First, foreign research and utilization of the current situation and development trend
1. Early stage of development
Shallow geothermal energy research and development and utilization is with the research and development of heat pump technology and the rise. As early as 186 years ago (1824) the French physicist Carnot laid the theoretical foundation of the heat pump. After that, the British physicist Joule demonstrated the principle that changing the pressure of a gas causes a change in temperature. British Lord Thomson, professor first put forward the "heat multiplier" can be heating ideas. 1912, Zurich, Switzerland, has successfully installed a set of river water as a low-grade heat source heat pump equipment for heating, and to declare a patent, which is the early water-source heat pump system, but also the world's first water-source heat pump system.
In the decades following this, ground source heat pumps are basically in the experimental research stage, and there have been surface water source heat pumps, groundwater source heat pumps and soil source heat pump system came out and development. 1930s surface water source heat pump system came out, is the earliest use of ground source heat pump in the form of one of the earliest heat pump system. Europe's first larger heat pump device is between 1938 and 1939 in Switzerland, Zurich City Hall put into operation, it is river water as a heat source, heating capacity of 175k W; the 20th century 40 ~ 50 years, Switzerland, the United Kingdom, the early use of surface water source heat pump groundwater source heat pump system in addition to heating buildings, but also used for swimming pool heating and rayon factory process heating and air conditioning for shoe factories and so on. Subsequently, some other countries in Europe also began to install surface water source heat pump system, heat pump system heating capacity continues to increase, the coefficient of performance has also greatly improved.
Groundwater source heat pumps were also born in the 1930s, to 1940, the United States has installed 15 large commercial heat pumps, most of which are well water as a heat source. 1937, Japan in a large office building installed 2 sets of 194k W compressor with heat storage box groundwater heat pump system, its coefficient of performance of 4.4. To the 20th century, 40 ~ 50 years, the United States application of the groundwater source heat pump system. The main application of groundwater ground source heat pump.
In 1941, after the outbreak of World War II, the impact and interruption of air conditioning and heating heat pump technology research and development. After the end of World War II, heat pump technology research and application gradually recovered, to 1950 the United States has 20 manufacturers and more than 10 university research units engaged in the development of heat pumps, in the 600 units of heat pumps owned at the time, 50% for house heating. Ground buried pipe ground source heat pump technology initial in the United States and the United Kingdom. 1950 around, the two countries began to use the buried pipe to absorb geothermal heat as a heat source for domestic housing heating small soil heat pumps. 1952, the United States, about 1,000 sets of heat pumps, about 2,000 sets of heat pumps factory in 1954. Because of the maturity of the ground source heat pump, strongly promote the wide application of shallow geothermal energy.
In 1957, the United States military base housing a large number of heat pump heating instead of gas heating program, heat pump production of 20,000 sets, 1963 annual production increased to 76,000 sets. To the early 1960s, the United States installed heat pump unit has reached nearly 80,000 units. But the quality of the compressor is not yet passable, the high cost of equipment affects the promotion of heat pump heating technology, began to be in a state of stagnation.
To 1964, the problem of heat pump reliability has become a very serious problem. 60's electricity prices continue to fall, making the application of electric heaters continue to increase, limiting the development of heat pumps.
2. Rapid development stage
The 1970s, the emergence of the world oil crisis, and caused people to pay attention to the groundwater source heat pumps and interest, and began a large number of installations and the use of groundwater source heat pumps, heat pumps, heat pumps, the industry has entered a golden age. During this period, the world's research on heat pumps are very important, such as the International Energy Agency and the European **** the same body have formulated a large-scale heat pump development program, heat pumps, new technologies emerge in an endless stream of heat pumps, heat pumps, the use of the continuous development, and widely used in the field of air conditioning and industry, in the energy saving and environmental protection plays a significant role.
Heat pumps in the real sense of the commercial application of only nearly 20 years of history. 1990s, with the further improvement of environmental protection requirements, the United States has been the application of groundwater source heat pump system has been on the rise. The U.S. Department of Energy Information survey shows that: the U.S. production of groundwater source heat pumps rose from 5924 units in 1994 to 9724 units in 1997. Again, in the United States, as of 1985 there were 14,000 ground source heat pumps in the country***, while 45,000 were installed in 1997, and 400,000 have been installed so far, and they have been growing steadily at a rate of 10% per year.In 1998, ground source heat pump systems in commercial buildings in the United States have accounted for 19% of total air-conditioning holdings, with 30% of them in new buildings. Currently, about 50,000 ground-source heat pumps are being installed each year, with open systems accounting for 5% of the total. The U.S. heat pump industry has been established by the U.S. Department of Energy, the Environmental Protection Agency, the Addison Electric Power Research Institute and many ground-source heat pump manufacturers composed of the U.S. Ground Source Heat Pump Association, which in recent years will be invested in 100 million U.S. dollars in development, research and promotion.
Some European countries due to the active promotion of policy (including financial subsidies, tax breaks, preferential tariffs and advertising, etc.), the heat pump market has been the rapid development of. 1997, the European Development Foundation reintroduced the heat pump development program. By 2000, the total number of heat pumps used for heating and hot water supply in Europe was about 467,000 units, of which groundwater source heat pumps accounted for about 11.75%. The development of heat pumps with the United States is different, central and northern Europe, such as Sweden, Switzerland, Austria, Germany and other countries mainly use shallow geothermal resources, underground soil buried coils of ground-source heat pumps for indoor radiant floor heating and the provision of domestic hot water. According to the statistics of 1999, the proportion of ground source heat pumps in heating devices in the home, Switzerland is 96%, Austria is 38%, Denmark is 27%.
3. Development trend
In recent years, the development and utilization scale and development speed of shallow geothermal energy in various countries are growing rapidly. The United States and Canada, some universities and research institutions, for soil source heat pump has carried out more in-depth experimental research, and achieved some important data. The U.S. Department of Energy (DOE), the U.S. Environmental Protection Agency (EPA) and Edison Electric Institute (EEI), the National Agricultural Power Cooperative Corporation and other consortiums to form a government to participate in the industrial facilities of the International Group, to promote the heat pump heating system. Currently from the foreign development trend, the development and utilization of shallow geothermal energy, will be the mainstream of geothermal resources development and utilization and direction.
Shallow geothermal energy is a valuable new energy source. Compared with wind energy, solar energy and other non-human control of natural resources, shallow geothermal energy is a mining and utilization of time, can be artificially controlled the use of renewable energy, is a set of heat, minerals, water as a whole, has a clean, cheap, wide range of new energy. Development and utilization of shallow geothermal energy can reduce conventional energy consumption, reduce environmental pollution, especially air pollution, and can play a role in the development of certain related industries and improve people's quality of life, with significant commercial value. Therefore, it has attracted the attention of countries to its development and utilization. Especially since the world energy crisis in 1973, the exploration and development and utilization of shallow geothermal energy is rapidly developing in depth and breadth.
4. Progress in numerical simulation of groundwater heat transport
After the operation of groundwater source heat pump, the cold and hot energy injected into the aquifer by recharge wells will be transported to pumping wells under the effect of convection and heat conduction, which will have an impact on the groundwater temperature field, and therefore it is necessary to carry out an in-depth study on the process of groundwater heat transport. Numerical simulation methods have gradually become an effective tool for studying this problem due to their many advantages such as high efficiency, convenience and flexibility. In view of this, this section reviews the research progress of numerical simulation of groundwater heat transport at home and abroad, which provides the basis and reference for the subsequent research on this topic.
From the late 1970s, many mathematical models describing heat transport in aquifers have been proposed abroad.Some simulation techniques for aquifer energy storage have been discussed by Mercer et al. (1985), Crawford et al. (1982), and Mirza et al.1985.P. Heijde and Y. Bachmat et al. counted the then Twenty-one mathematical models of heat transport were available, all of which considered only convection and heat transfer, ignoring the effect of natural convection on heat transport, and all of which were one- and two-dimensional, except for two which were three-dimensional coupled models of water flow.Tsang et al. (1981) and Sykes et al. (1982) have successively used finite-difference numerical simulation methods to simulate the second phase of Auburn University's subsurface Tsang et al. (1981) and Sykes et al. (1982) have used finite difference numerical simulation to simulate the water and heat transport in the second phase of the underground energy storage field test at Auburn University, and the simulation results are basically in agreement with the experimental observation results.Buscheck et al. (1983) used the data from the first two cycles of the energy storage test at Aubum University to carry out two-dimensional numerical simulation, and the effect of natural convection was taken into account during the simulation process. University of Stuttgart, Germany, to carry out a two-dimensional numerical simulation of a seasonal energy storage test in a man-made aquifer and optimize the spatial combination of permeability of each infill sublayer in the aquifer.Molson et al. (1992), using data from a submerged aquifer energy storage test at the Ontario Armed Base, Canada, carried out a three-dimensional finite element simulation of the test process, which took into account the influence of natural convection and the The model is relatively complete, but the test conditions are relatively simple and the continuity equation is not perfect.Forkeli et al. (1995) simulated the energy storage effect of artificial aquifer energy storage system by using a two-dimensional axisymmetric model and a three-dimensional finite-element model, and determined the best artificial energy storage system by comparing the simulations.Travi et al. (1996) A two-dimensional unsteady flow model was developed to give the variation of temperature over an aquifer profile by numerical calculations.Chevalier et al. (1999) applied the stochastic excursion method to simulate the energy storage in porous media aquifers and found that the flow of the regional groundwater can accelerate the diffusion of the stored thermal energy into the downstream aquifers, which can reduce the recovery rate of the stored thermal energy.Nagano (2002) Through laboratory experiments and finite-difference numerical simulations, it was found that if the temperature of the recharge water in the heat storage process is high (> 50°C), natural convection will likely occur in the aquifer, which will greatly affect the heat recovery rate of energy storage using the aquifer.Chounet et al. (1999) simulated the flow of water and heat transport in the soil by using a hybrid finite-element method, which improved the simulation accuracy, but the model used had a higher accuracy. The simulation accuracy was improved, but the model used was a profiled two-dimensional model.
The domestic research on geothermal numerical simulation began in the late 1980s, Zhang Juming et al. (1982) simulated a two-dimensional geothermal heat transport problem using the finite element method and gave a finite element program. Li Jingsheng et al.
Li Jingsheng, Wang Guangcai 1989.Sources of hot water recharge and condition ways in Pingdingshan eight mines. Scientific Research Report of Xi'an Branch of General Research Institute of Coal Science.
A two-dimensional and three-dimensional mathematical model of temperature field was established for the geothermal field of Pingdingshan respectively, and solved by finite element method, but this model is only a stable model, and the change rule of the water flow field was not studied. Xue Yuchun et al. (1987) established a three-dimensional mathematical model for the Shanghai energy storage test and considered the thermo-mechanical dispersion, but the water flow model is a stable model with a simple analytical expression instead of the water flow model, and did not consider the change of water density with temperature and hydrodynamic viscosity coefficient with temperature. Zhang Juming (1994) established a three-dimensional geothermal field mathematical model and proposed a finite element solution, but did not consider the water flow equation. Hu, B. G.Hu, B. G. 1995.Research on heat and mass transfer in geothermal field. Beijing: Tsinghua University PhD thesis.
The heat and mass transfer processes in geothermal fields were simulated using a two-dimensional double pore medium model, and the heat and mass transport laws in the Naqu geothermal field and the Yangbajing geothermal field in Tibet were simulated respectively. Renli et al. (1998) investigated the two-dimensional hydrothermal transport law of soil by the alternating direction finite difference method. He Manchao et al. (2002) firstly studied the change law of permeability coefficient in the process of underground hot water recharge, and then established a mathematical model of geothermal recharge seepage field for the dynamic change of seepage field in the process of recharge in a single well and a pair of wells, and deduced theoretical formulas of recharge in a single well and a pair of wells under the conditions of constant permeability coefficient and different changes.Domestic and foreign experts have also carried out some simulation studies on groundwater heat transport specifically for water source heat pumps.Gringarten et al. (1975) carried out a theoretical study on aquifer heat energy harvesting under the condition of uniform groundwater flow. By simplifying the boundary conditions and making appropriate conditional assumptions, a mathematical model of heat transfer in a pair-well system was established, and the model was used to quantitatively evaluate the thermal breakthrough events under different given conditions, which provided an effective guide to the design of a rational layout of a pair-well energy harvesting system in France. In order to quantitatively evaluate the heat transport characteristics in the target aquifer system so as to guide the design of the energy extraction system, Wiberg applied the finite unit method to conduct a comparative simulation study on the distribution characteristics of the ground temperature field in an ideal aquifer system under two different assumptions, namely, simple heat conduction and conduction-convection coexistence. Based on the heating and cooling load requirements in Wisconsin, USA, Andrews (1978) applied a two-dimensional finite element model to quantitatively evaluate and predict the effect of water source heat pump utilization on the ground temperature field. The simulation results showed that the temperature drop around the winter-irrigation wells was relatively small while the radius of influence increased when the regional groundwater flowed at a certain rate compared to the case when the regional groundwater was at a standstill, and the temperature disturbance zone was shifted along the direction of the water flow.Rahman (1984) developed a simulation model of a well recharge system by making assumptions about the aquifer conditions, with different Rahman (1984) established a simulation model for the well recharge system by making assumptions about the aquifer conditions, and conducted quantitative simulation studies for different recharge volumes, aquifer thicknesses, initial reservoir temperatures, and well spacing conditions. The results show that, except for the recharge volume and the distance between well pairs, the aquifer thickness has a significant effect on the time of thermal breakthrough, while the storage rate and permeability coefficient of the aquifer do not have a significant effect on the thermal breakthrough event. In order to determine the reasonable layout between the extraction well clusters and recharge well clusters, Paksoy (2000) applied the CONFLOW program to quantitatively simulate the transport characteristics of thermal fronts in the aquifer energy extraction process. By limiting the water level variability of the extraction and recharge wells, and at the same time ensuring that no thermal breakthrough occurs, the minimum distance between the extraction and recharge well clusters under the above constraints was finally determined.Tenma established an ideal pair-well model, and quantitative comparative simulations were carried out by using the FEHM software to simulate the situation with different extraction and recharge volumes, the length and location of the water-well filter tubes, and the operation cycle. The results of the study showed that the first two factors were the main influences controlling the magnitude of temperature changes in the model. In China, Xin Changzheng et al. (2002) simulated the velocity and temperature fields of a typical twin-well pressurized aquifer in year-round operation using the HST3D program written by the U.S. Geological Survey; due to the limitations of the program, the simulation was performed with a fixed flow rate and a fixed temperature throughout the year. Zhou et al. (2008) simulated a groundwater source heat pump system in Wuhan City using the HST3D-based Flowheat program, and analyzed the rationality of the well deployment method and the combination of pumping and irrigation. Zhang Kunfeng et al. (1998) simulated the winter operation work of a water source heat pump in a large-diameter well, and the results showed that the flow of well water in the large-diameter well was a uniform decline.
Two, the current status of domestic research and development trend
1. Early application of heat pumps and the beginning of the stage (1949 ~ 1966)
Relative to the development of the world heat pump, China's heat pump research work started about 20 to 30 years late. 1950s Tianjin University Institute of Thermal Energy Research Professor Lv Canren carried out the earliest research on China's heat pumps, and 1956, Professor Lv's "Heat Pumps in China", which was published by the Institute of Thermal Energy of Tianjin University, was published by the Institute of Thermal Energy of Tianjin University. In 1956, Prof. Lv's "heat pumps and their application in China's future" is the earliest existing literature on heat pump research in China. 1960s, China began to apply the development of heat pumps in HVAC, and achieved a large number of results. 1960 Tongji University, Prof. Wu Shenyttrium published "Introduction to heat pump heating and suggested that the city of Jinan trial of heat pump heating"; 1963, the former East China Architectural Design Institute and Shanghai In 1963, the former East China Architectural Design Institute and Shanghai Refrigerator Factory began to develop heat pump air conditioners; in 1965, Shanghai Refrigerator Factory successfully developed China's first heating capacity of 3,720W CKT-3A heat pump window air conditioner; in 1965, Tianjin University and Tianjin Refrigerator Factory successfully developed the first groundwater heat pump air conditioning unit; in 1966, Tianjin University and the Ministry of Railways Sifang Vehicle Research Institute*** with the cooperation of the mainline passenger car Air / air heat pump test; 1965, by the former Harbin Institute of Architecture and Engineering Professor Xu Bangyu, Professor Wu Yuanwei led the scientific research group, according to the theory of heat pumps for the first time proposed the application of auxiliary condenser as a constant temperature and humidity air-conditioning unit of the secondary heater of the new process, which is the world's first new process; Chongqing University of Architecture, the Tianjin University of Commerce and other units of the underground buried coils of the ground-source heat pumps have also carried out many years of research. Guangzhou Energy Research Institute of the Chinese Academy of Sciences and other units have also held many national symposiums on the development and application of heat pump technology. Tsinghua University, Tianjin University, respectively, and the relevant enterprises into an industry-university-research consortium, the development of China's brand of ground-source heat pump system, has built a number of demonstration projects, more and more Chinese users are beginning to familiarize themselves with the heat pump, and its application of keen interest.
China's early heat pump has experienced 17 years of development, through a long period of initial development stage. Its characteristics can be summarized as follows: ① for the new China, an early start, a high starting point, some of the research has the world's advanced level; ② due to the weak industrial base at that time, the energy structure and the price of the particularity of factors such as the impact of heat pump air conditioning in China's application and development has always been very slow; ③ in the study of foreign countries based on the road of innovation for China's future research on heat pumps to point out the direction of the development of the work.
2. Heat pump application and development of stagnation (1966-1977)
This period is in the "ten years of turmoil" period, during which the application and development of heat pumps are basically in a state of stagnation. During this period, there is no academic paper on heat pumps published and officially published translations and works on heat pumps, etc.; the country did not organize an academic seminar on heat pumps, and did not send anyone to participate in any of the international academic conference on heat pumps, isolated from the world for more than 10 years. Only the former Harbin Institute of Architecture and Engineering Xu Bangyu, Wu Yuanwei led the scientific research group in 1966 to 1969, insisted on the development of LHR20 heat pump unit to finish the work in 1969 through the technical appraisal, which is in the "Cultural Revolution" period of the country's only scientific research on heat pumps. After that, Harbin Air Conditioning Plant started small batch production, the first unit was installed in the finishing workshop of the General Mechanical Repair Plant in Anda City, Heilongjiang Province, and the operation effect measured on the spot fully met the requirements of constant temperature and humidity of (20±1)℃ and (60±10)%. This is the first case of constant temperature and humidity project realized by heat pump unit in China.
3. Heat pump application and development of recovery and prosperity (1978-1999)
1978 to 1988, China's heat pump application and development into a comprehensive recovery phase. During this period, in order to fully understand the current situation and progress of foreign heat pump development, a large number of publications, domestic publications actively publish translations of heat pumps, foreign heat pump products to test and analyze, and actively participate in international academic exchanges. At the same time, some well-known foreign heat pump manufacturers began to invest in China to build factories. For example, Carrier Corporation of the United States is one of the earliest foreign companies to invest in China, took the lead in establishing a joint venture in Shanghai in 1987.
1989 ~ 1999 period, China's heat pump and ushered in a new course of development. In China's application of heat pumps began to diversify the form of air - air heat pumps, air - water heat pumps, water - air heat pumps and water - water heat pumps and so on. During this period the country has state-owned, private, wholly-owned, joint ventures, such as no less than 300 home air conditioner manufacturers, and gradually formed a complete industrial system of heat pump air conditioners in China, and water-source heat pump air conditioning systems are widely used in China. According to statistics, by 1999 there are about 100 projects in the country, 20,000 units of groundwater source heat pumps in operation. the early 1990s began mass production of air-source heat pump chiller and water heater units, developed in the mid-1990s groundwater heat pump chiller and water heater units, and in the late 1990s began to appear sewage source heat pump system. The research of soil-coupled heat pump has become a popular research topic in the domestic HVAC industry. Domestic research direction and content mainly focus on underground buried pipe heat exchanger, innovation on the basis of foreign technology.
1978 to 1999, the second professional committee of the Chinese refrigeration society hosted 9 sessions of the "national waste heat refrigeration and heat pump technology conference". 1988, the Chinese Academy of Sciences, Guangzhou Energy Research Institute hosted the "heat pump in China's application and development of the problem of expert seminar In 1988, Guangzhou Energy Research Institute of Chinese Academy of Sciences organized "Expert Seminar on Heat Pump Application and Development in China". Since the 1990s, the Architectural Society of China HVAC Committee, the Chinese Institute of Refrigeration in its hosting of the National HVACR Academic Conference on the special addition of "heat pumps," the topic of exchange.
In 1988, the China Construction Industry Press published Professor Xu Bangyu, such as the preparation of the "heat pump" textbook; Machinery Industry Press published in 1993, Professor Yu Yongzhang edited "heat pump principles and applications", published in 1997, Professor Jiang Nengzhao edited the "air conditioning with the heat pump technology and applications," published in 1998, Dr. Zheng Zuyi's "heat pump technology in the air conditioning application of"; in 1994, Huazhong University of Science and Technology. In 1998, Dr. Zheng Zuyi's "Application of Heat Pump Technology in Air Conditioning" was published; in 1994, "Design and Innovation of Heat Pump Air Conditioning System" by Dr. Zheng Zuyi was published by the Press of Huazhong University of Science and Technology, etc. Between 1989 and 1999, there were 270 papers officially published on heat pumps, and the total number of patents on heat pumps was 161 while the number of patents on inventions was 77. The publication of these textbooks, books, translations and theses, and the application of patented technologies have promoted the popularization and promotion of heat pump technology in China.
4. The period of rapid development of heat pump technology
Entering the 21st century, due to the accelerated urbanization, per capita GDP growth, pulling the development of China's air-conditioning market, promoting the application of heat pumps in China, the scope of application is more and more extensive, the development of heat pumps is very rapid, and the research of heat pump technology continues to innovate. The application of heat pumps, research is unprecedentedly active and fruitful. 2000 to 2003, the total number of patents 287, 4.9 times the average number of patents from 1989 to 1999. invention patents **** 119 during 2000 to 2003, 4.25 times the average number of invention patents from 1989 to 1999. 2000 to 2003, the number of heat pumps literature dramatically increased, such as The number of literature in 2003 is 5 times of the number of literature in 1999. Almost all provinces and cities in China have engineering examples of applying heat pump technology. The research on heat pump technology is more active, and there are many innovative results. In just a few years there are three world-leading innovative results, including: the same well recharge heat pump system, soil cold storage and soil-coupled heat pump integrated system, for cold regions of the application of two-stage coupled heat pump system.
5. Application and Research of Ground Source Heat Pump
China's ground source heat pump research started in the 1980s, first of all, some colleges and universities and scientific research institutes on ground source heat pump technology related to thematic research. For example, Beijing Institute of Technology conducted research on deep geothermal water, and designed a number of vertically buried pipe and horizontally buried pipe soil source heat pump test system; Harbin Institute of Technology's water loop heat pump air-conditioning system application of basic research and evaluation, soil cooling storage and soil coupled heat pump integrated system numerical simulation and experimental research, soil source heat pump system in the ground of the buried pipe of the heat seepage coupling theory and key technology research; Hunan University to build the Hunan University has constructed a horizontal buried pipe soil source heat pump system. In addition, Qingdao Institute of Architectural Engineering, Shandong Institute of Architectural Engineering, Shanghai Tongji University, Tianjin Business School, Chongqing Architectural University and other universities have also carried out research in this area. In recent years, several domestic institutions of higher learning have carried out experimental research on soil-source heat pump system and water-source heat pump system, and have achieved some important results.
Currently, China's shallow geothermal energy development and utilization of research is developing rapidly, after nearly two decades of research and development, heat pump technology in China has made great progress, especially the rapid development of ground source heat pump technology. Has initially established various types of groundwater source heat pump system of water source well construction technology and technical requirements, well group design and calculation methods, water quality evaluation and treatment methods and environmental evaluation methods.
By the end of October 2008, China's shallow ground energy application area of more than 1 × 108m2 ("Ground Source Heat Pump" magazine May 2009 issue). It has been spread over Beijing, Shanghai, Tianjin, Hebei, Henan, Shanxi, Liaoning, Sichuan, Hunan, Tibet, Xinjiang and other places. The types of buildings applied include hotels, residences, shopping malls, office buildings, schools, stadiums, hospitals, exhibition halls, army barracks, villas and factories, etc. The application prospect is broad.
6. Development and Utilization of Shallow Geothermal Energy and Development Trend
The development and utilization of shallow geothermal energy involves the urban energy structure, environmental protection and improving the quality of people's lives is a major issue. In particular, the shallow groundwater source heat pump and soil source heat pump renewable energy collection system is the key to solving the above major issues, and its energy collection is basically independent of the use of geographic area and the influence of the climate in all seasons. Shallow geothermal energy as a building's initial collection of cooling and heating source is more popularization value.
The development and utilization of shallow geothermal energy has not only received attention from academia and the business community, but has also received more attention from the government. The People's Republic of China *** and the State Renewable Energy Law clearly states that: the State will renewable energy development and utilization of scientific and technological research and industrial development as a scientific and technological development and high-tech development of priority areas. The State financially supports the construction of resource surveys, evaluations and related information systems for renewable energy. The implementation of this law provides a strong basis and guarantee for the investigation, evaluation and development of shallow geothermal energy. The Ministry of Land and Resources, China Geological Survey and other departments have held many experience exchange meetings and technical seminars on the exploration and development of shallow geothermal energy, and have prepared and introduced specifications for the investigation and evaluation of shallow geothermal energy, so that there is a standard for the exploration and development of shallow geothermal energy. In recent years, as the country to increase the construction of "resource-saving, environmentally friendly" society, to achieve energy saving and emission reduction targets, the state from the central financial arrangements for special funds to support the demonstration and promotion of renewable energy building applications, the Ministry of Finance, the Ministry of Construction has been approved by the issuance of three batches of renewable energy building applications, including shallow geothermal energy utilization Demonstration and promotion projects. Various regions have also launched projects to support the development and utilization of shallow geothermal energy. For example, on May 31, 2006, the Beijing Municipal Development and Reform Commission, in conjunction with the Municipal Water Resources Bureau, the Land Bureau and other nine commissions and bureaus, jointly issued a document on the use of groundwater source heat pump system to achieve the standard of 35 yuan per square meter for heating and cooling projects, and on the use of ground-source heat pump system to achieve the standard of 50 yuan per square meter for heating and cooling projects; Shenyang Municipal Government issued the "Implementation Opinions on Ground Source Heat Pump System Construction and Application", in which it is required that the construction and application of ground-source heat pump system should be supported. The work of the implementation of the opinions" in Shenyang city requires in Shenyang city within the third ring of the 455km2 core area within the scope of the 409km2 range of buildings in line with the application of groundwater heat pump technology, in principle, should be used in the planning and study of groundwater source heat pump technology.
Entering the 21st century, along with the rapid development of China's economy, people's quality of life and comfort requirements continue to improve, the change of the urban energy structure, the construction market is huge, for the shallow geothermal energy development and utilization of technology to promote the creation of unprecedented opportunities. Domestic in the heat pump theory research, experimental research, product development and application of engineering projects have achieved promising results.
Currently, China has established a relatively complete development and utilization of shallow geothermal energy engineering technology, mechanical equipment, monitoring and control systems, but the recharge technology in the water quality control and recharge on the reservoir and the evaluation of the impact of the water pipe, the clogging of wells, the treatment technology, the wells group of extraction and irrigation system of the temperature field, the chemical field and the simulation of the pressure field, parameter acquisition methods are still under study.