CN101158507A - Cascade heat storage type air source heat pump water heater - Google Patents

Abstract

The invention discloses a cascade heat storage type air source heat pump water heater. The water heater is composed of a high-temperature loop and a low-temperature loop, including two compressors, a four-way reversing valve, a condenser, a water storage tank, an evaporation-condensation Two evaporators, two throttle valves, two stop valves, and two check valves; the condenser and phase-change heat storage materials are all installed in the water storage tank, and the water storage tank uses phase-change heat storage materials to store heat; The connection between the various components of the closed channel is connected by refrigerant pipelines, and the tubes are wrapped with thermal insulation and waterproof materials; the melting point of the phase change heat storage material is 60°C to 80°C. The cascade heat storage type air source heat pump water heater of the present invention effectively utilizes low-cost electric heat storage during off-peak hours, adjusts the power consumption pressure during peak hours, and reduces the volume of the water tank; it can make the COP value of the system tend to If the value is larger, the system will always work towards the trend that is most conducive to energy saving; it is safe, reliable and environmentally friendly when used, water and electricity are separated, and there is no harmful combustion emission.

Description

Cascade heat storage type air source heat pump water heater

technical field

The invention belongs to the technical field of water heaters, and specifically refers to a cascade heat storage type air source heat pump water heater.

Background technique

With the improvement of people's living standards, providing domestic hot water throughout the year has become an important part of people's comfortable life. Traditional gas and electric water heaters have potential safety hazards such as emission of harmful combustion products and easy leakage of electricity, while consuming high-quality energy such as gas and electricity, which is inconsistent with the sustainable development of new energy systems based on renewable energy. When the solar water heater has insufficient sunshine due to climate and seasonal changes, it has the disadvantages of poor heating capacity balance and low utilization rate of the device throughout the year.

Compared with traditional gas and electric water heaters, heat pump water heaters have obvious energy-saving effects, but when the ambient temperature is low, the compression ratio of the compressor of single-cycle air-source heat pump water heaters with a single working fluid is large, which will lead to a decrease in efficiency or even failure to work.

At present, a large number of in-depth researches on commercial heat pump water heaters have been carried out at home and abroad, and certain results have been obtained and they have been widely used. However, the current domestic heat pump water heaters still have technical problems such as the coefficient of heating performance needs to be improved, the thermal inertia is large, the hot water output is slow, and the temperature of the continuous output water drops rapidly with time.

Advantages of the cascade air source heat pump cycle: the air source heat pump that combines the single-stage cycle and the cascade cycle can still achieve the small compression ratio and the exhaust temperature when the outdoor temperature is very low. Low, high heating capacity requirements. At low temperatures, cascade cycle operation is more energy efficient than single stage operation. The heat pump operates under optimum energy-saving control conditions to achieve maximum energy savings.

Advantages of phase change heat storage hot water system: 1. Provide time delay between energy production and consumption and ensure effective use;

2. Provide thermal inertia and thermal protection (including temperature control); 3. Ensure energy supply security.

Contents of the invention

The purpose of the present invention is to solve the shortcomings of the above-mentioned prior art, absorb the respective advantages of the cascade heat pump circulation system and the phase change heat storage system, and provide a cascade heat storage type air source heat pump water heater.

In order to achieve the above object, the present invention adopts the following technical solutions:

The cascade heat storage type air source heat pump water heater of the present invention is composed of a high temperature loop and a low temperature loop, including two compressors H1, L1, four-way reversing valve L6, condenser H2, water storage tank SX, evaporation-condensation HL, two evaporators H5, L5, two throttle valves H3, L3, two stop valves H6, H7, two check valves H4, L4. The exhaust port of the high-temperature loop compressor H1 is connected to the inlet port of the condenser H2, the outlet of the condenser H2 is connected to the inlet of the throttle valve H3, the outlet of the throttle valve H3 is connected to the inlet of the shut-off valve H7, and the shut-off valve The outlet of H7 is connected to the inlet of the evaporator-condenser HL high-temperature fluid, the outlet of the evaporator-condenser HL high-temperature fluid is connected to the inlet of the check valve H4, and one is added before the inlet of the shut-off valve H7 and after the outlet of the check valve H4 A bypass pipe, in which the evaporator H5 and the shut-off valve H6 are indirectly connected, the outlet of the shut-off valve H6, the outlet of the check valve H4, and the inlet of the compressor H1 are connected to each other and have a node. The exhaust port of the low-temperature loop compressor L1 is connected to the four-way reversing valve L6, the outlet of the four-way reversing valve L6 is connected to the inlet of the low-temperature fluid of the evaporator-condenser HL, and the outlet of the low-temperature fluid of the evaporator-condenser HL is throttled The inlet of valve L3 is connected, the outlet of throttle valve L3 is connected to the inlet of evaporator L5, the outlet of evaporator L5 is connected to four-way reversing valve L6, the outlet of four-way reversing valve L6 is connected to the inlet of check valve L4, The outlet of the check valve L4 is connected to the air inlet of the compressor L1; the condenser H2 and the phase change heat storage material are installed in the water storage tank SX, and the water storage tank SX adopts the phase change heat storage material to store heat;

The connections between the various parts of the closed channel of the cycle are connected by refrigerant pipelines, and the tubes are wrapped with thermal insulation and waterproof materials.

The connection between the various parts of the closed channel of the cascade heat storage type heat pump cycle is connected by refrigerant pipelines, and the tubes are wrapped with thermal insulation and waterproof materials. The melting point of the phase change heat storage material is between 60°C and 80°C. A cascade heat pump cycle can be used in winter, and a single-stage heat pump cycle can be used in summer.

Both the high-temperature loop and the low-temperature loop of the present invention are independent compression refrigeration cycles. The evaporator of the low-temperature loop absorbs the heat of the air source, and the heat released by the condenser of the high-temperature loop heats the water to the target temperature. The high-temperature loop The circuit and the low-temperature loop utilize an evaporator-condenser for heat exchange. The water heated to the target temperature is stored in the water storage tank, and the heat storage material in the water storage tank is used for phase change heat storage, so as to achieve the purpose of heat storage.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The cascade heat storage type air source heat pump water heater of the present invention not only effectively utilizes low-cost electric heat storage during off-peak hours, adjusts the power consumption pressure during peak hours, but also reduces the volume of the water tank; it can increase the COP value of the system with the change of ambient temperature. Tend to a larger value, the system always works towards the trend that is most conducive to energy saving; it is safe, reliable and environmentally friendly when used, water and electricity are separated, and there is no harmful combustion emission.

Description of drawings

Fig. 1 is a structural schematic diagram of the cascade air source heat pump system of the present invention.

Among them: H ₁ and L ₁ are compressors, H ₃ and L ₃ are expansion devices, L ₆ is a four-way reversing valve, HL is a plate heat exchanger, H ₂ is a condenser to provide heat to users, H ₅ and L ₅ is an evaporator, H ₆ and H ₇ are stop valves, H ₄ and L ₄ are check valves.

Figure 2 is a pressure-enthalpy diagram of the system cycle process (including high temperature and low temperature loops). Δt represents the heat transfer temperature difference of the evaporator-condenser.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto.

As shown in Figure 1, the cascade heat storage type air source heat pump water heater of the present invention is composed of a high temperature loop and a low temperature loop, including two compressors H ₁ , L ₁ , a four-way reversing valve L ₆ , a Condenser H ₂ , a storage tank SX, an evaporator-condenser HL, two evaporators H ₅ , L ₅ , two throttle valves H ₃ , L ₃ , two shut-off valves H ₆ , H ₇ , two Check valves H ₄ , L ₄ . The exhaust port of the high-temperature loop compressor _H1 is connected to the inlet port of the condenser _H2 , the outlet of the condenser _H2 is connected to the inlet of the throttle valve _H3 , and the outlet of the throttle valve _H3 is connected to the shut-off valve _H7 The inlet connection of the shut-off valve H ₇ is connected with the inlet of the evaporator-condenser HL high-temperature fluid, the outlet of the evaporator-condenser HL high-temperature fluid is connected with the inlet of the check valve H ₄ , and before the inlet of the shut-off valve H ₇ is connected with A bypass pipe is added after the outlet of the check valve _H4 , the bypass pipe is connected with the evaporator _H5 and the shut-off valve _H6 indirectly, the outlet of the shut-off valve _H6 , the outlet of the check valve _H4 , the compressor H The imports of ₁ are connected to each other and have a node.

The exhaust port of the low-temperature loop compressor L ₁ is connected to the four-way reversing valve L ₆ , the outlet of the four-way reversing valve L ₆ is connected to the inlet of the low-temperature fluid of the evaporator-condenser HL, and the outlet of the low-temperature fluid of the evaporator-condenser HL Connect with the inlet of throttle valve _L3 , the outlet of throttle valve _L3 is connected with the inlet of evaporator _L5 , the outlet of evaporator _L5 is connected with four-way reversing valve _L6 , the outlet of four-way reversing valve _L6 It is connected with the inlet of the check valve _L4 , and the outlet of the check valve _L4 is connected with the air inlet of the compressor _L1 .

The condenser H ₂ and the heat storage material are all installed in the water storage tank SX, and the water storage tank SX is kept insulated by thermal insulation materials. The thermal storage material can be paraffin, or a composite phase change thermal storage material composed of paraffin and other organic matter, and its melting point can be in the range of 60°C to 80°C.

The connection between the components of the closed channel of the above-mentioned cascade heat storage type heat pump cycle is connected by refrigerant pipelines, and the tubes are wrapped with thermal insulation and waterproof materials.

Embodiment 1: The cascade heat pump circulation system of this embodiment is composed of a high-temperature loop and a low-temperature loop, so that it can still produce high-temperature hot water in cold weather.

High-temperature loop: After the high-temperature refrigerant is compressed by the compressor H ₁ , it forms a high-temperature and high-pressure mixed gas, and passes through the condenser H ₂ to heat the hot water to the target temperature. At this time, the refrigerant condenses into a medium-temperature and high-pressure liquid, and after throttling through the throttle valve _H3 , the low-temperature and low-pressure refrigerant gas-liquid mixture enters the evaporator-condenser HL for heat exchange (close the stop valve H ₆ ), absorbing heat from the low temperature The heat of the loop forms medium-temperature and low-pressure gas refrigerant and returns to the compressor H ₁ to complete a high-temperature loop cycle.

Low-temperature loop: After the low-temperature refrigerant is compressed by the compressor _L1 , it forms a high-temperature and high-pressure mixed gas, enters the evaporator-condenser HL for heat exchange, absorbs the cold energy from the high-temperature loop, and condenses into a medium-temperature and high-pressure liquid refrigerant. After throttling by the throttle valve _L3 , a low-temperature and low-pressure refrigerant gas-liquid mixture is formed, which absorbs heat from the outside air through the evaporator _L5 , forms a medium-temperature and low-pressure gas refrigerant, and returns to the compressor _L1 to complete a low-temperature cycle. road loop.

The two loops exchange heat through the evaporator-condenser HL. In order to improve efficiency, the heat transfer temperature difference Δt (Figure 2) is controlled at about 5°C.

The condenser H ₂ and the heat storage material are all installed in the water storage tank SX, and the water storage tank SX is kept insulated by thermal insulation materials. No. 70 paraffin wax is used as the heat storage material, and its melting point is 70°C.

The connection between the components of the closed channel of the above-mentioned cascade heat storage type heat pump cycle is connected by refrigerant pipelines, and the tubes are wrapped with thermal insulation and waterproof materials.

Embodiment 2: In this embodiment, only a high-temperature loop is used to form a single-stage heat pump circulation system to produce hot water, so that it can save more energy in the case of ensuring the temperature of hot water in summer.

After the high-temperature refrigerant is compressed by the compressor _H1 , it forms a high-temperature and high-pressure mixed gas, and passes through the condenser _H2 to heat the hot water to the target temperature. At this time, the refrigerant condenses into a medium-temperature and high-pressure liquid, enters the throttling valve L ₃ to throttle, forms a low-temperature and low-pressure refrigerant gas-liquid mixture after throttling, passes through the bypass pipe (close the stop valve H ₅ ) and directly passes through the evaporator H ₅ Absorb the heat from the outside air, form a medium-temperature and low-pressure gas refrigerant and return to the compressor H ₁ to complete a loop cycle.

Embodiment 3: In the air source heat pump water heater combined with the cascade heat pump cycle and the phase change heat storage system of this embodiment, the condenser _H2 directly exchanges heat with the water in the water storage tank SX to heat the water to the target temperature. No. 70 paraffin is used as the heat storage material. At this time, the temperature of the water reaches its melting point of 70°C. The paraffin wax of the heat storage material melts and absorbs the heat of the water, so that the heat is stored in the paraffin to achieve the purpose of heat storage.

When the power consumption is low, start the cascade heat pump system. Since the temperature of the hot water obtained by the cascade cycle operation is higher than that obtained by the single-stage operation, it can reach a temperature above 70°C. Choose the one that produces a phase change at this higher temperature. Heat storage material stores heat in the heat storage material. On the one hand, it can obtain higher energy density. On the other hand, the cop value of cascade operation is higher, and the energy utilization efficiency is higher; The heat cycle transfers the heat stored in the heat storage material to the water, outputs hot water, and improves the overall economy of the water heater.

Claims (2)

1. multiplex thermal storage type air source heat pump water heater, it is characterized in that forming by high temperature loop and low-temperature loop, comprise two compressors (H1), (L1), four-way change-over valve (L6), condenser (H2), storage tank (SX), evaporator-condenser (HL), two evaporimeters (H5), (L5), two choke valves (H3), (L3), two stop valves (H6), (H7), two check-valves (H4), (L4);

The exhaust outlet of high temperature loop compressor (H1) is connected with the air inlet of condenser (H2), the outlet of condenser (H2) is connected with the import of choke valve (H3), the outlet of choke valve (H3) is connected with the import of stop valve (H7), the outlet of stop valve (H7) is connected with the import of evaporator-condenser (HL) high temperature fluid, the outlet of evaporator-condenser (HL) high temperature fluid is connected with the import of check-valves (H4), before the import of stop valve (H7) and after the outlet of check-valves (H4), add a bypass pipe, be connected to evaporimeter (H5) and stop valve (H6), the outlet of stop valve (H6) in the middle of this bypass pipe, the outlet of check-valves (H4), interconnect between the import of compressor (H1) and a node arranged;

The exhaust outlet of low-temperature loop compressor (L1) connects four-way change-over valve (L6), the outlet of four-way change-over valve (L6) is connected with the import of evaporator-condenser (HL) cryogen, the outlet of evaporator-condenser (HL) cryogen is connected with the import of choke valve (L3), the outlet of choke valve (L3) is connected with the import of evaporimeter (L5), the outlet of evaporimeter (L5) connects four-way change-over valve (L6), the outlet of four-way change-over valve (L6) is connected with the import of check-valves (L4), and the outlet of check-valves (L4) is connected with the air inlet of compressor (L1); Condenser (H2), phase change heat storage material are installed in the storage tank (SX), and storage tank (SX) adopts the phase change heat storage material accumulation of heat;

Connection between each parts of the close passage of circulation adopts refrigerant line to connect, pipe outer wrapping thermal-insulating waterproof material.

2. multiplex thermal storage type air source heat pump water heater according to claim 1 is characterized in that, the fusing point of described phase change heat storage material is 60 ℃～80 ℃.