Heat pump unit and control method thereof

Abstract

The application provides a heat pump unit and a control method thereof. The heat pump unit comprises a compressor, a condenser, a main cycle throttling element and an evaporator forming a refrigerant refrigeration cycle. A gas-liquid separator is further arranged on a pipeline between the evaporator and a suction port of the compressor. The heat pump unit further comprises a cooling system, which comprises a first refrigerant pipeline. One end of the first refrigerant pipeline is communicated with the condenser, and refrigerant in the first refrigerant pipeline can heat refrigerant in the gas-liquid separator. Refrigerant flowing out of the first refrigerant pipeline can cool a motor in the compressor and / or lubricating oil of a lubricating oil system arranged in the heat pump unit. The first refrigerant pipeline takes high-temperature liquid-phase refrigerant from the bottom of the condenser to heat refrigerant in the gas-liquid separator, reduces the liquid-phase component of the refrigerant in the gas-liquid separator, and prevents the occurrence of suction liquid carrying. The high-temperature liquid-phase refrigerant is guided to cool the motor in the compressor and / or the lubricating oil of the lubricating oil system after being cooled, and the cooling effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of heat pump system design technology, specifically relating to a heat pump unit and its control method, and more particularly to an energy-saving refrigeration and air conditioning equipment. Background Technology

[0002] Driven by the need to achieve the "dual carbon" goal, the application of high-temperature heat pump centrifugal chillers (i.e., high-temperature heat pump units) in heating applications with higher heating temperatures is a future development trend. The main components of a high-temperature heat pump unit are a compressor, evaporator, condenser, and throttling electronic expansion valve. These components are connected by pipelines to form a refrigeration cycle system, completing the cycle of refrigerant compression, condensation, throttling, and evaporation. To ensure the normal operation of the unit, it is equipped with a cooling system to cool the motor and lubricating oil inside the compressor, as well as an oil supply system to supply oil to the compressor bearings.

[0003] High-temperature heat pump units utilize the heat generated during the condensation of the high-temperature refrigerant discharged from the compressor to heat the water inside the condenser and produce high-temperature hot water. The condenser water temperature in high-temperature heat pump units is often very high, and the water temperatures in the evaporator and condenser often differ significantly. Under conditions of large temperature difference (low evaporation temperature, high condensation temperature, correspondingly large temperature difference) and high condenser water temperature, the liquid refrigerant level in the evaporator can easily rise above the area above the internal filter screen, causing liquid carryover in the compressor's suction. Prolonged liquid carryover in the compressor's suction can lead to serious consequences such as compressor liquid slugging damage, bearing wear, and motor burnout. Summary of the Invention

[0004] Therefore, the present invention provides a heat pump unit and its control method, which can overcome the shortcomings of related technologies in heat pump units, such as the large temperature difference between the condenser and the evaporator, and the high water temperature of the condenser causing the compressor to easily suck in liquid, which in turn leads to serious consequences such as compressor liquid slugging damage, bearing wear, and motor burnout.

[0005] To address the aforementioned problems, this invention provides a heat pump unit, comprising a compressor, a condenser, a main circulation throttling element, and an evaporator forming a refrigerant refrigeration cycle. A gas-liquid separator is also provided on the pipeline between the evaporator and the suction port of the compressor. The heat pump unit further includes a cooling system, which includes a first refrigerant pipeline. A first end of the first refrigerant pipeline is connected to the bottom of the condenser, and the refrigerant in the first refrigerant pipeline can heat the refrigerant in the gas-liquid separator. The refrigerant flowing out from the second end of the first refrigerant pipeline can cool the motor in the compressor and / or cool the lubricating oil in the lubricating oil system configured in the heat pump unit.

[0006] In some embodiments, the gas-liquid separator has a gas phase refrigerant zone and a liquid phase refrigerant zone. The first refrigerant pipeline includes a first heat exchange tube and a second heat exchange tube connected in parallel. The first heat exchange tube corresponds to the position of the gas phase refrigerant zone, and the second heat exchange tube corresponds to the position of the liquid phase refrigerant zone. The refrigerant inlets of the first heat exchange tube and the second heat exchange tube are combined to form the first end of the first refrigerant pipeline, and the refrigerant outlets of the first heat exchange tube and the second heat exchange tube are combined to form the second end of the first refrigerant pipeline.

[0007] In some embodiments, the cooling system further includes a subcooling heat exchanger and a subcooling pipeline. The subcooling heat exchanger has a third heat exchange tube and a fourth heat exchange tube for heat exchange. The refrigerant inlet of the subcooling pipeline is connected to the bottom of the condenser. The refrigerant inlet of the third heat exchange tube is connected to the second end of the first refrigerant pipeline so that the refrigerant flowing out of the second end of the first refrigerant pipeline can flow out through the third heat exchange tube to cool the motor in the compressor and / or cool the lubricating oil in the lubricating oil system of the heat pump unit. The refrigerant inlet of the fourth heat exchange tube is connected to the refrigerant outlet of the subcooling pipeline, and the refrigerant outlet of the fourth heat exchange tube is connected to the evaporator. A first throttling element is connected in series on the subcooling pipeline.

[0008] In some embodiments, an electromagnetic on / off valve is connected in series on the subcooling line.

[0009] In some embodiments, the cooling system further includes a motor cooling branch, a second throttling element connected in series in the motor cooling branch, a refrigerant inlet of the motor cooling branch connected to a refrigerant outlet of the third heat exchange tube, and a refrigerant outlet of the motor cooling branch connected to a motor cavity of the compressor.

[0010] In some embodiments, the cooling system further includes a lubricating oil cooling branch and an oil-cooled heat exchanger. The oil-cooled heat exchanger has a fifth heat exchange tube and a sixth heat exchange tube for heat exchange. The refrigerant inlet of the lubricating oil cooling branch is connected to the refrigerant outlet of the third heat exchange tube, the refrigerant outlet of the lubricating oil cooling branch is connected to the fifth heat exchange tube, the refrigerant outlet of the fifth heat exchange tube is connected to the evaporator, the inlet of the sixth heat exchange tube is connected to the oil outlet of the oil reservoir of the lubricating oil system, and the outlet of the sixth heat exchange tube is connected to the high-level oil tank of the compressor.

[0011] In some embodiments, a third throttling element is connected in series in the lubricating oil cooling branch.

[0012] In some embodiments, the heat pump unit further includes a flash evaporator, the main circulation throttling element includes a first orifice plate and a second orifice plate, the inlet of the flash evaporator is connected to the refrigerant outlet of the condenser via a first connecting pipe, the first orifice plate is connected in series on the first connecting pipe, the liquid outlet of the flash evaporator is connected to the refrigerant inlet of the evaporator via a second connecting pipe, the second connecting pipe is connected in series with a second orifice plate, and the gas outlet of the flash evaporator is connected to the gas supply port of the compressor.

[0013] In some embodiments, a throttling pipe is provided between the condenser and the evaporator, and a fourth throttling element is connected in series on the throttling pipe.

[0014] The present invention also provides a control method for the above-mentioned heat pump unit, comprising the following steps:

[0015] Obtain the real-time water temperature inside the condenser;

[0016] When the real-time water temperature is higher than the preset temperature value, the solenoid valve is controlled to be in the connected state; otherwise, the solenoid valve is controlled to be in the disconnected state.

[0017] The heat pump unit and its control method provided by this invention have the following beneficial effects:

[0018] On the one hand, a gas-liquid separator is installed on the pipeline between the compressor and the evaporator to separate the liquid refrigerant in the suction gas when the first filter in the evaporator loses its gas-liquid separation function, thereby reducing the probability of liquid carryover in the suction gas. On the other hand, the high-temperature liquid refrigerant is taken out from the bottom of the condenser through the first refrigerant pipeline of the cooling system to heat the refrigerant in the gas-liquid separator, which can further reduce the liquid phase composition of the refrigerant in the gas-liquid separator and prevent liquid carryover in the compressor suction gas. At the same time, the high-temperature liquid refrigerant in the first refrigerant pipeline is cooled down and then guided to cool the motor and / or lubricating oil in the compressor's lubrication system, which can also improve the cooling effect. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the system principle of the heat pump unit in an embodiment of the present invention;

[0021] Figure 2 yes Figure 1 A schematic diagram of the structure of a gas-liquid separator.

[0022] The attached figures are labeled as follows:

[0023] 1. Compressor; 11. High-level oil tank; 2. Condenser; 21. First inlet pipe; 22. First outlet pipe; 23. Check valve; 3. Evaporator; 31. Second inlet pipe; 32. Second outlet pipe; 4. Gas-liquid separator; 41. Baffle plate; 42. Second filter screen; 5. Subcooling heat exchanger; 51. Third heat exchange tube; 52. Fourth heat exchange tube; 6. Oil-cooled heat exchanger; 61. Fifth heat exchange tube; 62. Sixth heat exchange tube; 7. Oil tank; 71. Oil pump; 81. First orifice plate; 82. Second orifice plate; 9. Flash evaporator; 101. First heat exchange tube; 102. Second heat exchange tube; 200. Subcooling pipeline; 201. First throttling element; 202. Solenoid on / off valve; 300. Motor cooling branch; 301. Second throttling element; 400. Lubricating oil cooling branch; 401. Third throttling element; 500. Throttling pipeline; 501. Fourth throttling element. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0026] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0027] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0028] See also Figures 1 to 2As shown in the embodiment of the present invention, a heat pump unit, particularly a high-temperature heat pump centrifugal chiller unit, is provided, including a compressor 1 forming a refrigerant refrigeration cycle, a condenser 2, a main cycle throttling element, and an evaporator 3. A gas-liquid separator 4 is also provided on the pipeline between the evaporator 3 and the suction port of the compressor 1. It is understood that a first filter screen (not shown in the figure) is generally provided in the upper region of the evaporator 3. This first filter screen can form a certain degree of gas-liquid separation for the refrigerant in the evaporator 3. However, when the temperature difference between the condenser 2 and the evaporator 3 in the heat pump unit is too large, the liquid refrigerant level in the evaporator 3 will be higher than the first filter screen. At this time, the gas-liquid separation function of the first filter screen will be lost. In this case, the gas-liquid separator 4 can separate the refrigerant flowing out of the evaporator 3 into gas and liquid phases. Liquid phase separation reduces the liquid carryover phenomenon in the suction of compressor 1 to some extent. However, it should be noted that even with the aforementioned gas-liquid separator 4 further installed in the suction line of compressor 1, the suction of compressor 1 can still easily carry liquid refrigerant during high-frequency operation. Based on this, the present invention further includes the following design: the heat pump unit also includes a cooling system (not shown in the figure), which includes a first refrigerant line (not labeled in the figure). The first end of the first refrigerant line is connected to the bottom of the condenser 2, and the refrigerant in the first refrigerant line can heat the refrigerant in the gas-liquid separator 4. The refrigerant flowing out from the second end of the first refrigerant line can cool the motor in compressor 1 and / or cool the lubricating oil in the lubrication system of the heat pump unit. The bottom of the aforementioned condenser 2 refers to the area below the condenser 2 when it is in use, which corresponds to the storage area of ​​the liquid refrigerant in the condenser 2.

[0029] In this technical solution, on the one hand, a gas-liquid separator 4 is installed on the pipeline between the compressor 1 and the evaporator 3 to separate the liquid refrigerant in the suction gas when the first filter in the evaporator 3 loses its gas-liquid separation function, thereby reducing the probability of liquid carryover in the suction gas. On the other hand, the high-temperature liquid refrigerant is taken out from the bottom of the condenser 2 through the first refrigerant pipeline of the cooling system to heat the refrigerant in the gas-liquid separator 4, which can further reduce the liquid phase composition of the refrigerant in the gas-liquid separator 4 and prevent liquid carryover in the compressor suction gas. At the same time, the high-temperature liquid refrigerant in the first refrigerant pipeline is cooled down and then guided to cool the motor and / or lubricating oil in the lubricating oil system of the compressor 1, which can also improve the cooling effect.

[0030] It should be noted that, since this invention can eliminate the phenomenon of liquid carrying in the compressor 1 during air intake and improve the cooling effect on the motor and lubricating oil, it can avoid serious consequences such as impeller damage, bearing wear, and motor burnout caused by liquid carrying in the air or poor cooling, thus greatly improving the operational reliability of the high-temperature heat pump unit.

[0031] In some embodiments, the gas-liquid separator 4 has a gas phase refrigerant zone (not labeled in the figure) and a liquid phase refrigerant zone (not labeled in the figure). The first refrigerant pipeline includes a first heat exchange tube 101 and a second heat exchange tube 102 connected in parallel. The first heat exchange tube 101 corresponds to the position of the gas phase refrigerant zone, and the second heat exchange tube 102 corresponds to the position of the liquid phase refrigerant zone. The refrigerant inlets of the first heat exchange tube 101 and the second heat exchange tube 102 are combined to form the first end of the first refrigerant pipeline, and the refrigerant outlets of the first heat exchange tube 101 and the second heat exchange tube 102 are combined to form the second end of the first refrigerant pipeline.

[0032] In this technical solution, the first heat exchange tube 101 and the second heat exchange tube 102, which are connected in parallel, are respectively set to correspond to the gas phase refrigerant zone and the liquid phase refrigerant zone in the gas-liquid separator 4. The high-temperature refrigerant in the first heat exchange tube 101 can heat the refrigerant in the gas phase refrigerant zone, and the high-temperature refrigerant in the second heat exchange tube 102 can heat the refrigerant in the liquid phase refrigerant zone. In this way, the liquid phase refrigerant in the gas-liquid separator 4 is vaporized while the suction superheat of the compressor 1 is increased, effectively preventing the occurrence of liquid carryover in the compressor suction.

[0033] Both the aforementioned first heat exchange tube 101 and second heat exchange tube 102 can be coiled structures, which can be wound around the outer wall of the gas-liquid separator 4. This arrangement simplifies the structural design of the gas-liquid separator 4. In another feasible embodiment, the first heat exchange tube 101 and the second heat exchange tube 102 each have an internal tube section located within the internal accommodating space of the gas-liquid separator 4. The internal tube section has a coiled structure, which allows direct contact with the refrigerant, resulting in higher heat exchange efficiency. It should be noted that the refrigerant temperature inside the gas-liquid separator 4 is the lowest in the entire refrigeration system, effectively cooling the refrigerant in the first refrigerant pipeline.

[0034] It is understood that, in use, the gas phase refrigerant zone of the gas-liquid separator 4 is above the liquid phase refrigerant zone, and the proportions of the gas phase refrigerant zone and the liquid phase refrigerant zone in the internal space of the gas-liquid separator 4 change dynamically under different system operating conditions. Therefore, in a specific embodiment, the first heat exchange tube 101 and the second heat exchange tube 102 are respectively located at the top and bottom of the gas-liquid separator 4.

[0035] See details Figure 2 As shown, the gas-liquid separator 4 includes a housing (not labeled in the figure), and a second filter screen 42 and a baffle plate 41 are arranged vertically and vertically inside the housing. There are at least two baffle plates 41 spaced vertically. The second filter screen 42 can further realize gas-liquid separation.

[0036] See details Figure 1As shown, the condenser 2 has a first inlet pipe 21 and a first outlet pipe 22. The first inlet pipe 21 and the first outlet pipe 22 form a water circulation with external load equipment (such as heating devices). The water entering through the first inlet pipe 21 exchanges heat with the refrigerant in the condenser 2 and then flows out through the first outlet pipe 22, realizing the transfer of heat from the refrigerant in the condenser 2 to the external load equipment. The evaporator 3 has a second inlet pipe 31 and a second outlet pipe 32. The second inlet pipe 31 and the second outlet pipe 32 form a water circulation with an external heat source (such as industrial wastewater). The water entering through the second inlet pipe 31 exchanges heat with the refrigerant in the evaporator 3 and then flows out through the second outlet pipe 32, realizing the absorption and transfer of waste heat from the external heat source by the refrigerant.

[0037] In some embodiments, the cooling system further includes a subcooling heat exchanger 5 and a subcooling pipe 200. The subcooling heat exchanger 5 has a third heat exchange tube 51 and a fourth heat exchange tube 52 that form a heat exchange. The refrigerant inlet of the subcooling pipe 200 is connected to the bottom of the condenser 2. The refrigerant inlet of the third heat exchange tube 51 is connected to the second end of the first refrigerant pipe so that the refrigerant flowing out of the second end of the first refrigerant pipe can flow out through the third heat exchange tube 51 to cool the motor in the compressor 1 and / or cool the lubricating oil in the lubricating oil system configured in the heat pump unit. The refrigerant inlet of the fourth heat exchange tube 52 is connected to the refrigerant outlet of the subcooling pipe 200. The refrigerant outlet of the fourth heat exchange tube 52 is connected to the evaporator 3. A first throttling element 201 is connected in series on the subcooling pipe 200. The first throttling element 201 may be, for example, a capillary tube.

[0038] In this technical solution, by setting a subcooling heat exchanger 5 at the second end of the first refrigerant pipeline, and using the refrigerant in the condenser 2 to subcool the refrigerant flowing out of the first refrigerant pipeline after throttling and cooling by the first throttling element 201, the cooling effect of the refrigerant on the motor and lubricating oil can be further improved. In a specific embodiment, the aforementioned subcooling heat exchanger 5 can be a plate heat exchanger.

[0039] In some embodiments, an electromagnetic on / off valve 202 is connected in series with the subcooling pipe 200.

[0040] In this technical solution, an electromagnetic on / off valve 202 is further connected in series on the subcooling pipeline 200. This allows the switching of its on / off state to be controlled according to the actual load requirements of the system, thereby enabling the refrigerant drawn from the first refrigerant pipeline to be subjected to primary or secondary cooling.

[0041] In some embodiments, the cooling system further includes a motor cooling branch 300, on which a second throttling element 301 is connected in series. The refrigerant inlet of the motor cooling branch 300 is connected to the refrigerant outlet of the third heat exchange tube 51, and the refrigerant outlet of the motor cooling branch 300 is connected to the motor cavity (not labeled in the figure) of the compressor 1. The aforementioned second throttling element 301 may, for example, be a capillary tube.

[0042] In this technical solution, a second throttling element 301 is further connected in series on the motor cooling branch 300, which can further throttle and cool the refrigerant, thereby improving the cooling effect on the motor.

[0043] In some embodiments, the cooling system further includes a lubricating oil cooling branch 400 and an oil-cooled heat exchanger 6. The oil-cooled heat exchanger 6 has a fifth heat exchange tube 61 and a sixth heat exchange tube 62 for heat exchange. The refrigerant inlet of the lubricating oil cooling branch 400 is connected to the refrigerant outlet of the third heat exchange tube 51, the refrigerant outlet of the lubricating oil cooling branch 400 is connected to the fifth heat exchange tube 61, the refrigerant outlet of the fifth heat exchange tube 61 is connected to the evaporator 3, and the inlet of the sixth heat exchange tube 62 is connected to the oil outlet of the oil reservoir 7 of the lubricating oil system. The outlet of the sixth heat exchange tube 62 is connected to the high-level oil tank 11 of the compressor 1. It is understood that an oil pump 71 is installed in the oil storage tank 7 to pump the lubricating oil in the oil storage tank 7 to the aforementioned high-level oil tank 11. The aforementioned high-level oil tank 11 is specifically located at a high position on the compressor 1 body. The lubricating oil entering the high-level oil tank 11 can be further guided to the bearings and other friction pairs within the compressor 1 for cooling and lubrication, preventing the compressor bearings from lacking oil and wearing out when the oil pump stops in the event of a power outage. In the event of a power outage, the oil in the high-level oil tank 11 can continue to supply oil to the bearings by gravity. Furthermore, a lubricating oil circulation can be formed between the oil storage tank 7 and the internal space of the compressor 1, as shown in the figure. The aforementioned oil-cooled heat exchanger 6 can also be a plate heat exchanger.

[0044] In this technical solution, the refrigerant achieves efficient cooling of the lubricating oil within the oil-cooled heat exchanger 6, ensuring effective lubrication and cooling of other friction pairs in the compressor and other systems.

[0045] In some embodiments, a third throttling element 401 is connected in series on the lubricating oil cooling branch 400 to further throttle and cool the refrigerant entering the oil-cooled heat exchanger 6, thereby improving the cooling effect on the lubricating oil.

[0046] In some embodiments, the third throttling element 401 is an electronic expansion valve, which allows for precise control of the lubricating oil temperature by adjusting the opening of the electronic expansion valve.

[0047] In some embodiments, the heat pump unit further includes a flash evaporator 9. The main circulation throttling element includes a first orifice plate 81 and a second orifice plate 82. The inlet of the flash evaporator 9 is connected to the refrigerant outlet of the condenser 2 via a first connecting pipe (not labeled in the figure). The first orifice plate 81 is connected in series with the first connecting pipe. The liquid outlet of the flash evaporator 9 is connected to the refrigerant inlet of the evaporator 3 via a second connecting pipe (not labeled in the figure). The second orifice plate 82 is connected in series with the second connecting pipe. The gas outlet of the flash evaporator 9 is connected to the gas supply port of the compressor 1. The purpose of supplying gas to the compressor 1 and increasing enthalpy is achieved by setting the flash evaporator 9, which can significantly improve the working performance of the heat pump unit. When the compression component of the compressor 1 is a two-stage impeller, the flash evaporator 9 should be configured.

[0048] In some embodiments, a throttling pipe 500 is provided between the condenser 2 and the evaporator 3, and a fourth throttling element 501 is connected in series on the throttling pipe 500. The aforementioned fourth throttling element 501 is specifically an electronic expansion valve. In this technical solution, a throttling pipe 500 connected in parallel with the aforementioned first orifice plate 81 and second orifice plate 82 is provided between the condenser 2 and the evaporator 3, so that the heat pump unit of the present invention can meet a wider range of operating load requirements.

[0049] According to an embodiment of the present invention, a control method for the above-described heat pump unit is also provided, comprising the following steps:

[0050] Obtain the real-time water temperature inside the condenser 2;

[0051] When the real-time water temperature is higher than the preset temperature value, the solenoid on / off valve 202 is controlled to be in the connected state, and the secondary cooling mode is activated. That is, the gas-liquid separator 4 and the subcooling heat exchanger 5 are used to cool the refrigerant in the first refrigerant pipeline to ensure sufficient cooling of the motor and lubricating oil. Otherwise, the solenoid on / off valve 202 is controlled to be in the disconnected state so that when the real-time water temperature in the condenser 2 decreases, only the primary cooling mode is activated. That is, only the gas-liquid separator 4 is used to cool the refrigerant in the first refrigerant pipeline, which improves the unit's energy efficiency under this condition and effectively prevents liquid from being carried in the compressor 1's suction.

[0052] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A heat pump unit, comprising a compressor (1) forming a refrigerant refrigeration cycle, a condenser (2), a main cycle throttling element, and an evaporator (3), characterized in that, A gas-liquid separator (4) is also provided on the pipeline between the evaporator (3) and the suction port of the compressor (1). The heat pump unit also includes a cooling system. The cooling system includes a first refrigerant pipeline. The first end of the first refrigerant pipeline is connected to the bottom of the condenser (2). The refrigerant in the first refrigerant pipeline can heat the refrigerant in the gas-liquid separator (4). The refrigerant flowing out from the second end of the first refrigerant pipeline can cool the motor in the compressor (1) and / or cool the lubricating oil in the lubricating oil system configured in the heat pump unit.

2. The heat pump unit according to claim 1, characterized in that, The gas-liquid separator (4) has a gas phase refrigerant zone and a liquid phase refrigerant zone. The first refrigerant pipeline includes a first heat exchange tube (101) and a second heat exchange tube (102) connected in parallel. The first heat exchange tube (101) corresponds to the position of the gas phase refrigerant zone, and the second heat exchange tube (102) corresponds to the position of the liquid phase refrigerant zone. The refrigerant inlets of the first heat exchange tube (101) and the second heat exchange tube (102) are combined to form the first end of the first refrigerant pipeline, and the refrigerant outlets of the first heat exchange tube (101) and the second heat exchange tube (102) are combined to form the second end of the first refrigerant pipeline.

3. The heat pump unit according to claim 1, characterized in that, The cooling system further includes a subcooling heat exchanger (5) and a subcooling pipeline (200). The subcooling heat exchanger (5) has a third heat exchange tube (51) and a fourth heat exchange tube (52) for heat exchange. The refrigerant inlet of the subcooling pipeline (200) is connected to the bottom of the condenser (2). The refrigerant inlet of the third heat exchange tube (51) is connected to the second end of the first refrigerant pipeline so that the refrigerant flowing out of the second end of the first refrigerant pipeline can flow out through the third heat exchange tube (51) to cool the motor in the compressor (1) and / or cool the lubricating oil of the lubricating oil system configured in the heat pump unit. The refrigerant inlet of the fourth heat exchange tube (52) is connected to the refrigerant outlet of the subcooling pipeline (200). The refrigerant outlet of the fourth heat exchange tube (52) is connected to the evaporator (3). A first throttling element (201) is connected in series on the subcooling pipeline (200).

4. The heat pump unit according to claim 3, characterized in that, An electromagnetic on / off valve (202) is connected in series on the subcooling pipeline (200).

5. The heat pump unit according to claim 3, characterized in that, The cooling system also includes a motor cooling branch (300), on which a second throttling element (301) is connected in series. The refrigerant inlet of the motor cooling branch (300) is connected to the refrigerant outlet of the third heat exchange tube (51), and the refrigerant outlet of the motor cooling branch (300) is connected to the motor cavity of the compressor (1).

6. The heat pump unit according to claim 5, characterized in that, The cooling system also includes a lubricating oil cooling branch (400) and an oil-cooled heat exchanger (6). The oil-cooled heat exchanger (6) has a fifth heat exchange tube (61) and a sixth heat exchange tube (62) for heat exchange. The refrigerant inlet of the lubricating oil cooling branch (400) is connected to the refrigerant outlet of the third heat exchange tube (51). The refrigerant outlet of the lubricating oil cooling branch (400) is connected to the fifth heat exchange tube (61). The refrigerant outlet of the fifth heat exchange tube (61) is connected to the evaporator (3). The inlet of the sixth heat exchange tube (62) is connected to the oil outlet of the oil storage tank (7) of the lubricating oil system. The outlet of the sixth heat exchange tube (62) is connected to the high-level oil tank (11) of the compressor (1).

7. The heat pump unit according to claim 6, characterized in that, A third throttling element (401) is connected in series on the lubricating oil cooling branch (400).

8. The heat pump unit according to claim 1, characterized in that, It also includes a flash evaporator (9), the main circulation throttling element includes a first orifice plate (81) and a second orifice plate (82), the inlet of the flash evaporator (9) is connected to the refrigerant outlet of the condenser (2) via a first connecting pipe, the first orifice plate (81) is connected in series on the first connecting pipe, the liquid outlet of the flash evaporator (9) is connected to the refrigerant inlet of the evaporator (3) via a second connecting pipe, the second connecting pipe is connected in series with a second orifice plate (82), and the gas outlet of the flash evaporator (9) is connected to the gas supply port of the compressor (1).

9. The heat pump unit according to claim 1, characterized in that, A throttling pipe (500) is also provided between the condenser (2) and the evaporator (3), and a fourth throttling element (501) is connected in series on the throttling pipe (500).

10. A control method for a heat pump unit as described in claim 4, characterized in that, Includes the following steps: Obtain the real-time water temperature inside the condenser (2); When the real-time water temperature is higher than the preset temperature value, the electromagnetic on / off valve (202) is controlled to be in the connected state; otherwise, the electromagnetic on / off valve (202) is controlled to be in the disconnected state.

Images