Green working medium assisted carbon dioxide heat pump combined heat supply system and control method

Abstract

The invention discloses a green working medium assisted carbon dioxide heat pump combined heat supply system and a control method. The environment-friendly working medium hydrofluoroolefin or ammonia and carbon dioxide are adopted, the water supply temperature is remarkably increased, and pollution of a traditional refrigerant to the environment is reduced; the water heating type green working medium heat pump assisted CO2 heat pump heating mode of the series connection type or the parallel connection type is used for extracting heat energy from water, reducing the return water temperature and improving the operation energy efficiency ratio of the carbon dioxide heat pump, or the CO2 heating type green working medium heat pump assisted CO2 heat pump heating mode is used for extracting heat energy from CO2, and the recovered heat is improved to the high grade, so that the energy efficiency ratio of the carbon dioxide heat pump is improved. The water supply temperature and the system energy efficiency are further improved; more energy is absorbed from an environment source; the CO2 heat pump unit improves the energy grade of an environmental source and transmits the improved energy to heating return water, the adaptability of the system under various environmental conditions is improved, and the overall performance and the energy-saving effect of the carbon dioxide heat pump are further enhanced.

Description

Technical Field

[0001] The invention relates to a green heating technology, and in particular to a green refrigerant heat pump assisted carbon dioxide heat pump combined heating system suitable for high return water temperature and a control method thereof. Background Art

[0002] The energy consumption and carbon emissions of building cooling and heat sources account for more than 50% of the total energy consumption and carbon emissions of buildings. The energy consumption is large, and the ozone depletion potential (ODP) and global warming potential (GWP) of traditional CFC refrigerants are high, which are extremely polluting to the environment. Therefore, it is urgent to use green and environmentally friendly refrigerants and high-efficiency building cooling and heat source systems.

[0003] As a natural working fluid, carbon dioxide has the advantages of being non-toxic, non-flammable, and highly safe. It also has extremely low ozone depletion potential (ODP) and global warming potential (GWP), so it can be widely used as a green refrigerant in heat pump systems. However, most parts of my country currently still use heat pump terminal equipment that matches traditional Freon refrigerants, resulting in a low degree of matching between existing terminal equipment and carbon dioxide heat pumps. Especially in the cold northern regions of my country, the energy efficiency ratio (COP) of carbon dioxide heat pumps will be further reduced, resulting in increased energy consumption, making the use of carbon dioxide heat pump units require non-standard terminal equipment, which greatly increases economic and design costs, making the popularization of carbon dioxide heat pumps difficult.

[0004] Therefore, how to ensure that the refrigerant has less environmental pollution while matching the existing terminal equipment as much as possible and reducing the cost and energy consumption of the heat pump unit is a key issue that needs to be solved urgently. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention proposes a green working fluid assisted carbon dioxide heat pump combined heating system and a control method thereof, which innovatively utilizes water heating type and CO2 heating type HFO or NH3 heat pump auxiliary heating methods by coupling a heat pump system with green refrigerant auxiliary heating as the working fluid, thereby improving the water supply temperature and operating energy efficiency ratio of the carbon dioxide heat pump, thereby achieving the goal of reducing the operating cost and energy consumption of the system while ensuring environmental friendliness, thereby promoting the widespread application of CO2 heat pump units in existing terminal equipment.

[0006] One object of the present invention is to propose a green working fluid assisted carbon dioxide heat pump combined heating system, which adopts a hydrothermal green working fluid heat pump assisted CO2 heat pump heating method, or a CO2 heating type green working fluid heat pump assisted CO2 heat pump heating method.

[0007] The green working medium assisted CO2 heat pump heating mode is adopted. The green working medium assisted carbon dioxide heat pump combined heating system of the present invention comprises: an auxiliary heat pump evaporation end, an auxiliary heat pump compressor, an auxiliary heat pump condensation end, an auxiliary heat pump throttling device, a CO2 heat pump air cooling end, a CO2 heat pump compressor, a CO2 heat pump evaporation end, a CO2 heat pump throttling device, first to third valves and a controller; wherein the evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through the auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, and the outlet of the CO2 heat pump compressor is connected to the air cooling inlet of the CO2 heat pump air cooling end through a pipeline, and the CO The air-cooling outlet of the air-cooling end of the 2 heat pump is connected to the evaporation inlet of the evaporation end of the CO2 heat pump through a pipeline through a CO2 heat pump throttling device. The air-cooling end of the CO2 heat pump, the CO2 heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as a CO2 heat pump unit; the domestic hot water return is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline, and the heat exchange outlet of the auxiliary heat pump evaporation end is respectively connected to the first heat exchange port of the air-cooling end of the CO2 heat pump and the heat exchange inlet of the condensation end of the auxiliary heat pump through a pipeline through a tee; a first valve is arranged in front of the heat exchange inlet of the condensation end of the auxiliary heat pump on the pipeline connecting the first heat exchange port of the air-cooling end of the CO2 heat pump and the heat exchange inlet of the condensation end of the auxiliary heat pump; the second heat exchange port of the air-cooling end of the CO2 heat pump and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet of the condensation end of the auxiliary heat pump and the outlet pipeline, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller;

[0008] The refrigerant in the evaporation end of the auxiliary heat pump adopts green refrigerant; the refrigerant completes the circulation in the auxiliary heating heat pump system;

[0009] The first heat exchange port and the second heat exchange port of the evaporation end of the CO2 heat pump are respectively connected to the environmental source. The evaporation end of the CO2 heat pump utilizes the energy of the environmental source. Carbon dioxide collects low-grade thermal energy from the environmental source in the CO2 heat pump unit and transfers high-grade thermal energy to domestic hot water return water.

[0010] The combined heating system has two heating modes: parallel heating and series heating;

[0011] Parallel heating: the first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, and exchanges heat with the internal refrigerant. The temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from environmental sources and improve CO2 The operation energy efficiency ratio of the heat pump unit; the domestic hot water return water flows to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively; the CO2 heat pump evaporation end absorbs the energy from the environmental source, upgrades it to high-grade heat energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end; the auxiliary heat pump evaporation end recovers the heat in the domestic hot water return water, and upgrades it to high-grade heat energy through the auxiliary heat pump compressor, and increases the temperature through the auxiliary heat pump condensing end; the domestic hot water return water exchanges heat at the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, and is mixed in the outlet pipeline after heat exchange. The mixed temperature is the second intermediate temperature T3, i.e., the domestic hot water supply temperature, and is output through the outlet pipeline to provide domestic hot water supply;

[0012] Series heating: the first valve is closed, the second valve is closed, and the third valve is opened, and the auxiliary heat pump condensing end is connected in series with the CO2 heat pump air-cooling end. At this time, the first heat exchange port of the CO2 heat pump air-cooling end serves as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air-cooling end serves as the heat exchange inlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, and exchanges heat with the internal refrigerant. The temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air-cooling end and reduce the temperature of the air-cooling outlet of the CO2 heat pump air-cooling end, thereby further promoting the CO2 heat pump unit to collect energy from environmental sources. Improve the operating energy efficiency ratio of the CO2 heat pump; the domestic hot water return water first passes through the CO2 heat pump air-cooled end, and the temperature rises from the first intermediate temperature T2 to the second intermediate temperature T3. The CO2 heat pump evaporation end absorbs energy from the environmental source, and is upgraded to high-grade thermal energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air-cooled end, where the temperature is increased by heating; then it flows into the auxiliary heat pump condensation end, and the auxiliary heat pump evaporation end recovers heat in the domestic hot water return water, and is upgraded to high-grade thermal energy through the auxiliary heat pump compressor, and the temperature is increased to the heating domestic hot water supply temperature through the auxiliary heat pump condensation end, and is output through the outlet pipeline to provide domestic hot water supply.

[0013] The first intermediate temperature T2 and the second intermediate temperature T3 change according to the changes of the auxiliary heating heat pump system and the CO2 heat pump unit; the first intermediate temperature T2 is 35℃~50℃; the second intermediate temperature T3 is 55℃~70℃.

[0014] The green working medium assisted carbon dioxide heat pump combined heating system of the present invention adopts a CO2 heating type green working medium heat pump to assist the CO2 heat pump heating mode. The green working medium assisted carbon dioxide heat pump combined heating system comprises: an auxiliary heat pump evaporation end, an auxiliary heat pump compressor, an auxiliary heat pump condensation end, an auxiliary heat pump throttling device, a CO2 heat pump air cooling end, a CO2 heat pump compressor, a CO2 heat pump evaporation end, and first to third valves, a CO2 heat pump throttling device and a controller; wherein, the evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through the auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, and the outlet of the CO2 heat pump compressor is connected to the air cooling inlet of the CO2 heat pump air cooling end through a pipeline, and the CO The air-cooling outlet of the air-cooling end of the heat pump is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline, and the heat exchange outlet of the auxiliary heat pump evaporation end is connected to the evaporation inlet of the CO2 heat pump evaporation end through a pipeline after passing through the CO2 heat pump throttling device. The CO2 heat pump air-cooling end, the CO2 heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as a CO2 heat pump unit; the domestic hot water return water is respectively connected to the first heat exchange port of the air-cooling end of the CO2 heat pump and the heat exchange inlet of the auxiliary heat pump condensation end through a pipeline through a tee; a first valve is arranged in front of the heat exchange inlet of the auxiliary heat pump condensation end on the pipeline connecting the first heat exchange port of the air-cooling end of the CO2 heat pump and the heat exchange inlet of the auxiliary heat pump condensation end; the second heat exchange port of the CO2 heat pump air-cooling end and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet of the auxiliary heat pump condensation end and the outlet pipeline, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller;

[0015] The refrigerant in the evaporation end of the auxiliary heat pump adopts green refrigerant; the refrigerant completes the circulation in the auxiliary heating heat pump system;

[0016] The heat exchange inlet and heat exchange outlet of the evaporation end of the CO2 heat pump are respectively connected to the environmental source. The evaporation end of the CO2 heat pump utilizes the energy of the environmental source. Carbon dioxide collects low-grade thermal energy from the environmental source in the CO2 heat pump unit and transfers high-grade thermal energy to the domestic hot water return water.

[0017] The combined heating system has two heating modes: parallel heating and series heating;

[0018] Parallel heating: the first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, exchanges heat with the internal refrigerant, and the temperature rises from the return water temperature T1 to the first intermediate temperature T2, and then outputs through the outlet pipe to provide domestic hot water supply; the CO2 heat pump evaporation end uses The energy quality of the environmental source is upgraded to high-quality heat energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air cooling end; the auxiliary heat pump evaporation end recovers the heat after passing through the CO2 heat pump air cooling end in the CO2 heat pump unit cycle, reduces the inlet temperature of the CO2 heat pump evaporation end, further promotes the CO2 heat pump evaporation end to collect energy from the environmental source, improves the operating energy efficiency of the CO2 heat pump unit, and upgrades it to high-quality heat energy through the auxiliary heat pump compressor, and raises the temperature to the domestic hot water temperature through the auxiliary heat pump condensation end, and outputs it through the outlet pipeline to provide domestic hot water supply;

[0019] Series heating: the first valve is closed, the second valve is closed, and the third valve is opened, and the auxiliary heat pump condensing end is connected in series with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet; the domestic hot water return water with return water temperature T1 first runs to the heat pump CO2 heat pump air cooling end, and the CO2 heat pump evaporation end uses the energy grade of the environmental source to increase it to high-grade thermal energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end. The heating temperature in the air-cooled end of the heat pump rises to the first intermediate temperature T2; then it flows into the auxiliary heat pump condensing end, and the auxiliary heat pump evaporating end recovers the heat in the CO2 heat pump unit cycle after passing through the CO2 heat pump air-cooled end, reduces the inlet temperature of the CO2 heat pump evaporating end, and further promotes the CO2 heat pump evaporating end to collect energy from the environmental source, improves the operating energy efficiency ratio of the CO2 heat pump unit, and is upgraded to high-grade thermal energy through the auxiliary heat pump compressor, and the temperature is raised to the domestic hot water temperature through the auxiliary heat pump condensing end, and output through the outlet pipeline to provide domestic hot water supply.

[0020] The refrigerant in the auxiliary heat pump evaporation end adopts green refrigerant; the liquid refrigerant auxiliary heating heat pump system is heated and evaporated in the auxiliary heat pump evaporation end, becomes gaseous and enters the auxiliary heat pump compressor; the high-temperature gas after passing through the auxiliary heat pump compressor enters the auxiliary heat pump condensation end to release heat and becomes liquid refrigerant; the liquid refrigerant after passing through the auxiliary heat pump condensation end is throttled by the auxiliary heat pump throttling device and becomes low-temperature liquid refrigerant and enters the auxiliary heat pump evaporation end to complete the cycle.

[0021] The heat exchange inlet and heat exchange outlet of the evaporation end of the CO2 heat pump are respectively connected to the environmental source. The evaporation end of the CO2 heat pump utilizes the energy of the environmental source. Carbon dioxide collects low-grade thermal energy from the environmental source at the evaporation end of the CO2 heat pump and absorbs heat to evaporate into a gaseous state; then it is compressed by the CO2 heat pump compressor to become a high-temperature and high-pressure supercritical carbon dioxide; then the supercritical carbon dioxide enters the air-cooling end of the CO2 heat pump to cool and release heat energy; then the carbon dioxide coming out of the air-cooling end of the CO2 heat pump passes through the CO2 heat pump throttling device and enters the CO2 heat pump compressor again to complete the cycle, thereby realizing the low-grade thermal energy collected by carbon dioxide in the environment at the CO2 evaporation end and upgrading it to high-grade thermal energy, and transferring the high-grade thermal energy to the domestic hot water return water at the air-cooling end of the CO2 heat pump.

[0022] Domestic hot water return water includes heating return water, shower water, hand washing water and other hot water required in life.

[0023] The environmental source is one or more of an air source, a ground source and a water source, and the heat exchange inlet and the heat exchange outlet of the evaporation end of the CO2 heat pump are respectively connected to the air, the buried pipe and the water source pipe.

[0024] Green refrigerants use hydrofluoroolefins (HFO) or ammonia (NH3).

[0025] The first intermediate temperature T2 changes according to changes in the auxiliary heating heat pump system and the CO2 heat pump unit; the first intermediate temperature T2 is 55°C to 70°C.

[0026] Another object of the present invention is to provide a control method for a green working medium assisted carbon dioxide heat pump combined heating system.

[0027] The control method of the green working medium assisted carbon dioxide heat pump combined heating system of the present invention adopts a water-heating type green working medium heat pump assisted CO2 heat pump heating method, and comprises the following steps:

[0028] 1) Combined heating system connection:

[0029] The evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through an auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, and the outlet of the CO2 heat pump compressor is connected to the air cooling inlet of the CO2 heat pump air cooling end through a pipeline, and the air cooling outlet of the CO2 heat pump air cooling end is connected to the evaporation outlet of the CO2 heat pump evaporation end through the CO2 heat pump throttling device through a pipeline. The inlet, the CO2 heat pump air-cooled end, the CO2 heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as the CO2 heat pump unit; the domestic hot water return is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline, and the heat exchange outlet of the auxiliary heat pump evaporation end is respectively connected to the first heat exchange port of the CO2 heat pump air-cooled end and the heat exchange inlet of the auxiliary heat pump condensation end through a pipeline through a tee; a first valve is arranged in front of the heat exchange inlet of the auxiliary heat pump condensation end on the pipeline connecting the first heat exchange port of the CO2 heat pump air-cooled end and the heat exchange inlet of the auxiliary heat pump condensation end; the second heat exchange port of the CO2 heat pump air-cooled end and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline;

[0030] A connecting pipe is provided between the heat exchange inlet and outlet pipes of the auxiliary heat pump condensation end, and a third valve is provided on the connecting pipe; the first to third valves are respectively connected to the controller;

[0031] 2) The refrigerant in the auxiliary heat pump evaporation end uses green refrigerant, and the refrigerant completes the cycle in the auxiliary heating heat pump system; the first heat exchange port and the second heat exchange port of the CO2 heat pump evaporation end are respectively connected to the environmental source, and the CO2 heat pump evaporation end utilizes the energy of the environmental source. Carbon dioxide collects low-grade thermal energy from the environmental source in the CO2 heat pump unit and transfers high-grade thermal energy to the domestic hot water return water;

[0032] 3) Combined heating system has two heating modes:

[0033] a) Parallel heating:

[0034] The first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, and exchanges heat with the internal refrigerant, and the temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from the environmental source and improve the CO2 heat pump unit. The operating energy efficiency ratio of the group; the domestic hot water return water flows to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively; the CO2 heat pump evaporation end absorbs the energy from the environmental source, and upgrades it to high-grade thermal energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end; the auxiliary heat pump evaporation end recovers the heat in the domestic hot water return water, and upgrades it to high-grade thermal energy through the auxiliary heat pump compressor, and increases the temperature through the auxiliary heat pump condensing end; the domestic hot water return water exchanges heat at the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, and is mixed in the outlet pipeline after heat exchange. The mixed temperature is the second intermediate temperature T3, that is, the water supply temperature of the domestic hot water, and is output through the outlet pipeline to provide domestic hot water supply;

[0035] b) Series heating:

[0036] The first valve is closed, the second valve is closed, and the third valve is opened, connecting the auxiliary heat pump condensing end and the CO2 heat pump air cooling end in series. At this time, the first heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange inlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, exchanges heat with the internal refrigerant, and the temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from the environmental source and improve C The operating energy efficiency ratio of the O2 heat pump unit; the domestic hot water return water first passes through the CO2 heat pump air cooling end, and the temperature rises from the first intermediate temperature T2 to the second intermediate temperature T3. The CO2 heat pump evaporation end absorbs energy from the environmental source, and is upgraded to high-grade thermal energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air cooling end, where the temperature is increased by heating; then it flows into the auxiliary heat pump condensation end, and the auxiliary heat pump evaporation end recovers the heat in the domestic hot water return water, and is upgraded to high-grade thermal energy through the auxiliary heat pump compressor, and the temperature is increased to the heating domestic hot water supply temperature through the auxiliary heat pump condensation end, and is output through the outlet pipeline to provide domestic hot water supply;

[0037] 4) The auxiliary heating heat pump system optimizes the heat absorption process of the transcritical CO2 heat pump unit, promotes the CO2 heat pump unit to absorb more energy from the environmental source, and improves the energy efficiency ratio of the combined heating system; reduces the ground source temperature, thereby improving the efficiency of the air-conditioning system in summer; by coupling the auxiliary heating heat pump system, the transcritical CO2 heat pump unit can fully utilize the environmental source energy, increase the water supply temperature and reduce the operating energy consumption while matching the existing terminal supply and return water temperature difference. It effectively solves the problem of the small supply and return water temperature difference between the transcritical CO2 heat pump unit and the existing terminal equipment.

[0038] Improve the overall energy efficiency of the system and ensure efficient, comfortable and low-energy operation.

[0039] The control method of the green working fluid assisted carbon dioxide heat pump combined heating system of the present invention adopts a CO2 heating type green working fluid heat pump assisted CO2 heat pump heating mode, comprising the following steps:

[0040] 1) Combined heating system connection:

[0041] The evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through an auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, and the outlet of the CO2 heat pump compressor is connected to the air cooling inlet of the CO2 heat pump air cooling end through a pipeline, and the air cooling outlet of the CO2 heat pump air cooling end is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline, and the heat exchange outlet of the auxiliary heat pump evaporation end is connected to the evaporation inlet of the CO2 heat pump evaporation end through a pipeline after passing through the CO2 heat pump throttling device, and the CO2 heat pump air cooling end, CO 2 The heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as the CO2 heat pump unit; the domestic hot water return water is respectively connected to the first heat exchange port of the CO2 heat pump air cooling end and the heat exchange inlet of the auxiliary heat pump condensing end through a pipeline through a tee; a first valve is arranged in front of the heat exchange inlet of the auxiliary heat pump condensing end on the pipeline connecting the first heat exchange port of the CO2 heat pump air cooling end and the heat exchange inlet of the auxiliary heat pump condensing end; the second heat exchange port of the CO2 heat pump air cooling end and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet and the outlet pipeline of the auxiliary heat pump condensing end, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller; the auxiliary heating heat pump system and the CO2 heat pump unit are connected to a combined heating system through the first to third valves;

[0042] 2) The refrigerant in the auxiliary heat pump evaporation end uses green refrigerant, and the refrigerant completes the cycle in the auxiliary heating heat pump system; the first heat exchange port and the second heat exchange port of the CO2 heat pump evaporation end are respectively connected to the environmental source, and the CO2 heat pump evaporation end uses the energy of the environmental source. Carbon dioxide collects low-grade thermal energy from the environmental source in the CO2 heat pump unit and transfers high-grade thermal energy to the domestic hot water return water;

[0043] 3) Combined heating system has two heating modes:

[0044] Parallel heating:

[0045] The first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange outlet; the domestic hot water return water with the return water temperature T1 runs to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, exchanges heat with the internal refrigerant, and the temperature rises from the return water temperature T1 to the first intermediate temperature T2, and then is output through the outlet pipe to provide domestic hot water supply; the CO2 heat pump evaporation end utilizes the energy grade of the environmental source, and is upgraded to high-grade thermal energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air cooling end;

[0046] The auxiliary heat pump evaporation end recycles the heat after passing through the CO2 heat pump air cooling end in the CO2 heat pump unit cycle, reduces the inlet temperature of the CO2 heat pump evaporation end, further promotes the CO2 heat pump evaporation end to collect energy from the environmental source, improves the operating energy efficiency of the CO2 heat pump unit, and increases it to high-grade heat energy through the auxiliary heat pump compressor, and increases the temperature to the domestic hot water temperature through the auxiliary heat pump condensation end, and outputs it through the outlet pipeline to provide domestic hot water supply;

[0047] Series heating: the first valve is closed, the second valve is closed, and the third valve is opened, and the auxiliary heat pump condensing end is connected in series with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet; the domestic hot water return water with return water temperature T1 first runs to the heat pump CO2 heat pump air cooling end, and the CO2 heat pump evaporation end uses the energy grade of the environmental source to increase it to high-grade thermal energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end. The heating temperature in the air-cooled end of the heat pump rises to the first intermediate temperature T2; then it flows into the auxiliary heat pump condensing end, and the auxiliary heat pump evaporating end recovers the heat after passing through the air-cooled end of the CO2 heat pump in the cycle of the CO2 heat pump unit, reduces the inlet temperature of the CO2 heat pump evaporating end, further promotes the CO2 heat pump evaporating end to collect energy from the environmental source, improves the operating energy efficiency ratio of the CO2 heat pump unit, and increases it to high-grade heat energy through the auxiliary heat pump compressor, and increases the temperature to the domestic hot water temperature through the auxiliary heat pump condensing end, and outputs it through the outlet pipeline to provide domestic hot water supply;

[0048] 4) The auxiliary heating heat pump system optimizes the heat absorption process of the transcritical CO2 heat pump unit, promotes the CO2 heat pump unit to absorb more energy from the environmental source, and improves the energy efficiency ratio of the combined heating system; reduces the ground source temperature, thereby improving the efficiency of the air-conditioning system in summer; by coupling the auxiliary heating heat pump system, the transcritical CO2 heat pump unit can fully utilize the environmental source energy, increase the water supply temperature and reduce the operating energy consumption while matching the existing terminal supply and return water temperature difference. It effectively solves the problem of the small supply and return water temperature difference between the transcritical CO2 heat pump unit and the existing terminal equipment.

[0049] Improve the overall energy efficiency of the system and ensure efficient, comfortable and low-energy operation.

[0050] Wherein, in step 2), in the auxiliary heating heat pump system, the liquid refrigerant is heated and evaporated in the auxiliary heat pump evaporation end, becomes gaseous and enters the auxiliary heat pump compressor; the high-temperature gas after passing through the auxiliary heat pump compressor enters the auxiliary heat pump condensation end to release heat and becomes liquid refrigerant; the liquid refrigerant after passing through the auxiliary heat pump condensation end is throttled by the auxiliary heat pump throttling device and becomes low-temperature liquid refrigerant and enters the auxiliary heat pump evaporation end to complete the cycle;

[0051] In the CO2 heat pump unit, carbon dioxide collects low-grade heat energy from the environment at the evaporation end of the CO2 heat pump, absorbs heat and evaporates into a gas; then it is compressed by the CO2 heat pump compressor to become high-temperature and high-pressure supercritical carbon dioxide; then the supercritical carbon dioxide enters the air-cooling end of the CO2 heat pump to be cooled and release heat energy; then the carbon dioxide coming out of the air-cooling end of the CO2 heat pump passes through the CO2 heat pump throttling device and enters the CO2 heat pump compressor again to complete the cycle, thereby realizing the low-grade heat energy collected by carbon dioxide in the environment at the CO2 evaporation end and upgrading it to high-grade heat energy, and transferring the high-grade heat energy to domestic hot water return water at the air-cooling end of the CO2 heat pump.

[0052] Advantages of the present invention:

[0053] 1. Use environmentally friendly working fluids such as hydrofluoroolefins or ammonia and carbon dioxide. The present invention uses hydrofluoroolefins and ammonia heat pumps to assist CO2 heat pump heating, which significantly increases the water supply temperature and reduces the pollution of traditional refrigerants to the environment. By using environmentally friendly working fluids such as hydrofluoroolefins (HFO) or ammonia (NH3) and carbon dioxide (CO2), while improving system performance, it has a low-carbon effect, ensuring the environmental friendliness and sustainability of the system.

[0054] 2. A water-thermal green working fluid heat pump assisting a CO2 heat pump heating method in two operating modes, either in series or in parallel, or a CO2-heating green working fluid heat pump assisting a CO2 heat pump heating method. The invention plays a role in two specific operating modes. The water-thermal green working fluid heat pump assisting a CO2 heat pump heating method extracts heat energy from water, reduces the return water temperature, and improves the operating energy efficiency ratio of the CO2 heat pump unit. The CO2-heating green working fluid heat pump assisting a CO2 heat pump heating method extracts heat energy from CO2, and further improves the water supply temperature and system energy efficiency by raising the recovered heat to a high grade. In series operation, the circulating water first absorbs heat from the air-cooled end of the CO2 heat pump and then absorbs heat from the HFO and NH3 auxiliary heat pumps. In parallel operation, the circulating water absorbs heat from the air-cooled end of the CO2 heat pump and the HFO and NH3 auxiliary heat pumps respectively. Through these two methods, the present invention effectively solves the problem of the small temperature difference between the supply and return water of the CO2 heat pump and the existing terminal equipment, and improves the overall energy efficiency of the system.

[0055] 3. Promote carbon dioxide to absorb more energy from air sources and / or ground sources or water sources. The present invention improves the energy efficiency ratio of the combined heating system by optimizing the heat absorption process of carbon dioxide. In summer operation, by using the HFO and NH3 heat pump auxiliary system, the ground source temperature is reduced, thereby improving the efficiency of the summer air conditioning system. This method not only improves the adaptability of the system under various environmental conditions, but also further enhances the overall performance and energy-saving effect of the CO2 heat pump unit.

[0056] 4. The CO2 heat pump unit increases the energy quality of the air source and / or water source or ground source, and transfers the increased energy to the heating return water; the auxiliary heating heat pump system takes heat from the heating return water or carbon dioxide and further increases the water supply temperature; the controller switches the valve switch to achieve the transition from series to parallel mode.

[0057] 5. It can solve the problem that the traditional heating terminal is poorly matched with the CO2 heat pump unit, and the small temperature difference between the supply and return water leads to the low efficiency of the CO2 heat pump unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a schematic diagram of the first embodiment of the green working medium assisted carbon dioxide heat pump combined heating system of the present invention;

[0059] Figure 2 It is a schematic diagram of the second embodiment of the green working medium assisted carbon dioxide heat pump combined heating system of the present invention. DETAILED DESCRIPTION

[0060] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0061] Embodiment 1

[0062] In this embodiment, a water-heating green working fluid heat pump is used to assist the CO2 heat pump heating method.

[0063] like Figure 1As shown, the green working fluid assisted carbon dioxide heat pump combined heating system of this embodiment includes: an auxiliary heat pump evaporation end, an auxiliary heat pump compressor, an auxiliary heat pump condensation end, an auxiliary heat pump throttling device, a CO2 heat pump air-cooling end, a CO2 heat pump compressor, a CO2 heat pump evaporation end, a CO2 heat pump throttling device, first to third valves and a controller; wherein, the evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through the auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, the outlet of the CO2 heat pump compressor is connected to the air-cooling inlet of the CO2 heat pump air-cooling end through a pipeline, and the air-cooling outlet of the CO2 heat pump air-cooling end is connected to the CO2 heat pump throttling device through a pipeline To the evaporation inlet of the CO2 heat pump evaporation end, the CO2 heat pump air-cooled end, the CO2 heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as the CO2 heat pump unit; the domestic hot water return is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline, and the heat exchange outlet of the auxiliary heat pump evaporation end is respectively connected to the first heat exchange port of the CO2 heat pump air-cooled end and the heat exchange inlet of the auxiliary heat pump condensation end through a pipeline through a tee; a first valve is arranged in front of the heat exchange inlet of the auxiliary heat pump condensation end on the pipeline connecting the first heat exchange port of the CO2 heat pump air-cooled end and the heat exchange inlet of the auxiliary heat pump condensation end; the second heat exchange port of the CO2 heat pump air-cooled end and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet of the auxiliary heat pump condensation end and the outlet pipeline, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller; the auxiliary heating heat pump system and the CO2 heat pump unit are connected to a combined heating system through the first to third valves;

[0064] The refrigerant in the evaporation end of the auxiliary heat pump adopts green refrigerant; the refrigerant completes the circulation in the auxiliary heating heat pump system;

[0065] The first heat exchange port and the second heat exchange port of the evaporation end of the CO2 heat pump are respectively connected to the environmental source. The evaporation end of the CO2 heat pump utilizes the energy of the environmental source. Carbon dioxide collects low-grade thermal energy from the environmental source in the CO2 heat pump unit and transfers high-grade thermal energy to domestic hot water return water.

[0066] The combined heating system has two heating modes: parallel heating and series heating;

[0067] Parallel heating: through the controller, the first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, and exchanges heat with the internal refrigerant. The temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from environmental sources and improve The operation energy efficiency ratio of the CO2 heat pump unit; the domestic hot water return water flows to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively; the CO2 heat pump evaporation end absorbs energy from the environmental source, upgrades it to high-grade thermal energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end; the auxiliary heat pump evaporation end recovers the heat in the domestic hot water return water, and upgrades it to high-grade thermal energy through the auxiliary heat pump compressor, and increases the temperature through the auxiliary heat pump condensing end; the domestic hot water return water exchanges heat at the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, and is mixed in the outlet pipeline after heat exchange. The mixed temperature is the second intermediate temperature T3, i.e., the domestic hot water supply temperature, and is output through the outlet pipeline to provide domestic hot water supply;

[0068] Series heating: through the controller, the first valve is closed, the second valve is closed, and the third valve is opened, and the auxiliary heat pump condensing end and the CO2 heat pump air cooling end are connected in series. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, and exchanges heat with the internal refrigerant. The temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from environmental sources. The amount of domestic hot water return water first passes through the CO2 heat pump air-cooled end, and the temperature rises from the first intermediate temperature T2 to the second intermediate temperature T3. The CO2 heat pump evaporation end absorbs energy from the environmental source, and is upgraded to high-grade thermal energy through the CO2 heat pump compressor. The heat is transferred to the CO2 heat pump air-cooled end, and the temperature is increased by heating in the CO2 heat pump air-cooled end. Then it flows into the auxiliary heat pump condensation end. The auxiliary heat pump evaporation end recovers heat in the domestic hot water return water, and is upgraded to high-grade thermal energy through the auxiliary heat pump compressor. The temperature is increased to the heating domestic hot water supply temperature through the auxiliary heat pump condensation end, and is output through the outlet pipeline to provide domestic hot water supply.

[0069] Embodiment 2

[0070] In this embodiment, a CO2 heating type green working fluid heat pump is used to assist the CO2 heat pump heating method.

[0071] like Figure 2 As shown, the green working fluid assisted carbon dioxide heat pump combined heating system of this embodiment includes: an auxiliary heat pump evaporation end, an auxiliary heat pump compressor, an auxiliary heat pump condensation end, an auxiliary heat pump throttling device, a CO2 heat pump air cooling end, a CO2 heat pump compressor, a CO2 heat pump evaporation end and first to third valves, a CO2 heat pump throttling device and a controller; wherein, the evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through the auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, the outlet of the CO2 heat pump compressor is connected to the air cooling inlet of the CO2 heat pump air cooling end through a pipeline, and the air cooling outlet of the CO2 heat pump air cooling end is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline. The heat exchange outlet of the auxiliary heat pump evaporation end passes through the CO2 heat pump throttling device and is connected to the evaporation inlet of the CO2 heat pump evaporation end through a pipeline. The CO2 heat pump air-cooled end, the CO2 heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as the CO2 heat pump unit; the domestic hot water return water passes through a pipeline and is connected to the first heat exchange port of the CO2 heat pump air-cooled end and the heat exchange inlet of the auxiliary heat pump condensing end respectively through a tee; a first valve is arranged on the pipeline connecting the first heat exchange port of the CO2 heat pump air-cooled end and the heat exchange inlet of the auxiliary heat pump condensing end before the heat exchange inlet of the auxiliary heat pump condensing end; the second heat exchange port of the CO2 heat pump air-cooled end and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet of the auxiliary heat pump condensing end and the outlet pipeline, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller; the auxiliary heating heat pump system and the CO2 heat pump unit are connected to a combined heating system through the first to third valves;

[0072] The refrigerant in the auxiliary heat pump evaporation end uses green refrigerant; the liquid refrigerant is heated and evaporated in the auxiliary heat pump evaporation end, becomes gaseous and enters the auxiliary heat pump compressor; after passing through the auxiliary heat pump compressor, it becomes high-temperature gas and enters the auxiliary heat pump condensation end to release heat and become liquid refrigerant; the liquid refrigerant after passing through the auxiliary heat pump condensation end is throttled by the auxiliary heat pump throttling device and becomes low-temperature liquid refrigerant and enters the auxiliary heat pump evaporation end to complete the cycle;

[0073] The heat exchange inlet and heat exchange outlet of the evaporation end of the CO2 heat pump are respectively connected to the environmental source, so that the evaporation end of the CO2 heat pump utilizes the energy of the environmental source, and the carbon dioxide collects the low-grade heat energy of the environmental source at the evaporation end of the CO2 heat pump to absorb heat and evaporate into a gaseous state; then it is compressed by the CO2 heat pump compressor to become a high-temperature and high-pressure supercritical carbon dioxide; then the supercritical carbon dioxide enters the air-cooling end of the CO2 heat pump to cool and release heat energy; then the carbon dioxide coming out of the air-cooling end of the CO2 heat pump passes through the throttling device and enters the CO2 heat pump compressor again to complete the cycle, thereby realizing that the low-grade heat energy collected by the carbon dioxide in the environment at the CO2 evaporation end is upgraded to high-grade heat energy, and the high-grade heat energy is transferred to the domestic hot water return water at the air-cooling end of the CO2 heat pump;

[0074] The combined heating system has two heating modes: parallel heating and series heating;

[0075] Parallel heating: through the controller, the first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end and the CO2 heat pump air cooling end are connected in parallel. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, exchanges heat with the internal refrigerant, and the temperature rises from the return water temperature T1 to the first intermediate temperature T2, and then is output through the outlet pipe to provide domestic hot water supply; CO2 heat pump steam The energy quality of the environmental source is utilized at the originating end, and is upgraded to high-quality heat energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air-cooling end; the auxiliary heat pump evaporation end recovers the heat after passing through the CO2 heat pump air-cooling end in the CO2 heat pump unit cycle, reduces the inlet temperature of the CO2 heat pump evaporation end, further promotes the CO2 heat pump evaporation end to collect energy from the environmental source, improves the operating energy efficiency ratio of the CO2 heat pump unit, and upgrades to high-quality heat energy through the auxiliary heat pump compressor, and raises the temperature to the domestic hot water temperature through the auxiliary heat pump condensation end, and outputs it through the outlet pipeline to provide domestic hot water supply;

[0076] Series heating: through the controller, the first valve is closed, the second valve is closed, and the third valve is opened, and the auxiliary heat pump condensing end and the CO2 heat pump air cooling end are connected in series. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet; the domestic hot water return water with return water temperature T1 first runs to the heat pump CO2 heat pump air cooling end, and the CO2 heat pump evaporation end uses the energy grade of the environmental source to increase it to high-grade thermal energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end. The heating temperature in the air-cooled end of the CO2 heat pump rises to the first intermediate temperature T2; then it flows into the auxiliary heat pump condensing end, and the auxiliary heat pump evaporating end recovers the heat after passing through the CO2 heat pump air-cooled end in the cycle of the CO2 heat pump unit, reduces the inlet temperature of the CO2 heat pump evaporating end, and further promotes the CO2 heat pump evaporating end to collect energy from environmental sources, improves the operating energy efficiency ratio of the CO2 heat pump unit, and upgrades it to high-grade thermal energy through the auxiliary heat pump compressor, and raises the temperature to the domestic hot water temperature through the auxiliary heat pump condensing end, and outputs it through the outlet pipeline to provide domestic hot water supply.

[0077] Finally, it should be noted that the purpose of publishing the embodiments is to help further understand the present invention, but those skilled in the art can understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

Claims

1. A green working fluid assisted carbon dioxide heat pump combined heating system, using a hydrothermal green working fluid heat pump assisted CO2 heat pump heating method, characterized in that: The combined heating system comprises: an auxiliary heat pump evaporation end, an auxiliary heat pump compressor, an auxiliary heat pump condensation end, an auxiliary heat pump throttling device, a CO2 heat pump air-cooling end, a CO2 heat pump compressor, a CO2 heat pump evaporation end, a CO2 heat pump throttling device, first to third valves and a controller; wherein, the evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through the auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, the outlet of the CO2 heat pump compressor is connected to the air-cooling inlet of the CO2 heat pump air-cooling end through a pipeline, and the air-cooling outlet of the CO2 heat pump air-cooling end is connected to the air-cooling outlet of the CO2 heat pump air-cooling end through the CO2 heat pump throttling device. The flow device is connected to the evaporation inlet of the CO2 heat pump evaporation end through a pipeline, and the CO2 heat pump air-cooled end, the CO2 heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as a CO2 heat pump unit; the domestic hot water return is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline, and the heat exchange outlet of the auxiliary heat pump evaporation end is respectively connected to the first heat exchange port of the CO2 heat pump air-cooled end and the heat exchange inlet of the auxiliary heat pump condensation end through a pipeline through a tee; a first valve is arranged in front of the heat exchange inlet of the auxiliary heat pump condensation end on the pipeline connecting the first heat exchange port of the CO2 heat pump air-cooled end and the heat exchange inlet of the auxiliary heat pump condensation end; the second heat exchange port of the CO2 heat pump air-cooled end and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet and the outlet pipeline of the auxiliary heat pump condensation end, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller; The refrigerant in the auxiliary heat pump evaporation end uses green refrigerant; the refrigerant completes the cycle in the auxiliary heating heat pump system; the first heat exchange port and the second heat exchange port of the CO2 heat pump evaporation end are respectively connected to the environmental source, and the CO2 heat pump evaporation end utilizes the energy of the environmental source. Carbon dioxide collects low-grade heat energy from the environmental source in the CO2 heat pump unit and transfers high-grade heat energy to the domestic hot water return water; The combined heating system has two heating modes: parallel heating and series heating; Parallel heating: the first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, and exchanges heat with the internal refrigerant. The temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from environmental sources and improve CO2 The operation energy efficiency ratio of the heat pump unit; the domestic hot water return water flows to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively; the CO2 heat pump evaporation end absorbs the energy from the environmental source, upgrades it to high-grade heat energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end; the auxiliary heat pump evaporation end recovers the heat in the domestic hot water return water, and upgrades it to high-grade heat energy through the auxiliary heat pump compressor, and increases the temperature through the auxiliary heat pump condensing end; the domestic hot water return water exchanges heat at the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, and is mixed in the outlet pipeline after heat exchange. The mixed temperature is the second intermediate temperature T3, i.e., the domestic hot water supply temperature, and is output through the outlet pipeline to provide domestic hot water supply; Series heating: the first valve is closed, the second valve is closed, and the third valve is opened, and the auxiliary heat pump condensing end is connected in series with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, and exchanges heat with the internal refrigerant. The temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from the environmental source and provide High CO2 heat pump unit operation energy efficiency ratio; domestic hot water return water first passes through the CO2 heat pump air-cooled end, and the temperature rises from the first intermediate temperature T2 to the second intermediate temperature T3; the CO2 heat pump evaporation end absorbs energy from the environmental source, and is upgraded to high-grade thermal energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air-cooled end, where the temperature is increased by heating; then it flows into the auxiliary heat pump condensation end, and the auxiliary heat pump evaporation end recovers heat in the domestic hot water return water, and is upgraded to high-grade thermal energy through the auxiliary heat pump compressor, and the temperature is increased to the heating domestic hot water supply temperature through the auxiliary heat pump condensation end, and is output through the outlet pipeline to provide domestic hot water supply.

2. A green working fluid assisted carbon dioxide heat pump combined heating system, using a CO2 heating type green working fluid heat pump assisted CO2 heat pump heating method, characterized in that: The combined heating system comprises: an auxiliary heat pump evaporation end, an auxiliary heat pump compressor, an auxiliary heat pump condensation end, an auxiliary heat pump throttling device, a CO2 heat pump air-cooling end, a CO2 heat pump compressor, a CO2 heat pump evaporation end, and first to third valves, a CO2 heat pump throttling device and a controller; wherein, the evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through the auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, the outlet of the CO2 heat pump compressor is connected to the air-cooling inlet of the CO2 heat pump air-cooling end through a pipeline, and the air-cooling outlet of the CO2 heat pump air-cooling end is connected to the auxiliary The heat exchange inlet of the evaporation end of the heat pump, the heat exchange outlet of the evaporation end of the auxiliary heat pump is connected to the evaporation inlet of the evaporation end of the CO2 heat pump through a pipeline after passing through the CO2 heat pump throttling device. The CO2 heat pump air-cooled end, the CO2 heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as a CO2 heat pump unit; the domestic hot water return water passes through a pipeline and is connected to the first heat exchange port of the air-cooled end of the CO2 heat pump and the heat exchange inlet of the condensation end of the auxiliary heat pump respectively through a tee; a first valve is arranged on the pipeline connecting the first heat exchange port of the air-cooled end of the CO2 heat pump and the heat exchange inlet of the condensation end of the auxiliary heat pump, in front of the heat exchange inlet of the condensation end of the auxiliary heat pump; the second heat exchange port of the air-cooled end of the CO2 heat pump and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet of the condensation end of the auxiliary heat pump and the outlet pipeline, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller; The refrigerant in the auxiliary heat pump evaporation end uses green refrigerant; the refrigerant completes the cycle in the auxiliary heating heat pump system; the heat exchange inlet and heat exchange outlet of the CO2 heat pump evaporation end are respectively connected to the environmental source, and the CO2 heat pump evaporation end uses the energy of the environmental source. Carbon dioxide collects low-grade heat energy from the environmental source in the CO2 heat pump unit and transfers high-grade heat energy to the domestic hot water return water; The combined heating system has two heating modes: parallel heating and series heating; Parallel heating: the first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, exchanges heat with the internal refrigerant, and the temperature rises from the return water temperature T1 to the first intermediate temperature T2, and then outputs through the outlet pipe to provide domestic hot water supply; the CO2 heat pump evaporation end uses The energy quality of the environmental source is upgraded to high-quality heat energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air cooling end; the auxiliary heat pump evaporation end recovers the heat after passing through the CO2 heat pump air cooling end in the CO2 heat pump unit cycle, reduces the inlet temperature of the CO2 heat pump evaporation end, further promotes the CO2 heat pump evaporation end to collect energy from the environmental source, improves the operating energy efficiency of the CO2 heat pump unit, and upgrades it to high-quality heat energy through the auxiliary heat pump compressor, and raises the temperature to the domestic hot water temperature through the auxiliary heat pump condensation end, and outputs it through the outlet pipeline to provide domestic hot water supply; Series heating: the first valve is closed, the second valve is closed, and the third valve is opened, and the auxiliary heat pump condensing end is connected in series with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet; the domestic hot water return water with return water temperature T1 first runs to the heat pump CO2 heat pump air cooling end, and the CO2 heat pump evaporation end uses the energy grade of the environmental source to increase it to high-grade thermal energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end. The heating temperature in the air-cooled end of the heat pump rises to the first intermediate temperature T2; then it flows into the auxiliary heat pump condensing end, and the auxiliary heat pump evaporating end recovers the heat in the CO2 heat pump unit cycle after passing through the CO2 heat pump air-cooled end, reduces the inlet temperature of the CO2 heat pump evaporating end, and further promotes the CO2 heat pump evaporating end to collect energy from the environmental source, improves the operating energy efficiency ratio of the CO2 heat pump unit, and is upgraded to high-grade thermal energy through the auxiliary heat pump compressor, and the temperature is raised to the domestic hot water temperature through the auxiliary heat pump condensing end, and output through the outlet pipeline to provide domestic hot water supply.

3. The combined heating system according to claim 1 or 2, characterized in that: In the auxiliary heating heat pump system, the liquid refrigerant is heated and evaporated in the auxiliary heat pump evaporation end, becomes gaseous and enters the auxiliary heat pump compressor; the high-temperature gas after passing through the auxiliary heat pump compressor enters the auxiliary heat pump condensation end to release heat and becomes liquid refrigerant; the liquid refrigerant after passing through the auxiliary heat pump condensation end is throttled by the auxiliary heat pump throttling device to become low-temperature liquid refrigerant and enter the auxiliary heat pump evaporation end to complete the cycle.

4. The combined heating system according to claim 1 or 2, characterized in that: In the CO2 heat pump unit, carbon dioxide collects low-grade heat energy from the environment at the evaporation end of the CO2 heat pump, absorbs heat and evaporates into a gaseous state; then it is compressed by the CO2 heat pump compressor to become high-temperature and high-pressure supercritical carbon dioxide; then the supercritical carbon dioxide enters the CO2 heat pump air-cooling end to be cooled and release heat energy; then the carbon dioxide coming out of the CO2 heat pump air-cooling end passes through the CO2 heat pump throttling device and enters the CO2 heat pump compressor again to complete the cycle, thereby realizing the low-grade heat energy collected by carbon dioxide in the environment at the CO2 evaporation end and upgrading it to high-grade heat energy, and transferring the high-grade heat energy to domestic hot water return water at the CO2 heat pump air-cooling end.

5. The combined heating system according to claim 1 or 2, characterized in that: The domestic hot water return water includes heating return water, shower water and hand washing water required for daily life.

6. The combined heating system according to claim 1 or 2, characterized in that: The environmental source is one or more of an air source, a ground source and a water source, and the heat exchange inlet and the heat exchange outlet of the evaporation end of the CO2 heat pump are respectively connected to the air, the buried pipe and the water source pipe.

7. The combined heating system according to claim 1 or 2, characterized in that: The green refrigerant uses hydrofluoroolefin or ammonia.

8. A control method for a green working medium assisted carbon dioxide heat pump combined heating system as claimed in claim 1, which adopts a water-heating type green working medium heat pump assisted CO2 heat pump heating method, characterized in that: The control method comprises the following steps: 1) Combined heating system connection: The evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through an auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, and the outlet of the CO2 heat pump compressor is connected to the air cooling inlet of the CO2 heat pump air cooling end through a pipeline, and the air cooling outlet of the CO2 heat pump air cooling end is connected to the evaporation inlet of the CO2 heat pump evaporation end through a pipeline through the CO2 heat pump throttling device, and the CO2 heat pump air cooling end, CO2 heat pump compressor, CO2 heat pump throttling device and CO2 heat pump condensation end are collectively referred to as an auxiliary heating heat pump system. The flow device and the evaporation end of the CO2 heat pump are collectively referred to as a CO2 heat pump unit; the domestic hot water return is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline, and the heat exchange outlet of the auxiliary heat pump evaporation end is respectively connected to the first heat exchange port of the CO2 heat pump air cooling end and the heat exchange inlet of the auxiliary heat pump condensation end through a pipeline through a tee; a first valve is arranged in front of the heat exchange inlet of the auxiliary heat pump condensation end on the pipeline connecting the first heat exchange port of the CO2 heat pump air cooling end and the heat exchange inlet of the auxiliary heat pump condensation end; the second heat exchange port of the CO2 heat pump air cooling end and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet and the outlet pipeline of the auxiliary heat pump condensation end, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller; 2) The refrigerant in the auxiliary heat pump evaporation end uses green refrigerant, and the refrigerant completes the cycle in the auxiliary heating heat pump system; the first heat exchange port and the second heat exchange port of the CO2 heat pump evaporation end are respectively connected to the environmental source, and the CO2 heat pump evaporation end utilizes the energy of the environmental source. Carbon dioxide collects low-grade thermal energy from the environmental source in the CO2 heat pump unit and transfers high-grade thermal energy to the domestic hot water return water; 3) Combined heating system has two heating modes: a) Parallel heating: The first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, and exchanges heat with the internal refrigerant, and the temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from the environmental source and improve the CO2 heat pump unit. The operating energy efficiency ratio of the group; the domestic hot water return water flows to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively; the CO2 heat pump evaporation end absorbs the energy from the environmental source, and upgrades it to high-grade thermal energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end; the auxiliary heat pump evaporation end recovers the heat in the domestic hot water return water, and upgrades it to high-grade thermal energy through the auxiliary heat pump compressor, and increases the temperature through the auxiliary heat pump condensing end; the domestic hot water return water exchanges heat at the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, and is mixed in the outlet pipeline after heat exchange. The mixed temperature is the second intermediate temperature T3, that is, the water supply temperature of the domestic hot water, and is output through the outlet pipeline to provide domestic hot water supply; b) Series heating: The first valve is closed, the second valve is closed, and the third valve is opened, connecting the auxiliary heat pump condensing end and the CO2 heat pump air cooling end in series. At this time, the first heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange inlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump evaporation end, exchanges heat with the internal refrigerant, and the temperature is reduced from the return water temperature T1 to the first intermediate temperature T2. The lower temperature can further absorb the heat in the CO2 heat pump air cooling end and reduce the temperature of the air cooling outlet of the CO2 heat pump air cooling end, thereby further promoting the CO2 heat pump unit to collect energy from the environmental source and improve C The operating energy efficiency ratio of the O2 heat pump unit; the domestic hot water return water first passes through the CO2 heat pump air cooling end, and the temperature rises from the first intermediate temperature T2 to the second intermediate temperature T3. The CO2 heat pump evaporation end absorbs energy from the environmental source, and is upgraded to high-grade thermal energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air cooling end, where the temperature is increased by heating; then it flows into the auxiliary heat pump condensation end, and the auxiliary heat pump evaporation end recovers the heat in the domestic hot water return water, and is upgraded to high-grade thermal energy through the auxiliary heat pump compressor, and the temperature is increased to the heating domestic hot water supply temperature through the auxiliary heat pump condensation end, and is output through the outlet pipeline to provide domestic hot water supply; 4) The auxiliary heating heat pump system optimizes the heat absorption process of the transcritical CO2 heat pump unit, promotes the CO2 heat pump unit to absorb more energy from the environmental source, and improves the energy efficiency of the combined heating system; reduces the ground source temperature, thereby improving the efficiency of the air-conditioning system in summer; by coupling the auxiliary heating heat pump system, the transcritical CO2 heat pump unit can make full use of the environmental source energy, increase the water supply temperature and reduce the operating energy consumption while matching the existing terminal supply and return water temperature difference.

9. A control method for a green working fluid assisted carbon dioxide heat pump combined heating system as claimed in claim 2, wherein a CO2 heating type green working fluid heat pump assists a CO2 heat pump heating method, characterized in that: The control method comprises the following steps: 1) Combined heating system connection: The evaporation outlet of the auxiliary heat pump evaporation end is connected to the inlet of the auxiliary heat pump compressor, and the outlet of the auxiliary heat pump compressor is connected to the condensation inlet of the auxiliary heat pump condensation end through a pipeline; the condensation outlet of the auxiliary heat pump condensation end is connected to the evaporation inlet of the auxiliary heat pump evaporation end through an auxiliary heat pump throttling device, and the auxiliary heat pump evaporation end, the auxiliary heat pump compressor, the auxiliary heat pump throttling device and the auxiliary heat pump condensation end are collectively referred to as an auxiliary heating heat pump system; the evaporation outlet of the CO2 heat pump evaporation end is connected to the inlet of the CO2 heat pump compressor through a pipeline, and the outlet of the CO2 heat pump compressor is connected to the air cooling inlet of the CO2 heat pump air cooling end through a pipeline, and the air cooling outlet of the CO2 heat pump air cooling end is connected to the heat exchange inlet of the auxiliary heat pump evaporation end through a pipeline, and the heat exchange outlet of the auxiliary heat pump evaporation end is connected to the CO2 heat pump evaporation through a pipeline after passing through the CO2 heat pump throttling device. The evaporation inlet of the end, the CO2 heat pump air-cooling end, the CO2 heat pump compressor, the CO2 heat pump throttling device and the CO2 heat pump evaporation end are collectively referred to as the CO2 heat pump unit; the domestic hot water return water passes through a pipeline and is respectively connected to the first heat exchange port of the CO2 heat pump air-cooling end and the heat exchange inlet of the auxiliary heat pump condensing end through a tee; a first valve is arranged in front of the heat exchange inlet of the auxiliary heat pump condensing end on the pipeline connecting the first heat exchange port of the CO2 heat pump air-cooling end and the heat exchange inlet of the auxiliary heat pump condensing end; the second heat exchange port of the CO2 heat pump air-cooling end and the heat exchange outlet of the auxiliary heat pump condenser are merged into an outlet pipeline through a tee, and a second valve is arranged on the outlet pipeline; a connecting pipeline is arranged between the heat exchange inlet and the outlet pipeline of the auxiliary heat pump condensing end, and a third valve is arranged on the connecting pipeline; the first to third valves are respectively connected to the controller; 2) The refrigerant in the auxiliary heat pump evaporation end uses green refrigerant, and the refrigerant completes the cycle in the auxiliary heating heat pump system; the first heat exchange port and the second heat exchange port of the CO2 heat pump evaporation end are respectively connected to the environmental source, and the CO2 heat pump evaporation end uses the energy of the environmental source. Carbon dioxide collects low-grade thermal energy from the environmental source in the CO2 heat pump unit and transfers high-grade thermal energy to the domestic hot water return water; 3) Combined heating system has two heating modes: Parallel heating: The first valve is opened, the second valve is opened, and the third valve is closed, and the auxiliary heat pump condensing end is connected in parallel with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange inlet, and the second heat exchange port of the CO2 heat pump air cooling end is used as the heat exchange outlet; the domestic hot water return water with return water temperature T1 runs to the auxiliary heat pump condensing end and the CO2 heat pump air cooling end respectively, exchanges heat with the internal refrigerant, and the temperature rises from the return water temperature T1 to the first intermediate temperature T2, and then outputs through the outlet pipe to provide domestic hot water supply; the CO2 heat pump evaporation end uses the environment The energy grade of the source is upgraded to high-grade thermal energy through the CO2 heat pump compressor, and the heat is transferred to the CO2 heat pump air cooling end; the auxiliary heat pump evaporation end recovers the heat after passing through the CO2 heat pump air cooling end in the cycle of the CO2 heat pump unit, reduces the inlet temperature of the CO2 heat pump evaporation end, further promotes the CO2 heat pump evaporation end to collect energy from the environmental source, improves the operating energy efficiency ratio of the CO2 heat pump unit, and upgrades it to high-grade thermal energy through the auxiliary heat pump compressor, and raises the temperature to the domestic hot water temperature through the auxiliary heat pump condensation end, and outputs it through the outlet pipeline to provide domestic hot water supply; Series heating: the first valve is closed, the second valve is closed, and the third valve is opened, and the auxiliary heat pump condensing end is connected in series with the CO2 heat pump air cooling end. At this time, the first heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange outlet, and the second heat exchange port of the CO2 heat pump air cooling end serves as the heat exchange inlet. The domestic hot water return water with return water temperature T1 first runs to the heat pump CO2 heat pump air cooling end. The CO2 heat pump evaporation end uses the energy grade of the environmental source to be upgraded to high-grade thermal energy through the CO2 heat pump compressor, and transfers the heat to the CO2 heat pump air cooling end. The heating temperature in the CO2 heat pump air cooling end is increased to the first intermediate temperature T2; then it flows into the auxiliary heat pump condensing end. The auxiliary heat pump evaporation end recovers the heat after passing through the CO2 heat pump air cooling end in the CO2 heat pump unit cycle, reduces the inlet temperature of the CO2 heat pump evaporation end, further promotes the CO2 heat pump evaporation end to collect energy from the environmental source, improves the operating energy efficiency ratio of the CO2 heat pump unit, and is upgraded to high-grade thermal energy through the auxiliary heat pump compressor. The temperature is increased to the domestic hot water temperature through the auxiliary heat pump condensation end. Provide domestic hot water supply through the outlet pipe; 4) The auxiliary heating heat pump system optimizes the heat absorption process of the transcritical CO2 heat pump unit, promotes the CO2 heat pump unit to absorb more energy from the environmental source, and improves the energy efficiency of the combined heating system; reduces the ground source temperature, thereby improving the efficiency of the air-conditioning system in summer; by coupling the auxiliary heating heat pump system, the transcritical CO2 heat pump unit can make full use of the environmental source energy, increase the water supply temperature and reduce the operating energy consumption while matching the existing terminal supply and return water temperature difference.

10. The control method according to claim 8 or 9, characterized in that: In step 2), in the auxiliary heating heat pump system, the liquid refrigerant is heated and evaporated in the auxiliary heat pump evaporation end, becomes gaseous and enters the auxiliary heat pump compressor; the high-temperature gas after passing through the auxiliary heat pump compressor enters the auxiliary heat pump condensation end to release heat and becomes liquid refrigerant; the liquid refrigerant after passing through the auxiliary heat pump condensation end is throttled by the auxiliary heat pump throttling device and becomes low-temperature liquid refrigerant and enters the auxiliary heat pump evaporation end to complete the cycle; In the CO2 heat pump unit, carbon dioxide collects low-grade heat energy from the environment at the evaporation end of the CO2 heat pump, absorbs heat and evaporates into a gas; then it is compressed by the CO2 heat pump compressor to become high-temperature and high-pressure supercritical carbon dioxide; then the supercritical carbon dioxide enters the air-cooling end of the CO2 heat pump to be cooled and release heat energy; then the carbon dioxide coming out of the air-cooling end of the CO2 heat pump passes through the CO2 heat pump throttling device and enters the CO2 heat pump compressor again to complete the cycle, thereby realizing the low-grade heat energy collected by carbon dioxide in the environment at the CO2 evaporation end and upgrading it to high-grade heat energy, and transferring the high-grade heat energy to domestic hot water return water at the air-cooling end of the CO2 heat pump.

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