First, an overview Water source heat pump system is the application of shallow surface water on the Earth's surface, such as rivers, lakes, sea water and groundwater absorption of solar and geothermal energy and the formation of low heat through a small amount of high energy input, after reverse heat cycle, grade heat A thermal system. Surface soil and water body is not only a huge solar collector, but also a huge dynamic energy balance system, and the surface soil and water body naturally maintain the relative balance of energy acceptance and divergence. The basic work situation of water source heat pump system in the summer will be building species of heat transferred to the water source, and winter through the reverse heat cycle, extract heat from the water. The temperature of water body is relatively stable throughout the year, the range of its fluctuation is far less than the air temperature, especially the groundwater temperature remains constant all the year round. It is a good source of air and heat pump heat. Because of the constant water temperature, the water source heat pump system is stable and reliable, free from the influence of external climate change, energy efficient, and does not exist in winter air defrosting heat pump difficult problems. Therefore, the water source heat pump system is an advanced technology worthy of further study and actively popularized and applied, which is characterized by energy conservation, environmental protection and renewable energy utilization. The technology started in 1912, the rapid development in the industrialized countries in Europe and the United States in the recent 10 years has become a mature application technology. In China, the research of water source heat pump technology has become a boom in engineering practices and blowing up of "water source air conditioners" in the late 1990s. Second, the working principle The working principle of the heat pump is to absorb heat from the surrounding environment and passed to the object being heated, and its working principle is the same with the refrigerator, reverse engine heat cycle work, the only difference is the scope of work for the heat pump That is reversible refrigeration cycle, the cycle is required by the refrigeration space and absorb heat to heat it to the air or water, known as the cooling conditions, the reverse cycle to the outside air or water to the heat needs and passed to the need Heating room called the heating conditions. (1) Refrigeration condition: During the cooling, the thermostatic controller starts the centrifugal blower and opens the direction valve to show the cooling direction. At this time, the low-temperature and low-pressure refrigerant enters the compressor to compress it into high-pressure gas and then enters the refrigerant (water radiator) through the directional valve Condensation into liquid. The refrigerant enters the refrigerant (air evaporator) through the capillary tube and evaporates into a cryogenic gas that absorbs the heat of the air blown from the fan through the coil to lower the temperature and circulates to and fro. (2) heating and heating conditions: Heating and heating, the thermostat controller to start the centrifugal fan to open the reverse valve to the heating and heating direction, when the low temperature and low pressure refrigerant into the compressor pressure into high temperature and pressure gas, and then by the reverse Valve into the refrigerant air blade coil radiator condensate to liquid, the secondary refrigerant liquid from the air blower through the coil to release heat, so that the temperature height, the refrigerant liquid and then through a thin tube into the refrigerant evaporator, absorbing circulating water heat The evaporation of low-temperature gas, low temperature and low pressure refrigerant gas through the reverse valve into the compressor inlet to be the beginning of the next cycle of reciprocating heating heating. Third, the feasibility analysis 1. Technical Feasibility Analysis Groundwater resources status analysis shows that in many parts of China groundwater resources are more abundant. Groundwater resources according to different depths of burial have not Oh it can change the temperature. The buried depth of 3 to 5 meters has the rule of day and night, and the depth of 5 to 50 meters has the annual variation rule. The groundwater temperature of deep well with the depth of more than 50 meters is seldom affected by the seasonal variation, and remains basically the same all the year round. The temperature of deep well water in North China is 14-18 ℃, while the middle and lower reaches of the Yangtze River is 19-24 ℃. Compared with the ambient temperature, the deep well water is warm in summer and cool in summer, which is very beneficial to the efficient and stable operation of the heat pump. China has successfully developed deep well water recharge technology and controlled land subsidence. At the same time, it has further improved the available water temperature of deep wells by adopting the technologies of "winter irrigation and summer irrigation" and "summer irrigation and winter use". 2. Policy Feasibility With the rapid economic development in our country, energy shortage and environmental problems have become increasingly serious. In order to realize the strategy of sustainable development, China has formulated a series of energy and environmental policies to encourage the development and utilization of new energy-saving and environmental protection technologies. The development and utilization of underground natural source of heat and cold air conditioning can bring double benefits of energy saving and environmental protection, more and more people's attention. According to a report by the United States Environmental Agency on the future development of air conditioning, water-source heat pump technology will become a major force in reducing energy consumption and environmental pollution in the country. In November 1997, the U.S. Department of Energy and China's Ministry of Science and Technology signed an agreement on cooperation in energy efficiency and renewable energy. Three heat pump demonstration projects for comprehensive utilization of geothermal resources in the northern, central and southern part of China should be established respectively. After the large-scale promotion, this provides a powerful policy support for this energy saving and environmental protection technology. 3. Economic Analysis Using this technology can make cold and hot water storage of groundwater temperature applied grade is much higher than the conventional groundwater temperature, can greatly improve the heat pump cooling and heating performance coefficient. Not only can reduce unit energy consumption, save operating costs, but also reduce unit size, reduce equipment investment. Due to the substantial increase in the temperature difference of groundwater available for economic use, the capacity of single-well heating and cooling can be doubled, greatly reducing the number of hot and cold water wells and saving well investment. Table l shows the initial investment and operating costs compared with the conventional system, can be seen from the table, in terms of savings in operating expenses and initial investment has more significant advantages, with economic feasibility. 4. Energy-saving Analysis Conventional groundwater source heat pump effectively utilizes low-grade geothermal energy and saves a lot of high-grade energy sources. In addition, the deep well water temperature in the field is warm in winter and cool in summer, which greatly improves the operation efficiency of the heat pump unit and saves obvious effects. Saves over 60% more energy than electric boiler heating systems, saves more than 50% energy compared to fuel-fired boiler heating systems and saves 30-40% energy compared to air-source heat pump systems, Technology to achieve the interaction between winter and summer hot water wells, not only make full use of low-grade geothermal energy, but also effectively use the heat pump heat emissions, to further improve the unit efficiency. Fourth, the existing problems China groundwater source heat pump technology research and application is still in its infancy, it is also facing some urgent problems to be solved. 1. Deep well water recharge is difficult to guarantee. According to the survey, a considerable part of the applied engineering of underground water source heat pump systems in operation in China has failed to guarantee 100% recharge of deep well water for three reasons. One is that groundwater recharge is a highly technical work and is not an ordinary Drilling team can afford; Second, to save the need for a one-time investment wells, there is no recharge wells; Third, if the pressure of recharge, it is bound to increase some of the energy consumption and operating costs, users do not want to set back Irrigation does not use pressure to recharge. 2. There is not a mature groundwater source heat pump product. Groundwater source heat pump hot and cold water unit to determine the condition parameters and the applicability of the performance of the groundwater source heat pump system is directly related to the normal operation and energy consumption. However, due to the fact that there is no standard in our country, most of the products provided by the market have not been properly and rigorously designed or calculated and have not been tested by authoritative Quguo countries. Not only are the rated cooling and heating conditions varied, but almost all of them No full performance parameters have been given, particularly on the cooling or heating capacity and input power under changing water conditions. Five, conclusion 1. Improve the existing deep well detection technology, improve well quality, water discharge and recharge volume, ensure long-term operation, further improve the recharge storage technology, protect groundwater resources and increase storage utilization. 2. Establish a good demonstration project, sum up experience in time in order to better promote the application. 3. Manufacturers should actively develop large temperature differential flow unit suitable for the characteristics of energy storage, and pay attention to the product performance and reliability, especially the reliability of variable operating conditions, in order to apply to users in different regions. 4. Actively carry out the performance test of the unit, develop national standards as soon as possible to standardize its technology. 5. National and local governments should formulate relevant policies and measures as soon as possible to encourage and support the development of this technology.