Direct-heating high-efficiency air source heat pump system with energy cascade utilization

Abstract

A direct-heating high-efficiency air source heat pump system with cascaded energy utilization, the system comprising a heat pump cycle, a water cycle and a sanitary hot water cycle. The present invention can not only ensure indoor heating, but also facilitate the production of sanitary hot water, ensuring stable and efficient operation of the system throughout the year. The first air cooler heats the constant temperature water tank to achieve heating through a multi-stage heating terminal, connects the low-temperature heating terminal and the high-temperature heating terminal in series at the water tank outlet, and controls it through four stop valves to achieve cascaded energy utilization, which can meet the comfort requirements of residents without causing excessive waste, and can be said to kill two birds with one stone. At the same time, the present invention controls the second air cooler to heat sanitary hot water through three stop valves to meet the water needs of residents. The present invention provides a direct-heating high-efficiency air source heat pump system with cascaded energy utilization that effectively improves system energy efficiency and has high efficiency.

Description

Technical Field

[0001] The invention belongs to the field of heat pumps and relates to a direct-heating heat pump. Background Art

[0002] A heat pump is a device that uses a small amount of driving energy to convert a large amount of low-temperature energy into high-temperature energy. According to the heat source medium, it can be divided into air-source heat pumps, water-source heat pumps, and ground-source heat pumps. Existing air-source heat pumps can be divided into two types according to their operating modes: circulation type and direct heating type. The inlet water temperature of the direct heating unit is always kept constant, the heat exchange efficiency is high, the heat absorption capacity is strong, the condensing temperature, exhaust temperature, exhaust pressure and operating current are stable, and the operating life of the compressor is greatly extended. Therefore, direct heating heat pumps are increasingly valued in actual projects.

[0003] The commonly used heat pump fan coil has low inlet and outlet temperatures and has a good energy-saving effect. However, the dry hot air blown out during heating in winter often makes people feel uncomfortable, the indoor air is not good, and the human comfort level is reduced. Some high-temperature heating terminals, such as radiators and water floor heating, use natural convection during heating, which can ensure the heating effect without the feeling of blowing, but requires a lot of pipeline laying and modification. At the same time, the inlet and outlet temperatures of the high-temperature heating terminals are relatively high, and the high-temperature heat source of the heat pump is at a high temperature for a long time, which will cause the system's energy efficiency coefficient COP to decrease, and the system's energy-saving effect is not good.

[0004] At present, the optimization of air source heat pumps mainly focuses on two aspects: one is to optimize the equipment, such as the optimization of the compressor, evaporator, condenser, etc.; the other is to optimize the circulation mode of the system, such as introducing an internal heat exchanger, using an ejector instead of a throttle valve, etc. These technologies are helpful to improve the efficiency of heat pumps, but they cannot completely solve the problem, and some key issues remain to be resolved. Summary of the invention

[0005] In order to overcome the disadvantage of low system energy efficiency of existing heat pumps, the present invention provides a direct-heating high-efficiency air source heat pump system that effectively improves system energy efficiency and has high-efficiency energy cascade utilization.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A direct-heating high-efficiency air source heat pump system with cascaded energy utilization comprises a compressor, a four-way valve, a first air cooler, a second air cooler, a throttle valve, an evaporator, a gas-liquid separator, a first stop valve, a second stop valve, a third stop valve and a one-way valve, wherein the inlet of the compressor is connected to the first interface of the four-way valve, the second interface of the four-way valve is respectively connected to the first interface of the first air cooler and the first interface of the first solenoid valve, the second interface of the four-way valve is connected to the first interface of the evaporator, and the third interface of the four-way valve is connected to the inlet of the gas-liquid separator; the second interface of the first air cooler is respectively connected to the first interface of the second stop valve and the first interface of the third stop valve, the second interface of the third stop valve is connected to the first interface of the second air cooler, the second interface of the second stop valve is respectively connected to the first interface of the throttle valve and the second interface of the second air cooler, and the second interface of the throttle valve is connected to the second interface of the evaporator.

[0008] Furthermore, the heat pump also includes a low-temperature heating terminal, a high-temperature heating terminal, a constant temperature water tank, a water pump, a fourth stop valve, a fifth stop valve, a sixth stop valve and a seventh stop valve. The third interface of the first air cooler is connected to the inlet of the constant temperature water tank, the outlet of the constant temperature water tank is connected to the inlet of the fourth stop valve, the first interface of the fifth stop valve, and the inlet of the sixth stop valve, respectively, the outlet of the fourth stop valve is connected to the inlet of the high-temperature heating terminal, the outlet of the high-temperature heating terminal is connected to the inlet of the low-temperature heating terminal and the second interface of the fifth stop valve, respectively, the outlet of the low-temperature heating terminal is connected to the inlet of the seventh stop valve, the outlet of the seventh stop valve is connected to the inlet of the water pump and the outlet of the sixth stop valve, respectively, and the outlet of the water pump is connected to the fourth interface of the first air cooler.

[0009] Furthermore, the heat pump also includes a sanitary hot water tank, the tap water interface is connected to the second inlet of the second air cooler, the second outlet of the second air cooler is connected to the sanitary hot water tank, and the outlet of the sanitary hot water tank is the sanitary hot water outlet.

[0010] Furthermore, the heat pump also includes a temperature sensor, a variable frequency fan and a control device. The temperature sensor is located at the air side inlet of the evaporator and is connected to the control device; the variable frequency fan is also connected to the control device.

[0011] The technical concept of the present invention is to connect the low-temperature heating terminal and the high-temperature heating terminal in series. This article takes the commonly used fan coil as the low-temperature heating terminal and the radiator as the high-temperature heating terminal as an example. The fan coil can be installed in the bathroom, kitchen, storage room and other places that are not used for a long time, and the radiator can be installed in the bedroom where comfort needs to be guaranteed, so as to ensure the best heating comfort for the residents. Based on the principle of energy cascade utilization, high-temperature hot water is first used for heating through the radiator, and then the fan coil is heated to blow out hot air, which reasonably utilizes the waste heat, reduces the temperature of the high-temperature heat source of the heat pump, optimizes the operating conditions of the heat pump, reduces the power consumption of the compressor, and improves the system performance coefficient. At the same time, the system adopts a reverse cycle defrosting method to quickly defrost the evaporator in winter.

[0012] The present invention is also provided with a second air cooler. The medium-temperature and high-pressure gas passing through the first air cooler will be further cooled in the second air cooler and used to heat tap water to obtain sanitary hot water, thereby further reducing the exhaust temperature and pressure of the compressor and improving the energy efficiency of the system. Sanitary hot water does not require a very high temperature (30°C-45°C). By heating it with the second air cooler, it can not only make full use of waste heat, but also produce sanitary hot water, which can be said to kill two birds with one stone. In some extreme climates, the ambient temperature is very low, resulting in a low condensation temperature of the system. The temperature at the high-temperature and low-temperature heating terminals is not enough to heat hot water, or when the residents have prepared enough hot water and do not need to produce additional hot water, the shut-off valve can be adjusted to achieve the alternation of the three modes of heating sanitary hot water, heating indoor rooms, and heating hot water while ensuring indoor warmth.

[0013] The beneficial effects of the present invention are mainly manifested in:

[0014] 1. When the system is running, especially in low temperatures in winter, compared with ordinary heat pump cycles, this system has a higher energy efficiency coefficient (COP) and is more energy-efficient. It consumes less electricity to provide indoor heating at the same temperature and is more efficient.

[0015] 2. When frost forms on the surface of the evaporator in winter, the defrosting time required by this system is very short, which will not cause much impact on indoor heating, and the system reliability is very good.

[0016] 3. Effectively utilize the waste heat released in the air cooler and adopt two-stage cooling, which can not only produce sanitary hot water for indoor use, but also reduce throttling losses, which can be said to kill two birds with one stone. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is a schematic diagram of a direct-heating high-efficiency air source heat pump system with cascaded energy utilization, in which 1: compressor; 2: first air cooler; 3: second air cooler; 4: throttle valve; 5: evaporator; 6: gas-liquid separator; 7: four-way valve; 8: first stop valve; 9: second stop valve; 10: third stop valve; 11: constant temperature water tank; 12: high-temperature heating terminal; 13: low-temperature heating terminal; 14: fourth stop valve; 15: fifth stop valve; 16: sixth stop valve; 17: seventh stop valve; 21: water pump; 22: sanitary hot water tank; 23: variable frequency fan; 24: temperature sensor; 25: control device

[0018] Figure 2 This is a schematic diagram of the system with a sub-low temperature heating terminal installed, where 1: compressor; 2: first air cooler; 3: second air cooler; 4: throttle valve; 5: evaporator; 6: gas-liquid separator; 7: four-way valve; 8: first stop valve; 9: second stop valve; 10: third stop valve; 11: constant temperature water tank; 12: high temperature heating terminal; 13: low temperature heating terminal; 14: sub-low temperature heating terminal; 15: fourth stop valve; 16: fifth stop valve; 17: sixth stop valve; 18: seventh stop valve; 19: eighth stop valve; 20: ninth stop valve; 21: water pump; 22: sanitary hot water tank; 23: variable frequency fan; 24: temperature sensor; 25: control device DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] Reference Figure 1 and Figure 2 , a direct-heating high-efficiency air source heat pump system with energy cascade utilization, comprising a compressor, a four-way valve, a first air cooler, a second air cooler, a throttle valve, an evaporator, a gas-liquid separator, a first stop valve, a second stop valve, a third stop valve and a one-way valve, wherein the inlet of the compressor is connected to the first interface of the four-way valve, the second interface of the four-way valve is respectively connected to the first interface of the first air cooler and the first interface of the first solenoid valve, the second interface of the four-way valve is connected to the first interface of the evaporator, and the third interface of the four-way valve is connected to the inlet of the gas-liquid separator; the second interface of the first air cooler is respectively connected to the first interface of the second stop valve and the first interface of the third stop valve, the second interface of the third stop valve is connected to the first interface of the second air cooler, the second interface of the second stop valve is respectively connected to the first interface of the throttle valve and the second interface of the second air cooler, and the second interface of the throttle valve is connected to the second interface of the evaporator.

[0021] Furthermore, the heat pump also includes a low-temperature heating terminal, a high-temperature heating terminal, a constant temperature water tank, a water pump, a fourth stop valve, a fifth stop valve, a sixth stop valve and a seventh stop valve. The third interface of the first air cooler is connected to the inlet of the constant temperature water tank, the outlet of the constant temperature water tank is connected to the inlet of the fourth stop valve, the first interface of the fifth stop valve, and the inlet of the sixth stop valve, respectively, the outlet of the fourth stop valve is connected to the inlet of the high-temperature heating terminal, the outlet of the high-temperature heating terminal is connected to the inlet of the low-temperature heating terminal and the second interface of the fifth stop valve, respectively, the outlet of the low-temperature heating terminal is connected to the inlet of the seventh stop valve, the outlet of the seventh stop valve is connected to the inlet of the water pump and the outlet of the sixth stop valve, respectively, and the outlet of the water pump is connected to the fourth interface of the first air cooler.

[0022] Furthermore, the heat pump also includes a sanitary hot water tank, the tap water interface is connected to the second inlet of the second air cooler, the second outlet of the second air cooler is connected to the sanitary hot water tank, and the outlet of the sanitary hot water tank is the sanitary hot water outlet.

[0023] Furthermore, the heat pump also includes a temperature sensor, a variable frequency fan and a control device. The temperature sensor is located at the air side inlet of the evaporator and is connected to the control device; the variable frequency fan is also connected to the control device.

[0024] Example 1: Normal working mode.

[0025] like Figure 1 As shown, the normal working mode of the system has two cycles, a heat pump cycle and a water cycle. In the water circulation system in the normal working mode, the fifth stop valve 16 and the sixth stop valve 17 are closed, the fourth stop valve 15 and the seventh stop valve 18 are opened, the high temperature heating terminal is connected to the low temperature heating terminal and is respectively in different rooms, and the two are connected in series to work, using water as a coolant to absorb the heat released in the air cooler, and then heating the room. The low temperature heating terminal can be installed in the bathroom, kitchen, storage room and other places that are not used for a long time, and the high temperature heating terminal can be installed in the bedroom that needs to ensure comfort to ensure the best heating comfort. By connecting the two in series, the waste heat after the high temperature heating terminal works can be used again, reducing the temperature difference required for heat transfer, greatly reducing irreversible losses, and improving thermal efficiency. At the same time, the second air cooler 3 is also working, constantly heating tap water to produce sanitary hot water and storing it in the water tank 27 to meet the bathing needs of residents. Compared with the existing market that only uses heat pump radiators as heating devices, the present invention has great energy saving, not to mention the heating furnace or electric heater with lower energy efficiency. If the household has prepared enough sanitary hot water, the household may choose to open the second stop valve 9, close the first stop valve 8 and the third stop valve 10, and stop preparing hot water.

[0026] Embodiment 2: Low temperature heating terminal working mode or high temperature heating terminal working mode

[0027] In some special cases, the residents may stay in one room, so it is not necessary to enable both heating devices. The present invention adds 4 stop valves in the water circulation system to control the two heating devices. For example, if only the low-temperature heating terminal 13 is needed to work and the high-temperature heating terminal 12 is not needed, the fourth stop valve 15 and the sixth stop valve 17 are closed, and the fifth stop valve 16 and the seventh stop valve 18 are opened. When only the high-temperature heating terminal is needed to work and the low-temperature heating terminal is not needed, the seventh stop valve is closed, and the fourth, fifth and sixth stop valves are opened. At the same time, the second air cooler 4 is also working, continuously heating tap water to produce sanitary hot water and store it in the water tank 27 to meet the bathing needs of the residents. If the residents have prepared enough sanitary hot water, they can choose to open the second stop valve 9, close the first stop valve 8 and the third stop valve 10, and stop producing hot water.

[0028] Example 3: Reverse cycle defrost mode

[0029] like Figure 1 As shown, when the temperature on the surface of the evaporator 5 is lower than the dew point temperature in the air, the water vapor in the air will gradually condense on the surface of the evaporator to form a frost layer, which is a very common phenomenon in the winter in the north. The present invention uses the reverse cycle defrosting system for a direct-heating high-efficiency air source heat pump system with energy cascade utilization. When the frost layer on the evaporator is too thick and affects the work, the four-way valve 7 will automatically turn to the heating mode. At this time, the original first air cooler 2 will act as an evaporator, and the original evaporator will act as an air cooler to absorb the heat released by the compressor, thereby achieving the purpose of melting the frost layer. When the frost layer is melted, the four-way valve turns again and returns to the normal working mode.

[0030] Example 4: Heating sanitary hot water mode

[0031] like Figure 1 As shown, the system is also provided with a second air cooler 3 for producing sanitary hot water. The medium-temperature high-pressure gas passing through the first air cooler will be further cooled in the second air cooler and used to heat tap water to obtain sanitary hot water. The sanitary hot water tank 24 is installed in the bathroom. During the day, with the indoor heating, hot water will be continuously stored in the constant temperature hot water tank for use by residents at night. When residents are in urgent need of hot water, they can also open the first stop valve and the third stop valve and close the second stop valve. All the heat in the compressor will be released through the second air cooler to heat the tap water, so as to achieve the purpose of quickly producing sanitary hot water.

[0032] Example 5: Multi-stage heating mode

[0033] like Figure 2As shown, the system adds a sub-low temperature heating terminal 14 and two stop valves to the original system, thereby further reducing the heat source temperature of the heat pump and improving the operating efficiency of the heat pump. Similarly, the heating terminal of the heat pump is divided into multiple stages, and the energy efficiency coefficient COP is further improved on the original basis. In principle, the number of stages at different temperature terminals can be continuously increased, and the specific number of stages can be changed according to the ambient temperature and economic conditions, which greatly improves the working conditions of the system.

[0034] Embodiment 6: Summer hot water production mode

[0035] In summer, residents do not need heating mode, they only need the system to provide a certain amount of domestic hot water every day. Figure 2 The structure in. Because the working conditions of each component of this system are designed based on the condition of -20℃ in winter, the high evaporation temperature in summer will cause the compressor to consume too much power and burn out. Therefore, this system installs a temperature sensor at the air side inlet of the evaporator and connects it to the control device, and the other end of the control device is connected to the variable frequency fan of the evaporator. When the air temperature exceeds the set value, the control device controls the variable frequency fan to reduce the speed, increase the evaporator temperature difference, reduce the refrigerant temperature in the evaporator, and thus reduce the power consumption of the compressor. Ensure that the system operates under reasonable and safe conditions.

Claims

1. A direct-heating high-efficiency air source heat pump system with cascaded energy utilization, characterized in that: It includes a compressor, a four-way valve, a first air cooler, a second air cooler, a throttle valve, an evaporator, a gas-liquid separator, a first stop valve, a second stop valve, a third stop valve and a one-way valve. The inlet of the compressor is connected to the first interface of the four-way valve, the second interface of the four-way valve is respectively connected to the first interface of the first air cooler and the first interface of the first solenoid valve, the second interface of the four-way valve is connected to the first interface of the evaporator, the third interface of the four-way valve is connected to the inlet of the gas-liquid separator, the second interface of the first air cooler is respectively connected to the first interface of the second stop valve and the first interface of the third stop valve, the second interface of the third stop valve is connected to the first interface of the second air cooler, the second interface of the second stop valve is respectively connected to the first interface of the throttle valve and the second interface of the second air cooler, and the second interface of the throttle valve is connected to the second interface of the evaporator.

2. The direct-heating high-efficiency air source heat pump system with cascaded energy utilization according to claim 1 is characterized in that: The heat pump also includes a low-temperature heating terminal, a high-temperature heating terminal, a constant temperature water tank, a water pump, a fourth stop valve, a fifth stop valve, a sixth stop valve and a seventh stop valve. The third interface of the first air cooler is connected to the inlet of the constant temperature water tank, the outlet of the constant temperature water tank is connected to the inlet of the fourth stop valve, the first interface of the fifth stop valve, and the inlet of the sixth stop valve, respectively, the outlet of the fourth stop valve is connected to the inlet of the high-temperature heating terminal, the outlet of the high-temperature heating terminal is connected to the inlet of the low-temperature heating terminal and the second interface of the fifth stop valve, respectively, the outlet of the low-temperature heating terminal is connected to the inlet of the seventh stop valve, the outlet of the seventh stop valve is connected to the inlet of the water pump and the outlet of the sixth stop valve, respectively, and the outlet of the water pump is connected to the fourth interface of the first air cooler.

3. The direct-heating high-efficiency air source heat pump system with cascaded energy utilization according to claim 1 or 2, characterized in that: The heat pump also includes a sanitary hot water tank, the tap water interface is connected to the second inlet of the second air cooler, the second outlet of the second air cooler is connected to the sanitary hot water tank, and the outlet of the sanitary hot water tank is the sanitary hot water outlet.

4. The direct-heating high-efficiency air source heat pump system with cascaded energy utilization according to claim 1 is characterized in that: The heat pump also includes a temperature sensor, a variable frequency fan and a control device. The temperature sensor is located at the air side inlet of the evaporator and is connected to the control device; the variable frequency fan is also connected to the control device.

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