1. Surface groundwater heat pump
In 1930s, surface water ground source heat pump system came out, which was one of the earliest forms of heat pump system used for ground source heat pump. The first large-scale heat pump device in Europe was put into operation in Zurich, Switzerland from 1938 to 1939. It uses river water as heat source, and the heating capacity is175 kw; . 1937, Japan installed a heat pump air conditioning system with spring water as the heat source in a large building.
From 1940s to 1950s, most of the early heat pump devices used in Switzerland and Britain were surface groundwater heat pumps. Table 3-2 lists the typical surface water heat pump systems used in Switzerland and Britain in the early days.
Table 3-2 Early Typical Surface Water Ground Source Heat Pump Systems in Switzerland and Britain
As can be seen from Table 3-2:
(1) The heating capacity of surface groundwater heat pump systems in Switzerland and Britain in the 1940s and 1950s was greater than that in the 1930s. Generally, it is above 1500kW, which is much greater than the heating capacity of surface groundwater heat pump in 1930s.
(2) Surface groundwater heat pumps in Switzerland and Britain are also more widely used than in 1930s. In addition to building heating, it is also used for swimming pool heating, rayon factory process heating and shoe factory air conditioning.
Other European countries have also begun to install surface water and groundwater heat pump systems, such as:
1 In 1954, Belgian installed1surface water ground source heat pump in Westley Waterworks, heating 465kW, using rivers as low-level heat source, with performance coefficient of 3.3 ~ 3.5.
1956, France installed 1 heat pump air conditioning system with spring water as low-level heat source in Paris Radio Building, with heating capacity of 4.9MW and cooling capacity of 2.8MW.
Although the surface water ground source heat pump system in this period is in the initial stage, it has fully demonstrated its energy saving in operation, which has played a certain demonstration role in the future development of surface water ground source heat pump.
In the late 1970s and early 1980s, large-scale heat pump stations with surface water, groundwater, municipal sewage and industrial wastewater as low-level heat sources began to be applied in countries with developed regional heating, such as Sweden and the former Soviet Union, with a single capacity of several megawatts. Since then, it has also developed rapidly in the United States, Japan, Romania, Denmark and Germany, with a stand-alone capacity of 30MW and an assembly capacity of 160MW.
Since 1980s, many large-scale heat pump stations have been established in Sweden. See Table 3-3 for the heat pump stations with lakes/seawater and groundwater as heat sources. By 1987, about 100 heat pump stations had been put into operation, and the total heating capacity reached 1200MW, making it one of the representative countries in the world to apply large-scale surface water ground source heat pump stations.
Table 3-3 Large-scale heat pump stations for surface water sources and underground water sources in Sweden
1987 The former Soviet Union Yang Tuvsky and others compared the heating of heat pump station with the central heating of heating power station and regional boiler room, and found that the fuel can be saved by 29.7% ~ 32%, and put forward the regional heating scheme of heat pump station with moscow river as the low-level heat source.
Later, European countries began to build large-scale surface water sources and underground groundwater heat pumps. Finland has six megawatt devices; There are 1 unit 1.5MW units in the Netherlands; Romania has 7.5MW absorption heat pumps 15, 2.9MW absorption heat pumps 10 and 8.7MW absorption heat pumps 1 0 for district heating. Together with other 400 medium-sized compression heat pumps, 30,000 tons of standard coal can be saved every year.
1982, Denmark built the earliest seawater and groundwater heat pump station for district heating. By 1990, the installed capacity of central heating heat pumps will reach 350MW, and the number of heat pumps will reach 100.
2. Underground groundwater heat pump
Underground groundwater heat pump was born in 1930s. Kemler and Oglesby mentioned in their book Application of Heat Pump that by 1940, the United States had installed 15 large commercial heat pumps, most of which used well water as heat source. Table 3-4 shows the underground groundwater heat pump system in the United States up to 1940. 1937, Japan installed two 194kW compressors and heat storage tanks in a large office building, and its performance coefficient reached 4.4.
Table 3-4 Groundwater Heat Pump Heating System 1940
In the United States, the ground source heat pump used in the 1940s and 1950s was mainly underground groundwater heat pump. After the operation of the underground groundwater heat pump system in Oregon from 65438 to 0948, a large number of ground source heat pumps were installed in the western United States and even in the United States, and Washington gradually became the leader in the installation and use of ground source heat pumps in the United States. From 65438 to 0950, there were about 600 heat pumps in the United States, of which 53% were groundwater heat pumps. Most of the early devices were underground groundwater heat pumps. Due to direct systems, these systems failed due to corrosion and rust in 5 ~ 15 years. Therefore, the application of groundwater heat pump system has entered a low tide period. Until the 1970s, the emergence of the world oil crisis aroused people's concern and interest in groundwater heat pumps, and a large number of groundwater heat pumps were installed and used. Due to the introduction of plate heat exchanger in Europe, the installation and use of closed underground water source heat pump system are more extensive. 1983 underground groundwater heat pump is considered as an energy-saving heating and air conditioning method.
Since 1990s, with the further improvement of environmental protection requirements, the application of groundwater heat pump system in the United States is on the rise. According to the investigation of the U.S. Department of Energy and Information, except 65438, the output of groundwater heat pumps in the United States is 5924, 86 1994, 1995, 1996 and 1997 respectively. In the past 10 years in the United States, the annual growth rate of ground source heat pumps was 12%, and about 50,000 ground source heat pumps were installed every year, of which the open system accounted for 15%. The underground groundwater heat pump air conditioning system installed in a hotel office building in Louisville, Kentucky, USA, has a heating capacity of 10MW, which is the largest underground groundwater heat pump system in the United States and the world.
Some European countries have adopted active promotion policies (including financial subsidies, tax cuts, preferential electricity prices and advertisements), so the heat pump market has developed rapidly. 1997 The European Development Foundation put forward the development plan of heat pump again. By 2000, the total number of heat pumps used for heating and hot water supply in Europe was about 467,000, of which groundwater heat pumps accounted for about 1 1.75%. Table 3-5 lists the applications of heat pumps in some countries.
Table 3-5 Application of Heat Pump in European Countries
3. Underground ground source heat pump
Ground source heat pump technology was first developed in the United States and Britain. In the late 1940s and early 1950s, due to the maturity of ground source heat pump technology, the extensive utilization of shallow geothermal energy was effectively promoted. In recent years, the scale and speed of shallow geothermal energy development and utilization in various countries are increasing rapidly. From the development trend of foreign countries, the development and utilization of shallow geothermal energy (low temperature energy contained in shallow rock and soil) will be the mainstream and direction of geothermal resources development and utilization.