Carbon dioxide cascade heat pump system

Abstract

The utility model belongs to the field of carbon dioxide heat pumps, and provides a carbon dioxide cascade heat pump system which comprises a heat pump subsystem and a water side heat exchange subsystem. The heat pump subsystem comprises a carbon dioxide transcritical compressor, an air cooler, an air cooling valve, an intermediate heat exchanger, a carbon dioxide expansion valve, an evaporator, a high-temperature stage compressor, a condenser and a high-temperature stage expansion valve; the water side heat exchange subsystem comprises a heating circulating pump, a heating water return pipeline, a first heating water supply pipeline, a heating flow dividing pipeline and a second heating water supply pipeline. Through the air cooler and the air cooling valve, the carbon dioxide transcritical compressor outputs steam and operates in a transcritical mode and a subcritical mode at the same time, primary high-temperature water is secondarily heated through the temperature slippage characteristic of carbon dioxide, and the hot water preparation efficiency and the heat exchange efficiency of carbon dioxide are improved.

Description

Technical Field

[0001] This utility model relates to the field of carbon dioxide heat pumps, and in particular to a carbon dioxide cascade heat pump system. Background Technology

[0002] Carbon dioxide, as a natural working fluid, has an ozone depletion potential of 0 and a global warming potential of 1. It is low-cost, readily available, non-toxic, and stable. Compared to traditional working fluid heat pump systems, carbon dioxide heat pumps offer advantages such as a wider range of hot water temperatures and less susceptibility to ambient temperature fluctuations. This can effectively reduce fossil fuel consumption and improve energy efficiency, thus contributing to carbon neutrality. Because carbon dioxide has a low critical temperature, the heat release process does not occur during condensation in the two-phase region, but rather in a gas cooler near or above the critical point. In the transcritical cycle, there is a significant temperature glide, allowing for the production of hot water at higher temperatures, making it a promising candidate for water heater applications.

[0003] The efficiency of existing carbon dioxide heat pump transcritical cycles depends on the exhaust pressure and the outlet temperature of the air cooler. It is suitable for heating hot water with large temperature differences. However, for actual heating cycles, the return water temperature is relatively high, which affects the efficiency of the heat pump. Therefore, it is not suitable for heating cycles with small temperature differences. In addition, in cascade units, the carbon dioxide system is a low-temperature stage that operates in the subcritical region. It does not utilize the temperature glide of carbon dioxide in the transcritical heat transfer process to produce high-temperature hot water. Utility Model Content

[0004] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide a carbon dioxide cascade heat pump system, which realizes the output steam of the carbon dioxide transcritical compressor to operate in both transcritical and subcritical modes at the same time through an air cooler and an air-cooled valve. It utilizes the temperature glide characteristics of carbon dioxide to reheat the primary high-temperature water, thereby improving the efficiency of hot water production and the heat exchange efficiency of carbon dioxide.

[0005] To achieve the above objectives, this utility model provides the following solution:

[0006] A carbon dioxide cascade heat pump system includes: a heat pump subsystem and a water-side heat exchange subsystem; the heat pump subsystem includes: a carbon dioxide transcritical compressor, an air cooler, an air-cooled valve, an intermediate heat exchanger, a carbon dioxide expansion valve, an evaporator, a high-temperature stage compressor, a condenser, and a high-temperature stage expansion valve; the water-side heat exchange subsystem includes: a heating circulation pump, a heating return water pipe, a first heating supply water pipe, a heating branch pipe, and a second heating supply water pipe;

[0007] The transcritical carbon dioxide compressor, the gas cooler, the gas-cooling valve, the intermediate heat exchanger, the carbon dioxide expansion valve, and the evaporator are connected in sequence; the high-temperature stage compressor, the condenser, the high-temperature stage expansion valve, and the intermediate heat exchanger are connected in sequence; the output end of the transcritical carbon dioxide compressor is connected to the input end of the first refrigerant side of the gas cooler; the output end of the first refrigerant side of the gas cooler is connected to the input end of the gas-cooling valve; the output end of the gas-cooling valve is connected to the input end of the first refrigerant side of the intermediate heat exchanger; the output end of the first refrigerant side of the intermediate heat exchanger is connected to the input end of the carbon dioxide expansion valve; the output end of the carbon dioxide expansion valve is connected to the input end of the evaporator; the output end of the evaporator is connected to the input end of the transcritical carbon dioxide compressor; the intermediate heat exchanger is connected to the second... The refrigerant-side output is connected to the input of the high-temperature stage compressor; the output of the high-temperature stage compressor is connected to the input of the second refrigerant-side of the condenser; the output of the second refrigerant-side of the condenser is connected to the input of the high-temperature stage expansion valve; the output of the high-temperature stage expansion valve is connected to the input of the second refrigerant-side of the intermediate heat exchanger; the input of the heating circulation pump is connected to the heating return water pipe; the input of the condenser water side is connected to the output of the heating circulation pump; the output of the condenser water side is connected to the first heating water supply pipe; the first heating water supply pipe is connected sequentially to the heating branch pipe and the second heating water supply pipe according to the water supply direction; the heating branch pipe is connected to the input of the water side of the air cooler; the output of the water side of the air cooler is connected to the second heating water supply pipe.

[0008] The transcritical carbon dioxide compressor is used to compress the input low-temperature, low-pressure first refrigerant vapor and output high-temperature, high-pressure first refrigerant vapor in the transcritical region; the gas cooler is used to heat the primary high-temperature water input from the intermediate hot water pipe using the high-temperature, high-pressure first refrigerant vapor; the gas-cooling valve is used to depressurize the high-temperature, high-pressure first refrigerant vapor to the subcritical superheated vapor region to obtain medium-temperature, medium-pressure first refrigerant vapor; the intermediate heat exchanger is used to evaporate the gas-liquid mixture of low-temperature, low-pressure second refrigerant using the heat released by the condensation of the medium-temperature, medium-pressure first refrigerant vapor to obtain low-temperature, low-pressure second refrigerant vapor and medium-temperature, medium-pressure first refrigerant solution; the carbon dioxide expansion valve is used to depressurize the medium-temperature, medium-pressure first refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure first refrigerant; the evaporator is used to evaporate the gas-liquid mixture of low-temperature, low-pressure first refrigerant to obtain the low-temperature, low-pressure first refrigerant. The system comprises: a high-temperature stage compressor for compressing the low-temperature, low-pressure second refrigerant vapor to obtain high-temperature, high-pressure second refrigerant vapor; a condenser for heating the low-temperature water input to the heating circulation pump using the heat released by the condensation of the high-temperature, high-pressure second refrigerant vapor to obtain primary high-temperature water and a high-temperature second refrigerant solution; a high-temperature stage expansion valve for depressurizing the high-temperature second refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure second refrigerant; a heating circulation pump for pumping the low-temperature water in the heating return water pipe into the condenser; a first heating water supply pipe for transporting the primary high-temperature water to the air cooler for heating according to a preset ratio through the heating distribution pipe; and a second heating water supply pipe for transporting the primary high-temperature water heated by the air cooler to the first heating water supply pipe to obtain mixed high-temperature water, which is then delivered to the target heating user.

[0009] Preferably, a method for implementing a carbon dioxide cascade heat pump includes:

[0010] The low-temperature, low-pressure first refrigerant vapor is compressed using the carbon dioxide transcritical compressor to obtain the high-temperature, high-pressure first refrigerant vapor;

[0011] The pressure of the high-temperature and high-pressure first refrigerant vapor is adjusted to the subcritical superheated vapor region using the air-cooled valve to obtain the medium-temperature and medium-pressure first refrigerant vapor.

[0012] The intermediate heat exchanger utilizes the heat released by the condensation of the medium-temperature and medium-pressure first refrigerant vapor to evaporate the gas-liquid mixture of the low-temperature and low-pressure second refrigerant, thereby obtaining the low-temperature and low-pressure second refrigerant vapor and the medium-temperature and medium-pressure first refrigerant solution.

[0013] The pressure of the medium-temperature and medium-pressure first refrigerant solution is reduced using the carbon dioxide expansion valve to obtain the low-temperature and low-pressure first refrigerant in a gas-liquid mixed state;

[0014] The evaporator is used to evaporate the gas-liquid mixture of the low-temperature, low-pressure first refrigerant to obtain the high-temperature, high-pressure first refrigerant vapor;

[0015] The low-temperature, low-pressure second refrigerant vapor is compressed using the high-temperature stage compressor to obtain the high-temperature, high-pressure second refrigerant vapor;

[0016] The condenser uses the heat released by the condensation of the high-temperature and high-pressure second refrigerant vapor to heat the low-temperature water input by the heating circulation pump, thereby obtaining the primary high-temperature water and the high-temperature second refrigerant solution.

[0017] The high-temperature second refrigerant solution is depressurized using the high-temperature expansion valve to obtain the low-temperature, low-pressure second refrigerant in a gas-liquid mixed state;

[0018] The heating circulation pump is used to pump the low-temperature water in the heating return water pipe into the condenser;

[0019] A fixed proportion of the primary high-temperature water is transported to the air cooler using the first heating water supply pipe and the heating diversion pipe.

[0020] The high-temperature and high-pressure first refrigerant vapor in the transcritical region is used to heat the primary high-temperature water, and the primary high-temperature water heated by the air cooler is transported to the first heating water supply pipeline through the second heating water supply pipeline to obtain mixed high-temperature water;

[0021] The mixed high-temperature water is delivered to the target heating user through the first heating water supply pipeline.

[0022] Preferably, the high-temperature, low-pressure first refrigerant vapor is carbon dioxide refrigerant.

[0023] Preferably, a carbon dioxide cascade heat pump system that simultaneously supplies water and heat includes: a heat pump subsystem and a water-side heat exchange subsystem; the heat pump subsystem includes: a carbon dioxide transcritical compressor, an air cooler, an air-cooled valve, an intermediate heat exchanger, a carbon dioxide expansion valve, an evaporator, a high-temperature stage compressor, a condenser, and a high-temperature stage expansion valve; the water-side heat exchange subsystem includes: a heating circulation pump, a hot water circulation pump, a heating return water pipe, a heating water supply first pipe, a hot water return water pipe, a hot water intermediate pipe, and a hot water heating pipe;

[0024] The transcritical carbon dioxide compressor, the air cooler, the air-cooling valve, the intermediate heat exchanger, the carbon dioxide expansion valve, and the evaporator are connected in sequence; the high-temperature stage compressor, the condenser, the high-temperature stage expansion valve, and the intermediate heat exchanger are connected in sequence; the output end of the transcritical carbon dioxide compressor is connected to the input end of the first refrigerant side of the air cooler; the output end of the first refrigerant side of the air cooler is connected to the input end of the air-cooling valve; the output end of the air-cooling valve is connected to the input end of the first refrigerant side of the intermediate heat exchanger; the output end of the first refrigerant side of the intermediate heat exchanger is connected to the input end of the carbon dioxide expansion valve; the output end of the carbon dioxide expansion valve is connected to the input end of the evaporator; the output end of the evaporator is connected to the input end of the transcritical carbon dioxide compressor; the output end of the second refrigerant side of the intermediate heat exchanger is connected to the high-temperature stage compressor. The following connections are made: The output of the high-temperature stage compressor is connected to the input of the second refrigerant side of the condenser; the output of the second refrigerant side of the condenser is connected to the input of the high-temperature stage expansion valve; the output of the high-temperature stage expansion valve is connected to the input of the second refrigerant side of the intermediate heat exchanger; the input of the heating circulation pump is connected to the heating return water pipe; the input of the hot water circulation pump is connected to the hot water return water pipe; the output of the heating circulation pump is connected to the first input of the water side of the condenser; the output of the hot water circulation pump is connected to the second input of the water side of the condenser; the first output of the water side of the condenser is connected to the first heating water supply pipe; the second output of the water side of the condenser is connected to the intermediate hot water pipe; the input of the water side of the air cooler is connected to the intermediate hot water pipe; and the output of the water side of the air cooler is connected to the hot water heating pipe.

[0025] The transcritical carbon dioxide compressor is used to compress the input low-temperature, low-pressure first refrigerant vapor and output high-temperature, high-pressure first refrigerant vapor in the transcritical region; the gas cooler is used to heat the primary high-temperature water input from the intermediate hot water pipe using the high-temperature, high-pressure first refrigerant vapor; the gas-cooling valve is used to depressurize the high-temperature, high-pressure first refrigerant vapor to the subcritical superheated vapor region to obtain medium-temperature, medium-pressure first refrigerant vapor; the intermediate heat exchanger is used to evaporate the gas-liquid mixture of low-temperature, low-pressure second refrigerant using the heat released by the condensation of the medium-temperature, medium-pressure first refrigerant vapor to obtain low-temperature, low-pressure second refrigerant vapor and medium-temperature, medium-pressure first refrigerant solution; the carbon dioxide expansion valve is used to depressurize the medium-temperature, medium-pressure first refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure first refrigerant; the evaporator is used to evaporate the gas-liquid mixture of low-temperature, low-pressure first refrigerant to obtain low-temperature, low-pressure first refrigerant vapor; The high-temperature stage compressor is used to compress the low-temperature, low-pressure second refrigerant vapor to obtain high-temperature, high-pressure second refrigerant vapor; the condenser is used to heat the low-temperature water input by the heating circulation pump and the hot water circulation pump through the heat released by the condensation of the high-temperature, high-pressure second refrigerant vapor to obtain primary high-temperature water and high-temperature second refrigerant solution; the high-temperature stage expansion valve is used to depressurize the high-temperature second refrigerant solution to obtain a gas-liquid mixed state of low-temperature, low-pressure second refrigerant; the heating circulation pump is used to pump the low-temperature water in the heating return water pipe into the condenser; the hot water circulation pump is used to pump the low-temperature water in the hot water return water pipe into the condenser; the heating water supply first pipe is used to deliver the primary high-temperature water to the target heating user; the hot water intermediate pipe is used to deliver the primary high-temperature water to the air cooler for heating; the hot water heating pipe is used to deliver the secondary high-temperature water output from the air cooler to the target water user.

[0026] The present invention discloses the following technical effects:

[0027] This invention provides a carbon dioxide cascade heat pump system, which solves the problems of existing systems being unable to operate simultaneously in transcritical and subcritical states and the low heat exchange efficiency of carbon dioxide by using an air cooler and an air-cooled valve. It enables the output steam of the carbon dioxide transcritical compressor to operate simultaneously in transcritical and subcritical states and utilizes the temperature glide characteristics of carbon dioxide to perform secondary heating of primary high-temperature water. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A structural diagram of a carbon dioxide cascade heat pump system provided for an embodiment of this utility model;

[0030] Figure 2 A structural diagram of a carbon dioxide cascade heat pump system that simultaneously supplies water and heat, provided for an embodiment of this utility model;

[0031] Explanation of reference numerals in the attached figures:

[0032] 1-Transcritical carbon dioxide compressor, 2-Air cooler, 3-Air cooler valve, 4-Intermediate heat exchanger, 5-Carbon dioxide expansion valve, 6-Evaporator, 7-High temperature stage compressor, 8-Condenser, 9-High temperature stage expansion valve, 10-Heating circulation pump, 11-Heating return water pipe, 12-First heating water supply pipe, 13-Heating branch pipe, 14-Second heating water supply pipe, 15-Hot water circulation pump, 16-Hot water return pipe, 17-Intermediate hot water pipe, 18-Hot water heating pipe. Detailed Implementation

[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0034] The purpose of this invention is to provide a carbon dioxide cascade heat pump system that, through an air cooler and an air-cooled valve, enables the output steam of a transcritical carbon dioxide compressor to operate simultaneously in both transcritical and subcritical modes. It utilizes the temperature glide characteristics of carbon dioxide to reheat primary high-temperature water, thereby improving the efficiency of hot water production and the heat exchange efficiency of carbon dioxide.

[0035] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 A structural diagram of a carbon dioxide cascade heat pump system provided for an embodiment of this utility model is shown below. Figure 1As shown, this utility model provides a carbon dioxide cascade heat pump system, including: a heat pump subsystem and a water-side heat exchange subsystem; the heat pump subsystem includes: a carbon dioxide transcritical compressor 1, an air cooler 2, an air-cooling valve 3, an intermediate heat exchanger 4, a carbon dioxide expansion valve 5, an evaporator 6, a high-temperature stage compressor 7, a condenser 8, and a high-temperature stage expansion valve 9; the water-side heat exchange subsystem includes: a heating circulation pump 10, a heating return water pipe 11, a first heating water supply pipe 12, a heating branch pipe 13, and a second heating water supply pipe 14;

[0037] A transcritical carbon dioxide compressor 1, an air cooler 2, an air-cooled valve 3, an intermediate heat exchanger 4, a carbon dioxide expansion valve 5, and an evaporator 6 are connected in sequence; a high-temperature stage compressor 7, a condenser 8, a high-temperature stage expansion valve 9, and an intermediate heat exchanger 4 are connected in sequence; the output end of the transcritical carbon dioxide compressor 1 is connected to the input end of the first refrigerant side of the air cooler 2; the output end of the first refrigerant side of the air cooler 2 is connected to the input end of the air-cooled valve 3; the output end of the air-cooled valve 3 is connected to the input end of the first refrigerant side of the intermediate heat exchanger 4; the output end of the first refrigerant side of the intermediate heat exchanger 4 is connected to the input end of the carbon dioxide expansion valve 5; the output end of the carbon dioxide expansion valve 5 is connected to the input end of the evaporator 6; the output end of the evaporator 6 is connected to the input end of the transcritical carbon dioxide compressor 1; the output end of the intermediate heat exchanger 4 is connected to the second refrigerant side of the intermediate heat exchanger 4. The output end of the high-temperature stage compressor 7 is connected to the input end of the second refrigerant side of the condenser 8; the output end of the second refrigerant side of the condenser 8 is connected to the input end of the high-temperature stage expansion valve 9; the output end of the high-temperature stage expansion valve 9 is connected to the input end of the second refrigerant side of the intermediate heat exchanger 4; the input end of the heating circulation pump 10 is connected to the heating return water pipe 11; the water side input end of the condenser 8 is connected to the output end of the heating circulation pump 10; the water side output end of the condenser 8 is connected to the first heating water supply pipe 12; the first heating water supply pipe 12 is connected to the heating branch pipe 13 and the second heating water supply pipe 14 in sequence according to the water supply direction; the heating branch pipe 13 is connected to the water side input end of the air cooler 2; the water side output end of the air cooler 2 is connected to the second heating water supply pipe 14.

[0038] A transcritical carbon dioxide compressor 1 is used to compress the input low-temperature, low-pressure first refrigerant vapor and output high-temperature, high-pressure first refrigerant vapor in the transcritical region; an air cooler 2 is used to heat the primary high-temperature water input into the heating distribution pipe 13 using the high-temperature, high-pressure first refrigerant vapor; an air-cooling valve 3 is used to depressurize the high-temperature, high-pressure first refrigerant vapor to the subcritical superheated vapor region to obtain medium-temperature, medium-pressure first refrigerant vapor; an intermediate heat exchanger 4 is used to evaporate the gas-liquid mixture of low-temperature, low-pressure second refrigerant using the heat released by the condensation of the medium-temperature, medium-pressure first refrigerant vapor to obtain low-temperature, low-pressure second refrigerant vapor and medium-temperature, medium-pressure first refrigerant solution; a carbon dioxide expansion valve 5 is used to depressurize the medium-temperature, medium-pressure first refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure first refrigerant; and an evaporator 6 is used to evaporate the gas-liquid mixture of low-temperature, low-pressure first refrigerant to obtain low-temperature, low-pressure first refrigerant. Steam; High-temperature stage compressor 7 is used to compress low-temperature, low-pressure second refrigerant vapor to obtain high-temperature, high-pressure second refrigerant vapor; Condenser 8 is used to heat the low-temperature water input by heating circulation pump 10 through the heat released by the condensation of high-temperature, high-pressure second refrigerant vapor to obtain primary high-temperature water and high-temperature second refrigerant solution; High-temperature stage expansion valve 9 is used to depressurize the high-temperature second refrigerant solution to obtain a gas-liquid mixed state of low-temperature, low-pressure second refrigerant; Heating circulation pump 10 is used to pump the low-temperature water in heating return water pipe 11 into condenser 8; Heating water supply first pipe 12 is used to transport primary high-temperature water to air cooler 2 for heating through heating diversion pipe 13 according to a preset ratio; Heating water supply second pipe 14 is used to transport the primary high-temperature water heated by air cooler 2 to heating water supply first pipe 12 to obtain mixed high-temperature water, and then deliver the mixed high-temperature water to the target heating user.

[0039] Preferably, when the working fluid of the system is carbon dioxide, the high temperature range is 80 to 130°C; the medium temperature range is 15 to 80°C; the low temperature range is -20 to 0°C; the high pressure range is 80 to 120 bar; the medium pressure range is 45 to 72 bar; and the low pressure range is 14 to 33 bar.

[0040] Furthermore, a method for implementing a carbon dioxide cascade heat pump includes:

[0041] Low-temperature, low-pressure first refrigerant vapor is compressed using a carbon dioxide transcritical compressor 1 to obtain high-temperature, high-pressure first refrigerant vapor;

[0042] By using air-cooled valve 3, the pressure of the high-temperature and high-pressure first refrigerant vapor is adjusted to the subcritical superheated vapor region to obtain medium-temperature and medium-pressure first refrigerant vapor;

[0043] The intermediate heat exchanger 4 utilizes the heat released by the condensation of the medium-temperature and medium-pressure first refrigerant vapor to evaporate the gas-liquid mixture of the low-temperature and low-pressure second refrigerant, thereby obtaining low-temperature and low-pressure second refrigerant vapor and medium-temperature and medium-pressure first refrigerant solution.

[0044] The pressure of the medium-temperature and medium-pressure first refrigerant solution is reduced by using carbon dioxide expansion valve 5 to obtain a gas-liquid mixture in a low-temperature and low-pressure state.

[0045] The gas-liquid mixture in the low-temperature, low-pressure first refrigerant is evaporated using evaporator 6 to obtain high-temperature, high-pressure first refrigerant vapor;

[0046] The low-temperature, low-pressure second refrigerant vapor is compressed using the high-temperature stage compressor 7 to obtain high-temperature, high-pressure second refrigerant vapor;

[0047] The condenser 8 uses the heat released by the condensation of the high-temperature and high-pressure second refrigerant vapor to heat the low-temperature water input into the heating circulation pump 10, thereby obtaining primary high-temperature water and high-temperature second refrigerant solution.

[0048] The high-temperature second refrigerant solution is depressurized using the high-temperature expansion valve 9 to obtain a low-temperature, low-pressure second refrigerant in a gas-liquid mixture state;

[0049] The heating circulation pump 10 pumps the low-temperature water in the heating return water pipe 11 into the condenser 8.

[0050] A fixed proportion of high-temperature water is transported to the air cooler 2 through the first heating water supply pipe 12 and the heating branch pipe 13.

[0051] The high-temperature and high-pressure first refrigerant vapor in the transcritical region is used to heat the primary high-temperature water, and the primary high-temperature water heated by the air cooler 2 is transported to the first heating water supply pipe 12 through the second heating water supply pipe 14 to obtain mixed high-temperature water.

[0052] The mixed high-temperature water is delivered to the target heating users through the first heating water supply pipeline 12.

[0053] Preferably, the high-temperature, low-pressure first refrigerant vapor is carbon dioxide refrigerant.

[0054] refer to Figure 2 A carbon dioxide cascade heat pump system that simultaneously supplies water and heat includes: a heat pump subsystem and a water-side heat exchange subsystem; the heat pump subsystem includes: a carbon dioxide transcritical compressor 1, an air cooler 2, an air-cooled valve 3, an intermediate heat exchanger 4, a carbon dioxide expansion valve 5, an evaporator 6, a high-temperature stage compressor 7, a condenser 8, and a high-temperature stage expansion valve 9; the water-side heat exchange subsystem includes: a heating circulation pump 10, a hot water circulation pump 15, a heating return water pipe 11, a heating water supply first pipe 12, a hot water return water pipe 16, a hot water intermediate pipe 17, and a hot water heating pipe 18;

[0055] A transcritical carbon dioxide compressor 1, an air cooler 2, an air-cooled valve 3, an intermediate heat exchanger 4, a carbon dioxide expansion valve 5, and an evaporator 6 are connected in sequence; a high-temperature stage compressor 7, a condenser 8, a high-temperature stage expansion valve 9, and an intermediate heat exchanger 4 are connected in sequence; the output end of the transcritical carbon dioxide compressor 1 is connected to the input end of the first refrigerant side of the air cooler 2; the output end of the first refrigerant side of the air cooler 2 is connected to the input end of the air-cooled valve 3; the output end of the air-cooled valve 3 is connected to the input end of the first refrigerant side of the intermediate heat exchanger 4; the output end of the first refrigerant side of the intermediate heat exchanger 4 is connected to the input end of the carbon dioxide expansion valve 5; the output end of the carbon dioxide expansion valve 5 is connected to the input end of the evaporator 6; the output end of the evaporator 6 is connected to the input end of the transcritical carbon dioxide compressor 1; the output end of the second refrigerant side of the intermediate heat exchanger 4 is connected to the input end of the high-temperature stage compressor 7; high-temperature stage compressor 7... The output end of the first compressor 7 is connected to the input end of the second refrigerant side of the condenser 8; the output end of the second refrigerant side of the condenser 8 is connected to the input end of the high-temperature stage expansion valve 9; the output end of the high-temperature stage expansion valve 9 is connected to the input end of the second refrigerant side of the intermediate heat exchanger 4; the input end of the heating circulation pump 10 is connected to the heating return water pipe 11; the input end of the hot water circulation pump 15 is connected to the hot water return water pipe 16; the output end of the heating circulation pump 10 is connected to the first input end of the water side of the condenser 8; the output end of the hot water circulation pump 15 is connected to the second input end of the water side of the condenser 8; the first output end of the water side of the condenser 8 is connected to the first heating water supply pipe 12; the second output end of the water side of the condenser 8 is connected to the hot water intermediate pipe 17; the input end of the water side of the air cooler 2 is connected to the hot water intermediate pipe 17; the output end of the water side of the air cooler 2 is connected to the hot water heating pipe 18.

[0056] A transcritical carbon dioxide compressor 1 is used to compress the input low-temperature, low-pressure first refrigerant vapor and output high-temperature, high-pressure first refrigerant vapor in the transcritical region; an air cooler 2 is used to heat the primary high-temperature water input into the heating distribution pipe 13 using the high-temperature, high-pressure first refrigerant vapor; an air-cooling valve 3 is used to depressurize the high-temperature, high-pressure first refrigerant vapor to the subcritical superheated vapor region to obtain medium-temperature, medium-pressure first refrigerant vapor; an intermediate heat exchanger 4 is used to evaporate the gas-liquid mixture of low-temperature, low-pressure second refrigerant using the heat released by the condensation of the medium-temperature, medium-pressure first refrigerant vapor to obtain low-temperature, low-pressure second refrigerant vapor and medium-temperature, medium-pressure first refrigerant solution; a carbon dioxide expansion valve 5 is used to depressurize the medium-temperature, medium-pressure first refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure first refrigerant; an evaporator 6 is used to evaporate the gas-liquid mixture of low-temperature, low-pressure first refrigerant to obtain low-temperature, low-pressure first refrigerant vapor; high temperature The compressor 7 is used to compress the low-temperature, low-pressure second refrigerant vapor to obtain high-temperature, high-pressure second refrigerant vapor; the condenser 8 is used to heat the low-temperature water input by the heating circulation pump 10 and the hot water circulation pump 15 through the heat released by the condensation of the high-temperature, high-pressure second refrigerant vapor to obtain primary high-temperature water and high-temperature second refrigerant solution; the high-temperature expansion valve 9 is used to depressurize the high-temperature second refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure second refrigerant; the heating circulation pump 10 is used to pump the low-temperature water in the heating return water pipe 11 into the condenser 8; the hot water circulation pump 15 is used to pump the low-temperature water in the hot water return water pipe 16 into the condenser 8; the first heating water supply pipe 12 is used to deliver the primary high-temperature water to the target heating user; the intermediate hot water pipe 17 is used to deliver the primary high-temperature water to the air cooler 2 for heating; the hot water heating pipe 18 is used to deliver the secondary high-temperature water output from the air cooler 2 to the target water supply user.

[0057] Preferably, the heating circulation pipeline design is as follows: the outlet of the condenser 8 is connected to the three-way distributor, the pipeline between the outlet of the condenser 8 and the three-way distributor and the pipeline from the three-way distributor to the target heating user constitute the first heating water supply pipeline 12, and the pipeline between the three-way distributor and the condenser 8 is the heating distribution pipeline 13.

[0058] Specifically, the user return water of the heating circulation is sent to the condenser 8 for heating through the heating variable frequency circulation pump. The circulating hot water exiting the condenser 8 is divided into two paths: one path goes to the user water supply (main path, i.e., the first heating water supply pipe 12), and the other path goes to the air cooler 2 to exchange sensible heat with high-temperature carbon dioxide to further increase the water temperature. After that, it merges with the main water supply path to the user side and increases the water supply temperature before being sent to the user.

[0059] Furthermore, when the system is in a combined heating and hot water supply state, high-temperature and high-pressure refrigerant vapor is discharged through the exhaust port of the carbon dioxide compressor. The outlet temperature of the air cooler 2 is controlled, and the exhaust pressure is controlled to be in the supercritical region by the opening of the air-cooling valve 3. After throttling, the exhaust pressure drops to the subcritical superheated vapor region, where it condenses and releases heat with the high-temperature refrigerant in the intermediate heat exchanger 4. The liquid refrigerant is throttled and depressurized by the carbon dioxide expansion valve 5, and then absorbs heat in the evaporator 6 to form superheated vapor, which returns to the compressor suction port for further compression, completing the carbon dioxide cycle. The high-temperature refrigerant is compressed into high-temperature and high-pressure refrigerant vapor by the high-temperature compressor 7, and then condenses and releases heat with the user return water in the condenser 8. The liquid refrigerant is throttled and depressurized by the high-temperature expansion valve 9, and then absorbs the condensation heat of carbon dioxide in the intermediate heat exchanger 4 to form superheated vapor, which returns to the suction port of the high-temperature compressor 7 for further compression, completing the high-temperature cycle. The user return water in the heating cycle is sent to the condenser 8 by the heating circulation pump 10 for heating before being delivered to the target heating user. Domestic hot water is pumped to condenser 8 for heating, and then enters air cooler 2 to exchange sensible heat with high-temperature carbon dioxide to further increase the water temperature before being delivered to the target hot water user.

[0060] This embodiment utilizes an air-cooled valve to control the exhaust pressure of the transcritical compressor and the outlet temperature of the air cooler, enabling the carbon dioxide system to simultaneously achieve transcritical and subcritical operation. It realizes the secondary heating of primary high-temperature water by utilizing the temperature glide characteristics of carbon dioxide, improving the hot water production efficiency and the heat exchange efficiency of carbon dioxide, and also realizes the characteristics of the cascade system suitable for circulating heating.

[0061] The beneficial effects of this utility model are as follows:

[0062] (1) This utility model heats hot water by taking advantage of the large temperature slip characteristics of the first refrigerant vapor during the high temperature and high pressure heat release process, which can fully recover and utilize energy and improve the overall thermal efficiency of the system.

[0063] (2) This utility model uses carbon dioxide as a refrigerant, which has low global warming potential (GWP) and zero ozone depletion potential (ODP), and meets environmental protection requirements.

[0064] (3) The unique multi-stage heat exchange and compression design of this utility model can improve the output water temperature while ensuring system stability, and adapt to more application scenarios.

[0065] (4) The system design of this utility model allows for simultaneous heating and water supply, and can be flexibly adapted to different seasons and user needs.

[0066] (5) The multi-stage circulation and exchange process of this utility model effectively improves the coefficient of performance (COP) of the heat pump system and provides a higher energy efficiency ratio.

[0067] (6) The reasonable arrangement and organization of the components of this utility model improves the reliability and service life of the system and reduces maintenance requirements.

[0068] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0069] This document uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. Furthermore, those skilled in the art will recognize that, based on the ideas of this utility model, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A carbon dioxide cascade heat pump system, characterized in that, include: Heat pump subsystem and water-side heat exchange subsystem; The heat pump subsystem includes: a transcritical carbon dioxide compressor, an air cooler, an air-cooled valve, an intermediate heat exchanger, a carbon dioxide expansion valve, an evaporator, a high-temperature stage compressor, a condenser, and a high-temperature stage expansion valve; the water-side heat exchange subsystem includes: a heating circulation pump, a heating return water pipe, a first heating supply water pipe, a heating branch pipe, and a second heating supply water pipe. The transcritical carbon dioxide compressor, the gas cooler, the gas-cooling valve, the intermediate heat exchanger, the carbon dioxide expansion valve, and the evaporator are connected in sequence; the high-temperature stage compressor, the condenser, the high-temperature stage expansion valve, and the intermediate heat exchanger are connected in sequence; the output end of the transcritical carbon dioxide compressor is connected to the input end of the first refrigerant side of the gas cooler; the output end of the first refrigerant side of the gas cooler is connected to the input end of the gas-cooling valve; the output end of the gas-cooling valve is connected to the input end of the first refrigerant side of the intermediate heat exchanger; the output end of the first refrigerant side of the intermediate heat exchanger is connected to the input end of the carbon dioxide expansion valve; the output end of the carbon dioxide expansion valve is connected to the input end of the evaporator; the output end of the evaporator is connected to the input end of the transcritical carbon dioxide compressor; the intermediate heat exchanger is connected to the second... The refrigerant-side output is connected to the input of the high-temperature stage compressor; the output of the high-temperature stage compressor is connected to the input of the second refrigerant-side of the condenser; the output of the second refrigerant-side of the condenser is connected to the input of the high-temperature stage expansion valve; the output of the high-temperature stage expansion valve is connected to the input of the second refrigerant-side of the intermediate heat exchanger; the input of the heating circulation pump is connected to the heating return water pipe; the input of the condenser water side is connected to the output of the heating circulation pump; the output of the condenser water side is connected to the first heating water supply pipe; the first heating water supply pipe is connected sequentially to the heating branch pipe and the second heating water supply pipe according to the water supply direction; the heating branch pipe is connected to the input of the water side of the air cooler; the output of the water side of the air cooler is connected to the second heating water supply pipe. The transcritical carbon dioxide compressor is used to compress the input low-temperature, low-pressure first refrigerant vapor and output high-temperature, high-pressure first refrigerant vapor in the transcritical region; the gas cooler is used to heat the primary high-temperature water input into the heating distribution pipe using the high-temperature, high-pressure first refrigerant vapor; the gas-cooling valve is used to depressurize the high-temperature, high-pressure first refrigerant vapor to the subcritical superheated vapor region to obtain medium-temperature, medium-pressure first refrigerant vapor; the intermediate heat exchanger is used to evaporate the gas-liquid mixture of low-temperature, low-pressure second refrigerant using the heat released by the condensation of the medium-temperature, medium-pressure first refrigerant vapor to obtain low-temperature, low-pressure second refrigerant vapor and medium-temperature, medium-pressure first refrigerant solution; the carbon dioxide expansion valve is used to depressurize the medium-temperature, medium-pressure first refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure first refrigerant; the evaporator is used to evaporate the gas-liquid mixture of low-temperature, low-pressure first refrigerant to obtain low-temperature, low-pressure first refrigerant vapor. The system comprises: a high-temperature compressor for compressing the low-temperature, low-pressure second refrigerant vapor to obtain high-temperature, high-pressure second refrigerant vapor; a condenser for heating the low-temperature water input to the heating circulation pump using the heat released by the condensation of the high-temperature, high-pressure second refrigerant vapor to obtain primary high-temperature water and a high-temperature second refrigerant solution; a high-temperature expansion valve for depressurizing the high-temperature second refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure second refrigerant; a heating circulation pump for pumping the low-temperature water in the heating return water pipe into the condenser; a first heating water supply pipe for transporting the primary high-temperature water to the air cooler for heating according to a preset ratio through the heating distribution pipe; and a second heating water supply pipe for transporting the primary high-temperature water heated by the air cooler to the first heating water supply pipe to obtain mixed high-temperature water, which is then delivered to the target heating user.

2. A carbon dioxide cascade heat pump system that simultaneously supplies water and heat, characterized in that, include: The system comprises a heat pump subsystem and a water-side heat exchange subsystem; the heat pump subsystem includes: a transcritical carbon dioxide compressor, an air cooler, an air-cooled valve, an intermediate heat exchanger, a carbon dioxide expansion valve, an evaporator, a high-temperature stage compressor, a condenser, and a high-temperature stage expansion valve; the water-side heat exchange subsystem includes: a heating circulation pump, a hot water circulation pump, a heating return water pipe, a heating supply first pipe, a hot water return water pipe, a hot water intermediate pipe, and a hot water heating pipe. The transcritical carbon dioxide compressor, the air cooler, the air-cooling valve, the intermediate heat exchanger, the carbon dioxide expansion valve, and the evaporator are connected in sequence; the high-temperature stage compressor, the condenser, the high-temperature stage expansion valve, and the intermediate heat exchanger are connected in sequence; the output end of the transcritical carbon dioxide compressor is connected to the input end of the first refrigerant side of the air cooler; the output end of the first refrigerant side of the air cooler is connected to the input end of the air-cooling valve; the output end of the air-cooling valve is connected to the input end of the first refrigerant side of the intermediate heat exchanger; the output end of the first refrigerant side of the intermediate heat exchanger is connected to the input end of the carbon dioxide expansion valve; the output end of the carbon dioxide expansion valve is connected to the input end of the evaporator; the output end of the evaporator is connected to the input end of the transcritical carbon dioxide compressor; the output end of the second refrigerant side of the intermediate heat exchanger is connected to the high-temperature stage compressor. The following connections are made: The output of the high-temperature stage compressor is connected to the input of the second refrigerant side of the condenser; the output of the second refrigerant side of the condenser is connected to the input of the high-temperature stage expansion valve; the output of the high-temperature stage expansion valve is connected to the input of the second refrigerant side of the intermediate heat exchanger; the input of the heating circulation pump is connected to the heating return water pipe; the input of the hot water circulation pump is connected to the hot water return water pipe; the output of the heating circulation pump is connected to the first input of the water side of the condenser; the output of the hot water circulation pump is connected to the second input of the water side of the condenser; the first output of the water side of the condenser is connected to the first heating water supply pipe; the second output of the water side of the condenser is connected to the intermediate hot water pipe; the input of the water side of the air cooler is connected to the intermediate hot water pipe; and the output of the water side of the air cooler is connected to the hot water heating pipe. The transcritical carbon dioxide compressor is used to compress the input low-temperature, low-pressure first refrigerant vapor and output high-temperature, high-pressure first refrigerant vapor in the transcritical region; the gas cooler is used to heat the primary high-temperature water input from the intermediate hot water pipe using the high-temperature, high-pressure first refrigerant vapor; the gas-cooling valve is used to depressurize the high-temperature, high-pressure first refrigerant vapor to the subcritical superheated vapor region to obtain medium-temperature, medium-pressure first refrigerant vapor; the intermediate heat exchanger is used to evaporate the gas-liquid mixture of low-temperature, low-pressure second refrigerant using the heat released by the condensation of the medium-temperature, medium-pressure first refrigerant vapor to obtain low-temperature, low-pressure second refrigerant vapor and medium-temperature, medium-pressure first refrigerant solution; the carbon dioxide expansion valve is used to depressurize the medium-temperature, medium-pressure first refrigerant solution to obtain a gas-liquid mixture of low-temperature, low-pressure first refrigerant; the evaporator is used to evaporate the gas-liquid mixture of low-temperature, low-pressure first refrigerant to obtain low-temperature, low-pressure first refrigerant vapor; The high-temperature stage compressor is used to compress the low-temperature, low-pressure second refrigerant vapor to obtain high-temperature, high-pressure second refrigerant vapor; the condenser is used to heat the low-temperature water input by the heating circulation pump and the hot water circulation pump through the heat released by the condensation of the high-temperature, high-pressure second refrigerant vapor to obtain primary high-temperature water and high-temperature second refrigerant solution; the high-temperature stage expansion valve is used to depressurize the high-temperature second refrigerant solution to obtain a gas-liquid mixed state of low-temperature, low-pressure second refrigerant; the heating circulation pump is used to pump the low-temperature water in the heating return water pipe into the condenser; the hot water circulation pump is used to pump the low-temperature water in the hot water return water pipe into the condenser; the heating water supply first pipe is used to deliver the primary high-temperature water to the target heating user; the hot water intermediate pipe is used to deliver the primary high-temperature water to the air cooler for heating; the hot water heating pipe is used to deliver the secondary high-temperature water output from the air cooler to the target water user.

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