Optimization Design And Economical Analysis Of A Ground Source Heat Pump System

In recent years, GSHP systems are developing rapidly in China, but there still exist some problems to be solved. This paper is presented to perform the optimization design and economical analysis of a GSHP system. The main contents are as follows:Firstly, based on the analysis on main problems existed in the present GSHP systems, the influences of key design parameters on the performance of GSHP systems are discussed in detail. Then, a new approach to the optimization design of GSHP systems is presented, which is based on thermal response tests of rock soils and dynamic analysis of building air-conditioning loads, and in which the long-term performance of GSHP systems is treated as an ultimate optimization objective. Further, this method is applied successfully for an actual GSHP system located in Caofeidian Industrial Zone, Hebei province.Secondly, the dynamic heating and cooling loads of the object building is calculated using the software DeST-c, and the ground thermal properties is obtained using the in-situ constant heating-flux TRT method. Then, the heat-influencing range of ground heat exchangers (GHEs) as well as the temperatures of the ground and fluid through the GHEs is simulated numerically using the CFD software Fluent. Further, some experiments on the operation performance of the object GSHP system are carried out in both summer and winter. The results show that the COPs of the heat pump units and the whole system are 4.21 and 3.04 in winter, and 5.22 and 3.42 in summer, respectively, which indicates that the present GSHP system can run under a high-efficiency condition.Finally, a whole economical analysis is performed for the object GSHP system. Its present value, annual value and addition investment are calculated and compared with that of the conventional air-conditioning system. The results show that the entire cost during the lifetime of the object GSHP system is much lower than that of the conventional air-conditioning system. In detail, the annual operation cost of 999,100Yuan can be saved, which is equivalent to 18.68Yuan per unit floor area. Therefore, after optimization the present GSHP system has a better tech-economical performance.