A fluorine pump double-cycle air conditioning system and a control method thereof

Abstract

The application discloses a fluorine pump double-cycle air conditioning system and a control method thereof. The air conditioning system comprises a compressor, a condenser, a liquid accumulator, a pump, a throttler and an evaporator which are connected in sequence through pipelines. The air conditioning system further comprises a heat exchanger. The pipeline between the condenser and the liquid accumulator is divided into a heat exchange section and two non-heat exchange sections which are connected with two ends of the heat exchange section. The heat exchanger absorbs heat of the heat exchange section through evaporation. An input end of the heat exchanger is communicated with one of the non-heat exchange sections, and an output end of the heat exchanger is communicated with an input end of the compressor. The control method adopts the air conditioning system. The air conditioning system and the control method thereof can increase the supercooling degree of liquid in the liquid accumulator and control the superheating degree of gas at the compressor inlet, thereby avoiding cavitation of the pump and liquid knock of the compressor. The whole system has a simple structure, is more reliable in operation, is simple in pipeline laying and is more convenient in engineering application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of air conditioners, in particular to a fluorine pump double-cycle air conditioning system and a control method thereof. BACKGROUND

[0002] The direct expansion air conditioner used in the traditional old data center adopts a refrigeration mode in which a compressor drives refrigerant to complete cooling in winter, summer and transitional seasons, which is low in energy efficiency and causes energy waste. In northern areas, the outdoor temperature is much lower than the indoor temperature in winter and even in transitional seasons, so the outdoor air becomes a free natural cold source, and the pump can efficiently utilize this natural cold source. By utilizing this natural cold source, the working time of the compressor is reduced, so as to achieve the purpose of energy saving.

[0003] The pump system (also referred to as a refrigerant pump system because the refrigerant commonly used in air conditioning refrigeration systems is freon) is an air conditioning system in which a pump is used to replace a compressor to drive refrigerant. In summer, the data center special air conditioner starts the refrigeration compressor to normally refrigerate, and when the outdoor temperature is lower than the temperature preset by the controller, the controller automatically switches from the compressor refrigeration to the refrigerant pump refrigeration: the freon liquid cooled by the outdoor air-cooled condensing part is delivered to the evaporating part by the refrigerant pump, and after absorbing the heat of the indoor, the freon changes from liquid to gas, enters the air-cooled condensing part, and is cooled into liquid again, and the cycle is repeated. Since the power of the refrigerant pump is much smaller than that of the refrigeration compressor, under the premise of the same refrigeration capacity, the energy efficiency ratio of the refrigerant pump is higher than that of the refrigeration compressor, so that the cooling effect and the energy saving effect are achieved at the same time.

[0004] The fluid passing through the pump should be liquid, and if there is gas in the fluid passing through the pump, cavitation will occur, and the surface of the pump (also referred to as a fluorine pump) impeller will be impacted and eroded by cavitation, resulting in peeling and damage, i.e. cavitation occurs. In addition, cavitation will also cause noise and vibration of the pump, and lead to a decrease in the performance of the pump, and in severe cases, the liquid in the pump will be interrupted and cannot work normally. Therefore, before the pump system is operated, it is necessary to ensure that no gas enters the pump. Similarly, the suction of liquid by the compressor should also be avoided to prevent liquid impact.

[0005] For the current fluorine pump and compressor combined air conditioning system, in order to prevent the problems of cavitation and liquid impact of the fluorine pump and the compressor respectively when the working mode is switched, an additional electromagnetic valve needs to be arranged at the refrigerant inlet side of the fluorine pump and the compressor, and a gas-liquid separator may also need to be arranged at the inlet side of the compressor, which makes the structure of the entire air conditioning system complex and increases the control difficulty of the entire system. SUMMARY

[0006] The present application aims to overcome the above-mentioned defects or problems existing in the background art, and provides a fluorine pump double-cycle air conditioning system and a control method thereof, which can increase the subcooling degree of liquid in a liquid accumulator and control the superheating degree of gas at the inlet of a compressor, thereby avoiding cavitation of the pump and liquid knock of the compressor without using external cold sources, and the whole system is simple in structure, reliable in operation, simple in pipeline laying and convenient in engineering application.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] Technical solution one, a fluorine pump double-cycle air conditioning system, comprising a compressor, a condenser, a liquid accumulator, a pump, a throttler and an evaporator connected in sequence through pipelines, and further comprising a heat exchanger, the pipeline between the condenser and the liquid accumulator is divided into a heat exchange section and two non-heat exchange sections connected with both ends of the heat exchange section, the heat exchanger absorbs heat of the heat exchange section through evaporation, the input end of the heat exchanger is communicated with one of the non-heat exchange sections, and the output end of the heat exchanger is communicated with the input end of the compressor.

[0009] Based on technical solution one, technical solution two is further provided, in which the heat exchanger comprises a bypass expansion valve and a heat exchange chamber, the outlet of the heat exchange chamber forms the output end of the heat exchanger, the pipeline between the inlet of the heat exchange chamber and the non-heat exchange section is a first pipeline, and the bypass expansion valve is connected in series on the first pipeline.

[0010] Based on technical solution two, technical solution three is further provided, in which the inlet of the heat exchange chamber is communicated with the non-heat exchange section close to the liquid accumulator, and the flow direction of gas in the heat exchange chamber is opposite to the flow direction of liquid in the heat exchange section.

[0011] Based on technical solution three, technical solution four is further provided, in which the air conditioning system is divided into an indoor part and an outdoor part, the indoor part comprises the throttler and the evaporator, and the outdoor part comprises the compressor, the condenser, the liquid accumulator, the pump and the heat exchanger.

[0012] Based on technical solution four, technical solution five is further provided, in which the inlet of the liquid accumulator is higher than the outlet thereof.

[0013] Based on technical solution five, technical solution six is further provided, which further comprises a first control valve and a second control valve, the first control valve is connected in parallel through a pipeline between the input end and the output end of the compressor, and the second control valve is connected in parallel through a pipeline between the input end of the liquid accumulator and the output end of the pump.

[0014] The seventh aspect of the present application also provides a control method of the fluorine pump double-cycle air conditioning system, which adopts the air conditioning system of the sixth aspect of the present application, and the control method comprises the following steps: obtaining an outdoor temperature Tout, determining a running refrigeration mode according to a relationship between the Tout, a first set value T1 and a second set value T2, determining to run in a first refrigeration mode if Tout>T1, determining to run in a second refrigeration mode if T2<Tout≤T1, and determining to run in a third refrigeration mode if Tout≤T2; adjusting the running refrigeration mode according to a relationship between the outdoor temperature Tout, the first set value T1, the second set value T2 and a third set value Δt and a current running refrigeration mode; if the current running refrigeration mode is the first refrigeration mode, switching to the second refrigeration mode if T2<Tout≤T1-Δt, switching to the first refrigeration mode if Tout≥T1+Δt, and switching to the third refrigeration mode if Tout≤T2-Δt; if the current running refrigeration mode is the second refrigeration mode, switching to the first refrigeration mode if Tout≥T1+Δt, and switching to the third refrigeration mode if Tout≤T2-Δt; if the current running refrigeration mode is the third refrigeration mode, switching to the second refrigeration mode if T2+Δt≤Tout≤T1; in the first refrigeration mode, the compressor is started and forms a refrigeration cycle with the condenser and the evaporator, and the pump is stopped; in the second refrigeration mode, the compressor and the pump are both started and form a refrigeration cycle with the condenser and the evaporator; and in the third refrigeration mode, the compressor is stopped, the pump is started and forms a refrigeration cycle with the condenser and the evaporator.

[0015] Based on the seventh aspect of the present application, the eighth aspect of the present application is also provided, and in the first refrigeration mode, the first control valve is stopped, and the second control valve and the bypass expansion valve are both started.

[0016] The eighth aspect of the present application is a control method of the fluorine pump double-cycle air conditioning system, which adopts the air conditioning system of the sixth aspect of the present application, and the control method comprises the following steps: obtaining an outdoor temperature Tout, an indoor temperature Tin and a refrigeration demand, obtaining a first set value T1, running in a first refrigeration mode if Tin-Tout<T1 and the refrigeration demand is greater than 100%, running in a second refrigeration mode if Tin-Tout≥T1 and the refrigeration demand is greater than or equal to 100%, and running in a third refrigeration mode if Tin-Tout≥T1 and the refrigeration demand is greater than 30% and less than 100%; in the first refrigeration mode, the compressor is started and forms a refrigeration cycle with the condenser and the evaporator, and the pump is stopped; in the second refrigeration mode, the compressor and the pump are both started and form a refrigeration cycle with the condenser and the evaporator; and in the third refrigeration mode, the compressor is stopped, the pump is started and forms a refrigeration cycle with the condenser and the evaporator.

[0017] Based on technical solution nine, technical solution ten is further provided, in which the refrigeration requirement is obtained by obtaining the indoor target temperature Tset and the second set value T2, and the refrigeration requirement is (Tin-Tset) / T2*100%.

[0018] From the above description of the present application, the present application has the following beneficial effects compared with the prior art:

[0019] 1. In technical solution one, the pipeline between the condenser and the liquid accumulator is divided into a heat exchange section and two non-heat exchange sections connected to both ends of the heat exchange section, that is, the liquid refrigerant of the condenser will pass through the non-heat exchange section, the heat exchange section and the non-heat exchange section in sequence to reach the liquid accumulator; a heat exchanger is provided, the input end of the heat exchanger is communicated with one of the non-heat exchange sections, and the output end of the heat exchanger is communicated with the input end of the compressor; the heat exchanger absorbs the heat of the heat exchange section by evaporation, that is, part of the liquid in one of the non-heat exchange sections flows to the liquid accumulator or the heat exchange section, and part of the liquid flows to the heat exchanger; the liquid flowing to the heat exchanger is evaporated to carry away the heat of the heat exchange section; in this way, the temperature of the liquid refrigerant is reduced after passing through the heat exchange section, and the temperature is greatly reduced after flowing to the liquid accumulator, thereby increasing the supercooling degree of the liquid in the liquid accumulator, ensuring that the pump sucks liquid refrigerant during the starting or refrigeration mode switching process of the pump, rather than gaseous liquid refrigerant, preventing cavitation of the pump, thereby protecting the pump, and the gaseous refrigerant evaporated by the heat exchanger flows to the inlet of the compressor, which can better control the superheat degree of the suction gas of the compressor, thereby preventing the problem of liquid hammering of the compressor due to the suction of liquid refrigerant, improving the stability and reliability of the entire air conditioning system; in addition, in this technical solution, the supercooling degree of the liquid in the liquid accumulator and the superheat degree of the gas at the inlet of the compressor can be increased by providing the heat exchanger, without using an external cold source; the entire system structure is simple, the system operation is more reliable, the pipeline laying is simple, and the engineering application is more convenient.

[0020] 2. In technical solution two, the condenser dissipates the heat of the high-temperature and high-pressure gas delivered by the compressor into low-temperature and high-pressure liquid; the heat exchanger includes a bypass expansion valve and a heat exchange chamber, and the bypass expansion valve is connected in series to the first pipeline, which is conducive to making the low-temperature and high-pressure liquid delivered by the condenser to the heat exchange section become low-temperature and low-pressure wet steam through throttling, and the wet steam is evaporated in the heat exchange chamber to carry away the heat of the heat exchange section, which has a simple structure and is easy to implement.

[0021] 3. In technical solution three, the inlet of the heat exchange chamber is close to the liquid storage tank, that is, the inlet of the heat exchange chamber is connected to the non-heat exchange section connected to the liquid storage tank. Since the non-heat exchange section is connected to the outlet of the heat exchange section, the liquid temperature at the outlet of the heat exchange section is lower than the temperature at the inlet of the heat exchange section. After the liquid at the outlet of the heat exchange section enters the heat exchange chamber through the bypass expansion valve, the heat exchange efficiency is better. The flow direction of the gas in the heat exchange chamber is opposite to the flow direction of the liquid in the heat exchange section, resulting in a larger heat exchange area and higher heat exchange efficiency. In addition, this design is more convenient for pipeline connection and the overall pipeline length is shorter.

[0022] 4. In technical solution four, the outdoor section includes a compressor, condenser, liquid receiver, pump and heat exchanger, which facilitates the connection of the heat exchanger with the non-heat exchange section and the input end of the compressor. The overall pipeline length is shorter, the pipeline laying is simpler, and the engineering application is more convenient.

[0023] 5. In technical solution five, the inlet of the liquid storage pipe is higher than its outlet, which further prevents gas from entering the pump.

[0024] 6. In technical solution six, the setting of the first control valve and the second control valve is conducive to the air conditioning system operating in different cooling modes, which is more energy-efficient and environmentally friendly.

[0025] 7. In technical solution seven, the present invention also provides a control method for a refrigerant pump dual-cycle air conditioning system, which adopts the air conditioning system of technical solution six and has the same advantages as above; and in this solution, when switching from the first cooling mode to the second cooling mode, the outdoor temperature must be less than or equal to T1-△t, and when switching from the second cooling mode to the first cooling mode, the outdoor temperature must be greater than or equal to T1+△t, thus avoiding frequent switching between the first and second cooling modes; when switching from the second cooling mode to the third cooling mode, the outdoor temperature must be less than or equal to T2-△t, and when switching from the third cooling mode to the second cooling mode, the outdoor temperature must be greater than or equal to T2+△t, thus avoiding frequent switching between the second and third cooling modes, thereby avoiding frequent start-stop of the pump or compressor and avoiding unstable indoor operating conditions.

[0026] 8. In technical solution eight, in the first refrigeration mode, the first control valve is closed, and the second control valve and the bypass expansion valve are open. At this time, the refrigerant flows through the compressor and condenser in sequence. After the refrigerant comes out of the condenser, the gas evaporated by the heat exchanger flows into the compressor inlet, ensuring the superheat of the compressor inlet and avoiding liquid slugging in the compressor. In the second and third refrigeration modes, the bypass expansion valve is in the open state, which avoids the compressor from being subjected to liquid slugging. Thus, the compressor can be protected from liquid slugging in all three refrigeration modes.

[0027] 9、In technical solution nine, the application also provides a control method of the fluorine pump double-cycle air conditioning system, which adopts the air conditioning system of technical solution six and has the same advantages as above; in this technical solution, the refrigeration mode is adjusted according to the indoor and outdoor temperature difference and the refrigeration demand, which is more in line with the actual use, so as to ensure that the air conditioning system can always meet the refrigeration demand and ensure the stable operation of the indoor working condition.

[0028] 10、In technical solution ten, the refrigeration demand is determined by the target temperature and the indoor temperature, which is more in line with the actual use. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following briefly introduces the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 It is a schematic diagram of the air conditioning system of the embodiment 1 of the application.

[0031] Figure 2 It is a schematic diagram of the air conditioning system of the embodiment 2 of the application.

[0032] MAIN REFERENCE NUMERALS EXPLANATION

[0033] Compressor 10; Condenser 20; Liquid accumulator 30; Pump 40; Throttling device 50; Evaporator 60; First control valve 70; Second control valve 80; Heat exchanger 90; Heat exchange chamber 91; By-pass expansion valve 92; First branch 01; Second branch 02; Heat exchange section 03; Non-heat exchange section 04; First pipeline 05; Second pipeline 06; Indoor part 100. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are the preferred embodiments of the application, and should not be regarded as exclusion of other embodiments. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0035] In the claims, specification and above drawings of the application, unless otherwise explicitly limited, the terms such as "first", "second" or "third" are used only to distinguish different objects, and are not used to describe a specific order.

[0036] In the claims, the specification, and the drawings of the present application, terms such as "center", "transverse", "longitudinal", "horizontal", "vertical", "top", "bottom", "inner", "outer", "upper", "lower", "front", "rear", "left", "right", "clockwise", "counterclockwise", etc. are used to indicate orientation or positional relationships based on the orientation and position of the apparatus or element shown in the drawings, and are only used for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the apparatus or element referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the specific protection scope of the present application.

[0037] In the claims, the specification, and the drawings of the present application, unless otherwise expressly defined, the term "fixedly connected" or "fixedly connected" should be understood in a broad sense, that is, any connection mode between the two without displacement relationship and relative rotation relationship, that is, it includes non-detachable fixed connection, detachable fixed connection, integration and fixed connection through other devices or elements.

[0038] In the claims, the specification, and the drawings of the present application, the terms "include", "have" and their variants are intended to mean "contain but not limited to".

[0039] Example 1

[0040] Reference Figure 1 , Figure 1 A fluorine pump double-circuit air conditioning system is shown, which includes a compressor 10, a condenser 20, a liquid accumulator 30, a pump 40, a throttling device 50, an evaporator 60, a first control valve 70, a second control valve 80 and a heat exchanger 90.

[0041] The compressor 10, the condenser 20, the liquid accumulator 30, the pump 40, the throttling device 50 and the evaporator 60 are connected in series by pipelines, the first control valve 70 is connected in parallel by pipelines between the input end and the output end of the compressor 10 to form a first branch 01, and the second control valve 80 is connected in parallel by pipelines between the input end of the liquid accumulator 30 and the output end of the pump 40 to form a second branch 02. In this embodiment, the first control valve 70 and the second control valve 80 are both one-way valves, and the throttling device 50 is an electronic expansion valve.

[0042] The embodiment avoids the occurrence of cavitation and liquid hammer mainly by arranging the heat exchanger 90. The pipeline between the condenser 20 and the liquid accumulator 30 is divided into a heat exchange section 03 and two non-heat exchange sections 04 connected with the two ends of the heat exchange section 03, that is, the liquid of the condenser 20 passes through the non-heat exchange sections 04, the heat exchange section 03 and the non-heat exchange sections 04 in sequence to reach the liquid accumulator 30. The heat exchanger 90 absorbs the heat of the heat exchange section 03 by evaporation. The input end of the heat exchanger 90 is communicated with one of the non-heat exchange sections 04, and the output end of the heat exchanger 90 is communicated with the input end of the compressor 10. In the embodiment, the input end of the heat exchanger 90 is communicated with the non-heat exchange section close to the liquid accumulator 30. Thus, part of the liquid of the non-heat exchange section 04 communicated with the input end of the heat exchanger 90 flows to the liquid accumulator 30, and part of the liquid flows to the heat exchanger 90. The liquid flowing to the heat exchanger 90 is evaporated to take away the heat of the heat exchange section 03. Thus, after the liquid passes through the heat exchange section 03, the temperature is reduced, and after the liquid flows to the liquid accumulator 30, the temperature is also greatly reduced, thereby increasing the supercooling degree of the liquid in the liquid accumulator 30, ensuring that the pump 40 sucks the liquid refrigerant instead of the gaseous refrigerant during the starting of the pump 40 or the switching of the refrigeration mode, preventing the cavitation of the pump 40, and protecting the pump 40. The gas evaporated by the heat exchanger 90 flows to the inlet of the compressor 10, which can better control the suction superheat degree of the compressor 10, thereby preventing the liquid hammer of the compressor 10 caused by the suction of the liquid refrigerant, and improving the stability and reliability of the entire air conditioning system.

[0043] Specifically, the heat exchanger 90 includes a bypass expansion valve 92 and a heat exchange chamber 91. The outlet of the heat exchange chamber 91 forms the output end of the heat exchanger 90. The pipeline between the outlet of the heat exchange chamber 91 and the input end of the compressor 10 is the second pipeline 06. The pipeline between the inlet of the heat exchange chamber 91 and the non-heat exchange section 04 is the first pipeline 05. The bypass expansion valve 92 is connected in series with the first pipeline 05. In the embodiment, the inlet of the heat exchange chamber 91 is close to the liquid accumulator 30, that is, the inlet of the heat exchange chamber 91 is communicated with the non-heat exchange section 04 connected with the liquid accumulator 30. Since the non-heat exchange section 04 is communicated with the outlet of the heat exchange section 03, the temperature of the liquid at the outlet of the heat exchange section 03 is lower than the temperature of the liquid at the inlet of the heat exchange section 03. The liquid at the outlet of the heat exchange section 03 has a higher heat exchange efficiency after entering the heat exchange chamber 91 through the bypass expansion valve 92. Moreover, the design is convenient for pipeline connection, and the overall pipeline length is shorter. In the embodiment, the bypass expansion valve 92 is an electronic bypass expansion valve 92. The electronic bypass expansion valve 92 has higher adjustment capacity and adjustment precision, which is beneficial to making the liquid with low temperature and high pressure delivered by the non-heat exchange section 04 into wet steam with low temperature and low pressure through throttling. The wet steam is evaporated in the heat exchange chamber 91 to take away the heat of the heat exchange section 03. The structure is simple and easy to realize.

[0044] The heat exchange chamber 91 mainly adopts the structure of the plate heat exchanger 90 in the embodiment, the plate heat exchanger 90 belongs to the prior art, and details are not repeated in the embodiment, wherein the inlet and the outlet of the heat exchange chamber 90 are located at two ends thereof, so that the flow direction of the gas in the heat exchange chamber 91 is opposite to the flow direction of the liquid in the heat exchange section 03, the heat exchange area is large, and the heat exchange efficiency is higher.

[0045] The liquid storage tank 30 is a liquid storage tank, the inlet of the liquid storage tank is higher than the outlet, and the gas is further prevented from entering the pump 40.

[0046] In the embodiment, the air conditioning system is divided into an indoor part 100 and an outdoor part, the indoor part 100 includes the throttling device 50 and the evaporator 60, and the outdoor part includes the compressor 10, the condenser 20, the liquid storage tank 30, the pump 40 and the heat exchanger 90, so that the first branch 01, the second branch 02, the first pipeline 05 and the second pipeline 06 are located in the outdoor part, the overall pipeline length is shorter, the pipeline laying is simple, and the engineering application is more convenient.

[0047] In actual application, the air conditioning system further includes a controller, the controller is electrically connected with the first control valve 70, the second control valve 80, the compressor 10, the pump 40, the bypass expansion valve 92, the condenser 20, the throttling device 50 and the evaporator 60, and controls the first control valve 70, the second control valve 80, the compressor 10, the pump 40, the bypass expansion valve 92, the condenser 20, the throttling device 50 and the evaporator 60.

[0048] Based on the above air conditioning system, the air conditioning system of the application can operate three refrigeration modes, which are a first refrigeration mode, a second refrigeration mode and a third refrigeration mode.

[0049] In the first refrigeration mode, the first control valve 70 is closed, the second control valve 80 is opened, the bypass expansion valve 92 and the throttling device 50 are opened, the pump 40 is closed, the compressor 10 is opened and forms a refrigeration cycle with the condenser 20 and the evaporator 60, and specifically, the compressor 10 highly compresses the refrigerant circulating from the evaporator 60, compresses the gaseous refrigerant into a high-temperature and high-pressure state and sends it to the condenser 20 to condense into low-temperature and high-pressure refrigerant liquid, the refrigerant liquid passes through the heat exchange section 03, is branched at the outlet of the heat exchange section 03, part of the branched refrigerant liquid flows to the evaporator 60 through the non-heat exchange section 04, the second branch 02 and the throttling device 50, and the other part of the branched refrigerant liquid flows to the heat exchange chamber 91 through the first pipeline 05 and the bypass expansion valve 92, and then flows to the inlet of the compressor 10 through the second pipeline 06, the liquid refrigerant is evaporated into the compressor 10 by absorbing heat through the evaporator 60, and a refrigeration cycle is completed.

[0050] In the second refrigeration mode, the first control valve 70 and the second control valve 80 are closed, the bypass expansion valve 92 and the throttling device 50 are opened, the compressor 10 and the pump 40 are both opened and form a refrigeration cycle with the condenser 20 and the evaporator 60, specifically, the refrigerant out of the compressor 10 is condensed into refrigerant liquid in the condenser 20, the refrigerant liquid passes through the heat exchange section 03, is branched at the outlet of the heat exchange section 03, one part passes through the non-heat exchange section 04, the liquid accumulator 40, the pump 40, the throttling device 50 and flows to the evaporator 60, and the other part passes through the first pipeline 05, the bypass expansion valve 92 and flows to the heat exchange chamber 91, then passes through the second pipeline 06 and flows to the inlet of the compressor 10, the liquid refrigerant absorbs heat and evaporates in the evaporator 60 and enters the compressor 10, to complete a refrigeration cycle.

[0051] In the third refrigeration mode, the first control valve 70, the bypass expansion valve 92 and the throttling device 50 are opened, the second control valve 80 is closed, the compressor 10 is closed, and the pump 40 forms a refrigeration cycle with the condenser 20 and the evaporator 60, specifically, the refrigerant out of the evaporator 60 passes through the first branch 01, is condensed into refrigerant liquid in the condenser 20, the refrigerant liquid passes through the heat exchange section 03, is branched at the outlet of the heat exchange section 03, one part passes through the non-heat exchange section 04, the pump 40, the throttling device 50 and flows to the evaporator 60, and the other part passes through the first pipeline 05, the bypass expansion valve 92 and flows to the heat exchange chamber 91, then passes through the second pipeline 06 and the first branch 01 and flows to the condenser 20, the liquid refrigerant absorbs heat and evaporates in the evaporator 60 and enters the first branch 01, to complete a refrigeration cycle.

[0052] In the embodiment, the supercooling degree of the liquid in the liquid accumulator 30 and the superheating degree of the gas at the inlet of the compressor 10 can be increased by arranging the heat exchanger 90, without using external cold sources, the whole system has simple structure, the system operation is more reliable, the pipeline is simple to lay, and the engineering application is more convenient.

[0053] Embodiment 2

[0054] Embodiment 2 is basically the same as embodiment 1, except that, referring to Figure 2 , the inlet of the heat exchange chamber 91 is communicated with the non-heat exchange section 04 close to the condenser 20, thus, the liquid refrigerant condensed by the condenser 20 flows to the heat exchange chamber 91 through the first pipeline 05 and flows to the heat exchange section 03, the electronic expansion valve 92 makes the liquid at low temperature and high pressure become wet steam at low temperature and low pressure through throttling, so as to take away the heat of the heat exchange section 03, since the flow direction of the gas in the heat exchange chamber 91 is basically the same as the flow direction of the liquid in the heat exchange section 03, the liquid in the heat exchange section 03 is synchronously heat-exchanged, and the heat exchange efficiency is high.

[0055] Embodiment 3

[0056] The present application provides a control method of a control system, which adopts the air conditioning system of embodiment 1 or 2, and the control method comprises:

[0057] An outdoor temperature Tout is acquired, and a running refrigeration mode is determined according to a relationship of Tout with a first set value T1 and a second set value T2, wherein if Tout>T1, the first refrigeration mode is determined to run; if T2<Tout≤T1, the second refrigeration mode is determined to run; and if Tout≤T2, the third refrigeration mode is determined to run;

[0058] The running refrigeration mode is adjusted according to a relationship of the outdoor temperature Tout with the first set value T1, the second set value T2 and a third set value Δt and a current running refrigeration mode;

[0059] If the current is the first refrigeration mode: if T2<Tout≤T1-Δt, the second refrigeration mode is switched to;

[0060] If the current is the second refrigeration mode: if Tout≥T1+Δt, the first refrigeration mode is switched to; and if Tout≤T2-Δt, the third refrigeration mode is switched to;

[0061] If the current is the third refrigeration mode: if T2+Δt≤Tout≤T1, the second refrigeration mode is switched to.

[0062] In the specific implementation, the temperature sensor can be arranged to acquire the outdoor temperature, the first set value is generally 15℃, and the second set value is generally 5℃. The third set value Δt can be set according to the actually measured temperature curve, and in the embodiment, Δt is 2-3℃.

[0063] The control method of the embodiment has the same advantages as the above-mentioned air conditioning system of the embodiments 1 or 2; and in the embodiment, when the first refrigeration mode is switched to the second refrigeration mode, the outdoor temperature needs to be less than or equal to T1-Δt; when the second refrigeration mode is switched to the first refrigeration mode, the outdoor temperature needs to be greater than or equal to T1+Δt, thereby avoiding frequent switching between the first refrigeration mode and the second refrigeration mode; when the second refrigeration mode is switched to the third refrigeration mode, the outdoor temperature needs to be less than or equal to T2-Δt; and when the third refrigeration mode is switched to the second refrigeration mode, the outdoor temperature needs to be greater than or equal to T2+Δt, thereby avoiding frequent switching between the second refrigeration mode and the third refrigeration mode, avoiding frequent starting and stopping of the pump 40 or the compressor 10, and avoiding unstable indoor working conditions.

[0064] Embodiment 3

[0065] The application provides a control method of a control system, which adopts the air conditioning system of the embodiments 1 or 2, and the control method comprises the following steps:

[0066] Obtaining outdoor temperature Tout, indoor temperature Tin, first set value T1 and refrigeration demand; obtaining refrigeration demand includes the following steps, obtaining indoor target temperature Tset and second set value T2, and the refrigeration demand is (Tin-Tset) / T2*100%.

[0067] If Tin-ToutT1 and the refrigeration demand is greater than 100%, the first refrigeration mode is run;

[0068] If Tin-ToutT1 and the refrigeration demand is greater than or equal to 100%, the second refrigeration mode is run;

[0069] If Tin-ToutT1 and the refrigeration demand is greater than 30% and less than 100%, the third refrigeration mode is run.

[0070] In the specific implementation, the temperature sensor can be arranged to collect the outdoor temperature and the indoor temperature, which belongs to the prior art, and the present embodiment will not be described any more. In the actual application, T1 is generally 20℃, and T2 is generally 3℃.

[0071] The control method of the present embodiment has the same advantages as the air conditioning system of the embodiments 1 or 2. In the present technical solution, the refrigeration mode is adjusted according to the indoor and outdoor temperature difference and the refrigeration demand, which is more in line with the actual use, so as to ensure that the air conditioning system can always meet the refrigeration demand and ensure the stable operation of the indoor working condition.

[0072] The description of the above specification and embodiments is used to explain the protection scope of the present application, but does not constitute the limitation of the protection scope of the present application. Through the inspiration of the present application or the above embodiments, the modification, equivalent replacement or other improvement of the embodiments of the present application or one part of the technical features can be obtained by the ordinary skilled in the art combining with the common knowledge, the ordinary technical knowledge and / or the prior art in the field, through the logical analysis, reasoning or limited test, which should be included in the protection scope of the present application.

Claims

1. A fluorine pump double cycle air conditioning system comprising a compressor (10), a condenser (20), a liquid accumulator (30), a pump (40), a throttling device (50) and an evaporator (60) connected in series through pipes, characterized in that, The air conditioning system further comprises a heat exchanger (90), a pipeline between the condenser (20) and the liquid reservoir (30) is divided into a heat exchange section (03) and two non-heat exchange sections (04) connected with both ends of the heat exchange section (03), the heat exchanger (90) absorbs heat of the heat exchange section (03) by evaporation, an input end of the heat exchanger (90) is communicated with one of the non-heat exchange sections (04), and an output end of the heat exchanger (90) is communicated with an input end of the compressor (10); The heat exchanger (90) comprises a bypass expansion valve (92) and a heat exchange chamber (91), the heat exchange chamber (91) forms the output end of the heat exchanger (90), a pipeline between an inlet of the heat exchange chamber (91) and the non-heat exchange section (04) is a first pipeline (05), and the bypass expansion valve (92) is connected in series with the first pipeline (05).

2. A fluorine pump dual cycle air conditioning system as claimed in claim 1, wherein, The inlet of the heat exchange chamber (91) is communicated with the non-heat exchange section (04) close to the liquid reservoir (30), and a flow direction of gas in the heat exchange chamber (91) is opposite to a flow direction of liquid in the heat exchange section (03).

3. A fluoro-pump dual-cycle air conditioning system as set forth in claim 2, characterized in that, The air conditioning system is divided into an indoor part (100) and an outdoor part, the indoor part (100) comprises the throttling device (50) and the evaporator (60), and the outdoor part comprises the compressor (10), the condenser (20), the liquid reservoir (30), the pump (40) and the heat exchanger (90).

4. A fluoro-pump dual-cycle air conditioning system as set forth in claim 3, characterized in that, The inlet of the liquid reservoir (30) is higher than the outlet thereof.

5. A fluoro-pump dual-cycle air conditioning system as set forth in claim 4, characterized in that, The air conditioning system further comprises a first control valve (70) and a second control valve (80), the first control valve (70) is connected in parallel with the compressor (10) through a pipeline, and the second control valve (80) is connected in parallel with the liquid reservoir (30) through a pipeline.

6. A control method of a fluorine pump double cycle air conditioning system, characterized by, The air conditioning system adopts the fluorine pump double-cycle air conditioning system of claim 5, and the control method comprises the following steps of: An outdoor temperature Tout is acquired, a running refrigeration mode is determined according to a relationship between the outdoor temperature Tout and first and second set values T1 and T2, if Tout>T1, the first refrigeration mode is determined to run, if T2 The running refrigeration mode is adjusted according to a relationship between the outdoor temperature Tout and the first, second and third set values T1, T2 and Δt and the current running refrigeration mode; If the current running refrigeration mode is the first refrigeration mode, if T2 If the current running refrigeration mode is the second refrigeration mode, if Tout≥T1+Δt, the first refrigeration mode is switched to; if Tout≤T2-Δt, the third refrigeration mode is switched to; If the current running refrigeration mode is the third refrigeration mode, if T2+Δt≤Tout≤T1, the second refrigeration mode is switched to; In the first refrigeration mode, the compressor (10) is started and forms a refrigeration cycle with the condenser (20) and the evaporator (60), and the pump (40) is stopped; In the second refrigeration mode, the compressor (10) and the pump (40) are both turned on and form refrigeration cycle with the condenser (20) and the evaporator (60). In the third refrigeration mode, the compressor (10) is turned off, and the pump (40) is turned on and forms refrigeration cycle with the condenser (20) and the evaporator (60).

7. The control method of a fluoro-pump dual cycle air conditioning system as set forth in claim 6, characterized in that, in In the first refrigeration mode, the first control valve (70) is turned off, and the second control valve (80) and the bypass expansion valve (92) are both turned on.

8. A control method of a fluorine pump double cycle air conditioning system, characterized by, The control method comprises: Obtaining outdoor temperature Tout, indoor temperature Tin and refrigeration demand, obtaining a first set value T1; If Tin-Tout < T1 and the refrigeration demand is greater than 100%, the first refrigeration mode is used for operation; If Tin-Tout ≥ T1 and the refrigeration demand is greater than or equal to 100%, the second refrigeration mode is used for operation; If Tin-Tout ≥ T1 and the refrigeration demand is greater than 30% and less than 100%, the third refrigeration mode is used for operation; In the first refrigeration mode, the compressor (10) is turned on and forms refrigeration cycle with the condenser (20) and the evaporator (60), and the pump (40) is turned off. In the second refrigeration mode, the compressor (10) and the pump (40) are both turned on and form refrigeration cycle with the condenser (20) and the evaporator (60). In the third refrigeration mode, the compressor (10) is turned off, and the pump (40) is turned on and forms refrigeration cycle with the condenser (20) and the evaporator (60).

9. The control method of a fluoro-pump dual cycle air conditioning system according to claim 8, wherein, Obtaining the refrigeration demand comprises the following steps: obtaining indoor target temperature Tset and a second set value T2, and the refrigeration demand is (Tin-Tset) / T2*100%.

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