Where is the ground source heat pump air conditioning system suitable for?

Introduction of central air conditioning system: 1. Traditional central air conditioning has two forms: air source heat pump (air cooling unit)+auxiliary electric heating water cooling chiller+boiler. Air-source heat pump (air-cooled unit) and water-cooled chiller both discharge indoor heat into outdoor air during refrigeration, which is greatly influenced by outdoor air temperature, and their refrigeration capacity decreases with the increase of outdoor air temperature, especially in high temperature and high humidity areas, the refrigeration performance of the unit is extremely unstable, inefficient and sometimes even unable to work. When heating, the air source heat pump needs an auxiliary electric heating device when the outdoor temperature drops below zero, which consumes a lot of electricity and has low efficiency; However, the air-conditioning form of water-cooled chiller+boiler needs electric boiler or coal-fired or oil-fired boiler for heating, which has serious pollution and high operating cost. 2. Ground source heat pump central air conditioning: Ground source heat pump central air conditioning is divided into two forms: water source heat pump and soil heat exchanger. 2. 1 water source heat pump central air conditioning concept, principle and classification 2. 1. 1 water source heat pump concept Water source heat pump technology is a kind of utilization of surface or shallow water sources (such as groundwater, rivers and lakes). Or the low-temperature and low-level thermal energy resources of artificially regenerated water sources (industrial wastewater, geothermal tail water, etc.). ), using the principle of heat pump, through a small amount of high-level electric energy input, the conversion from low-level heat energy to high-level heat energy is realized. It is an efficient, environmentally friendly and energy-saving air conditioning system, which can provide heat and refrigeration. 2. 1.2. Principle of water source heat pump Shallow water sources on the earth's surface (generally within 1000m), such as groundwater, rivers, lakes and oceans on the surface, absorb considerable radiation energy from the sun entering the earth, and the temperature of water sources is generally very stable. The working principle of water source heat pump technology is: in summer, the heat in the building is "taken out" and released into the water body. Because of the low temperature of water source, it can take away heat efficiently and achieve the purpose of cooling buildings indoors in summer; In winter, heat energy is "extracted" from the water source by the water source heat pump unit and sent to the building for heating. Usually, the water source heat pump consumes 1kW of energy, and users can get more than 4kW of heat or cooling capacity. 2. 1.3, classification of water source heat pump When the object of use is the energy storage of water bodies and strata (aquifers), and water is used as the cold and heat source of heat pump units, it can all be classified as water source heat pump systems. Water source heat pump can be divided into underground water source heat pump and surface water source heat pump. Groundwater heat pump system, also known as deep well reinjection water source heat pump system. Through the construction of pumping wells, the groundwater is pumped out and directly sent to the water source heat pump unit through secondary heat exchange. After the heat is extracted or released, it is pumped back to the ground through the recharge well. Surface water heat pump system. Through direct extraction or indirect heat exchange, river water, river water, lake water, reservoir water and seawater are used as cold and heat sources of heat pumps. 2.2 Ground source air conditioning system of soil heat exchanger. This air conditioning system embeds the heat exchanger underground, and water circulates in a closed loop composed of high-strength plastic pipes, thus achieving the purpose of exchanging heat and cold with the earth soil. In summer, the indoor heat is transferred from the unit to the underground to cool the room. At the same time, store heat for winter use. In winter, the heat in the soil is transferred to the room through the heat pump, which provides indoor heating and stores cold energy for use in summer. The earth's soil provides a good source of free energy storage, thus realizing the seasonal conversion of energy. Vertical ground source heat pump system Horizontal ground source heat pump system Working principle: The heart of ground source heat pump air conditioner is a "heat pump" (cooling and heating). When heating, geothermal energy is absorbed and discharged to users, and only a small amount of electricity is consumed, as shown in figure 1. When cooling, it absorbs the heat in the user's room and discharges it underground, which also consumes a small amount of heat energy. As shown in Figure 2, the operation process of the unit: in winter, the refrigerant in the heat pump flows forward, and the high-temperature and high-pressure R22 gas discharged by the compressor enters the condenser to release heat to the water in the water collector, and then becomes a high-temperature and high-pressure liquid, which is throttled and depressurized by the thermal expansion valve and becomes a low-temperature and low-pressure liquid to enter the evaporator. After absorbing low-temperature heat from underground circulating liquid, it becomes low-temperature and low-pressure saturated steam, and then enters the suction end of the water collector, so that the underground low-temperature heat energy is "transported" to the water collector, thus continuously providing users with hot water of 45℃-50℃. As shown in figure 3. In summer, the refrigerant in the heat pump flows reversely, and the condenser that exchanges heat with users becomes an evaporator, which extracts heat energy from the low-temperature water (7- 12℃) in the water collector, and the evaporator that exchanges heat with the underground circulating liquid becomes a condenser, which discharges heat into the underground circulating liquid, and then discharges the heat in the circulating liquid to the underground low-temperature area, so as to provide users with 7- 12℃ repeatedly. < 3 > buried pipe form of soil heat exchanger: there are two main forms of underground buried pipe heat exchanger, namely horizontal buried pipe and vertical buried pipe. Which form to choose depends on the available surface area on site, local rock and soil types and drilling cost. Although horizontal buried pipes are usually shallow and can be excavated manually, the initial investment is smaller than that of vertical buried pipes, but their heat transfer performance is much smaller than that of vertical buried pipes, and they are often limited by the available land area, so vertical buried pipes are generally used in practical engineering applications. (See Figure 4) 2.3 Overview of Ground Source Heat Pump Development The concept of ground source heat pump first appeared in a Swiss patent of 19 12. In 1950s, Europe and America began the first climax of studying ground source heat pump. But at that time, the energy price was low and the system was not economical, so it was not popularized. Until the 1970s, the oil crisis and deteriorating environment focused people's attention on energy saving, efficient use of energy and environmental protection, and the research of ground source heat pump entered another climax. In recent 20 years, it has achieved rapid development in industrialized countries such as Europe and America, and has become a mature application technology. In the United States, the ground source heat pump air conditioning system accounts for 40% of the whole air conditioning system, which is an energy-saving and environmental protection technology vigorously promoted by the American government. In order to show his support for this technology, President Bush installed this ground source heat pump air conditioning system in his villa in Texas (see 5438+0 reference on May 28th, 2006). So far, the United States has installed 600,000 units, and plans to install 400,000 units a year, which can reduce greenhouse gas emissions by one million tons, which is equivalent to reducing the pollution emissions of 500,000 cars or planting one million acres of trees, and can save energy costs of 400 million to 200 million US dollars every year. Sweden, Switzerland, Austria, Germany and other countries mainly use ground source heat pump for heating and providing domestic hot water. According to 1999 statistics, the proportion of ground source heat pump in domestic heating devices is 96% in Switzerland, 38% in Austria and 27% in Denmark. In China, due to the particularity of energy price and people's awareness of energy conservation and environmental protection, the application and development of ground source heat pump air conditioning technology is slow, and people don't know much about it, so it is difficult to popularize it. However, with the improvement of people's living standards, the increase of per capita energy consumption, the depletion of disposable mineral energy and the deterioration of the environment, ground source heat pump technology has attracted more and more attention. Under the current trend of energy saving and environmental protection, this technology has attracted the attention of the industry for its unique energy saving and stability, and many domestic universities and research institutes have done a lot of application research. The Ministry of Construction made a special recommendation in the Design Standard for Energy Efficiency of Residential Buildings in Hot Summer and Cold Winter Areas. According to statistics, the ground source heat pump system air-conditioning projects completed and put into operation in Beijing in 2004 accounted for more than 2/3 of the total air-conditioning projects in the whole year. It can be predicted that with the development of economy, people's awareness of energy conservation and environmental protection is increasing. As an energy-saving and environment-friendly green air-conditioning equipment, ground source heat pump will have broad application and development prospects in China. 2.4 Characteristics of ground source air conditioning system Compared with conventional air conditioning technology, ground source heat pump has unparalleled advantages. (1) Utilization of renewable energy: Ground source heat pump is a renewable energy utilization technology, which absorbs or releases heat from normal temperature soil or surface water (groundwater) and uses renewable clean energy for sustainable utilization. (2) High efficiency and low operating cost: it is an economical and effective energy-saving technology. The temperature of cold and heat sources of ground source heat pump is relatively stable all year round, which is higher than the ambient temperature in winter and lower than the ambient temperature in summer. This temperature characteristic makes the operating efficiency of ground source heat pump 40% higher than that of traditional air conditioning system, so it needs to save energy and operating costs by about 40%. In addition, the constant temperature of geothermal energy makes the heat pump unit run more reliably and stably, and also ensures the efficiency and economy of the system. When heating and cooling, input 1KW of electricity can get more than 5KW of cooling and heating. The operating cost is only per square meter 15- 18 yuan per year, which is about 40% lower than that of the conventional central air conditioning system. (3) Save water and land: 1) Take soil (water) as cold and heat source, and release or absorb heat to it, without consuming water resources and causing pollution to it. 2) The boiler room, auxiliary coal yard, oil storage room, cooling tower and other facilities are omitted, and the area of the machine room is much smaller than that of the conventional air conditioning system, which saves the building space and is also beneficial to the beauty of the building. (4) Significant environmental benefits. The device can be built in residential areas without any pollution, burning, smoke exhaust and waste during heating, and there is no need to pile up fuel waste, which will not produce urban heat island effect and is very friendly to the environment. (5) Safe and stable operation, high reliability: the ground source heat pump system has no combustion equipment in operation, so it is impossible to produce waste gas such as carbon dioxide and carbon monoxide, and there is no propane gas, so there is no danger of explosion and it is safe to use. The combustion products of oil-fired and gas-fired boilers for heating have greatly polluted the living environment and affected people's life and health. Because the temperature in the deep soil is very constant, the heat absorption or release of the main engine is not affected by the external climate, and the operating condition is very stable, which is superior to other air conditioning equipment. There is no problem that the air source heat pump is insufficient or even unable to heat. The maintenance cost of the whole system is also much lower than that of the boiler-refrigerator system, which ensures the efficiency and economy of the system. There is little maintenance, and the depreciation and maintenance costs are much lower than those of traditional air conditioners. (6) A ground source heat pump system has two functions and a wide range of applications, which can be used for heating and cooling. One system can replace the original boilers and refrigerators. It can be used in hotels, shopping malls, office buildings, schools and other buildings, and is more suitable for heating and cooling houses. (7) Because of the stable working condition, the automatic ground source heat pump unit can design a simple system with fewer parts, which is simple and reliable in operation and low in maintenance cost; High degree of automatic control, unattended; In addition, the service life of the unit is over 20 years. 2.5 Social Benefits of Ground Source Air Conditioning System In some developed cities in China, the energy consumed by cooling in summer, heating in winter and heating has accounted for 40-50% of the total energy consumption of buildings. Especially in winter, a large number of coal-fired boilers and oil-fired boilers are used for heating, which has caused great pollution to the atmospheric environment and threatened people's health. Therefore, building pollution control and energy saving have become a major issue in the development of national economy. Traditional heating and air conditioning methods are facing severe challenges because of their environmental pollution. For buildings with refrigeration in summer, with the popularization of air heat pump air conditioning, the actual use effect of air conditioning is declining year by year, which is due to the cross interference of the increase of installed capacity of air conditioning and local heat island effect of air conditioning. The hotter the weather, the higher the outdoor temperature and the greater the air conditioning load. At this time, when the air conditioner radiates heat, the smaller the heat transfer temperature difference, the lower the operating efficiency of the air conditioner and the more power consumption of the equipment. In other words, in addition to coal-fired heating, air conditioning can also cause air pollution. On the other hand, Leng Xia is hot in winter in most parts of China, and air-cooled air conditioners are widely used in summer, which leads to power shortage in some big cities. In order to ensure that there will be no power failure, some cities restrict the use of electricity in summer. In addition, due to the lack of heating in some areas, electric furnaces are used for heating in winter, which leads to tight power supply. About 3/4 of the energy required for cooling and heating of ground source heat pump unit comes from ground energy, and about 1/4 comes from power input, which reduces the one-time consumption of mineral energy; Do not exhaust hot and cold air to the outside, thus reducing the urban heat island effect. Very friendly to the environment. Ground source heat pump air conditioning is an efficient, energy-saving and environment-friendly engineering system using renewable energy. Heating the building in winter and cooling it in summer. It can be widely used in various buildings, such as commercial buildings, public buildings, residential apartments, schools, hospitals and so on. Now 2 1, China has higher and higher requirements for building energy efficiency. It is the duty of every citizen to reduce the air pollution caused by warm winter and cool summer, reduce the energy consumption of heating and air conditioning systems and save energy. Especially in recent years, in order to improve the atmospheric environment, large and medium-sized cities have vigorously promoted the use of clean energy, including renewable energy. With the improvement of people's living standards, buildings should not only meet the requirements of heating in winter, but also need air conditioning to cool down in summer. Ground source heat pump technology provides an effective solution to this problem. Ground source heat pump system can provide heating and cooling for buildings, as well as domestic hot water. One system can replace the original boiler and refrigerator. The system is compact, which saves the boiler room and cooling tower, saves the building space and is also beneficial to the beauty of the building. A remarkable feature of ground source heat pump system is that it greatly improves the utilization rate of primary energy, so it has the advantages of high efficiency and energy saving. Ground source heat pump is about 40 ~ 60% more efficient than traditional air conditioning system, and saves about 50% energy. In addition, the constant temperature of the ground source makes the operation of the heat pump unit more reliable and stable, and the maintenance cost of the whole system is greatly reduced compared with that of the boiler-refrigerator system, thus ensuring the efficiency and economy of the system.