| At present, China’s building energy consumption is still dominated by fossil energy.The problem of energy consumption and environmental pollution is very serious, and it is is of great significance to look for clean, renewable alternative energy sources for the building heating for cooling. However, the heat pump technology with remarkable energy saving effect is one of the most effective ways to utilize the low grade energy, which will be one of the most effective ways to utilize the renewable energy. Among them, using lake water as low grade heat source, the lake-water-source heat pump system has been studied and demonstrated in the south of China. However, the temperature of lake-water distributed in cold regions in northern China during the winter is pretty low, generally at2~3℃. In view of the stability, economy and reliability of heat pump system under this condition, the system technology, operating conditions, system efficiency, system energy consumption and economic efficiency of the lake-water-source heat pump system in the cold region are discussed.First of all, the system forms and advantages and disadvantages of open and closed systems, direct and indirect systems, prefix-filter heat exchange system and direct guidance heat transfer system are compared and analyzed. The results show that the direct guidance heat transfer system can be used to solve the problems of anti freezing, anti clogging and scaling, which is more suitable for the lake-water-source heat pump system in cold region. According to different way of the pipeline connection system, the advantages and disadvantages of a machine of a pump system, parallel system and the hybrid system are contrasted and analyzed. Put forward the air-heat-increasing assisted lake-water-source heat pump system and the solar photothermic assisted lake-water-source heat pump system, and analyzed the reliability and stability of system optimization.Secondly, in view of the operating condition that the low water-temperature of coldregion in winter is 3~5℃ and the outlet temperature of evaporator is less than-3℃, the influence of anti-freeze fluid on the operation of the system is analyzed and the calculation formula between the heat transfer and flow characteristics and the physical property parameter of anti-freeze fluid is deduced and established. 20% ethylene glycol solution and 30% glycerol solution are selected as the research object, and water is added as the third party comparison. The calculation results show that the convection heat transfer coefficient is increased by about 1.5~2.5%, and the energy consumption is reduced by 0.5~1% at each increase of 1℃. However, considering the safety, economy and environmental protection, because of the metal corrosive and toxic of the ethylene glycol solution, 30% glycerol solution is more suitable for the system.And then, in order to ensure the system energy consumption, by means of the combination of the theoretical average COP calculation and the measured data, calculated and analyzed the unit efficiency and energy consumption in the whole heating season, and carried out the energy saving and environmental benefit evaluation compared with traditional heating system. Studies have shown that average performance coefficient of whole heating season is about 3.1, which is basically the same as the experimental data,and compared with the traditional heating system, the energy-saving rate is more than50%, which has a certain potential of energy saving and environmental protection.Besides, a set of detailed system initial investment and operation cost evaluation system is established to make a quantitatively comparison of economic benefit between FHSHP system, air source heat pump system, municipal centralized heating and gas boiler system.. The results show that the initial investment of FHSHP system can reduce by 20%~40%, and the operating cost savings is more than 30~50%. The economic benefits is significant.Finally, tracked and analyzed the operating conditions, the energy consumption and the economic benefits of two demonstration projects which are the ALHP of Qingdao Kechuang New Energy Company(building area is 6000 square meters) and Xi’anBailuyuan water source heat pump system(building area is 4000 square meters). Survey results show that the indoor temperature in winter is above 20 ℃, and indoor temperature in summer is from 24 to 26 degrees adjustable, that the-lake-water source heat pump system can be used both in winter and summer. Annual operating costs(heating and cooling) is 28~33 yuan/m2, and compared with the traditional way of heating and air conditioning the energy saving is about 30~50%, the initial investment is reduced by20~40% and the running costs savings is about 30~50%. The popularization and application of this system in the cold area of our country not only has the value of scientific research and social significance, but also has a very high practical significance.
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