CN115289708A

CN115289708A - Heat pump system suitable for low ring temperature

Info

Publication number: CN115289708A
Application number: CN202210958850.7A
Authority: CN
Inventors: 顾众; 陈旭升
Original assignee: Zhejiang Yingnuo Green Energy Technology Co ltd
Current assignee: Zhejiang Yingnuo Green Energy Technology Co ltd
Priority date: 2022-08-10
Filing date: 2022-08-10
Publication date: 2022-11-04

Abstract

The application discloses heat pump system that adapts to low ring temperature, including compressor, gas cooler, first tee bend control valve, regenerator, electronic expansion valve, evaporimeter, second tee bend control valve and vapour and liquid separator. When the system runs in a normal mode, carbon dioxide cooled at the gas cooler is recooled at the heat regenerator to obtain the supercooling degree. At the same time, the superheated steam from the evaporator is reheated at the regenerator. On one hand, supercooling can improve the refrigeration efficiency, on the other hand, overheating can improve the exhaust temperature, and both the supercooling and overheating can improve the heating efficiency; when the compressor operates in the low-temperature mode, the exhaust temperature of the compressor is reduced through the adjustment of the second three-way control valve, and the situation that the viscosity of the refrigeration oil of the compressor is too low and the oil film is too thin is avoided.

Description

Heat pump system suitable for low ring temperature

Technical Field

The invention relates to a refrigeration system, in particular to a heat pump system suitable for low ring temperature.

Background

The carbon dioxide is a natural refrigerant, is green and environment-friendly, and can not pollute the environment when leaked or not recycled; the material has good thermodynamic characteristics and high heat conductivity coefficient; the unit volume refrigerating capacity is high, the size of the equipment can be obviously reduced, the material is saved, particularly, the matching degree of high-temperature cooling and cold water temperature rise is high, and high-temperature hot water at 70-90 ℃ can be easily obtained. In a heat pump system, at a low ambient temperature (for example, below-10 ℃), the discharge temperature of a compressor is increased to more than 140 ℃ due to a large pressure ratio and a large suction superheat degree, which causes a huge challenge to cooling and lubrication of the compressor, and the operation capacity of the heat pump system is weakened, so that the compressor is unstable in operation and poor in user experience.

Disclosure of Invention

The invention aims at the problems and overcomes at least one defect, and provides a heat pump system adaptive to low loop temperature.

The technical scheme adopted by the invention is as follows:

a heat pump system suitable for low ring temperature comprises a compressor, a gas cooler, a first three-way control valve, a heat regenerator, an electronic expansion valve, an evaporator, a second three-way control valve and a gas-liquid separator; the gas cooler is provided with a gas inlet and a gas outlet, and the heat regenerator is provided with a first heat exchange tube and a second heat exchange tube which exchange heat with each other; the first three-way control valve is provided with a first end, a second end and a third end, and the first end of the first three-way control valve can be communicated with the second end of the first three-way control valve or the third end of the first three-way control valve; the second three-way control valve is provided with a first end, a second end and a third end, and the first end of the second three-way control valve can be communicated with the second end of the second three-way control valve or the third end of the second three-way control valve;

an outlet of the compressor is connected with a gas inlet of the gas cooler, and a gas outlet of the gas cooler is connected with a second end of the first three-way control valve; the first end of the first three-way control valve is connected with the inlet of the first heat exchange tube; the outlet of the compressor is also connected with the third end of the first three-way control valve;

an outlet of the first heat exchange tube is connected with an inlet of the electronic expansion valve, an outlet of the electronic expansion valve is connected with an inlet of the evaporator, and an outlet of the evaporator is connected with a first end of the second three-way valve; the second end of the second three-way valve is connected with the inlet of the second heat exchange tube, the outlet of the second heat exchange tube is connected with the inlet of the gas-liquid separator, and the third end of the second three-way valve is connected with the inlet of the gas-liquid separator;

and the gas outlet of the gas-liquid separator is connected with the inlet of the compressor.

Further, the coolant of the heat pump system which is suitable for the low ring temperature is carbon dioxide.

Furthermore, the heat pump system adapting to the low ring temperature has a normal mode, a defrosting mode and a low-temperature mode;

in a normal mode, the first end of the first three-way control valve is communicated with the second end of the first three-way control valve, and the first end of the second three-way control valve is communicated with the second end of the second three-way control valve;

in the defrosting mode, the first end of the first three-way control valve is communicated with the third end of the first three-way control valve, and the first end of the second three-way control valve is communicated with the second end of the second three-way control valve;

and in the low-temperature mode, the first end of the first three-way control valve is communicated with the second end of the first three-way control valve, and the first end of the second three-way control valve is communicated with the third end of the second three-way control valve.

In situations where the temperature is not particularly low, such as ambient temperatures above-14 ℃, the low loop temperature compliant heat pump system preferably operates in a normal mode where the compression cycle of the low loop temperature heat pump system is: discharging high-temperature and high-pressure carbon dioxide from an outlet of the compressor, cooling the carbon dioxide to the gas cooler through a pipeline, and performing primary heat exchange with water in the gas cooler; then enters a first heat exchange tube of the heat regenerator through a first three-way control valve and is cooled again (the aim is to increase the supercooling degree and improve the heating efficiency of the system by 2 to 5 percent); then the carbon dioxide enters an evaporator after passing through an electronic expansion valve after coming out of the first heat exchange pipe, and exchanges heat with the environment to obtain low-pressure superheated carbon dioxide steam; the carbon dioxide steam enters a second heat exchange tube of the heat regenerator through a second three-way control valve to be reheated (for the purpose of improving the exhaust temperature and improving the heat exchange efficiency of the gas cooler); then the carbon dioxide steam from the second heat exchange tube enters a gas-liquid separator, and finally returns to the inlet of the compressor from the gas-liquid separator, so that the single compression and heating cycle is completed.

And when the gas cooler operates in the normal mode, the carbon dioxide cooled at the gas cooler is recooled at the heat regenerator to obtain the supercooling degree. At the same time, the superheated steam from the evaporator is reheated at the regenerator. On one hand, supercooling can improve the refrigeration efficiency, on the other hand, overheating can improve the exhaust temperature, and the supercooling and overheating can improve the heating efficiency.

This application compressor exhaust hot-gas under the defrosting mode does not pass through gas cooler, directly switches on to regenerator, electronic expansion valve, evaporimeter by first tee bend control valve, and steam heats the evaporimeter, melts the frost on surface, and by the carbon dioxide after the condensation heating in regenerator department, then the entering vapour and liquid separator carries out gas-liquid separation, prevents that the compressor from taking liquid operation. This application is different from other steam defrosting modes, and the hot-gas that the compressor discharged reenters in the evaporimeter after the electronic expansion valve throttle, firstly in order to establish high low pressure difference, exhaust temperature risees, also adjusts the pressure of defrosting simultaneously when defrosting, and control low pressure is within 40-45bar, and pressure is too high, will mean that the design pressure of evaporimeter needs to improve, and high-pressure side pressure is higher, leads to appearing high-pressure protection or energy consumption height. Too low pressure results in long defrosting time and increased power consumption. The defrosting pressure is adjusted by adjusting the electronic expansion valve through monitoring the outlet temperature of the evaporator. In addition, the electronic expansion valve is used for reducing the cold and hot fatigue effect before and after defrosting of the evaporator and prolonging the service life of the product. In addition, in order to save energy consumption investment during defrosting, the defrosting energy consumption is high due to high defrosting pressure, accurate defrosting control is realized, and a reasonable balance point can be found in defrosting time and energy consumption.

In the case of a low temperature, such as an ambient temperature below-15 ℃, the low loop temperature heat pump system preferably operates in a low temperature mode, where the compression cycle of the low loop temperature heat pump system is: high-temperature and high-pressure carbon dioxide is discharged from an outlet of the compressor, is cooled at a gas cooler through a pipeline, exchanges heat with water in the gas cooler for the first time, enters a first heat exchange pipe of a heat return gas after passing through a first three-way control valve, enters an evaporator after passing through an electronic expansion valve after exiting from the first heat exchange pipe, and exchanges heat with the environment to obtain low-pressure superheated carbon dioxide steam; and the carbon dioxide steam enters the gas-liquid separator through the second three-way control valve and finally returns to the inlet of the compressor from the gas-liquid separator to complete single compression and heating cycle. At this time, the ambient temperature is low enough, the inlet water temperature is also low enough, and the high-temperature and high-pressure carbon dioxide can be cooled sufficiently at the gas cooler. At the evaporator, the evaporation temperature needs to be low enough to extract heat from the environment, at which time the compressor has a large pressure ratio, the discharge temperature is high enough, and the suction does not need to be too hot. On the contrary, in order to reduce the exhaust temperature, the viscosity of the refrigeration oil is not too low, the oil film is too thin, the ductility of the refrigeration oil is too poor, the exhaust temperature is reduced through the adjustment of the second three-way control valve, and the running reliability of the equipment is improved.

Further, the conditions for triggering the defrost mode are: when the fan of the evaporator continuously runs for a certain time and the accumulated running time is longer than the defrosting interval time, detecting that the outlet temperature of the evaporator is less than or equal to the defrosting entering set temperature and the outlet temperature of the evaporator is less than or equal to the environmental temperature-defrosting temperature difference value;

the conditions for exiting the defrost mode are: when the outlet temperature of the evaporator is larger than the defrosting exit set temperature, or the defrosting time reaches the set defrosting maximum time.

When the defrosting is not carried out in time, the heat exchange efficiency of the evaporator is reduced, and the heating efficiency is reduced. Frequent defrosting means that heating is interrupted and continuous, the temperature of outlet water is unstable, and the heating quantity cannot meet the requirement. Excessive defrosting reduces heating time and wastes work of the compressor. The low-environment-temperature heat pump system solves the problem of defrosting at low environment temperature, and improves energy efficiency and stability.

Further, an oil outlet is formed in the lower portion of the gas-liquid separator, and an electronic oil level balancer is installed in an oil cavity of the compressor;

the heat pump system suitable for the low ring temperature further comprises an oil supplementing pipe, one end of the oil supplementing pipe is connected with the oil outlet of the gas-liquid separator, and the other end of the oil supplementing pipe is connected with the oil cavity of the compressor;

the oil supplementing electromagnetic valve is installed on the oil supplementing pipe, or the oil supplementing electromagnetic valve and the oil sight glass are installed on the oil supplementing pipe.

Further, the heat pump system suitable for the low ring temperature can automatically supplement oil, and the control method for automatically supplementing oil comprises the following steps:

after the heat pump system adaptive to the low ring temperature operates for a set time, the electronic oil level balancer detects the oil level of the compressor;

when the oil level of the compressor is lower than the preset low oil level, the oil supplementing electromagnetic valve is opened, so that the oil at the bottom of the gas-liquid separator returns to an oil cavity or an air suction port of the compressor through the oil supplementing pipe until the set oil supplementing time is reached or the oil level of the compressor reaches the preset high oil level.

Through setting up electron oil level equalizer, mend oil pipe and mend oil solenoid valve, can guarantee that the compressor obtains continuous, reliable lubrication. If the oil level is still lower than the low oil level after the oil supplementing time, the oil return fault is indicated, and the system is stopped at the moment, so that the compressor is protected from being abraded and burnt out.

Furthermore, the gas cooler is also provided with a water inlet and a water outlet, the water inlet of the gas cooler is provided with a water inlet pipe, and the water outlet of the gas cooler is provided with a water outlet pipe;

the water inlet pipe is provided with a water pump and a first control valve, and the first control pump is arranged on one side of the inlet end of the water pump;

and an automatic exhaust valve and a dry-burning-resistant water flow switch are arranged on the water outlet pipe.

The hot water circulation of the low-loop-temperature heat pump system is as follows: the cold water enters the gas cooler through the water inlet pipe by the water pump, is heated to 55-90 ℃, and then enters the heat preservation water storage tank through the water outlet pipe. The automatic exhaust valve is arranged, so that gas in the water channel can be automatically exhausted, and the heat exchange efficiency of the gas cooler is improved; the water outlet pipe is provided with a water flow switch, and the system can be stopped in time when the water channel is lack of water, so that the equipment is protected from dry burning.

Furthermore, a filter is arranged between the water pump and the first control valve of the water inlet pipe; a second control valve is installed at the inlet of the gas-liquid separator;

the filter is a Y-shaped filter; the water pump is a variable frequency water pump; the fan of the evaporator is a variable frequency fan.

The frequency conversion water pump can be according to the operating frequency of the temperature regulation pump of water route export.

In different seasons, the environmental temperature is different, and the running frequency of the fan is also different. The environment temperature is high in summer, the heat exchange temperature difference of the evaporator is large, the suction temperature is high and the exhaust temperature is too high due to too large superheat degree, and the fan operates in a low-frequency state, so that the reliability of system operation is guaranteed. The environment temperature is low in winter, the heat exchange temperature difference of the evaporator is small, and in order to obtain enough heat from the environment, the fan operates in a high-frequency state, so that the stability of the heating quantity and the stability of the water outlet temperature are guaranteed.

Furthermore, a third control valve is installed at the outlet end of the water pump on the water inlet pipe, and a fourth control valve is also installed on the water outlet pipe;

the heat pump system suitable for the low ring temperature also comprises two descaling pipelines which are both provided with a fifth control valve;

one end of one descaling pipeline is connected with the water inlet pipe, and the connection point is arranged between the water inlet of the gas cooler and the third control valve;

one end of the other descaling pipeline is connected with the water outlet pipe, and the connection point is arranged between the water outlet of the gas cooler and the fourth control valve.

When the ambient temperature is lower than-10 ℃, the compressor has large suction superheat degree due to large pressure ratio, the exhaust temperature of the compressor is increased to more than 140 ℃, and the higher the exhaust temperature is, the more serious the scaling is. The descaling operation can be conveniently carried out by arranging the descaling pipeline.

Furthermore, the two descaling pipelines are respectively a first descaling pipeline and a second descaling pipeline, the gas cooler can be descaled through the two descaling pipelines, and the descaling method comprises the following steps:

closing the third control valve and the fourth control valve, and opening two fifth control valves;

pumping the descaling liquid into the gas cooler from the first descaling pipeline through an external pump, discharging the liquid after descaling from the second descaling pipeline, circulating for a set time, pumping the descaling liquid into the gas cooler from the second descaling pipeline, and discharging the liquid after descaling from the first descaling pipeline; after alternately circulating for a plurality of times, completing the descaling work;

the descaling liquid is 2-10% oxalic acid or phosphoric acid.

The beneficial effects of the invention are: when the system operates in a normal mode, carbon dioxide cooled at the gas cooler is recooled at the heat regenerator to obtain the supercooling degree. At the same time, the superheated steam from the evaporator is reheated at the regenerator. On one hand, supercooling can improve the refrigeration efficiency, on the other hand, overheating can improve the exhaust temperature, and both the supercooling and overheating can improve the heating efficiency; when the compressor operates in the low-temperature mode, the exhaust temperature of the compressor is reduced through the adjustment of the second three-way control valve, and the situation that the viscosity of the refrigeration oil of the compressor is too low and the oil film is too thin is avoided.

Drawings

FIG. 1 is a schematic diagram of a heat pump system adapted to low loop temperatures according to the present application.

The figures are numbered:

1. a compressor; 2. a gas cooler; 3. a first three-way control valve; 31. a first end of a first three-way control valve; 32. a second end of the first three-way control valve; 33. a third end of the first three-way control valve; 4. a heat regenerator; 5. an electronic expansion valve; 6. an evaporator; 7. a second three-way control valve; 71. a first end of a second three-way control valve; 72. a second end of a second three-way control valve; 73. a third end of the second three-way control valve; 8. a gas-liquid separator; 9. supplementing an oil pipe; 10. an oil supplementing electromagnetic valve; 11. oil sight glasses; 12. a first control valve; 13. a second control valve; 14. a third control valve; 15. a fourth control valve; 16. a fifth control valve; 17. a water pump; 18. a filter; 19. a water flow switch; 20. an automatic exhaust valve; 21. a descaling pipeline; 22. a water inlet pipe; 23. and (5) discharging a water pipe.

Detailed Description

The present invention will now be described in detail with reference to the drawings.

Referring to fig. 1, a heat pump system adapted to low loop temperature includes a compressor 1, a gas cooler 2, a first three-way control valve 3, a heat regenerator 4, an electronic expansion valve 5, an evaporator 6, a second three-way control valve 7, and a gas-liquid separator 8; the gas cooler 2 is provided with a gas inlet and a gas outlet, and the heat regenerator 4 is provided with a first heat exchange tube and a second heat exchange tube which exchange heat with each other; the first three-way control valve 3 has a first end 31, a second end 32 and a third end 33, the first end 31 of the first three-way control valve being capable of communicating with the second end 32 of the first three-way control valve or the third end 33 of the first three-way control valve; the second three-way control valve 7 has a first end 71, a second end 72 and a third end 73, the first end 71 of the second three-way control valve being capable of communicating with either the second end 72 of the second three-way control valve or the third end 73 of the second three-way control valve;

the outlet of the compressor 1 is connected with the gas inlet of the gas cooler 2, and the gas outlet of the gas cooler 2 is connected with the second end 32 of the first three-way control valve; the first end 31 of the first three-way control valve is connected with the inlet of the first heat exchange tube; the outlet of the compressor 1 is also connected with a third end 33 of the first three-way control valve;

an outlet of the first heat exchange tube is connected with an inlet of an electronic expansion valve 5, an outlet of the electronic expansion valve 5 is connected with an inlet of an evaporator 6, and an outlet of the evaporator 6 is connected with a first end of a second three-way valve; the second end of the second three-way valve is connected with the inlet of the second heat exchange pipe, the outlet of the second heat exchange pipe is connected with the inlet of the gas-liquid separator 8, and the third end of the second three-way valve is connected with the inlet of the gas-liquid separator 8;

the gas outlet of the gas-liquid separator 8 is connected to the inlet of the compressor 1.

In this embodiment, the coolant of the heat pump system adapted to the low ring temperature is carbon dioxide. In other embodiments, other refrigerants may be used.

In the present embodiment, the heat pump system adapted to low loop temperature has a normal mode, a defrost mode, and a low temperature mode;

in the normal mode, the first end 31 of the first three-way control valve is communicated with the second end 32 of the first three-way control valve, and the first end 71 of the second three-way control valve is communicated with the second end 72 of the second three-way control valve;

in the defrosting mode, the first end 31 of the first three-way control valve is communicated with the third end 33 of the first three-way control valve, and the first end 71 of the second three-way control valve is communicated with the second end 72 of the second three-way control valve;

in the low temperature mode, the first end 31 of the first three-way control valve is communicated with the second end 32 of the first three-way control valve, and the first end 71 of the second three-way control valve is communicated with the third end 73 of the second three-way control valve.

In situations where the temperature is not particularly low, such as ambient temperatures above-14 ℃, the low loop temperature compliant heat pump system preferably operates in a normal mode where the compression cycle of the low loop temperature heat pump system is: high-temperature and high-pressure carbon dioxide is discharged from an outlet of the compressor 1, is cooled by a pipeline to the gas cooler 2, and exchanges heat with water in the gas cooler 2 for the first time; then enters a first heat exchange tube of a heat regenerator 4 through a first three-way control valve 3 and is cooled again (the aim is to increase the supercooling degree and improve the heating efficiency of the system by 2 to 5 percent); then the carbon dioxide enters an evaporator 6 after passing through an electronic expansion valve 5 after coming out of the first heat exchange tube, and exchanges heat with the environment to obtain low-pressure superheated carbon dioxide steam; carbon dioxide steam enters a second heat exchange tube of the heat regenerator 4 through a second three-way control valve 7 to be reheated (aiming at improving the exhaust temperature and improving the heat exchange efficiency of the gas cooler 2); then the carbon dioxide steam from the second heat exchange tube enters the gas-liquid separator 8, finally returns to the inlet of the compressor 1 from the gas-liquid separator 8, and completes the single compression and heating cycle.

When the gas cooler operates in the normal mode, the carbon dioxide cooled at the gas cooler 2 is recooled at the heat regenerator 4 to obtain the supercooling degree. At the same time, the superheated steam from the evaporator 6 is reheated at the regenerator 4. On one hand, supercooling can improve the refrigeration efficiency, on the other hand, overheating can improve the exhaust temperature, and the supercooling and overheating can improve the heating efficiency.

This application is at compressor 1 exhaust hot-gas under the mode of changing frost and is not through gas cooler 2, directly switches on to regenerator 4, electronic expansion valve 5, evaporimeter 6 by first tee bend control valve 3, and the hot gas heats evaporimeter 6, melts the frost on surface, and the carbon dioxide after being condensed is in regenerator 4 department heating, then goes into gas-liquid separator 8 and carries out gas-liquid separation, prevents that compressor 1 from taking liquid operation. The difference of this application and other steam defrosting modes is, the hot-gas that compressor 1 discharged reenters in evaporator 6 after 5 throttles through electronic expansion valve, firstly in order to establish high-low pressure difference, exhaust temperature risees, also adjust the pressure of defrosting simultaneously when defrosting, control low pressure within 40-45bar, pressure is too high, will mean that evaporator 6's design pressure need improve, high-pressure side pressure is higher, lead to appearing high pressure protection or energy consumption height. Too low pressure results in long defrosting time and increased power consumption. The defrosting pressure is adjusted by adjusting the electronic expansion valve 5 through monitoring the temperature of the outlet of the evaporator 6. In addition, the electronic expansion valve 5 is also used for reducing the cold and hot fatigue effect before and after defrosting of the evaporator 6 and prolonging the service life of the product. In addition, in order to save energy consumption investment during defrosting, the defrosting energy consumption is high due to high defrosting pressure, accurate defrosting control is realized, and a reasonable balance point can be found in defrosting time and energy consumption.

In the case of a low temperature, such as an ambient temperature below-15 ℃, the low loop temperature heat pump system preferably operates in a low temperature mode, where the compression cycle of the low loop temperature heat pump system is: high-temperature and high-pressure carbon dioxide is discharged from an outlet of the compressor 1, is cooled in the gas cooler 2 through a pipeline, is subjected to primary heat exchange with water in the gas cooler 2, then enters a first heat exchange pipe of a heat return gas after passing through a first three-way control valve 3, then enters an evaporator 6 after passing through an electronic expansion valve 5 after coming out of the first heat exchange pipe, and is subjected to heat exchange with the environment to obtain low-pressure superheated carbon dioxide steam; carbon dioxide steam enters the gas-liquid separator 8 through the second three-way control valve 7, and finally returns to the inlet of the compressor 1 from the gas-liquid separator 8, so that the single compression and heating cycle is completed. At this time, the ambient temperature is sufficiently low, the temperature of the feed water is also sufficiently low, and the high-temperature, high-pressure carbon dioxide can be sufficiently cooled at the gas cooler 2. At the evaporator 6, the evaporation temperature needs to be low enough to extract heat from the environment, where the compressor 1 is at a high pressure and the discharge temperature is high enough that the suction does not need to be at a high superheat. On the contrary, in order to reduce the exhaust temperature, the viscosity of the refrigeration oil is not too low, the oil film is too thin, the ductility is too poor, the exhaust temperature is reduced through the adjustment of the second three-way control valve 7, and the reliability of the operation of the equipment is improved.

In this embodiment, the conditions for triggering the defrost mode are: when the fan of the evaporator 6 continuously operates for a certain time and the accumulated operation time is longer than the defrosting interval time, detecting that the outlet temperature of the evaporator 6 is less than or equal to the defrosting entering set temperature, and the outlet temperature of the evaporator 6 is less than or equal to the ambient temperature-defrosting temperature difference value;

the conditions for exiting the defrost mode are: when the outlet temperature of the evaporator 6 is higher than the defrosting exit set temperature, or the defrosting time reaches the set defrosting maximum time.

The defrosting is not carried out in time, and the heat exchange efficiency of the evaporator 6 is reduced, so that the heating efficiency is reduced. Frequent defrosting means that heating is interrupted and continuous, the water outlet temperature is unstable, and the heating quantity cannot meet the requirement. Excessive defrosting reduces heating time and wastes work of the compressor 1. The low-environment-temperature heat pump system solves the problem of defrosting at low environment temperature, and improves energy efficiency and stability.

In the embodiment, the lower part of the gas-liquid separator 8 is provided with an oil outlet, and an electronic oil level balancer is arranged in an oil cavity of the compressor 1;

the heat pump system suitable for the low ring temperature also comprises an oil supplementing pipe 9, one end of the oil supplementing pipe 9 is connected with an oil outlet of the gas-liquid separator 8, and the other end of the oil supplementing pipe is connected with an oil cavity of the compressor 1;

an oil supplementing electromagnetic valve 10 is installed on the oil supplementing pipe 9, or the oil supplementing electromagnetic valve 10 and an oil observation mirror 11 are installed on the oil supplementing pipe 9.

In this embodiment, the heat pump system adapted to the low ring temperature can automatically supply oil, and the control method of automatic oil supply includes:

after the heat pump system suitable for the low ring temperature operates for a set time, the electronic oil level balancer detects the oil level of the compressor 1;

when the oil level of the compressor 1 is lower than the preset low oil level, the oil supplementing electromagnetic valve 10 is opened, so that the oil at the bottom of the gas-liquid separator 8 returns to the oil cavity or the air suction port of the compressor 1 through the oil supplementing pipe 9 until the set oil supplementing time is reached or the oil level of the compressor 1 reaches the preset high oil level.

By arranging the electronic oil level balancer, the oil supplementing pipe 9 and the oil supplementing electromagnetic valve 10, the compressor 1 can be ensured to be lubricated continuously and reliably. If the oil level is still lower than the low oil level after the oil supplementing time, the oil return fault is indicated, and the system is stopped at the moment, so that the compressor 1 is protected from being abraded and burnt out.

In this embodiment, the gas cooler 2 further has a water inlet and a water outlet, the water inlet of the gas cooler 2 is provided with a water inlet pipe 22, and the water outlet of the gas cooler 2 is provided with a water outlet pipe 23;

the water inlet pipe 22 is provided with a water pump 17 and a first control valve 12, and the first control pump is arranged on one side of the inlet end of the water pump 17;

an automatic exhaust valve 20 and a dry-burning-resistant water flow switch 19 are arranged on the water outlet pipe 23.

The hot water circulation of the low-loop temperature heat pump system is as follows: the cold water enters the gas cooler 2 through the water inlet pipe 22 by the water pump 17, is heated to 55-90 ℃, and then enters the heat preservation water storage tank through the water outlet pipe 23. The automatic exhaust valve 20 is arranged, so that the gas in the water channel can be automatically exhausted, and the heat exchange efficiency of the gas cooler 2 is improved; the water outlet pipe 23 is provided with a water flow switch 19, and the system can be stopped in time when the water path is lack of water, so that the equipment is protected from dry burning.

In this embodiment, the water inlet pipe 22 is further provided with a filter 18 between the water pump 17 and the first control valve 12; a second control valve 13 is arranged at the inlet of the gas-liquid separator 8;

the filter 18 is a Y-filter 18; the water pump 17 is a variable frequency water pump 17; the fan of the evaporator 6 is a variable frequency fan.

The variable frequency water pump 17 can adjust the operating frequency of the pump according to the temperature of the water path outlet.

In different seasons, the environmental temperature is different, and the running frequency of the fan is also different. The environmental temperature is high in summer, the heat exchange temperature difference of the evaporator 6 is large, and in order to prevent the overhigh degree of superheat from causing high suction temperature and overhigh exhaust temperature, the fan operates in a low-frequency state, so that the reliability of system operation is ensured. The winter environmental temperature is low, and the heat transfer difference in temperature of evaporimeter 6 is little, for obtaining sufficient heat from the environment, the fan moves under the high frequency state to this guarantees the stability of heating and the stability of play water temperature.

In this embodiment, the water inlet pipe 22 is provided with a third control valve 14 at the outlet end of the water pump 17, and the water outlet pipe 23 is further provided with a fourth control valve 15;

the heat pump system suitable for the low ring temperature also comprises two descaling pipelines 21 which are both provided with a fifth control valve 16;

one end of one descaling pipeline 21 is connected with the water inlet pipe 22, and the connection point is between the water inlet of the gas cooler 2 and the third control valve 14;

one end of another descaling pipeline 21 is connected with a water outlet pipe 23, and the connection point is between the water outlet of the gas cooler 2 and the fourth control valve 15.

When the ambient temperature is lower than-10 ℃, the compressor 1 has large suction superheat degree due to large pressure ratio, the exhaust temperature is increased to more than 140 ℃, and the higher the exhaust temperature is, the more serious the scaling is. The descaling operation can be conveniently carried out by arranging the descaling pipeline 21.

In this embodiment, the two descaling pipelines 21 are a first descaling pipeline 21 and a second descaling pipeline 21, respectively, and the two descaling pipelines 21 can descale the gas cooler 2, and the descaling method includes:

the third control valve 14 and the fourth control valve 15 are closed, and the two fifth control valves 16 are opened;

pumping descaling liquid from the first descaling pipeline 21 into the gas cooler 2 through an external pump, discharging the liquid after descaling from the second descaling pipeline 21, circulating for a set time, pumping the descaling liquid from the second descaling pipeline 21 into the gas cooler 2, and discharging the liquid after descaling from the first descaling pipeline 21; after the circulation is performed for a plurality of times alternately, the descaling work is finished.

In practical application, the descaling liquid is 2-10% oxalic acid or phosphoric acid. In this embodiment, the concentration is preferably 5%.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structural changes made by using the contents of the present specification and the drawings, which are directly or indirectly applied to other related technical fields, are also included in the scope of the present invention.

Claims

1. A heat pump system suitable for low ring temperature is characterized by comprising a compressor, a gas cooler, a first three-way control valve, a heat regenerator, an electronic expansion valve, an evaporator, a second three-way control valve and a gas-liquid separator; the gas cooler is provided with a gas inlet and a gas outlet, and the heat regenerator is provided with a first heat exchange tube and a second heat exchange tube which exchange heat with each other; the first three-way control valve is provided with a first end, a second end and a third end, and the first end of the first three-way control valve can be communicated with the second end of the first three-way control valve or the third end of the first three-way control valve; the second three-way control valve is provided with a first end, a second end and a third end, and the first end of the second three-way control valve can be communicated with the second end of the second three-way control valve or the third end of the second three-way control valve;

an outlet of the first heat exchange pipe is connected with an inlet of the electronic expansion valve, an outlet of the electronic expansion valve is connected with an inlet of the evaporator, and an outlet of the evaporator is connected with a first end of the second three-way valve; the second end of the second three-way valve is connected with the inlet of the second heat exchange tube, the outlet of the second heat exchange tube is connected with the inlet of the gas-liquid separator, and the third end of the second three-way valve is connected with the inlet of the gas-liquid separator;

2. The low loop temperature compliant heat pump system as recited in claim 1 wherein the coolant of the low loop temperature compliant heat pump system is carbon dioxide.

3. The low loop temperature compliant heat pump system as recited in claim 1 wherein the low loop temperature compliant heat pump system has a normal mode, a defrost mode and a low temperature mode;

In situations where the temperature is not particularly low, such as ambient temperatures above-14 ℃, the low loop temperature compliant heat pump system preferably operates in a normal mode where the compression cycle of the low loop temperature heat pump system is: high-temperature and high-pressure carbon dioxide is discharged from an outlet of the compressor, is cooled at the gas cooler through a pipeline and exchanges heat with water in the gas cooler for the first time; then enters a first heat exchange tube of the heat regenerator through a first three-way control valve and is cooled again (the aim is to increase the supercooling degree and improve the heating efficiency of the system by 2 to 5 percent); then the carbon dioxide enters an evaporator after passing through an electronic expansion valve after coming out of the first heat exchange pipe, and exchanges heat with the environment to obtain low-pressure superheated carbon dioxide steam; carbon dioxide steam enters a second heat exchange tube of the heat regenerator through a second three-way control valve to be reheated (aiming at improving the exhaust temperature and improving the heat exchange efficiency of the gas cooler); and then the carbon dioxide steam from the second heat exchange tube enters a gas-liquid separator, and finally returns to the inlet of the compressor from the gas-liquid separator, so that the single compression and heating cycle is completed.

When the system operates in a normal mode, the carbon dioxide cooled at the gas cooler is recooled at the heat regenerator to obtain the supercooling degree. At the same time, the superheated steam from the evaporator is reheated at the regenerator. On one hand, supercooling can improve the refrigeration efficiency, on the other hand, overheating can improve the exhaust temperature, and the supercooling and overheating can improve the heating efficiency.

This application compressor exhaust hot gas does not pass through gas cooler under the mode of changing frost, directly switches on to regenerator, electronic expansion valve, evaporimeter by first tee bend control valve, and the evaporimeter heating is heated with the evaporimeter to hot gas, melts the frost on surface, and the carbon dioxide after the condensation is heated in regenerator department, then goes into vapour and liquid separator and carries out gas, liquid separation, prevents that the compressor from taking liquid operation. This application is different with other steam defrosting modes, in the reentrant evaporimeter of compressor exhaust hot-gas after the electronic expansion valve throttle, firstly in order to establish high-low pressure difference, exhaust temperature risees, also adjust the pressure of defrosting simultaneously in order when defrosting, control low pressure is within 40-45bar, pressure is too high, will mean that the design pressure of evaporimeter needs to improve, high-pressure side pressure is higher, lead to appearing high-pressure protection or energy consumption height. Too low pressure results in long defrosting time and increased power consumption. The defrosting pressure is adjusted by adjusting the electronic expansion valve through monitoring the temperature of the outlet of the evaporator. In addition, the electronic expansion valve is used for reducing the cold and hot fatigue effect before and after defrosting of the evaporator and prolonging the service life of the product. In addition, in order to save energy consumption investment during defrosting, high defrosting pressure can lead to high defrosting energy consumption, accurate defrosting control can be realized, and a reasonable balance point can be found in defrosting time and energy consumption.

In the case of a low temperature, such as an ambient temperature below-15 ℃, the low loop temperature heat pump system preferably operates in a low temperature mode, where the compression cycle of the low loop temperature heat pump system is: high-temperature and high-pressure carbon dioxide is discharged from an outlet of the compressor, is cooled at a gas cooler through a pipeline, is subjected to primary heat exchange with water in the gas cooler, then enters a first heat exchange pipe of returned gas after passing through a first three-way control valve, then enters an evaporator after passing through an electronic expansion valve after exiting from the first heat exchange pipe, and is subjected to heat exchange with the environment to obtain low-pressure superheated carbon dioxide steam; and the carbon dioxide steam enters the gas-liquid separator through the second three-way control valve and finally returns to the inlet of the compressor from the gas-liquid separator, so that the single compression and heating cycle is completed. At this time, the ambient temperature is low enough, the inlet water temperature is also low enough, and the high-temperature and high-pressure carbon dioxide can be cooled sufficiently at the gas cooler. At the evaporator, the evaporation temperature needs to be low enough to extract heat from the environment, at which time the compressor does not need to have a large superheat due to the high pressure ratio, the discharge temperature is high enough, and the suction air does not need to have a large superheat. Conversely, in order to reduce the exhaust temperature, the viscosity of the refrigerant oil is not too low, the oil film is too thin, the ductility of the oil film is too poor, the exhaust temperature is reduced through the adjustment of the second three-way control valve, and the running reliability of the equipment is improved.

4. A low loop temperature compliant heat pump system as recited in claim 3 wherein said defrost mode is triggered by conditions comprising: when the fan of the evaporator continuously runs for a certain time and the accumulated running time is longer than the defrosting interval time, detecting that the outlet temperature of the evaporator is less than or equal to the defrosting entering set temperature, and the outlet temperature of the evaporator is less than or equal to the ambient temperature-defrosting temperature difference value;

When the frost is not melted in time, the heat exchange efficiency of the evaporator is reduced, thereby causing the reduction of the heating efficiency. Frequent defrosting means that heating is interrupted and continuous, the temperature of outlet water is unstable, and the heating quantity cannot meet the requirement. Excessive defrosting reduces heating time and wastes work of the compressor. The low-environment-temperature heat pump system solves the problem of defrosting at low environment temperature, and improves energy efficiency and stability.

5. The heat pump system according to claim 1, wherein the gas-liquid separator has an oil outlet at a lower portion thereof, and an electronic oil level balancer is installed in an oil chamber of the compressor;

6. The heat pump system adapted to the low ring temperature of claim 5, wherein the heat pump system adapted to the low ring temperature is capable of automatically supplying oil, and the control method of the automatic oil supply is as follows:

Through setting up electron oil level equalizer, mend oil pipe and mend the oil solenoid valve, can guarantee that the compressor obtains lasting, reliable lubrication. If the oil level is still lower than the low oil level after the oil supplementing time, the oil return fault is indicated, and the system is stopped at the moment, so that the compressor is protected from being abraded and burnt out.

7. The heat pump system according to claim 1, wherein the gas cooler further has a water inlet and a water outlet, the water inlet of the gas cooler is provided with a water inlet pipe, and the water outlet of the gas cooler is provided with a water outlet pipe;

and an automatic exhaust valve and an anti-dry-burning water flow switch are installed on the water outlet pipe.

The hot water circulation of the low-loop temperature heat pump system is as follows: cold water is pumped into the gas cooler through the water inlet pipe by the water pump, heated to 55-90 ℃, and then pumped into the heat preservation water storage tank through the water outlet pipe. The automatic exhaust valve is arranged, so that gas in the water channel can be automatically exhausted, and the heat exchange efficiency of the gas cooler is improved; the water outlet pipe is provided with a water flow switch, and the system can be stopped in time when the water path is short of water, so that the equipment is protected from dry burning.

8. The heat pump system accommodating low loop temperatures of claim 7, wherein the water inlet pipe is further provided with a filter between the water pump and the first control valve;

9. The heat pump system according to claim 7, wherein the inlet pipe is provided with a third control valve at the outlet end of the water pump, and the outlet pipe is provided with a fourth control valve;

10. The low loop temperature compliant heat pump system of claim 9, wherein the two de-scaling lines are a first de-scaling line and a second de-scaling line, respectively, through which the gas cooler can be de-scaled by:

pumping descaling liquid from the first descaling pipeline into the gas cooler through the external pump, discharging the liquid after descaling from the second descaling pipeline, and pumping the descaling liquid from the second descaling pipeline into the gas cooler after circulating for a set time, and discharging the liquid after descaling from the first descaling pipeline; after alternately circulating for a plurality of times, completing the descaling work;

the descaling liquid is 2-10% oxalic acid or phosphoric acid.