Non-azeotropic internal cascade heat pump high-temperature hot water preparation system and preparation method thereof

Abstract

The application provides a non-azeotropic internal cascade heat pump high-temperature hot water preparation system, which comprises a non-azeotropic refrigerant cascade heating circuit for providing core temperature rising heat and a high-temperature hot water preparation flow path for cooperating with the non-azeotropic refrigerant cascade heating circuit to stepwise heat and raise the temperature of normal temperature water to 100 DEG high-temperature hot water; the non-azeotropic refrigerant cascade heating circuit comprises a high-boiling-point refrigerant flow path and a low-boiling-point refrigerant flow path; the application further provides a method for preparing high-temperature hot water by using the non-azeotropic internal cascade heat pump high-temperature hot water preparation system; the non-azeotropic internal cascade heat pump high-temperature hot water preparation system and the method only adopt single-stage compression, a conventional pressure ratio and a single compressor to realize high-temperature hot water preparation, the irreversible heat loss is small, the system energy efficiency is high, the system is simple, the working modes are various, and instant high-temperature hot water supply with large flow rate can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of heat pump systems, and particularly relates to a non-azeotropic internal cascade heat pump high-temperature hot water preparation system and a high-temperature hot water preparation method. BACKGROUND

[0002] The existing high-temperature heat pump usually adopts multi-stage compression, cascade, jet augmenting enthalpy, supercritical CO2 heating and the like, and has low system energy efficiency, high working pressure and pressure ratio, higher requirements for the performance of a compressor, and a hot water supply temperature is usually lower than 90 DEG C, so the heating temperature is low, and the high-temperature heating demand in production and life cannot be fully met.

[0003] In view of the above-mentioned defects of the prior art, the application aims to provide a heat pump system with simple structure and high system energy efficiency, which can realize instant large-flow high-temperature hot water supply. SUMMARY

[0004] In view of the above-mentioned defects of the prior art, the application aims to provide a heat pump system with simple structure and high system energy efficiency, which can realize instant large-flow high-temperature hot water supply.

[0005] The application also aims to provide a preparation method for preparing large-flow high-temperature hot water continuously output by using the heat pump system.

[0006] To achieve the above object and other related objects, the present application provides a non-azeotropic internal cascade heat pump high-temperature hot water preparation system, which comprises a non-azeotropic refrigerant cascade heat production circuit for providing core temperature rise heat and a high-temperature hot water preparation circuit for heating and rising the temperature of normal-temperature water to 100 DEG high-temperature hot water in cooperation with the non-azeotropic refrigerant cascade heat production circuit. The non-azeotropic refrigerant cascade heat production circuit comprises a high-boiling-point refrigerant circuit and a low-boiling-point refrigerant circuit. The high-boiling-point refrigerant circuit comprises mixed gaseous refrigerant mixed with high-boiling-point and low-boiling-point refrigerants, which is pressurized by a single-stage compressor and then flows through a condenser. The high-boiling-point refrigerant in the condenser is condensed into liquid state and separated from the gaseous low-boiling-point refrigerant by a vapor-liquid separator. The high-boiling-point refrigerant flows through a high-boiling-point refrigerant storage tank and a first throttling device, and then flows into a three-stream heat exchanger as a first cold fluid to be evaporated by heat absorption. The high-boiling-point refrigerant is in gaseous state after evaporation, and returns to the single-stage compressor for circulation. The gaseous low-boiling-point refrigerant separated by the vapor-liquid separator flows through a gas cooler, and then enters the three-stream heat exchanger as a hot fluid to exchange heat with the first cold fluid. After heat release and condensation, the low-boiling-point refrigerant flows through a heat recovery device, a low-boiling-point refrigerant storage tank, a second throttling device, and then enters an evaporator to exchange heat with a low-temperature heat source for evaporation into gaseous state. The low-boiling-point refrigerant enters the heat recovery device again to exchange heat with the first cold fluid flowing into the heat recovery device, and is overheated to form overheated gaseous low-boiling-point refrigerant. The overheated gaseous low-boiling-point refrigerant is mixed with the gaseous high-boiling-point refrigerant to form the mixed gaseous refrigerant, which enters the single-stage compressor for circulation. The high-temperature hot water preparation circuit comprises a medium-temperature water storage tank. Water flowing out of the medium-temperature water storage tank is mixed with normal-temperature water input from a normal-temperature water pipe, and is pressurized by a first water pump to enter the three-stream heat exchanger as a second cold fluid to exchange heat with the hot fluid for temperature rise to form medium-temperature hot water, which returns to the medium-temperature water storage tank. The medium-temperature hot water in the medium-temperature water storage tank flows through the gas cooler to exchange heat with the gaseous low-boiling-point refrigerant, and then is mixed with water flowing out of a high-temperature water storage tank to form circulating water, which enters the condenser to exchange heat with the high-temperature and high-pressure mixed gaseous refrigerant for temperature rise, and then flows through a second water pump to return to the high-temperature water storage tank to form high-temperature hot water for output.

[0007] Preferably, the high-boiling-point refrigerant is R114 refrigerant, and the low-boiling-point refrigerant is R134a refrigerant.

[0008] Preferably, the temperature of the overheated gaseous low-boiling-point refrigerant is not lower than the evaporation temperature of the gaseous high-boiling-point refrigerant.

[0009] Preferably, the three-stream heat exchanger is of plate-fin or plate structure, and the cold fluid and hot fluid channels in the three-stream heat exchanger are arranged alternately.

[0010] Preferably, the first throttling device and the second throttling device are throttling valves.

[0011] Preferably, a stop valve is arranged on the pipeline connecting the high-temperature water storage tank and the medium-temperature water storage tank.

[0012] Preferably, the temperature of the low-pressure high-boiling-point refrigerant reaching the three-stream heat exchanger is 55-65℃, the temperature of the high-pressure low-boiling-point refrigerant is 60-70℃, and the temperature of the circulating water is 40-50℃.

[0013] Preferably, a one-way valve is arranged on the pipeline connecting the vapor cooler and the high-temperature water storage tank to prevent the hot water in the high-temperature water storage tank from flowing back to the medium-temperature water storage tank.

[0014] A preparation method of high-temperature hot water using the above system, comprising the following modes,

[0015] Cold start mode: the medium-temperature water storage tank and the high-temperature water storage tank store normal-temperature water, no normal-temperature water is input into the water storage tank, the first throttling device is closed, the shut-off valve, the single-stage compressor, the first water pump, the second water pump, the second throttling device and the one-way valve are opened, and the system is initialized for cold start; the high-boiling-point refrigerant is stored in the high-boiling-point refrigerant storage reservoir and does not participate in the refrigerant circulation; the high-pressure superheated low-boiling-point refrigerant is cooled and cooled down by the condenser and the vapor cooler, enters the three-stream heat exchanger, exchanges heat with the second cold fluid flowing out of the first water pump to condense, and then enters the regenerator, the low-boiling-point refrigerant storage reservoir and the second throttling device to exchange heat with the low-temperature heat source to evaporate into a gaseous state, and then enters the regenerator again to exchange heat with the first cold fluid flowing into the regenerator to be superheated and then flows into the single-stage compressor to be pressurized to form the high-pressure superheated low-boiling-point refrigerant to enter the condenser to circulate; the water flow rate through the condenser is adjusted by the second water pump to make the circulating water in the condenser only cool and cool down the high-pressure superheated low-boiling-point refrigerant therein without condensing; after the cold start is stabilized, the system enters the subsequent mode for free switching;

[0016] Medium-temperature and high-temperature hot water dual-output mode: the first throttling device is closed, the shut-off valve is closed, normal-temperature water is input from the normal-temperature water pipe, the single-stage compressor, the first water pump, the second water pump, the second throttling device and the one-way valve are opened; the water mixed with the water flowing out of the medium-temperature water storage tank under the driving of the first water pump is heated by the condensation heat of the low-boiling-point refrigerant in the three-stream heat exchanger to become medium-temperature hot water, which is returned to the medium-temperature water storage tank for output; the medium-temperature hot water flowing out of the medium-temperature water storage tank is heated in the vapor cooler, mixed with the water flowing out of the high-temperature water storage tank, and then forms the circulating water, which is further heated in the condenser by exchanging heat with the high-pressure superheated low-boiling-point refrigerant, and finally forms high-temperature hot water under the pressurization of the second water pump to return to the high-temperature water storage tank for output;

[0017] High-temperature hot water output mode: open the first throttling device, the single-stage compressor, the first water pump and the second water pump, close the stop valve, the normal-temperature water is input from the normal-temperature water pipe, the circulating water volume of the second water pump is increased; the medium-temperature water storage tank is only used as a transition water tank; the medium-temperature hot water flowing out from the medium-temperature water storage tank flows through the vapor cooler and exchanges heat with the high-pressure superheated low-boiling-point gaseous refrigerant in the vapor cooler, then mixes with the water flowing out from the high-temperature water storage tank, and then flows through the condenser, absorbs the condensation heat of the high-pressure high-boiling-point refrigerant in the condenser to be warmed up, and then forms high-temperature hot water under the pressure of the second water pump and returns to the high-temperature water storage tank for output.

[0018] Preferably, the temperature of the medium-temperature hot water is 60-65℃, the temperature of the high-temperature hot water is 100℃, in the cold start mode, the pressure ratio of the single-stage compressor gradually increases, and in the medium-temperature and high-temperature hot water double-output mode and the high-temperature hot water output mode, the pressure ratio of the single-stage compressor is stable at 3.5-4.

[0019] The non-azeotropic internal cascade heat pump high-temperature hot water preparation system and method provided by the application has the following beneficial effects:

[0020] 1) Single-stage compression, conventional pressure ratio, and single compressor can realize high-temperature hot water preparation;

[0021] 2) Combination of direct heating type and circulating type hot water preparation, which can realize instant large-flow high-temperature hot water continuous supply;

[0022] 3) Utilizing different temperatures and gaseous and liquid states of low-boiling-point and high-boiling-point refrigerants, reasonably matching the heat exchange structure, realizing step-by-step increase of normal-temperature water to 100℃ high-temperature, small irreversible heat loss, and high system energy efficiency;

[0023] 4) In the hot water preparation process, only in the cold start mode, the pressure ratio of the compressor gradually increases, and in other modes, the pressure ratio of the compressor is stable, so that the efficiency and service life of the compressor can be improved;

[0024] 5) The system is simple, and has various working modes, which can realize medium-temperature and high-temperature double output, and can also increase all normal-temperature water to high-temperature hot water. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a structure schematic view of the non-azeotropic internal cascade heat pump high-temperature hot water preparation system of the application;

[0026] Among them, 1-single-stage compressor; 2-condenser; 3-vapor-liquid separator; 4-high-boiling-point refrigerant storage tank; 5-first throttling device; 6-vapor cooler; 7-three-stream heat exchanger; 8-heat regenerator; 9-low-boiling-point refrigerant storage tank; 10-second throttling device; 11-evaporator; 12-medium-temperature water storage tank; 13-first water pump; 14-one-way valve; 15-high-temperature water storage tank; 16-second water pump; 17-stop valve. DETAILED DESCRIPTION

[0027] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0028] Example 1:

[0029] This invention provides a non-azeotropic internal cascade heat pump high-temperature hot water preparation system, comprising a non-azeotropic refrigerant cascade heating circuit that provides the core heat for temperature rise in the system, and a high-temperature hot water preparation flow path that cooperates with the non-azeotropic refrigerant cascade heating circuit to progressively heat room temperature water to 100°C (boiling point); wherein the non-azeotropic refrigerant cascade heating circuit includes a high-boiling-point refrigerant flow path and a low-boiling-point refrigerant flow path; wherein the high-boiling-point refrigerant flow path includes a mixed vapor refrigerant containing high- and low-boiling-point refrigerants being fed by a single-stage compressor 1. After compression, the refrigerant flows through condenser 2, where the high-boiling-point refrigerant condenses into a liquid state and is separated from the low-boiling-point refrigerant in the vapor state by vapor-liquid separator 3. It then flows through high-boiling-point refrigerant receiver 4 and first throttling device 5, becoming the first cold fluid before entering the three-stream heat exchanger 7 to absorb heat and evaporate, becoming vaporized high-boiling-point refrigerant, which returns to the single-stage compressor 1 for recirculation. In the low-boiling-point refrigerant flow path, the vaporized low-boiling-point refrigerant separated by vapor-liquid separator 3 flows through gas cooler 6 for cooling, becoming a hot fluid before entering the three-stream heat exchanger 7 to react with the first cold fluid. After exchanging heat and condensing, the refrigerant flows through the regenerator 8, the low-boiling-point refrigerant receiver 9, and the second throttling device 10 before entering the evaporator 11. There, it exchanges heat with a low-temperature heat source and evaporates to a vapor state. It then re-enters the regenerator 8 and exchanges heat with the first cold fluid flowing into the regenerator 8, resulting in superheated vaporized low-boiling-point refrigerant. This superheated vaporized low-boiling-point refrigerant then mixes with the evaporated vaporized high-boiling-point refrigerant to form a mixed vaporized refrigerant that enters the single-stage compressor 1 for circulation. The high-temperature hot water preparation path involves water flowing from the medium-temperature water tank 12 mixing with ambient-temperature water input through the ambient-temperature water pipe and passing through the first... The water pump 13 pressurizes the water, which then enters the three-stream heat exchanger 7 as the second cold fluid. There, it exchanges heat with the hot fluid, absorbing heat and increasing in temperature to form medium-temperature hot water, which returns to the medium-temperature storage tank 12. The medium-temperature hot water in the medium-temperature storage tank 12 flows through the gas cooler, where it exchanges heat with the vaporous low-boiling-point refrigerant, absorbing heat and increasing in temperature. This hot water then merges with water flowing from the high-temperature storage tank 15 to form circulating water, which enters the condenser 2 and exchanges heat with the high-temperature, high-pressure mixed vaporous refrigerant, absorbing heat and increasing in temperature. This water then flows through the second water pump 16 and returns to the high-temperature storage tank 15 to form high-temperature hot water for output. The high-boiling-point refrigerant is R114, and the low-boiling-point refrigerant is R134a. The temperature of the superheated vaporous low-boiling-point refrigerant is not lower than the evaporation temperature of the vaporized vaporous high-boiling-point refrigerant. The three-stream heat exchanger 7 is a plate-fin or plate structure, with alternating hot and cold fluid channels inside. The first throttling device 5 and the second throttling device 10 are throttling valves (the first throttling device 5 and the second throttling device 10 have throttling, shut-off and opening functions, and can be switched according to needs). A shut-off valve 17 is installed on the pipeline connecting the high-temperature water storage tank 15 and the medium-temperature water storage tank 12. The temperature of the low-pressure high-boiling-point refrigerant reaching the three-stream heat exchanger 7 is 55-65℃, the temperature of the high-pressure low-boiling-point refrigerant is 60-70℃, and the temperature of the circulating water is 40-50℃.A one-way valve 14 is installed on the pipeline connecting the gas cooler 6 and the high-temperature water storage tank 15 to prevent the hot water in the high-temperature water storage tank 15 from flowing back to the medium-temperature water storage tank 12.

[0030] Example 2:

[0031] A method for preparing high-temperature hot water using the system described in Example 1 includes the following steps:

[0032] Cold start mode: Medium-temperature water tank 12 and high-temperature water tank 15 store room-temperature water; no room-temperature water is input into the water tanks (no room-temperature water is input into the room-temperature water pipe); the first throttling device 5 is shut off; the shut-off valve 17, single-stage compressor 1, first water pump 13, second water pump 16, second throttling device 10, and check valve 14 are opened; high-boiling-point refrigerant is stored in the high-boiling-point refrigerant receiver 4 and does not participate in refrigerant circulation; high-pressure superheated low-boiling-point refrigerant is cooled by condenser 2 and gas cooler 6 and enters the three-stream heat exchanger 7 to exchange heat with the second cold fluid flowing from the first water pump 13, then passes through regenerator 8 and low-temperature refrigerant... The boiling point refrigerant liquid is fed into the evaporator 11 via the second throttling device 10 and exchanges heat with the low-temperature heat source to evaporate to a vapor state. It then enters the regenerator 8 again and exchanges heat with the first cold fluid flowing into the regenerator 8. After being superheated, it flows into the single-stage compressor 1 and is pressurized to form the high-pressure superheated low-boiling point refrigerant, which then enters the condenser 2 for circulation. The second water pump 16 is adjusted to control the water flow through the condenser 2, so that the circulating water in the condenser 2 only cools and lowers the temperature of the high-pressure superheated low-boiling point refrigerant without condensing. After the initial cold start of the system is stable, the system can enter the subsequent modes for free switching.

[0033] Dual output mode for medium and high temperature hot water: Turn off the first throttling device 5 and close the shut-off valve 17. Normal temperature water is input from the normal temperature water pipe. Turn on the single-stage compressor 1, the first water pump 13, the second water pump 16, the second throttling device 10, and the one-way valve 14. Driven by the first water pump 13, the water mixed with the water flowing out of the medium temperature water tank 12 is heated into medium temperature hot water by the condensation heat of the low boiling point refrigerant in the three-stream heat exchanger 7. The hot water flows back to the medium temperature water tank 12 for output. The medium temperature hot water flowing out of the medium temperature water tank 12 absorbs heat and rises in temperature in the gas cooler 6. After mixing with the water flowing out of the high temperature water tank 15, the circulating water in the condenser 2 exchanges heat with the high-pressure superheated low boiling point refrigerant and absorbs heat to further rise in temperature. Finally, under the pressure of the second water pump 16, it forms high temperature hot water and returns to the high temperature water tank 15 for output.

[0034] High-temperature hot water output mode: The first throttling device 5, single-stage compressor 1, first water pump 13, and second water pump 16 are activated, and the shut-off valve 17 is closed. Room temperature water is input from the room temperature water pipe, increasing the circulating water volume of the second water pump. The medium-temperature storage tank 12 serves only as a transition tank. The medium-temperature hot water flowing from the medium-temperature storage tank 12 flows through the gas cooler 6, exchanges heat with the high-pressure superheated low-boiling-point vapor refrigerant inside, mixes with the water flowing from the high-temperature storage tank 15, and then flows through the condenser 2. It absorbs the condensation heat of the high-pressure high-boiling-point refrigerant in the condenser 2, raising its temperature. Then, under the pressure of the second water pump 16, it forms high-temperature hot water that flows back to the high-temperature storage tank 15 for output. The temperature of the medium-temperature hot water is 60–65°C; the temperature of the high-temperature hot water is 100°C. In cold start mode, the pressure ratio of the single-stage compressor 1 gradually increases. In the dual output mode of medium and high-temperature hot water and the high-temperature hot water output mode, the pressure ratio of the single-stage compressor 1 is stable at 3.5–4.

[0035] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A non-azeotropic internal-reverberation heat pump high-temperature hot water production system, characterized by, The system comprises a non-azeotropic refrigerant cascade heating circuit for providing core temperature rise heat and a high-temperature hot water preparation circuit for heating normal-temperature water to 100 DEG C. The non-azeotropic refrigerant cascade heating circuit comprises a high-boiling-point refrigerant circuit and a low-boiling-point refrigerant circuit. The high-boiling-point refrigerant circuit comprises mixed gaseous refrigerant mixed with high-boiling-point and low-boiling-point refrigerants, which is compressed by a single-stage compressor and then flows through a condenser, wherein the high-boiling-point refrigerant is condensed into liquid state and separated from gaseous low-boiling-point refrigerant by a vapor-liquid separator, and then flows through a high-boiling-point refrigerant reservoir and a first throttling device to enter a three-stream heat exchanger as first cold fluid to be evaporated by heat absorption, and then returns to the single-stage compressor to circulate. The low-boiling-point refrigerant circuit comprises gaseous low-boiling-point refrigerant separated from the vapor-liquid separator, which flows through a gaseous body cooler to enter the three-stream heat exchanger as hot fluid to be condensed by heat release, and then flows through a heat recovery device, a low-boiling-point refrigerant reservoir and a second throttling device to enter an evaporator to be evaporated by heat exchange with low-temperature heat source, and then enters the heat recovery device again to be superheated by heat exchange with the first cold fluid flowing into the heat recovery device, and then forms superheated gaseous low-boiling-point refrigerant to be mixed with the evaporated gaseous high-boiling-point refrigerant to form the mixed gaseous refrigerant to enter the single-stage compressor to circulate. The high-temperature hot water preparation circuit comprises water from a medium-temperature water storage tank and normal-temperature water from a normal-temperature water pipe, which are mixed and pressurized by a first water pump to enter the three-stream heat exchanger as second cold fluid to be heated by heat exchange with the hot fluid to form medium-temperature hot water to return to the medium-temperature water storage tank; the medium-temperature hot water in the medium-temperature water storage tank flows through a gaseous cooler to be heated by heat exchange with the gaseous low-boiling-point refrigerant, and then is mixed with water from a high-temperature water storage tank to form circulating water to enter the condenser to be heated by heat exchange with the high-temperature and high-pressure mixed gaseous refrigerant, and then flows through a second water pump to return to the high-temperature water storage tank to form high-temperature hot water to be output. The high-boiling-point refrigerant is R114 refrigerant, and the low-boiling-point refrigerant is R134a refrigerant. The temperature of the superheated gaseous low-boiling-point refrigerant is not lower than the evaporation temperature of the evaporated gaseous high-boiling-point refrigerant.

2. The non-azeotropic internal-recovery heat pump high-temperature hot water production system according to claim 1, characterized by, The three-stream heat exchanger is of plate-fin type or plate type, and the cold fluid passage and the hot fluid passage are arranged alternately.

3. The non-azeotropic internal-recovery heat pump high-temperature hot water production system according to claim 2, characterized in that, The first throttling device and the second throttling device are throttling valves.

4. The non-azeotropic internal-recovery heat pump high-temperature hot water production system according to claim 3, characterized in that, A stop valve is arranged on the pipeline connecting the high-temperature water storage tank and the medium-temperature water storage tank.

5. The non-azeotropic internal-recovery heat pump high-temperature hot water production system according to claim 4, characterized in that, The temperature of the low-pressure high-boiling-point refrigerant entering the three-stream heat exchanger is 55-65 DEG C, the temperature of the high-pressure low-boiling-point refrigerant is 60-70 DEG C, and the temperature of the circulating water is 40-50 DEG C.

6. The non-azeotropic internal-recovery heat pump high-temperature hot water production system according to claim 5, characterized in that, A one-way valve is arranged on the pipeline connecting the gaseous body cooler and the high-temperature water storage tank to prevent the hot water in the high-temperature water storage tank from flowing back to the medium-temperature water storage tank.

7. A method for the production of high temperature hot water, c h a r a c t e r i s e d in that The system comprises the following modes: Cold start mode: the normal temperature water is reserved in the medium temperature water storage tank and the high temperature water storage tank, the water storage tank does not input the normal temperature water, the first throttling device is closed, the stop valve, the single-stage compressor, the first water pump, the second water pump, the second throttling device and the one-way valve are opened, the system is initialized and cold started; the high boiling point refrigerant is reserved in the high boiling point refrigerant reservoir and does not participate in the refrigerant circulation; the high pressure overheated low boiling point refrigerant is cooled and cooled in the condenser and the vapor cooler, enters the three-flow heat exchanger, exchanges heat with the second cold fluid flowing out from the first water pump, is condensed, passes through the regenerator, the low boiling point refrigerant reservoir and the second throttling device, enters the evaporator, exchanges heat with the low temperature heat source, is evaporated to the gaseous state, enters the regenerator again, exchanges heat with the first cold fluid flowing into the regenerator, is overheated, flows into the single-stage compressor, is pressurized to form the high pressure overheated low boiling point refrigerant, enters the condenser and circulates; the water flow passing through the condenser is controlled by adjusting the second water pump, so that the circulating water in the condenser only cools and cools the high pressure overheated low boiling point refrigerant therein and does not condense; after the cold start is stable, the system enters the subsequent mode and freely switches; Medium and high temperature hot water double output mode: the first throttling device is closed, the stop valve is closed, the normal temperature water is input from the normal temperature water pipe, the single-stage compressor, the first water pump, the second water pump, the second throttling device and the one-way valve are opened; the water mixed with the water flowing out from the medium temperature water storage tank under the driving of the first water pump is heated to the medium temperature hot water by the condensation heat of the low boiling point refrigerant in the three-flow heat exchanger, and flows back to the medium temperature water storage tank for output; the medium temperature hot water flowing out from the medium temperature water storage tank is heated in the vapor cooler, mixes with the water flowing out from the high temperature water storage tank, forms the circulating water, exchanges heat with the high pressure overheated low boiling point refrigerant in the condenser, is further heated, and finally forms the high temperature hot water under the pressurization of the second water pump and flows back to the high temperature water storage tank for output; High temperature hot water output mode: the first throttling device, the single-stage compressor, the first water pump and the second water pump are opened, the stop valve is closed, the normal temperature water is input from the normal temperature water pipe, and the circulating water amount of the second water pump is increased; the medium temperature water storage tank is only a transition water tank; the medium temperature hot water flowing out from the medium temperature water storage tank exchanges heat with the high pressure overheated low boiling point gaseous state refrigerant in the vapor cooler, mixes with the water flowing out from the high temperature water storage tank, flows through the condenser, absorbs the condensation heat of the high pressure high boiling point refrigerant in the condenser, is heated, and then forms the high temperature hot water under the pressurization of the second water pump and flows back to the high temperature water storage tank for output.

8. The method of claim 7, wherein the temperature of the water is between 150°C and 250°C. The temperature of the medium temperature hot water is 60-65℃; the temperature of the high temperature hot water is 100℃; in the cold start mode, the pressure ratio of the single-stage compressor gradually increases; in the medium and high temperature hot water double output mode and the high temperature hot water output mode, the pressure ratio of the single-stage compressor is stable at 3.5-4.

Images