| As a kind of new HVAC technology utilizing renewable energy, ground source heat pump technology has been generally used in building energy conservation field. At present, one of the hottest topic studies about ground source heat pump technology is the hybrid system combining with other sources.However, due to the difference of geographical condition, the system cost, the climate characteristics, technical characteristics of integrated technology, the conclusion obtained abroad may not be applicable to the specific conditions in China. Therefore, in order to provide reference for the engineering design, the research on the adaptability and economy of hybrid system with solar energy in northern China has been carried on.From the view of taking the soil and solar energy as compound heat sources, the following research has been carried:①Select single low-density building in Beijing as the benchmark building, use TRNSYS software to model the building and make hourly calculation of annual cooling and heating load to get the load data.②According to the technical code and actual situation, design the ground-source heat pump system, solar energy system and discuss the selection of some key parameters.③Take TRNSYS software as the platform, establish the calculation model of ground-coupled heat pump system and the two operation mode of hybrid system.④Select different depth of the borehole and several representative parameters, analyze the effect of the hybrid system compared with the single buried tube system in system performance, and make the selection of the optimum operation model.⑤Use the optimization software, with the minimum life cycle cost(LCC)as objective function, choose Hooke-Jeeves Algorithm, make the optimization of the single buried tube system and hybrid system.⑥Analyze and discuss on the variation trend and laws of soil temperature field of ground-coupled heat pump systemThe main conclusions of the paper include:①When the operation condition of ground-coupled heat pump system in the heating season is not good, such as the ground heat exchanger size is insufficient, the hybrid system can obviously improve the operating performance of the system.②The comprehensive effect of operation mode 2 is the best.If using solar energy as the auxiliary heat source only in winter heating conditions, this mode can be used as the optimization scheme in the design and operation of practical engineering.③In the design of the ground heat exchanger, both the annual inlet and outlet temperature and the ground heat exchanger cost must be considered.④The average soil temperature can be used as a optimum parameter to predict the system operational state. In the design of ground-source heat pump system, the allowed decrease value of soil average temperature at the end of operating period is related with the drilling cost. In this paper, the values are between 2 and 2.4 degrees Celsius. Or ground heat exchanger size should be increased or adding auxiliary heat source.⑤It is not economic to select and design solar energy system according to the principle of compensation heat in the heating season. It should be considered seasonal heat-storage measures to reduce the collector area and make the best of using the solar energy system by the way of providing domestic hot water in the non-heating season at the same time.⑥The application condition that the hybrid system should be used is that the ground heat exchanger size is insufficient caused by various reasons.Due to the restriction of available resource, it is mostly discussed the operating situation of hybrid system in Beijing. The results have to be verified by experiments, but they can provide some references for practical design, operation and administration of hybrid system.
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