CN210861771U - A multi-stage evaporative-condensing mechanical subcooling transcritical CO2 medium-high temperature heat pump system - Google Patents

Abstract

The utility model discloses a multi-stage evaporative condensation mechanical supercooling transcritical CO2 medium and high temperature heat pump system. The utility model is composed of a _CO2 mechanical supercooling heat pump subsystem and a multi-stage evaporation and multistage condensation subsystem; the _CO2 mechanical supercooling heat pump subsystem is composed of a _CO2 compressor, a _CO2 gas cooler, a _CO2 supercooler, a flow valve and _CO2 evaporator; the multistage evaporation and multistage condensation subsystem includes low pressure stage compressor, high pressure stage compressor, high temperature stage condenser, medium temperature stage condenser, _CO2 subcooler, low temperature stage evaporation device, gas-liquid separator, throttle valve at all levels. The utility model improves the exergy efficiency of the system, the overall energy efficiency and the economic benefit through the multi-stage pressurization, condensation and evaporation processes of the refrigerant.

Description

A multi-stage evaporative-condensing mechanical subcooling transcritical CO2 medium-high temperature heat pump system

technical field

The utility model relates to the technical field of environmentally friendly refrigerants, in particular to a multi-stage evaporative condensation mechanical subcooling transcritical CO ₂ medium and high temperature heat pump system.

Background technique

Food drying, tobacco, chemical industry, papermaking, ceramics and other industries have huge demand for medium and high temperature hot water and steam. However, the production of medium and high temperature hot water (steam) by traditional electric heating and coal-fired boilers often consumes a lot of electricity and fuel. resources and cause serious pollution to the environment. As a clean, efficient and stable equipment, heat pump products can be used to produce medium and high temperature hot water (steam). Through medium and high temperature heat pump equipment, energy utilization rate can be improved, energy saving and emission reduction can be promoted, which is of great practical significance for improving economic benefits and social value.

However, at present, most of the heat pump products on the market are filled with HFCs refrigerants, which have high global warming potential (GWP) and belong to the category of "high GWP".

Utility model content

The purpose of this utility model is to provide a multi-stage evaporative-condensing mechanical supercooling transcritical CO ₂ medium-high temperature heat pump system, through the multi-stage evaporative-condensing system, the hot water produced by the CO ₂ medium-high temperature heat pump system and the heat exchanged by it can achieve good thermal matching At the same time, it can reduce the irreversible loss in the matching process and improve the performance of the heat pump system.

The utility model is a multi-stage evaporative-condensing mechanical sub-cooling transcritical CO ₂ medium-high temperature heat pump system, which is composed of a CO ₂ mechanical sub-cooling heat pump subsystem and a multi-stage evaporative and multi-stage condensing subsystem;

_CO2 mechanical subcooling heat pump subsystem consists of _CO2 compressor, _CO2 gas cooler, _CO2 subcooler, throttle valve and _CO2 evaporator;

The multi-stage evaporation and multi-stage condensation subsystem includes a low pressure stage compressor, a medium pressure stage compressor, a high pressure stage compressor, a high temperature stage condenser, a medium temperature stage condenser, a CO ₂ subcooler, a low temperature stage evaporator, a gas Liquid separator, throttle valve at all levels;

The outlet of the _CO2 compressor is connected to the refrigerant side inlet of the _CO2 gas cooler, the outlet of the _CO2 gas cooler is connected to the refrigerant side inlet of the _CO2 subcooler, and the _CO2 subcooler is a multi-stage subcooler , which is composed of multiple subcoolers in series; the outlet of the CO ₂ subcooler is connected to the CO ₂ refrigerant side inlet of the low-temperature stage evaporator, and the outlet of the low-temperature stage evaporator is connected to the inlet of a throttle valve, and the throttle valve The first valve outlet is connected with the inlet of the _CO2 evaporator, and the outlet of the _CO2 evaporator is connected with the inlet of the _CO2 compressor;

The outlet of the low pressure stage compressor is respectively connected with the outlet of the conventional working medium side of the CO ₂ subcooler and the inlet of the medium pressure stage compressor, and the outlet of the medium pressure stage compressor is respectively connected with the inlet of the conventional working medium side of the medium temperature stage condenser and the inlet of the high pressure stage. The inlet of the compressor is connected, the outlet of the high-pressure stage compressor is connected with the inlet of the conventional working medium side of the high-temperature stage condenser, the high-temperature stage condenser is connected with the fifth inlet of the throttle valve, and the fifth outlet of the throttle valve is connected with the gas-liquid separator The two inlets are connected, the two gas outlets of the gas-liquid separator are connected to the inlet of the high-pressure stage compressor, the two liquid outlets of the gas-liquid separator are connected to the outlet of the conventional working medium side of the intermediate temperature stage condenser, and the outlet of the intermediate temperature stage condenser is connected to The three inlets of the throttle valve are connected, the three inlets of the throttle valve are connected with the first inlet of the gas-liquid separator, the first gas outlet of the gas-liquid separator is connected with the fourth inlet of the throttle valve, and the fourth inlet of the throttle valve is connected with the medium pressure The inlet of the stage compressor is connected, the liquid outlet of the gas-liquid separator is divided into two paths, and one is connected with the sixth inlet of the throttle valve, and the sixth outlet of the throttle valve is connected with the inlet of the conventional working medium side of the CO ₂ subcooler. The outlet of the CO ₂ subcooler is connected to the inlet of the medium pressure stage compressor; the first liquid outlet of the gas-liquid separator is connected to the second inlet of the throttle valve, and the second outlet of the throttle valve is connected to the conventional working medium side of the low temperature stage evaporator The inlet is connected, and the outlet of the low temperature stage evaporator is connected with the inlet of the low pressure stage compressor.

The working fluids used are pure refrigerants such as R1234ze(Z), R1234ze(E), R1233zd(E), R1224yd(Z), R1336mzz(Z), R365mfc, R1234yf, R245fa, etc., or CO ₂ /R1234ze ( E), CO ₂ /R1234ze(Z), CO ₂ /R1234yf, R41/R1234ze(E), R41/R1234ze(Z), R41/R1234yf, R32/R1234ze(E), R32/R1234ze(Z), R32/ R1234yf and other non-azeotropic mixtures.

The hot water side circulation is mainly divided into two paths. One path first flows through the medium temperature stage condenser for heat exchange, and then the water temperature rises, and then flows through the high temperature stage condenser for heat exchange. After the heat exchange, the water temperature continues to rise to achieve water supply. desired temperature. The other way is to flow through the _CO2 gas cooler for heat exchange, and the water temperature rises to the water supply temperature. The hot water after the two circuits is combined in the water storage tank, and the combined hot water is transported to the user through the pipeline.

The utility model has the following beneficial effects:

The multi-stage evaporation and multi-stage condensation mechanical supercooling transcritical CO ₂ medium and high temperature heat pump system of the utility model can replace the traditional HFCs working medium and improve the energy efficiency, and can effectively solve the problems of energy waste and environmental pollution. The irreversible losses due to throttling can be reduced by subcooling the _CO2 fluid at the outlet of the gas cooler through a multi-stage evaporative multi-stage condensation system. The application of this system can effectively save energy, has obvious economic and social benefits, and has huge market potential.

(1) The refrigerant of the high temperature heat pump system is the natural working medium CO ₂ . The GWP of CO ₂ is 1, and the ODP is 0. It is safe, non-toxic, non-flammable, cheap and easy to obtain. It is an environmentally friendly refrigerant. Compared with other chemicals, the greenhouse effect is greatly alleviated, and the environmental protection advantage is obvious.

(2) The multi-stage evaporation process of the multi-stage evaporative-condensing system performs cascaded subcooling of _CO2 , the multi-stage evaporation process of the multi-stage evaporative-condensation system performs cascade heating of the return water, and the evaporation and condensation processes of the multi-stage evaporative-condensation system are related to the heat source. The side fluid ( _CO fluid) and the heat sink side fluid (water) simultaneously achieve good temperature matching, significantly reducing irreversible losses during thermal matching. The cascade subcooling of _CO2 fluid through the multi-stage evaporation process can simultaneously reduce the irreversible loss of heat exchange in the subcooling process and the irreversible loss of the throttling process, and improve the energy efficiency of the system.

(3) Compared with the currently used refrigerants, CO ₂ has a supercritical heat release process, which has a large temperature glide, and is more suitable for high temperature heat pump systems. The volume is reduced, the charging amount of the refrigerant is reduced, the equipment is compact, and the weight of the system is reduced.

(4) After the mixed refrigerant is used in the multi-stage evaporative condensation system, a better heat matching between the heat source and the heat sink side can be achieved, and the irreversible loss of the heat exchange process can be further reduced, which improves the performance of the heat pump system and saves energy.

Description of drawings

Fig. 1 is the system schematic diagram of the present utility model;

FIG. 2 is a schematic diagram of the system of the present invention.

Detailed ways

In order to further understand the inventive content, features and effects of the present utility model, the following embodiments are exemplified and described in detail as follows with the accompanying drawings.

Embodiment 1: a two-stage evaporative condensation mechanical subcooling transcritical CO ₂ medium and high temperature heat pump system,

See Figure 1, how it works:

The first step: the working medium charged in the high temperature heat pump system is CO ₂ , the low temperature and low pressure CO ₂ vapor enters the suction port of the CO ₂ compressor 1, and is compressed by the CO ₂ compressor 1 to a high temperature and high pressure supercritical fluid, and enters the CO ₂ The gas cooler 2 exchanges heat with the cooling water. Due to the heat exchange temperature difference in the gas cooler, the temperature of _CO2 is slightly higher than the temperature of the cooling water. The _CO2 flow cooled by the gas cooler 2 is cooled again through the cooler 3. At this time, the refrigerant in the multi-stage evaporation and multi-stage condensation system is exchanging heat with it, and the cooled CO ₂ flows through the multi-stage evaporation and multi-stage condensation. The low-temperature stage evaporator 4 of the system performs heat exchange and cooling again and then flows through the throttle valve 5 for throttling. The throttled CO ₂ gas-liquid two-phase state flows through the CO ₂ evaporator 6 for cooling and is sucked by the CO ₂ compressor 1 Then compress again.

The second step: the refrigerant from the low-temperature stage evaporator 4 is compressed by the low-pressure stage compressor 7 and mixed with the refrigerant heat-exchanged in the CO ₂ subcooler 3, passes through a section of pipeline, and flows through the throttle valve 4 10 The refrigerant (the main function is to balance the pressure of the refrigerant on both sides of the valve body) is mixed and compressed by the medium-pressure stage compressor 12 and then divided into two paths, one of which flows through the medium-temperature stage condensing heat exchanger 13 for heat exchange with the cooling water, The other one is mixed with the gas refrigerant in the second gas-liquid separator 14 and then compressed again by the high temperature stage compressor 15 .

The third step: the compressed high-temperature and high-pressure refrigerant flows through the high-temperature condensing heat exchanger 16 for re-heat exchange with the cooling water flowing through the medium-temperature condensing heat exchanger 13, and then flows through the throttle valve 5 17 for throttling. The flow is depressurized to the second gas-liquid separator 14, and the refrigerant liquid at the bottom of the second gas-liquid separator 14 is mixed with the refrigerant in the medium-temperature condensing heat exchanger 13, and then flows to the gas-liquid after being throttled by the throttle valve 39. Separator one 11, the refrigerant gas in the gas-liquid separator one 11 passes through the throttle valve four 10 and is mixed with the refrigerant after heat exchange with the CO ₂ subcooler 3 and the refrigerant compressed by the low pressure stage compressor 7 Compress again.

Step 4: The refrigerant liquid in gas-liquid separator one 11 is divided into two paths, one path is throttled by throttle valve six 19 and then flows through CO ₂ subcooler 3 for heat exchange, and the other path passes through the throttle valve. After the 28 is throttled, it flows through the low-temperature stage evaporative heat exchanger 4 for heat exchange, and then is sucked into the low-pressure stage compressor 7 for compression, and the cycle is completed.

Example 2: A three-stage evaporative condensation mechanical subcooling transcritical _CO2 high temperature heat pump system

See Figure 2, how it works:

The first step: the working medium charged in the high temperature heat pump system is CO ₂ , the low temperature and low pressure CO ₂ vapor enters the suction port of the CO ₂ compressor 1, and is compressed by the CO ₂ compressor 1 to a high temperature and high pressure supercritical fluid, and enters the CO ₂ The gas cooler 2 exchanges heat with the cooling water. Due to the heat exchange temperature difference in the gas cooler, the temperature of _CO2 is slightly higher than the temperature of the cooling water. The _CO2 flow cooled by the gas cooler 2 is cooled again through the cooler 3. At this time, the refrigerant in the multi-stage evaporation and multi-stage condensation system exchanges heat with it, and the cooled CO ₂ flows through the multi-stage evaporation and multi-stage condensation. The low-temperature stage evaporator 4 of the system performs heat exchange and cooling again and then performs throttling 5. The throttled CO ₂ gas-liquid two-phase state flows through the CO ₂ evaporator 6 and is sucked by the CO ₂ compressor 1 and then compressed again.

The second step: the refrigerant from the low-temperature stage evaporator 4 is compressed by the low-pressure stage compressor 7 and mixed with the refrigerant heat-exchanged in the CO ₂ subcooler 3. After compression, it is divided into two paths, one path is mixed with another part of the gas compressed by the medium-pressure stage compressor 20 in the gas-liquid separator 11, and then flows through the medium-temperature stage condensing heat exchanger 13 for heat exchange with cooling water, and the other path is After mixing with the gas refrigerant in the second gas-liquid separator 14, it is compressed again by the high-pressure stage compressor 15.

The third step: the compressed high-temperature and high-pressure refrigerant flows through the high-temperature condensing heat exchanger 16 for re-heat exchange with the cooling water flowing through the medium-temperature condensing heat exchanger 13, and then flows through the throttle valve 5 17 for throttling. The flow is depressurized to the second gas-liquid separator 14, and the refrigerant liquid at the bottom of the second gas-liquid separator 14 is mixed with the refrigerant in the medium-temperature condensing heat exchanger 13, and then flows to the gas-liquid after being throttled by the throttle valve 39. Separator one 11, the refrigerant gas in the gas-liquid separator one 11 is sucked by the medium pressure stage compressor 20 and compressed.

Step 4: The refrigerant liquid in gas-liquid separator one 11 is divided into two paths, one path is throttled by throttle valve six 19 and then flows through CO ₂ subcooler 3 for heat exchange, and the other path passes through the throttle valve. After the 28 is throttled, it flows through the low-temperature stage evaporative heat exchanger 4 for heat exchange, and then is sucked into the low-pressure stage compressor 7 for compression to complete the cycle.

Although the preferred embodiments of the present utility model have been described above in conjunction with the accompanying drawings, the present utility model is not limited to the above-mentioned specific embodiments, which are only illustrative and not restrictive. Under the inspiration of the present utility model, those of ordinary skill can also make many forms without departing from the scope of protection of the present utility model and the claims, which all belong to the protection scope of the present utility model.

Claims (3)

1. a multistage evaporative condensation mechanical supercooling transcritical _CO middle-high temperature heat pump system, is characterized in that, by _CO mechanical supercooling heat pump subsystem and multistage evaporation multistage condensation subsystem form; _CO2 mechanical subcooling heat pump subsystem consists of _CO2 compressor, _CO2 gas cooler, _CO2 subcooler, throttle valve and _CO2 evaporator; The multi-stage evaporation and multi-stage condensation subsystem includes a low-pressure stage compressor, a high-pressure stage compressor, a high-temperature stage condenser, a medium-temperature stage condenser, a CO ₂ subcooler, a low-temperature stage evaporator, a gas-liquid separator, a throttle valve; The outlet of the _CO2 compressor is connected to the refrigerant side inlet of the _CO2 gas cooler, the outlet of the _CO2 gas cooler is connected to the refrigerant side inlet of the _CO2 subcooler, and the _CO2 subcooler is a multi-stage subcooler , which is composed of multiple subcoolers in series; the outlet of the CO ₂ subcooler is connected to the CO ₂ refrigerant side inlet of the low-temperature stage evaporator, and the outlet of the low-temperature stage evaporator is connected to the inlet of a throttle valve, and the throttle valve The first valve outlet is connected with the inlet of the _CO2 evaporator, and the outlet of the _CO2 evaporator is connected with the inlet of the _CO2 compressor; The outlet of the low pressure stage compressor is respectively connected with the outlet of the conventional working medium side of the CO ₂ subcooler and the inlet of the medium pressure stage compressor, and the outlet of the medium pressure stage compressor is respectively connected with the inlet of the conventional working medium side of the medium temperature stage condenser and the inlet of the high pressure stage. The inlet of the compressor is connected, the outlet of the high-pressure stage compressor is connected with the inlet of the conventional working medium side of the high-temperature stage condenser, the high-temperature stage condenser is connected with the fifth inlet of the throttle valve, and the fifth outlet of the throttle valve is connected with the gas-liquid separator The two inlets are connected, the two gas outlets of the gas-liquid separator are connected to the inlet of the high-pressure stage compressor, the two liquid outlets of the gas-liquid separator are connected to the outlet of the conventional working medium side of the intermediate temperature stage condenser, and the outlet of the intermediate temperature stage condenser is connected to The three inlets of the throttle valve are connected, the three inlets of the throttle valve are connected with the first inlet of the gas-liquid separator, the first gas outlet of the gas-liquid separator is connected with the fourth inlet of the throttle valve, and the fourth inlet of the throttle valve is connected with the medium pressure The inlet of the stage compressor is connected, the liquid outlet of the gas-liquid separator is divided into two paths, and one is connected with the sixth inlet of the throttle valve, and the sixth outlet of the throttle valve is connected with the inlet of the conventional working medium side of the CO ₂ subcooler. The outlet of the CO ₂ subcooler is connected to the inlet of the medium pressure stage compressor; the first liquid outlet of the gas-liquid separator is connected to the second inlet of the throttle valve, and the second outlet of the throttle valve is connected to the conventional working medium side of the low temperature stage evaporator The inlet is connected, and the outlet of the low temperature stage evaporator is connected with the inlet of the low pressure stage compressor. 2. The multi-stage evaporative-condensing mechanical subcooling transcritical CO ₂ medium-high temperature heat pump system according to claim 1, is characterized in that, the CO ₂ evaporator is a fin-and-tube heat exchanger; Stage condenser, CO ₂ subcooler, CO ₂ gas cooler, and low temperature stage evaporator are all casing heat exchangers. 3. The multi-stage evaporative condensation mechanical subcooling transcritical CO ₂ medium-high temperature heat pump system according to claim 1, wherein the working fluid used is R1234ze, R1233zd, R1224yd, R1336mzz, R365mfc, R1234yf, R245fa pure refrigerants , or use R1234ze(E)/CO ₂ , R1234ze/CO ₂ , R1234yf/CO ₂ , R1234ze/R41, R1234yf/R41, R1234ze/R32, R1234yf/R32 non-azeotropic mixed working fluid.

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