Optimization Method Of Heating Mode For Surface Water Heat Pump Systems In Areas Cold In Winter And Hot In Summer

Sustainable development is a great challenge and an urgent task for all over the world nowadays. In HVAC&R field, while creating good indoor environment to ensure health and comfort of occupants, it becomes extremely exigent and significant to energy conservation and larger environment protection from building standpoint. Energy conservation includes using energy resources which is benefit for the optimization of energy structure, exploiting and utilizing renewable energy resources, and raising conventional energy using efficiency. Surface water heat pumps (SWHPs) are energy-efficient devices for heating and cooling that use surface water as a heat source and sink. They offer many advantages over air-source heat pumps (ASHPs) and avoid frosting in winter due to outstanding heat transfer properties of water and much more favorable temperatures of river or lake water.Taking an SWHP project in Xiangtan city, Hunan province as an example, the performance of SWHP is investigated in this thesis. Firstly, related literature was reviewed and the application range of SWHP was put forwarded. Based on experiment, the performance of the lake water heat pump system at heating mode was studied, its energy consumption and Coefficient of Performance (COP) were calculated and analyzed. To optimize the installating position of feed and return water pipe in the lake, a model was developed to simulate the horizontal water temperature distribution of small lakes. The simulation result was validated by experiment. Furthermore, in order to determine the optimal heating parameters of the SWHP system, a new simplified procedure to calculate the Heating Seasonal Performance Factor (HSPF) of SWHP systems was proposed. Based on evaluation of heating energy requirement of buildings with daily average water temperature and outdoor air temperature, this model suggest the optimal parameters of the SWHP system. Moreover, the initial and operation costs of the SWHP system were calculated and the annual economical analysis was made. At last, based on the comparison between SWHP system and ASHP system, it was concluded that SWHP can save 31.5% of energy per year and 2.99 yuan/(m~2·a) of costs, which indicated the SWHPs are superior to the ASHPs evidently.