The sewage source heat pump system is one of the most promising prospects for the development and application of all kinds of heat pump technology in China. The principle is very simple. Heat is exchanged from the sewage through the special heat exchanger of intermediate water and sewage. The intermediate water with heat enters the evaporator, and the heat is absorbed by the refrigerant. The intermediate water circulate between the evaporator and the heat exchanger through the circulating pump power.
In comparison, a sewage source heat pump system can make use of less power to get more energy from the sewage, and then supply the user with refrigeration and heating. At the same time, the sewage source air conditioning system does not need to set up the cooling tower in the summer, which not only reduces a considerable part of the operation energy consumption, but also eliminates the adverse effects of the cooling tower on the environment. This aspect is more obvious in its winter use. Because there is no boiler in the traditional air conditioning system for building heating, the sewage source heat pump system can avoid causing serious air pollution. As a result, the traditional cooling and heating schemes have low efficiency and high energy consumption, while the sewage source heat pump system has obvious advantages no matter from the efficiency of heating and cooling, or from the future energy cost. Stainless steel chemical pump
Sewage is the key to cold and heat source of this kind of heat pump system, which is defined as the sum of industrial wastewater and domestic sewage. Although sewage is a dirty water for ordinary people, but in the eyes of experts, it is a treasure, a rare renewable energy in the city.
According to the introduction, the primary sewage (main canal sewage) and the two stage effluent from the sewage treatment plant as the cold and heat source, have the following characteristics: first, the urban sewage volume accounts for more than 80%% of the urban water supply volume. Second, the city sewage water temperature is relatively high and the seasonal variation of smaller, usually at 10 degrees or less, with Dongnuanxialiang characteristics; annual temperature ranges from 10 DEG ~25 DEG, suitable for HVAC system of summer and winter; high underground water temperature when heating water temperature is 3 DEG ~5 DEG, cooling air temperature is low 10 ~15 oc. Third, the distribution of urban sewage heat energy is basically proportional to the population and the degree of urban industrialization. As a new energy source, urban sewage can effectively alleviate the problem of energy shortage and uneven distribution while optimizing the energy structure. Fourth, sewage as a heat carrying water body, its heat capacity is large, relative to the air source and soil source, the heat exchanger has higher heat transfer coefficient, which makes the operation efficiency of the heat pump system improve. Fifth, urban sewage has more economic value than air source, underground water source, soil source and other cold and heat sources far away from buildings. It shows that the initial investment of the system is relatively low, even if compared with the conventional cold and heat source system, the initial investment is also much lower. Sixth, the sewage source heat pump system can avoid the existence of the fatal killer Legionella in the centralized air conditioning system to the maximum extent. There is no cooling water (cooling tower) system for the sewage source air conditioning, which effectively reduces the spread and way of the pathogen.
Nowadays, the sustainable development has become a hot topic. As one of the three elements of sustainable development, environmental factors have aroused the close attention of all parties. Sustainable development means reasonable maintenance and use, which means the concern and consideration of the environment in development plans and policies. It is precisely because of this consensus that the sewage source heat pump system has been recognized both inside and outside the industry, and it is possible to further develop to the depth of the system.
Deputy general manager of China refrigeration and air conditioning industry association, Beijing zhonglengtong Quality Certification Center Co. Ltd. Guo Yong believes that with the city sewage in heat recovery heat pump system, the development of a clean energy, and the reduction of the city waste heat emissions and protect the environment, sewage source heat pump system should have a broad application prospect. His view has been confirmed by the Architectural Society of Chinese HVAC branch honorary chairman Wu Yuanwei and other senior people agree, but they have said, from the current point of view, there is still a sewage source heat pump system including cleaning technology and system selection, sewage source water temperature and flow as well as the guarantee of economic and other problems to be solved, these the technical threshold will directly affect the sewage source heat pump system application and development in the future Chinese.
In the sewage source heat pump system, the heat exchanger directly contact with the sewage is particularly prominent because of the problem of clogging, corrosion and scaling caused by the water quality. Taking scaling as an example, according to the survey, at present, in all domestic sewage source system projects, there are varying degrees of fouling in the heat exchanger above 90%%. Fouling increases heat transfer resistance, which not only worsens the heat transfer performance of the heat exchanger, but also increases the thickness of the fouling layer and reduces the flow area. When the flow rate keeps constant, the average velocity increases. Meanwhile, fouling also makes the surface of the channel rough, increasing the friction coefficient and the local resistance coefficient, resulting in the increase of the flow resistance and pressure drop of the whole heat exchanger, and the increase of the power consumption of the unit. Therefore, in the design and use of heat exchangers in the sewage source heat pump system, how to prevent scale, scale and scale removal is a very important and key topic.
Experts believe that the content of impurities, taking into account the factors of corrosion, the sewage heat exchanger fouling and so on, with corrosion resistance, long service life, easy cleaning plastic sewage heat exchanger is preferred; for the use of sewage source heat pump system of sewage treatment plant two grade water or reclaimed water can be used. Using recycled water as cooling water quality standard. If the reclaimed water reaches the corresponding water quality
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