R&D And Application Of The Geothermal Response Test Device

The ground source heat pump (GSHP) is a kind of renewable air-conditioning technology using the geothermal energy , with the features of highly efficient ,energy-saving and environmentally friendly. The thermal property parameters of the soil are the key parameters in the design of the borehole heat exchanger, directly determine the length of buried pipe and the initial investment. So,to obtain thermal parameters of the soil accurately is significant.This paper analyzes the development and research of the thermal properties test device at home and abroad, and manufactured a thermal property test device based on the thermal response principle,with a PLC as the core of data collection and processing. Meanwhile a set of software is developed for the calculation of soil thermal property parameters. Practical application shows that the test device, with a feature of user friendly, safe, stable, reliable and a high test precision, can be competent for the thermal response test.In the thesis,a thermal resistance correction factor aiming at the backfill material of the borehole was developed by analyzing the unsteady heat transfer of vertical embedded pipe for ground source heat pump, and the heat short-circuit modification is introduced to modify the mean temperature of the circulating water as well, meanwhile, a cylindrical source integrated modified model is developed based on the existing modification of the Carslaw cylindrical source model.Through comparing the calculation results of the DST model inTrnsys software,based on the modified model and the original one, the accuracy of the modified model is proved, and the influence of the backfill grout, the equivalent radius, thermal ununiformity and the heat short-circuit on the result is also further analysed. The research improves the calculation accuracy of the thermal property parameters, promoting the development of the geothermal property test as well.