CN1515850A - Direct Expansion Solar Heat Pump Air Conditioning and Hot Water System - Google Patents

Abstract

The present invention relates to a directly-expanded type solar heat pump air conditioning and water-heating system, the directly-expanded type solar heat pump and ice cold-storage air conditioner are combined organically, and it is mainly formed from solar heat collector/evaporator, compressor, condenser, electronic expansion valve, four-way reverse valve, heat water storage tank, hot water tank, air conditioner tail end cover and system control component. The solar heat collector/evaporator adopts the plate type heat collector which has no cover plate and whose bottom is heat insulated and whose surface is coated with solar spectrum absorbing material, and the energy storage device adopts a closed pressure-bearing heat storage water tank whose interior is equipped with high-effective heat exchange equipment which can store heat in winter and can store ice in summer.

Description

Direct Expansion Solar Heat Pump Air Conditioning and Hot Water System

Technical field:

The invention relates to a solar light and heat utilization system, in particular to a direct expansion solar heat pump air conditioner and hot water system, which belongs to the technical field of energy heating and air conditioning.

Background technique:

In recent years, with the rapid development of my country's construction industry, the energy consumption of heating and air conditioning in buildings has continued to expand. According to statistics, my country's building energy consumption accounts for about 1/4 of the country's total energy consumption, ranking first in energy consumption. Energy consumption has not only exacerbated the increasing shortage and depletion of fossil fuels, but also seriously polluted the environment. The best way to meet the ever-increasing building energy demand without affecting the energy demand of other sectors or exacerbating the already serious pollution situation is to implement building energy conservation. The use of solar thermal technology to meet the needs of buildings for heating, air conditioning and hot water is currently the most realistic and promising field of development and utilization. The application of solar thermal technology in buildings mainly includes passive solar house, direct solar heating, solar heat pump, solar absorption or adsorption air conditioning and other forms. Among them, the passive solar house has special requirements for architectural design, and its applicability and flexibility are poor, while the direct solar heating system is generally relatively large, with low solar energy dependence rate and poor economic performance. Promote apps. Due to the use of existing solar heat collectors and adsorption refrigerators, solar absorption air conditioners can usually only operate under single-effect conditions, making the actual heating performance coefficient COP 50% lower than double-effect COP. For example, the document "Latest Refrigeration and Air-Conditioning Technology" (Wang Ruzhu, Ding Guoliang, etc., Science Press 2002, 9: 113-116) pointed out that two relatively large solar absorption air-conditioning systems (100kW ), the investment amount is as high as more than 2 million yuan, but the actual COP is limited to below 0.6-0.7, and the technical and economic performance is very poor, which fundamentally limits its promotion and use. In addition, solar adsorption air conditioners are still in the preliminary research stage, and problems such as intermittent operation, low system efficiency, and low cooling-to-weight ratio must be overcome before they can be truly applied.

The solar heat pump overcomes the shortcomings of the above-mentioned solar heating and air conditioning systems, and organically combines solar thermal technology with electric heat pump technology, which greatly reduces the working temperature of the collector and increases the evaporation temperature of the heat pump, so it has a higher heat collection efficiency. In addition, it has compact structure, strong applicability, and good technical and economic performance, which provides an effective way for solar air conditioners to embark on the road of industrialization development. However, conventional non-direct expansion solar heat pumps have disadvantages such as complex structure, difficulty in integrating heat collectors with building structures, single function, and low annual utilization rate of equipment, which limits their popularization and application.

Invention content:

The purpose of the present invention is to address the deficiencies in the prior art and provide a new type of direct expansion solar heat pump air conditioner and hot water system, which combines solar heat pump with ice storage air conditioner to integrate winter heating, summer air conditioning and year-round domestic hot water. The integration of multiple functions, such as supply, makes the structure more compact, the applicability is better, the equipment utilization rate is high, the energy saving effect is more significant, and the heat collecting device is easy to integrate with the building structure.

In order to achieve such a goal, in the technical solution of the present invention, a direct expansion solar heat pump system is adopted, that is, the solar heat collector is directly used as the evaporator of the heat pump, so that the absorption process of solar energy and the evaporation process of refrigerant are completed in the same equipment . In the case of ice storage in summer, the solar heat collector/evaporator will be used as a night radiation radiator and also as a heat pump condenser, where the refrigerant vapor will be condensed through radiation and convective heat exchange. The whole system includes solar heat collector/evaporator, compressor, condenser, electronic expansion valve, four-way reversing valve, heat storage (cold) tank, domestic hot water tank, gas-liquid separator, liquid storage, dry filter , pipelines and valves, etc. The outlet of the solar heat collector/evaporator is connected to the suction port of the compressor through the four-way reversing valve and the gas-liquid separator. The reversing valve is connected to the inlet of the heat exchange coil, and the liquid outlet of the heat exchange coil is connected to the liquid reservoir, and then passes through the one-way valve, dry filter, electronic expansion valve and the liquid inlet of the heat collector/evaporator respectively. Connected to form a closed circulation channel for refrigerant. The condensing coil is arranged in the hot water tank to produce domestic hot water at 40-60°C, while the heat exchange coil is arranged in the heat storage (cold) tank, and a part of the heat (cold) is used for room heating (air conditioning) ), and another part of heat (cold) is stored in the water tank as a backup. Both the condensing coil and the heat exchange coil are equipped with bypass pipes and are controlled by solenoid valves. The upper and lower ends of the heat storage (cold) tank are respectively provided with water supply and return pipes, so that they can be connected with the air conditioner terminal device. The inlet and outlet of the air heat exchanger are respectively connected in parallel with the solar heat collector/evaporator through the electromagnetic three-way valve, as the auxiliary evaporator or condenser of the heat pump.

The invention adopts a flat-plate solar heat collector/evaporator which is easy to be integrated with a building structure. The heat absorber can be made of copper-aluminum composite welded plate or all-aluminum hot-pressed inflation plate, with no cover plate on the top, proper insulation on the bottom and its surroundings, spraying spectral absorption materials on the surface, and the pressure requirement of the pipeline is 15-20 kgf/cm ² or more. Because the solar heat collector/evaporator has a simple structure, light weight and thin body, it is easy to be installed obliquely on the roof or vertically hung on the south-facing outer wall, and is especially suitable for multi-storey or high-rise buildings. In summer ice storage conditions, the solar heat collector/evaporator is also used as a night radiation heat sink/condenser.

The present invention adopts a closed pressurized hot water storage tank, and a high-efficiency copper tube heat exchanger is arranged in the water tank. There is a refrigerant passage in the tube, which exchanges heat with water through natural convection and heat conduction. In winter, the sensible heat of water is used to realize heat storage. In summer, the latent heat of water (including a part of sensible heat) is used to store cold.

The invention adopts the form of direct expansion solar heat pump system, so that the working temperature of the heat collector is always consistent with the evaporation temperature of the refrigerant, and close to the ambient temperature, which greatly improves the efficiency of the heat collector and the coefficient of performance of the heat pump (the efficiency of the heat collector is generally It can reach 60% to 80%, and the COP of heat pumps can generally exceed 3). The invention adopts an inexpensive flat-plate heat collector/evaporator which is easy to be integrated with the building structure, and the heat collection cost is very low, which greatly improves the economic performance of the system. The present invention can use air as the heat source of the heat pump in the case of rainy days or relatively insufficient solar radiation, which ensures the continuity and stability of heating in winter and does not consume other high-grade energy sources. In summer, the present invention can use late-night power to carry out cold storage operation to meet the demand of daytime air-conditioning load, which not only improves the utilization rate of equipment, meets various energy demands of buildings, but also facilitates peak shifting of urban power.

The invention integrates various functions such as heating in winter, air conditioning in summer, and domestic hot water supply throughout the year, and has many advantages such as good applicability, high equipment utilization rate, remarkable energy-saving effect, long service life, and good technical and economic performance. A new type of green and environment-friendly building composite energy system is suitable for the majority of urban and rural buildings in my country.

Description of drawings:

Fig. 1 is a schematic diagram of the system structure and winter heating conditions of the present invention.

Fig. 2 is a schematic diagram of the summer ice storage working condition of the present invention.

In Fig. 1 and Fig. 2, 1 is the solar collector/evaporator, 2 is the four-way reversing valve, 3 is the gas-liquid separator, 4 is the compressor, 5 is the condensing coil, 6 is the domestic hot water tank, 7 8 is a heat exchange coil, 9 is a heat storage (cold) tank, 10 is a one-way valve, 11 is a liquid storage device, 12 is a filter drier, 13 is an electronic expansion valve, and 14 is an electromagnetic three-way valve , 15 is an air-cooled heat exchanger.

Detailed ways:

The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings.

The system structure of the present invention is shown in Figure 1. The whole system consists of solar heat collector/evaporator 1, four-way reversing valve 2, gas-liquid separator 3, frequency conversion compressor 4, condensation coil 5, domestic hot water tank 6, heat exchange coil 8, heat storage (cold ) tank 9, liquid reservoir 11, dry filter 12, electronic expansion valve 13, air-cooled heat exchanger 15, refrigeration pipelines and valves, etc. The outlet of the solar heat collector/evaporator 1 is connected to the suction port of the inverter compressor 4 through the four-way reversing valve 2 and the gas-liquid separator 3, and the exhaust port of the inverter compressor 4 is connected to the air inlet of the condensing coil 5 The outlet of the condensing coil 5 is connected to the inlet of the heat exchange coil 8 through the four-way reversing valve 2, the liquid outlet of the heat exchange coil 8 is connected to the liquid reservoir 11, and then passes through the dry filter 12, the electronic The expansion valve 13 is connected with the liquid inlet of the heat collector/evaporator 1 to form a closed circulation channel of the refrigerant. Among them, the condensing coil 5 is arranged in the domestic hot water tank 6 for producing domestic hot water at 40-60°C, while the heat exchange coil 8 is arranged in the heat storage (cold) tank 9, and the condensing coil 5 And the heat exchange coil 8 are all provided with a bypass pipeline, and the solenoid valve 7 is used for on-off control on the pipeline. The upper and lower parts of the heat storage (cold) tank 9 are respectively provided with a connecting pipe to be connected with the water supply and return pipelines of the air-conditioning terminal device, and a forced circulation loop of water is formed by a water pump. The air-cooled heat exchanger 15 is used as an auxiliary device of the solar heat collector/evaporator 1, and its inlet and outlet are respectively connected in parallel with the solar heat collector/evaporator 1 through an electromagnetic three-way valve 14.

In winter heating conditions, the system cycle work process is described as follows: During the day, the refrigerant flows into the solar collector/evaporator 1 after being throttled by the electronic expansion valve 13, evaporates by absorbing solar radiation energy, and then passes through the gas-liquid separator The separation of 3 causes the refrigerant steam to be inhaled by the compressor 4, and the high-temperature and high-pressure steam generated is first discharged into the condensation coil 5 to exchange heat with the water in the domestic hot water tank 6, a part of the steam is condensed, and then the wet steam flows into The heat exchange coil 8 in the heat storage tank 9 continues to condense, a part of the heat is used for room heating, and the other part is stored. And the electronic expansion valve 13 flows back to the solar collector/evaporator 1 to reabsorb solar energy, thereby completing a cycle. At night, if the water temperature in the heat storage tank 9 is high enough, then the heat is directly taken from the heat storage tank 9 through the air-conditioning terminal circulation without starting the compressor 4 . However, if the heat stored during the day is not enough to meet the needs of continuous heating at night (or in rainy days), the electromagnetic three-way valve 14 opens the bypass line, and the air-cooled heat exchanger 15 is used as the auxiliary heat source device of the system to meet Comfort requirements for room heating.

Fig. 2 is a schematic diagram of the summer ice storage working condition of the present invention.

Through the reversing of the four-way reversing valve 2, the solar heat collector/evaporator 1 is used as a radiation cooling/condenser at night, and the inlet of the radiation cooling/condenser 1 passes through the four-way reversing valve 2 and the outlet of the condensation coil 5 At the same time, the heat storage tank 9 is used as an ice storage tank, and the outlet of the heat exchange coil 8 is connected to the air inlet of the gas-liquid separator 3 through the four-way reversing valve 2. The connection relationship between the other components constant.

Under ice storage conditions in summer, the cycle of the system works as follows: at night, the refrigerant vapor from the compressor 4 first flows into the condensing coil 5, and is partially condensed by heating the domestic hot water, and then the wet steam passes through the four-way reversing valve 2 Flow into the night radiation heat dissipation/condenser 1, continue to condense through convection and radiation heat dissipation, and the obtained liquid refrigerant flows into the heat exchange coil 8 through the check valve 10, liquid receiver 11, dry filter 12 and electronic expansion valve 13 , by absorbing the heat of the water in the cold storage tank 9 and evaporating, so that the temperature of the water continues to drop to the freezing point, part of the ice produced is used for the air conditioner at night, and the other part is stored in the ice tank for the use of the air conditioner during the day, and the evaporated refrigerant passes through the air The liquid separator 3 is sucked and compressed by the compressor 4 again, thus completing a cycle. If the amount of ice stored at night is sufficient to meet the needs of the daytime air conditioner, then the cooling capacity can be directly extracted from the ice storage tank 9 by utilizing the air conditioner terminal circulation without starting the heat pump unit. If the amount of ice storage is insufficient at night, the bypass line of the electromagnetic three-way valve 14 is opened, and the air-cooled heat exchanger 15 is used as the auxiliary condenser of the system to ensure the needs of room air conditioning during the day.

In the hot water condition in the transitional season, reduce the circulation of the refrigerant by reducing the frequency of the compressor 4, and open the solenoid valve 7 at the same time, so that the refrigerant vapor is completely condensed in the condensing coil 5 to produce hot water, and the condensed The final refrigerant liquid flows directly into the liquid receiver 11 through the bypass pipe of the heat exchange coil 8 .

In terms of system control, the present invention mainly adopts the following measures: 1) adopting a four-way reversing valve to switch between winter and summer working conditions; 2) adopting an electronic expansion valve to control the suction superheat of the compressor, and , through the frequency converter to control the motor speed of the compressor, so that the whole system can always maintain efficient and stable operation; 3) According to the change of the temperature of the energy storage medium and the weather conditions, the temperature difference controller is used to start the backup air-cooled heat exchanger and control The opening of the electromagnetic three-way valve; 4) In winter conditions, the thermostat in the hot water tank is used to control the opening and closing of the electromagnetic valve on the bypass pipeline, that is, when the hot water temperature reaches the set temperature, the bypass is opened pipeline. In the transitional season, the thermostat is used to control the start and stop of the compressor, that is, when the hot water temperature reaches the set temperature, the compressor will automatically stop.

Claims (3)

1. A direct expansion solar heat pump air conditioner and hot water system, characterized in that the outlet of the solar heat collector/evaporator (1) passes through a four-way reversing valve (2), a gas-liquid separator (3) and a variable frequency compressor ( 4) is connected to the suction port, the exhaust port of the compressor (4) is connected to the air inlet of the condensing coil (5), and the outlet of the condensing coil (5) is connected to the heat exchange valve (2) through the four-way reversing valve (2). The inlet of the coil (8) is connected, and the liquid outlet of the heat exchange coil (8) is connected to the liquid reservoir (11), and then through the dry filter (12), the electronic expansion valve (13) and the solar collector/ The liquid inlets of the evaporators (1) are connected to form a closed circulation channel for refrigerant, the condensation coil (5) is arranged in the domestic hot water tank (6), and the heat exchange coil (8) is arranged in the heat storage/cooling tank (9), and the condensing coil (5) and the heat exchange coil (8) are provided with bypass pipelines, the solenoid valve (7) is used for on-off control on the pipeline, and the heat storage/cold tank (9) The upper and lower parts of the air-cooled heat exchanger (15) are connected to the air-cooled heat exchanger (15) through a three-way valve (14) and the solar heat collector/evaporator (1 )in parallel. 2. The direct expansion solar heat pump air-conditioning and hot water system according to claim 1, characterized in that the solar heat collector/evaporator (1) adopts a flat plate type without cover plate, bottom heat preservation, and surface sprayed with solar spectrum absorbing materials. The heat collector doubles as the evaporator of the heat pump in winter, and as the night radiation radiator and condenser of the heat pump in summer. 3. The direct expansion solar heat pump air conditioner and hot water system according to claim 1, characterized in that the heat storage/cold tank (9) adopts a closed pressurized heat storage tank, and a copper tube heat exchanger is arranged in the water tank , inside the tube is a refrigerant passage, heat storage in winter and cold storage in summer.

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