| While the energy-saving and environmental protection becomes an important direction of science and technology development, more and more attention has been paid to reduce the energy consumption in buildings. In this background, more and more ground-source heat pump (GSHP) systems have been used because of their advantages such as making use of the low-grade energy source for building heating and air-conditioning, highly efficiency and environmental protection features. The GSHP system is quietly different from conventional HVAC system in its ground heat exchanger (GHE), which is buried underground to absorb or dissipate heat. Reasonable designing of the GHE would reduce the first cost of the project, make rational use of the field, ensure reliably operate and save operation cost of the project.The ground heat exchanger is the important constituent of the ground-source heat pump system. Reasonable inlet and outlet temperature of the circulating fluid in the ground heat exchanger is significant. So it is very necessary to research the ground heat exchanger.First, the reasonable accurate building load computation is the foundation of the GHE designing. This thesis introduces methods of the building load computation and the software that using computer technology to simulate. To get the load that put into GHE, we cumulate sum the hourly building load.Second, while the "Geothermal Stars v3.0" is applied on a building of the Jinan area to simulate the situation, different inlet and outlet temperatures of circulating fluid in the ground heat exchanger was set to analyze and discuss the designed length of the ground heat exchanger, and then analyze the average heat exchange capacity per meter in a varying temperature conditions. Compared simulation was done to the heat transfer properties of the ground heat exchanger of different styles (single-U, double-U) and backfill materials. And the varying temperature of the underground circulating fluid in the two different styles (single-U, double U) were analyzed and compared. It's negative to the running of the system while the temperature around the heat exchanger continues to deteriorate during the continuous operation process. By the way that adoption of controlled space, which allows the soil temperature has a certain recovery time and improve the heat transfer rate in order to reduce the number of heat exchangers, and it can also save soil resources and construction costs.In the simulation of the intermittent operation, the corresponding inlet and outlet temperatures of circulating fluid in the ground heat exchanger was analyzed.Again, take the actual ground-source heat pump project for example, and make the choice of equipment as well as the calculation of the first cost, and then the total annual operating costs was derived from adding up the operating costs in winter and summer of the ground-source heat pump system. And it was analyzed in economic with the other three kinds of air-conditioned form, the annual cost indicators was used to compare these schemes. As a result, the way that the ground-source heat pump when the temperature of the circulating fluid is appropriate was more economic and reasonable than any other air-conditioning systems and it had obvious technical and economic advantages.The main work this paper done was to design an optimal different inlet and outlet temperature of the circulating fluid in ground-source heat pump,the enactment of the outlet temperature of the circulating fluid not only affected the efficiency but also the initial investment of the system. According to this article, studies have shown that:With the concentration of 7% NaCl solution the optimal outlet temperature in summer of Jinan is:27℃～32℃,and the corresponding outlet temperature in winter is:3℃～9℃.These researches had a certain reference value on the design and construction of the ground-source heat pump project and they can provide strong support for promotion of this technology.
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