Study On Performance Of Underground Heat Exchangers In A Hybrid System In Guangdong

With the increasing concern with the environmental problems, sustainable development policy has been becoming a household word all over the world. With the features of energy saving and environment friendly, ground source heat pump(GSHP) systems for HVAC have aroused greater and greater interest in China during recent years. GSHP, which has been widely used in developed countries in Europe and American, is a facility that utilizes the vast geothermal energy stored under the earth for heating air conditioning in commercial and residential buildings. At present, GSHP is researched and applied widely in the north of China. Also, the local governments promulgate some standard and criterions to design and construction. However, in the south of China where it is hot in summer and warm in winter, the research on GSHP settles on the theory at present. Therefore, this paper studies the GSHP in Guangzhou which locates in the south of China. Some experimental data and conclusions are acquired, which are helpful to application in southern GSHP.The paper collects hydrological and geographical information about the local. Soil's temperature and inlet and outlet water temperature are measured by data acquisition with high accuracy, Agilent34970A. On the basis, heat exchanged capacity is calculated, and the thermal performances of different kinds of immersion heat exchanger were compared. As follows:1. The soil temperature was measured while the heat pump didn't running during a whole day.2. The soil temperature and inlet/outlet water temperature was gained with the operation time in continuous cooling/heating mode. On the basis, calculate heat exchanged capacity is calculated.3. The heat transfer capacity of the heat exchanger with the same type was compared in different climatic regions when they are during the same time. As well as, the main factors affected heat transfer capacity are analyzed, which include soil characteristic and weather condition.4. The soill temperature was tested from intial to unchanged-temperature state, which is defined as the end one and the heat pump system was stopped. And then the soill temperature was measured from this point to temperature unchanged. During an intermittent heating and cooling operation, draw the soil temperature curve. Compare heat exchanged capacity between continuous mode and intermittent mode. Put forward discontinuous mode to enhance heat transfer.5. The economic performances of the hybrid ground source heat pump systems (HGSHPS) are analyzed. Taken into account investment and operation cost, pay off period of investment is found for each system.