged on the liquid return pipe 12.

[0050] Embodiment 6

[0051] The embodiment provides a magnetic suspension centrifugal water chiller based on thermosyphon cooling, which is different from the embodiment 4 in that:

[0052] The installation position of the evaporative condenser 2 needs to be higher than that of the thermosyphon tank 5, and the installation position of the thermosyphon tank 5 needs to be higher than that of the liquid accumulator 3.

[0053] Embodiment 7

[0054] The embodiment provides a magnetic suspension centrifugal water chiller based on thermosyphon cooling, which is different from the embodiment 4 in that:

[0055] The installation position of the thermosyphon tank 5 is higher than that of the magnetic suspension refrigeration compressor 1, and the pipeline resistance in the first cooling passage is smaller than the driving force generated by the thermosyphon effect; for example, when the vertical distance is greater than or equal to 2 meters and the horizontal distance is less than or equal to 2 meters, the thermosyphon demand of the R134a refrigerant can be met.

[0056] Taking a 200RT (refrigerating capacity of 200 tons) magnetic suspension refrigeration compressor 1 as an example, the design principle of cooling the motor by using the thermosyphon effect is explained in detail through theoretical calculation.

[0057] Theoretical explanation: The thermosyphon effect is to use the density difference (Δρ) and height difference (ΔH) of the refrigerant in the pipeline between the thermosyphon tank 5 and the magnetic suspension refrigeration compressor 1 to generate a static pressure head, drive the refrigerant circulation, and the static pressure head needs to be greater than the total pressure drop of the pipeline. The circulation ratio is defined as the ratio of the total circulating refrigerant mass flow rate to the evaporation amount, and sufficient ratio needs to be ensured to avoid dryout, and the circulation ratio is generally set to be between 3-6.

[0058] 1. Calculate the initial conditions: 200RT magnetic suspension refrigeration compressor 1, motor power 120KW, motor efficiency 97%, motor heat 3.6KW, magnetic suspension refrigeration compressor 1 is provided with a motor cooling annular flow channel. The vertical distance ΔH between the thermosyphon tank 5 and the magnetic suspension refrigeration compressor 1 is 2m, and the horizontal distance is 1.5m. The condensation temperature of the evaporative condenser 2 is 36℃, the supercooling degree is 2℃, the temperature of the refrigerant in the thermosyphon tank 5 is 34℃, the density of the liquid refrigerant R134a (1,1,1,2-tetrafluoroethane) in the first liquid outlet pipe 6 is ρ_ L 1171kg / m³, the density of the gaseous refrigerant R134a in the first return pipe 7 is ρ_ v 42kg / m³, and the circulation ratio is set to 3.

[0059] 2. Driving force calculation: ΔP=[ρ_ L −(1 / 3*ρ_ v +2 / 3*ρ_ L ]*g*ΔH=7400pa;

[0060] Wherein, g is the acceleration of gravity, which is 9.81, and the numerical value can be obtained: ΔP=7.4kpa.

[0061] Pipe design and pressure drop calculation:

[0062] The pressure drop includes pipe friction pressure drop and local pressure drop. The first liquid outlet pipe 6 between the thermosyphon tank 5 and the magnetic suspension refrigeration compressor 1 uses a copper pipe with a diameter of 16mm, and the first return pipe 7 selects a copper pipe with a diameter of 28mm. There are three 90-degree bends on the first liquid outlet pipe 6 and the first return pipe 7 respectively. The pipe diameter of the first liquid outlet pipe 6 and the first return pipe 7 is reasonably designed to reduce the pipe resistance during the flow of the refrigerant.

[0063] Pipe friction pressure drop (Darcy formula): ΔP f = f * L / D*(ρ*u 2 / 2);

[0064] Local pressure drop (bend): ΔP l =ξ*(ρ*u 2 / 2); In the formula, f is the friction factor, L is the pipe length, D is the pipe diameter, u is the flow rate, and ξ is the local resistance coefficient.

[0065] The calculation result is:

[0066] The pressure drop ΔP of the motor cooling annular flow passage inside the magnetic suspension refrigeration compressor 1 n = 3600 pa; the pipeline friction pressure drop ΔP f = 800 pa; the local pressure drop ΔP l = 400 pa; the total pressure drop ΔP t = 4800 pa.

[0067] The driving force ΔP = 7400 pa > the total pressure drop ΔP t = 4800 pa, the design scheme theoretical calculation is correct, the pipeline resistance is less than the driving force generated by the thermosyphon effect, and the circulation condition of the first cooling channel can be met.

[0068] Embodiment 8

[0069] The magnetic suspension centrifugal water chiller based on the thermosyphon cooling provided in any one of embodiments 4-7, the embodiment provides a corresponding control method, comprising:

[0070] The first cooling channel is connected, the magnetic suspension refrigeration compressor 1 is started, under the thermosyphon effect, the liquid refrigerant flowing out of the thermosyphon tank 5 absorbs the heat of the magnetic suspension refrigeration compressor 1, and then vaporizes to form a gas-liquid mixed state, and then returns to the thermosyphon tank 5, circulates between the magnetic suspension refrigeration compressor 1 and the thermosyphon tank 5, and cools the magnetic suspension refrigeration compressor 1;

[0071] Under the pressure difference between the thermosyphon tank 5 and the evaporative condenser 2, the gaseous refrigerant returning to the thermosyphon tank 5 enters the evaporative condenser 2 to condense into liquid refrigerant, and then the liquid refrigerant is delivered to the thermosyphon tank 5;

[0072] When the liquid level of the liquid refrigerant in the thermosyphon tank 5 exceeds the set value, the liquid refrigerant is delivered to the liquid storage tank 3 through the liquid return pipe 12, and the main refrigeration cycle of the magnetic suspension centrifugal water chiller is continued.

[0073] Embodiment 9

[0074] The control method of the magnetic suspension centrifugal water chiller provided in the embodiment is different from that of embodiment 8 in that:

[0075] The solenoid valve 13 is further arranged on the second liquid outlet pipe 8, and the control method further comprises:

[0076] Real-time monitoring of the motor temperature T of the magnetic suspension refrigeration compressor 1, the motor temperature T takes the maximum value detected by the motor internal temperature as the motor temperature T, temperature sensors can be arranged at the motor winding, rotor and bearing, and the maximum value is T; when T≥the first set threshold T1, open the electromagnetic valve 13 and the second expansion valve 17 on the second liquid outlet pipe 8, connect the second cooling channel; the liquid refrigerant in the liquid accumulator 3 enters the magnetic suspension refrigeration compressor 1 through the second liquid outlet pipe 8, evaporates into gaseous refrigerant after absorbing heat, and returns to the evaporator 4 through the second return pipe 9; the second expansion valve 17 on the second liquid outlet pipe 8 adjusts the refrigerant flow to match the compressor heat dissipation demand.

[0077] When T

[0078] The cooling of the magnetic suspension refrigeration compressor 1 by the thermosyphon effect is limited by the relationship between the pipeline resistance and the gravitational potential energy. If the installation height of the thermosyphon tank 5 is insufficient due to site conditions, the cooling effect of the first cooling channel will be weakened, which may cause the temperature of the magnetic suspension refrigeration compressor 1 to be too high. When the magnetic suspension refrigeration compressor 1 is running under extreme conditions or heavy load, the heat generation may exceed the upper limit of the cooling capacity of the thermosyphon effect. Therefore, in order to ensure the safe and efficient operation of the magnetic suspension refrigeration compressor 1 under various conditions, when the motor heat exceeds the maximum heat exchange capacity of the first cooling channel, the temperature of the magnetic suspension refrigeration compressor 1 continues to rise, and the refrigerant needs to be controlled to enter the second cooling channel for auxiliary cooling.

[0079] The above description shows and describes the preferred embodiments of the present application, but as previously mentioned, the present application is not limited to the forms disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the present application by the above teachings or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the claims of the present application.

Claims

1. A magnetic levitation centrifugal water chiller based on thermosyphon cooling, characterized in that, The magnetic suspension refrigeration compressor, the evaporative condenser, the thermosyphon tank, the liquid accumulator, the first expansion valve and the evaporator are sequentially connected. In the main refrigeration cycle of the magnetic suspension centrifugal water chiller, gaseous refrigerant output from the evaporator is compressed by the magnetic suspension refrigeration compressor, condensed by the evaporative condenser into liquid refrigerant, and then flows from the evaporative condenser into the thermosyphon tank. The first cooling channel is further arranged between the thermosyphon tank and the magnetic suspension refrigeration compressor. The first cooling channel includes a first liquid outlet pipe and a first return pipe. The second cooling channel is further arranged between the liquid accumulator and the magnetic suspension refrigeration compressor. The second cooling channel includes a second liquid outlet pipe and a second return pipe. The magnetic suspension centrifugal water chiller is configured to: After starting, the liquid refrigerant circulates in the first cooling channel by the thermosyphon effect to cool the magnetic suspension refrigeration compressor. The motor temperature T of the magnetic suspension refrigeration compressor is monitored in real time. When the motor temperature T reaches or exceeds the first set threshold T1, the electromagnetic valve and the second expansion valve on the second cooling channel are opened. When the motor temperature T drops below the second set threshold T2, the electromagnetic valve and the second expansion valve are closed, where T2 < T1.

2. The magnetic levitation centrifugal cold water unit based on thermosyphon cooling according to claim 1, characterized in that, A liquid discharge pipe is arranged between the thermosyphon tank and the liquid accumulator.

3. The magnetic levitation centrifugal cold water unit based on thermosyphon cooling according to claim 1, characterized in that, A liquid return pipe is arranged between the liquid accumulator and the evaporator, and the first expansion valve is arranged on the liquid return pipe.

4. The thermosiphon-cooled magnetic levitation centrifugal water chiller according to claim 1, characterized in that, The installation position of the evaporative condenser needs to be higher than that of the thermosyphon tank.

5. The control method of a magnetic levitation centrifugal cold water unit according to any one of claims 1 to 4, characterized in that, The installation position of the thermosyphon tank is higher than that of the liquid accumulator. The installation position of the thermosyphon tank is higher than that of the magnetic suspension refrigeration compressor, and the pipe resistance in the first cooling channel is smaller than the driving force generated by the thermosyphon effect. The magnetic suspension centrifugal water chiller is configured to: After starting, the liquid refrigerant circulates in the first cooling channel by the thermosyphon effect to cool the magnetic suspension refrigeration compressor. Gaseous refrigerant flowing back into the thermosyphon tank enters the evaporative condenser under the action of pressure difference and is condensed into liquid refrigerant, which is transported to the thermosyphon tank again under the action of gravity; when the liquid level of the liquid refrigerant in the thermosyphon tank exceeds the set height, the liquid refrigerant is transported to the liquid accumulator, and the main refrigeration cycle of the magnetic suspension centrifugal chiller continues; The first cooling channel is isolated from the main refrigeration cycle at the suction port and the exhaust port of the magnetic suspension refrigeration compressor; The motor temperature T of the magnetic suspension refrigeration compressor is monitored in real time, and when T≥the first set threshold T1, the electromagnetic valve and the expansion valve on the second liquid outlet pipe are opened to connect the second cooling channel; When T When T When T

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