Abstract: The heat pump technology in building heating and air conditioning can effectively improve the primary energy efficiency, reduce the emissions of greenhouse gas CO2 and other atmospheric pollutants, minimize the impact of air-conditioning equipment on the appearance of the building. This paper expounds the principle of using heat pump to heat energy than the direct combustion of boiler, and gives a detailed introduction of the main heat pump heating modes, especially the technical characteristics, applicable scope and economy of the ground source heat pump. Keywords: heat pump building environment, energy-saving 1, heat pump and building heating and air conditioning With the economic development and improvement of people's living standards, public buildings and residential heating and air conditioning has become a universal demand. In developed countries, heating and air conditioning energy consumption can account for 25-30% of the total social energy consumption. The energy mix in our country depends mainly on fossil fuels, especially coal. A large number of pollutants generated by the combustion of fossil fuels, including a large number of harmful gases such as SO2, NOX and greenhouse gases such as CO2. The environmental problems arising from burning large quantities of fossil fuels have increasingly become the focus of attention of all governments and the public. China's heating has experienced a change from a small coal-fired boiler to a coal-fired boiler. Now further prohibit the construction of small and medium-sized coal-fired boiler rooms in urban areas, reflecting the government attaches great importance to the protection of the atmospheric environment. Therefore, in addition to the type of district heating, there is an urgent need to develop alternative alternative heating methods. Heat pump is a new technology for heating and air-conditioning that can effectively save energy, reduce air pollution and CO2 emissions. 1.1 Heat Pump Principle and Composition Heat pump (refrigerator) is through the work of the heat from the low temperature medium to high temperature medium flow device. Building air-conditioning system should generally meet the winter heating and summer cooling two opposite requirements. Traditional air-conditioning systems usually require separate sets of cold sources (chillers) and heat sources (boilers). Because of the need to have a cold source (chiller) in a building air conditioning system, boiler and boiler rooms can be eliminated if it is run in heat pump mode in winter, saving not only initial investment, but also the use of clean energy such as electricity throughout the year, Greatly reduce the air pollution caused by heating problems. Heat pump air conditioning system usually consists of a refrigerant loop, indoor loop and low temperature heat exchanger loop loop. Some also have a loop of hot water heating. Different types of heat pump, the refrigerant loop and the indoor loop is basically the same, but the low temperature heat source heat transfer loop are different. Such as split air conditioners outdoor unit is the air source heat pump low temperature heat source heat exchange loop, and the geothermal heat exchanger is the ground source heat pump low temperature heat source heat exchange loop. A closed pressurized loop that circulates water from the domestic hot water tank to the condenser is a loop through which domestic hot water can be selectively heated. For summer conditions, this cycle takes full advantage of the heat released by the condenser and does not consume additional energy to get a hot water supply; in winter it consumes significantly less energy than the electric water heater (see Figure 1). Figure 1 Schematic diagram of the ground source heat pump 1.2 Heat Pump Features The use of heat pumps for building heating can greatly reduce the consumption of primary energy. Normally we generate heat by burning direct fossil fuels (coal, oil, natural gas) and eventually heat the building through several heat transfer links. In the ideal case where there is no heat loss from the boiler and heating pipelines, primary energy utilization (ie, the ratio of the heat of the building heating to the heating of the fuel) can be up to 100%. If the first use of high-temperature thermal energy combustion power generation, and then use the electric energy-driven heat pump to absorb low-grade thermal energy from the surrounding environment, the appropriate increase in temperature and heating the building, you can take full advantage of high-grade fuel energy, greatly reducing the Primary energy consumption for heating. The coefficient of performance of the heat pump with heat, that is, the ratio of the amount of heat supplied and the amount of energy consumed, can now reach 3 to 4. The resistivity heating device to convert electrical energy into thermal performance coefficient of 1. Heat pumps are the most cost-effective technology to reduce CO2 emissions. About 130 million heat pumps are operating around the world today, with a total heat output of 4.7 × 109 GJ / year and a reduction of about 130 million tons of CO2 emissions each year. With the further improvement of heat pump technology and the further improvement of power generation efficiency, it is possible to reduce the global CO2 emissions by 16% with heat pump technology. Therefore, it is one of the key technologies for building energy efficiency and reducing CO2 emissions. In addition to reducing the consumption of fossil fuels, the centralized combustion of fossil fuel power generation in large power stations facilitates the use of advanced technologies to remove or reduce airborne pollutants such as dust, SO2 and NOx in combustion products, boiler rooms with electric heat pumps for heating and distribution Compared to heating can also greatly reduce the coal-fired air pollution. Heat pumps, which take full advantage of renewable energy, are a sustainable technology. Heat pumps use low-temperature heat sources are usually the environment (air, surface water and earth) or a variety of waste heat. The heat absorbed by these heat sources by the heat pump is a renewable energy source. Such as ground source heat pump in the heat of the earth after the heat of the building heating, while reducing the temperature of the earth, that is, the storage of cold for summer use; summer heat transfer to the building through the heat pump to the earth , Cooling the building while storing the heat in the ground for winter use. This land played the role of accumulator to further improve the energy efficiency of the air-conditioning system throughout the year. As mentioned above, geothermal heat pumps use geothermal heat exchangers as a low-temperature heat source loop, eliminating the need for cooling towers and outdoor heat exchangers; replacing chillers with chillers (heat pumps). Therefore, for architects, there is another important advantage of GSHH air-conditioning system, which is to remove the boiler room and cooling tower required by traditional air-conditioning system. The need for and restrictions on building space at these facilities often become a problem for architects. The ground source heat pump air conditioning system does not have outdoor facilities, no effect on the appearance of the building. Therefore, this technology is especially suitable for landscape architecture, ancient buildings and air-conditioning projects that make it difficult to set up cooling towers. This technology helps to protect the façade and the surrounding environment of these buildings from being damaged and solves the problem of having no place for a cooling tower or a boiler room. For example, in the landmark area of ​​Wenzhou Century Plaza, air-conditioning system uses a ground source heat pump as a source of cold and heat, mainly due to landscape considerations. 2. Classification and technical analysis of air-conditioning heat pumps There are many types of heat-pump systems for the purpose of building air-conditioning (including heating and cooling), such as heat-recovery type heat pumps utilizing heat (cooling capacity) of building ventilation systems, Large-scale building within the different sections of the water ring heat pump system. This article focuses on the use of the surrounding environment as a hot and cold air conditioning heat pump system. By their nature, foreign literature usually divides them into two categories: air source heat pump (ASHP) and ground source heat pump (GSHP). Ground-source heat pumps can be further divided into surface-water heat pumps (SWHPs), groundwater heat pumps (GWHPs) and ground-coupled heat pumps (GCHPs). Our country on the heat pump system terminology has not yet formed a normative usage. For example, commercial names for "ground temperature air conditioning" are used for groundwater heat pump systems; underground heat pumps are referred to in some literature as "ground source heat pumps," or directly as "ground source heat pumps." 2.1 air source heat pump air source heat pump to outdoor air as a heat source. Under the condition of heating, the outdoor air is taken as a low-temperature heat source to absorb the heat from the outdoor air, and the heat pump is used to raise the temperature and send it into the room for heating. The coefficient of performance (COP) is generally 2 to 3. Air source heat pump system is simple, the initial investment is low. Air source (air-cooled) heat pump current products are mainly household heat pump air conditioners, commercial unit heat pump air-conditioning units and air-cooled heat pump hot and cold water units. The main disadvantage of air-source heat pumps is that the efficiency of the heat pump is greatly reduced during high temperatures in summer and cold weather in winter. In addition, the necessary outdoor unit or cooling tower on the building have a certain impact or damage. Air-source heat pump heating with the outdoor air temperature decreases and reduce, which is the opposite of the building thermal load demand. Therefore, when outdoor air temperature is lower than the balance of the heat pump temperature, you need to use electricity or other auxiliary heat source to heat the air. Moreover, air-source heat pump evaporators frost on heating conditions and require regular defrost, which also consumes a lot of energy. Frosting of heat pump evaporators in cold and high humidity areas can be a major technical obstacle. In summer hot weather, as its cooling capacity decreases with outdoor air temperature, the same may cause the system can not work properly. Air source heat pump is not suitable for cold areas, in the more temperate winter climate regions, such as China's midstream and downstream areas of the Yangtze River, has been widely used. 2.2 Ground Source Heat Pump Another type of heat pump using the earth (soil, groundwater, groundwater) as a heat source, can be called "ground source heat pump." Ground-source heat pumps overcome the technical barriers to air-source heat pumps because they remain constant throughout the year in undisturbed conditions, well above the outdoor temperature in winter and outside the summer, and the efficiency Greatly improve. In addition, in winter, the heat in the ground is raised by the heat pump to heat the building and the temperature in the ground is reduced, that is, the cold is stored for use in summer. In summer, the heat in the building is transmitted to The earth, cooling the building, while storing heat in the earth for winter use. This ground source heat pump system in the earth played the role of accumulator to further improve the air conditioning system annual energy efficiency. 2.2.1 Groundwater heat pumps Groundwater sources Heat pumps are the source of groundwater drawn from wells or abandoned mines. The heat-exchanged groundwater can be discharged into the surface water system, but for larger applications it is often required to recharge the groundwater to the groundwater level through the recharge well. Groundwater with good water quality can directly enter the heat pump for heat exchange. Such a system is called open loop. In practice, more closed loop heat pump circulating water system is adopted, that is, the plate heat exchanger is used to separate the groundwater from the circulating water through the heat pump to prevent the influence of the sediment and corrosive impurities in the groundwater on the heat pump. The groundwater heat pump system is more efficient than the air source heat pump because the groundwater temperature is basically constant over the years, the temperature in summer is lower than that in outdoor air, the temperature in winter is higher than that in outdoor air, and the heat capacity is larger. The COP value is usually between 3 and 4.5, There are frosting and other issues. Groundwater source heat pump system has been rapidly developed in our country in recent years. The use of groundwater heat pump systems is also limited by many conditions. First of all, such systems require a rich and stable groundwater resource as a prerequisite. As a general rule, the air conditioning area of ​​10,000 m2 requires about 120 m3 / hr of groundwater. The economics of groundwater heat pump systems also have a large relationship to the depth of the groundwater layer. If the water table is low
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