| Because of its huge energy saving advantage, ground source heat pump, as arenewable energy technology, has been widely used in the heating, cooling and otherfields. As one of the types of ground source heat pump heating technology, soil sourceheat pump hot water system moves low grade thermal energy from the soil side to thehot water, with the less consumption of compressor power, so as to realize the purposeof heating. Even in the bad weather conditions, the temperature of underground soil ishigher than the outdoor environment, and has the characteristic of relatively constant,so the utilization of soil source heat pump for making hot water has the advantages ofhigh efficiency and operation smoothly.Basing on a soil source heat pump hot water system in a student apartment, thedesign principle is introduced. In order to realize the simulation of the whole systemand make it be a guildance to the application of GSHP hot water system to studentapartments, the system operation data has been tested, and the simulation program hasbeen established with TRNSYS in this paper. The test time is scheduled in threetypical days, respectively representing winter, summer and transition seasons. Thetest items include outdoor environment temperature, outlet temperature of the hotwater tank, inlet and outlet water temperature of the heat pump, water outlet flow ofthe tank and hourly electricity consumption. By comparing the test data of actualproject with the data of TRNSYS software simulation program, the correctness of theTRNSYS simulation program is vertified.The system optimization is carried out on the basis of the TRNSYS simulationprogram,to make the ground source heat pump hot water system more energy-efficientand economical. According to the operation characteristics of soil source heat pumphot water system, once the hot water load is selected, what affect the design of thesystem are the choice of the units, the water pump and water tank. The choice of thewater pump and water tank can be did based on the maximum calculated heat. Theselection of the size to the heat pump units can be determined by the design work time,which is usually from12to20hours. The different size of the heat pump unit used forthe hot water system may result in different efficiency and investment. The studentapartment is a special group, whose fluctuation pattern of water consumption alsoinevitably has its particularity, so that to identify the optimal design work time for the unit is necessary. Based on the cost-benefit ratio as a reference index of theoptimization design, after calculation, the most optimal design work time is17hoursthat for the soil source heat pump hot water project in this study. After analyzed, thebest values to the design work time ranges is from16to18hours when the soil sourceheat pump hot water system used in colleges. With the use of the dynami c economicanalysis method, which under the most optimal design, this paper analyzes theeconomic indicators for the soil source heat pump hot water system and air sourceheat pump hot water system from present cost, annual cost and dynamic investmentpayback period. The result show that the soil source heat pump hot water system has agreater economic benefit when compared with air source heat pump hot water systemin the whole life period. |
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