Variable working condition high temperature heat pump system with simultaneous refrigeration and heating

Abstract

The application discloses a variable working condition high-temperature heat pump system with simultaneous refrigeration and heating, relates to the field of heat pumps, and can solve the problems of the prior art, such as the fact that a single unit cannot simultaneously prepare high-temperature hot water and low-temperature ice water, and the fact that a double-compressor start is unstable. The system comprises a first compressor, a second compressor, a low-temperature evaporator, a water evaporator, an economizer, a condenser and multiple sets of valves and throttles. By controlling the on-off of the valves and the start-stop of the compressors, low-temperature ice water of-5 DEG C to-15 DEG C and high-temperature hot water of 65 DEG C to 100 DEG C can be simultaneously prepared. Therefore, a unit covers the full range of water temperature requirements of-10 DEG C to 98 DEG C, supports seamless switching of cold and hot water temperatures, has stable start, and is suitable for scenes, such as chemical industry and distilleries, which require cold and hot sources in multiple temperature ranges.

Description

Technical Field

[0001] This solution relates to the field of heat pumps, specifically a high-temperature heat pump system with variable operating conditions that can simultaneously cool and heat. Background Technology

[0002] High-temperature heat pump systems refer to heat pump units that produce hot water at a temperature of not less than 65°C. In many chemical, winery and other application scenarios, users may need both high-temperature hot water and low-temperature chilled water at the same time. The temperatures of the low-temperature chilled water and high-temperature hot water need to be adjusted according to the usage conditions. In order to ensure the stability of process requirements, this requirement can currently only be met by connecting multiple units in series with water circuits. It is currently impossible for a single unit to meet this operating condition.

[0003] Existing heat pump systems with two compressors connected in series can switch between several common operating conditions, but they can only choose to operate in either heating or cooling mode. They cannot provide hot water at around 98°C while also providing chilled water at around -10°C.

[0004] In addition, in the existing technology, the output end of the low-stage compressor is the input end of the high-stage compressor. Therefore, the requirements for the matching of the operating conditions of the two compressors during startup are very high, and the requirements for the order and timing of startup of the two compressors are very strict, which often results in the inability to start. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-temperature heat pump system with variable operating conditions that can simultaneously cool and heat.

[0006] The specific technical solution of the present invention to solve the above-mentioned technical problems is as follows: A variable operating condition high-temperature heat pump system capable of simultaneous cooling and heating includes a first compressor, a second compressor, a low-temperature evaporator, a water evaporator, an economizer, and a condenser. The gas phase outlet of the low-temperature evaporator is connected to the suction end of the second compressor via a fourth valve; The vapor phase outlet of the water evaporator is connected to the suction end of the second compressor via a third valve; The exhaust end of the second compressor is connected to the gas phase inlet end of the economizer via the first valve; The gas phase outlet of the economizer is connected to the suction end of the first compressor; The exhaust end of the first compressor is connected to the gas phase inlet end of the condenser; The first compressor is also equipped with a tenth valve at the suction end, which is used to control the opening and closing of the suction pipe of the first compressor; The liquid phase outlet of the condenser is connected to the economizer via a first throttle. The liquid phase outlet of the economizer is connected to the low-temperature evaporator via the fifth valve and the second throttle. The liquid phase outlet of the economizer is connected to the water evaporator via the sixth valve and the third throttle. The liquid phase end of the water evaporator and the liquid phase end of the low-temperature evaporator are also connected by a first connecting pipe and a second connecting pipe. The first connecting pipe is used to transport liquid refrigerant from the water evaporator to the low-temperature evaporator and is equipped with an eighth valve. The second connecting pipe is used to transport liquid refrigerant from the low-temperature evaporator to the water evaporator and is equipped with a seventh valve and a refrigerant pump. The exhaust end of the second compressor is also connected to the gas phase inlet end of the condenser via a second valve; The gas supply end of the second compressor is connected to the gas supply outlet end of the economizer via the ninth valve.

[0007] For the sake of simplicity, the following text refers to water at -5°C to -15°C (actually brine) as low-temperature ice water; water at 65°C to 100°C as high-temperature hot water; water at 3°C ​​to 6°C as cold water; water at 6°C to 10°C as cool water; and water at 40°C to 65°C as conventional hot water.

[0008] Furthermore, when the system operates in the first condition, the first valve is open, the second valve is closed, the third valve is closed, the fourth valve is open, the fifth valve is open, the sixth valve is closed, the seventh valve is closed, the eighth valve is open, the refrigerant pump is closed, the ninth valve is closed, and the tenth valve is open; the gaseous refrigerant is compressed by the first compressor and the second compressor, condensed into liquid refrigerant in the condenser, evaporated into gaseous refrigerant in the low-temperature evaporator, and high-temperature hot water is obtained in the tube side of the condenser, and low-temperature ice water is obtained in the tube side of the low-temperature evaporator.

[0009] Furthermore, when the system operates in the second condition, the first valve opens, the second valve closes, the third valve opens, the fourth valve closes, the fifth valve closes, the sixth valve opens, the seventh valve opens, the eighth valve closes, the refrigerant pump opens, the ninth valve closes, and the tenth valve opens. The gaseous refrigerant is compressed by the first compressor and the second compressor, condensed into liquid refrigerant in the condenser, evaporated into gaseous refrigerant in the water evaporator, and high-temperature hot water is obtained in the tube side of the condenser, while cold water is obtained in the tube side of the water evaporator.

[0010] Furthermore, when the system operates in the third condition, the first valve is closed, the second valve is open, the third valve is open, the fourth valve is closed, the fifth valve is closed, the sixth valve is open, the seventh valve is open, the eighth valve is closed, the refrigerant pump is on, the ninth valve is open, and the tenth valve is closed; the gaseous refrigerant is compressed by the second compressor, condensed into liquid refrigerant in the condenser, evaporated into gaseous refrigerant in the water evaporator, and conventional hot water is obtained in the tube side of the condenser, while cool water is obtained in the tube side of the water evaporator.

[0011] Compared with existing technologies, this solution has the following beneficial technical effects: This unit can select the first and second compressors to work simultaneously, or select to start only one compressor, by controlling the valves. By adjusting the pressure in the water evaporator and the low-temperature evaporator, and by selecting whether to use the water evaporator or the low-temperature evaporator to vaporize the refrigerant, hot water and cold water at different temperatures can be obtained simultaneously.

[0012] When operating at full load, this unit can generate high-temperature hot water at 65°C to 100°C on the condenser side while simultaneously obtaining low-temperature chilled water at approximately -15°C to -5°C on the evaporator side. This allows a single unit to meet water temperature requirements across the entire range from -15°C to 100°C.

[0013] In addition, this solution sets up an economizer between the first compressor and the second compressor as an intermediate buffer for gaseous refrigerant, which greatly reduces the timing and operating conditions requirements of the two compressors during startup, making the startup of the two compressors stable and reliable, and facilitating the switching between single and dual compressor heads for various operating conditions. Attached Figure Description Figure 1 This is a schematic diagram of the variable operating condition high-temperature heat pump system of the present invention, which has the function of simultaneous cooling and heating. Figure 2 This is a schematic diagram of the first operating condition of the high-temperature heat pump system of the present invention; Figure 3 This is a schematic diagram of the second operating condition of the high-temperature heat pump system of the present invention; Figure 4 This is a schematic diagram of the third operating condition of the high-temperature heat pump system of the present invention.

[0014] The following is a list of component names represented by the reference numerals in the attached diagram: 1. First compressor; 2. Second compressor; 3. Condenser; 4. Low-temperature evaporator; 5. Water evaporator; 6. Economizer; 7. First valve; 8. Second valve; 9. Third valve; 10. Fourth valve; 11. Fifth valve; 12. Sixth valve; 13. Seventh valve; 14. Eighth valve; 15. Refrigerant pump; 16. Ninth valve; 17. Tenth valve. Detailed Implementation

[0015] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0016] like Figure 1As shown, a heat pump unit capable of simultaneously producing high-temperature hot water and low-temperature chilled water includes a first compressor 1, a second compressor 2, a low-temperature evaporator 4, a water evaporator 5, an economizer 6, and a condenser 3. The gas phase outlet of the low-temperature evaporator 4 is connected to the suction end of the second compressor 2 via the fourth valve 10; The vapor phase outlet of the water evaporator 5 is connected to the suction end of the second compressor 2 via the third valve 9; The exhaust end of the second compressor 2 is connected to the gas phase inlet end of the economizer 6 via the first valve 7; The gas phase outlet end of the economizer 6 is connected to the suction end of the first compressor 1; The exhaust end of the first compressor 1 is connected to the gas phase inlet end of the condenser 3; The first compressor 1 is also provided with a tenth valve 17 at the suction end, which is used to control the opening and closing of the suction pipe of the first compressor 1; The liquid phase outlet of the condenser 3 is connected to the economizer 6 via the first throttle. The liquid phase outlet of the economizer 6 is connected to the low-temperature evaporator 4 via the fifth valve 11 and the second throttle. The liquid phase outlet of the economizer 6 is connected to the water evaporator 5 via the sixth valve 12 and the third throttle. The liquid phase end of the water evaporator 5 and the liquid phase end of the low-temperature evaporator 4 are also connected by a first connecting pipe and a second connecting pipe. The first connecting pipe is used to transport liquid refrigerant from the water evaporator 5 to the low-temperature evaporator 4 and is equipped with an eighth valve 14. The second connecting pipe is used to transport liquid refrigerant from the low-temperature evaporator 4 to the water evaporator 5 and is equipped with a seventh valve 13 and a refrigerant pump 15. The exhaust end of the second compressor 2 is also connected to the gas phase inlet end of the condenser 3 via the second valve 8; The suction end of the second compressor 2 is connected to the replenishment outlet end of the economizer 6 via the ninth valve 16.

[0017] The above system can operate under different conditions based on the on-site requirements for hot and cold water: First operating condition: Simultaneous production of low-temperature ice water and high-temperature hot water.

[0018] Please refer to Figure 1 and Figure 2 As shown, Figure 2 This is the structural diagram after removing the closed pipelines in this operating condition; First valve 7 is open, second valve 8 is closed, third valve 9 is closed, fourth valve 10 is open, fifth valve 11 is open, sixth valve 12 is closed, seventh valve 13 is closed, eighth valve 14 is open, refrigerant pump 15 is closed, ninth valve 16 is closed, and tenth valve 17 is open.

[0019] The system works as follows: The low-temperature evaporator 4 contains a low-temperature, low-pressure gaseous refrigerant. This refrigerant is compressed by the second compressor 2, becoming a medium-temperature, medium-pressure gaseous refrigerant. It then enters the economizer 6 for pressure equalization and buffering before flowing into the first compressor 1. The first compressor 1 further compresses the gaseous refrigerant, resulting in a high-temperature, high-pressure gaseous refrigerant, which is then discharged to the condenser 3. Inside the condenser 3, the high-temperature, high-pressure gaseous refrigerant releases heat to the external cold source in the tube side of the condenser 3, raising the temperature of the external cold source while condensing itself into liquid refrigerant. The liquid refrigerant is throttled, cooled, and depressurized by the first throttling device before entering the economizer 6. In the economizer 6, some of the liquid refrigerant flashes back into gaseous refrigerant and enters the suction port of the first compressor 1, thereby improving the efficiency of the first compressor 1. The liquid refrigerant in the economizer 6 is further depressurized and cooled by the second throttling device before entering the low-temperature evaporator 4. It should be noted that if liquid refrigerant is present in the water evaporator 5 at this time, it is introduced into the low-temperature evaporator 4 through the eighth valve 14. The low-temperature, low-pressure liquid refrigerant absorbs heat from the external heat source in the tube side of the low-temperature evaporator (4th tube), undergoes a phase change, and evaporates into a gaseous refrigerant. The external heat source releases heat within the low-temperature evaporator, causing its temperature to drop. The gaseous refrigerant in the low-temperature evaporator then enters the suction end of the second compressor (2), and this cycle continues continuously.

[0020] In the above process, the external cold source in the condenser tube side is the high-temperature hot water to be produced. It absorbs the heat from the high-temperature and high-pressure gaseous refrigerant, and its own temperature is raised to 65°C to 100°C. The external heat source in the low-temperature evaporator tube side is actually the low-temperature ice water to be produced. By transferring heat to the low-temperature and low-pressure refrigerant in the low-temperature evaporator 4, the refrigerant undergoes a phase change, and its own temperature is lowered, ultimately resulting in low-temperature ice water at -5°C to -15°C.

[0021] Second operating condition: Simultaneous production of cold water and high-temperature hot water: Please refer to Figure 1 and Figure 3 As shown, Figure 3 This is the structural diagram after removing the closed pipelines in this operating condition; First valve 7 is open, second valve 8 is closed, third valve 9 is open, fourth valve 10 is closed, fifth valve 11 is closed, sixth valve 12 is open, seventh valve 13 is open, eighth valve 14 is closed, refrigerant pump 15 is open, ninth valve 16 is closed, and tenth valve 17 is open.

[0022] The working principle of this system is as follows: The pressure in the water evaporator 5 is higher than that in the low-temperature evaporator 4. The low-temperature, low-pressure gaseous refrigerant in the water evaporator 5 is compressed by the second compressor 2 to form a medium-temperature, medium-pressure gaseous refrigerant, which is then sent to the economizer 6 for pressure equalization and buffering before entering the first compressor 1. The first compressor 1 further increases the temperature and pressure of the gaseous refrigerant, resulting in a high-temperature, high-pressure gaseous refrigerant, which is then discharged to the condenser 3. In the condenser 3, the high-temperature, high-pressure gaseous refrigerant releases heat to the external cold source in the tube side of the condenser 3, raising the temperature of the external cold source while condensing itself into liquid refrigerant. The liquid refrigerant is throttled and cooled by the first throttling device before entering the economizer 6. Inside the economizer 6, some of the liquid refrigerant flashes back into gaseous refrigerant and enters the suction port of the first compressor 1, improving the efficiency of the first compressor 1. The liquid refrigerant in the economizer 6 is further cooled and depressurized by the third throttling device before entering the water evaporator 5. It absorbs heat from the external heat source inside and outside the tube side of the water evaporator 5. During this process, the liquid refrigerant evaporates into gaseous refrigerant, while lowering the temperature of the external heat source. The gaseous refrigerant then enters the suction end of the second compressor 2, and so on.

[0023] Because the pressure in the low-temperature evaporator 4 is lower than that in the water evaporator 5, the refrigerant pump 15 is needed to pump the refrigerant from the low-temperature evaporator 4 into the water evaporator 5. This operation is only required when switching operating conditions, that is, when there is liquid refrigerant in the low-temperature evaporator 4, the refrigerant pump 15 is needed to pump it. When the liquid refrigerant in the water evaporator 5 reaches a certain level, the seventh valve 13 and the refrigerant pump 15 can be closed.

[0024] Under this operating condition, the gaseous refrigerant undergoes two stages of compression, resulting in sufficient heat. As a result, high-temperature hot water of 65°C to 100°C can be obtained in the tube side of the condenser. Furthermore, since the pressure inside the water evaporator 5 is higher than that inside the low-temperature evaporator 4, the evaporation temperature of the refrigerant inside the water evaporator is higher than that inside the low-temperature evaporator 4. Therefore, cold water of 3°C to 6°C can be obtained in the tube side of the water evaporator.

[0025] Third operating condition, air conditioning operating condition with only the refrigeration compressor running: Please refer to Figure 1 and Figure 4 As shown, Figure 4 This is the structural diagram after removing the closed pipelines in this operating condition; Under this condition, only the second compressor is activated, the first valve 7 is closed, the second valve 8 is open, the third valve 9 is open, the fourth valve 10 is closed, the fifth valve 11 is closed, the sixth valve 12 is open, the seventh valve 13 is open, the eighth valve 14 is closed, the refrigerant pump 15 is open, the ninth valve 16 is open, and the tenth valve 17 is closed.

[0026] The working principle under this condition is as follows: The second compressor 2 draws in low-temperature, low-pressure gaseous refrigerant from the evaporator 5. After compression by the second compressor 2, the temperature and pressure of the gaseous refrigerant increase, and it then enters the condenser 3 to exchange heat with an external cold source. In the condenser 3, the gaseous refrigerant is converted into liquid refrigerant, and the external cold source absorbs the heat from the gaseous refrigerant, thus increasing its temperature. The liquid refrigerant in the condenser 3 is then throttled, cooled, and depressurized by the first throttling device before flowing into the economizer 6. In the economizer 6, some of the liquid refrigerant flashes into gaseous refrigerant, which enters through the middle suction port of the second compressor 2, improving the efficiency of the second compressor 2. The liquid refrigerant in the economizer 6 is then cooled and depressurized by the third throttling device before entering the evaporator 5 to exchange heat with an external heat source. In the evaporator 5, the liquid refrigerant absorbs heat and evaporates into gaseous refrigerant, while the external heat source in the tube side of the evaporator 5 releases heat, causing its temperature to drop. The gaseous refrigerant produced by evaporation in the evaporator 5 is then drawn away by the second compressor 2, and the cycle continues. Under this operating condition, the condenser side can obtain conventional hot water at 40°C to 65°C, and the evaporator side can obtain cold water at 6°C to 10°C.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A variable operating condition high temperature heat pump system with simultaneous refrigeration and heating, comprising a first compressor, a second compressor, a low temperature evaporator, a water evaporator, a condenser, characterized in that, It also includes an economizer, wherein the gas phase outlet of the low-temperature evaporator is connected to the suction end of the second compressor via a fourth valve; The vapor phase outlet of the water evaporator is connected to the suction end of the second compressor via a third valve; The pressure inside the water evaporator is higher than the pressure inside the low-temperature evaporator; The exhaust end of the second compressor is connected to the gas phase inlet end of the economizer via the first valve; The gas phase outlet of the economizer is connected to the suction end of the first compressor; The exhaust end of the first compressor is connected to the gas phase inlet end of the condenser; The first compressor is also equipped with a tenth valve at the suction end, which is used to control the opening and closing of the suction pipe of the first compressor; The liquid phase outlet of the condenser is connected to the economizer via a first throttle. The liquid phase outlet of the economizer is connected to the low-temperature evaporator via the fifth valve and the second throttle. The liquid phase outlet of the economizer is connected to the water evaporator via the sixth valve and the third throttle; the economizer serves as an intermediate buffer for the gaseous refrigerant. The liquid phase end of the water evaporator and the liquid phase end of the low-temperature evaporator are also connected by a first connecting pipe and a second connecting pipe. The first connecting pipe is used to transport liquid refrigerant from the water evaporator to the low-temperature evaporator and is equipped with an eighth valve. The second connecting pipe is used to transport liquid refrigerant from the low-temperature evaporator to the water evaporator and is equipped with a seventh valve and a refrigerant pump. The exhaust end of the second compressor is also connected to the gas phase inlet end of the condenser via a second valve; The gas supply end of the second compressor is connected to the gas supply outlet end of the economizer via the ninth valve.

2. The variable-condition high-temperature heat pump system with simultaneous cooling and heating as described in claim 1, characterized in that, When the system operates in the first condition, the first valve is open, the second valve is closed, the third valve is closed, the fourth valve is open, the fifth valve is open, the sixth valve is closed, the seventh valve is closed, the eighth valve is open, the refrigerant pump is closed, the ninth valve is closed, and the tenth valve is open. The gaseous refrigerant is compressed by the first compressor and the second compressor, condensed into liquid refrigerant in the condenser, and evaporated into gaseous refrigerant in the low-temperature evaporator. Water at 65°C to 100°C is obtained in the tube side of the condenser, and water at -5°C to -15°C is obtained in the tube side of the low-temperature evaporator.

3. The variable-condition high-temperature heat pump system with simultaneous cooling and heating as described in claim 1, characterized in that, When the system operates in the second condition, the first valve is open, the second valve is closed, the third valve is open, the fourth valve is closed, the fifth valve is closed, the sixth valve is open, the seventh valve is open, the eighth valve is closed, the refrigerant pump is on, the ninth valve is closed, and the tenth valve is open. The gaseous refrigerant is compressed by the first compressor and the second compressor, condensed into liquid refrigerant in the condenser, and evaporated into gaseous refrigerant in the water evaporator. Water at 65°C to 100°C is obtained in the tube side of the condenser, and water at 3°C ​​to 6°C is obtained in the tube side of the water evaporator.

4. The variable-condition high-temperature heat pump system with simultaneous cooling and heating as described in claim 1, characterized in that, When the system operates in the third condition, the first valve is closed, the second valve is open, the third valve is open, the fourth valve is closed, the fifth valve is closed, the sixth valve is open, the seventh valve is open, the eighth valve is closed, the refrigerant pump is on, the ninth valve is open, and the tenth valve is closed. The gaseous refrigerant is compressed by the second compressor, condensed into liquid refrigerant in the condenser, and evaporated into gaseous refrigerant in the water evaporator. Water at 40°C to 65°C is obtained in the tube side of the condenser, and water at 6°C to 10°C is obtained in the tube side of the water evaporator.

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