The Open Fuels & Energy Science Journal

2014, 7 : 169-175
Published online 2014 December 31. DOI: 10.2174/1876973X01407010169
Publisher ID: TOEFJ-7-169

An Assessment Methodology of Shallow Geothermal Energy Projects

You Shuang , Li Xiangyu , Gao Yu and Tang Wend
No.30, Xueyuan Road, Haidian District, Beijing, 100083, P. R. China.

ABSTRACT

Combination of theoretical and numerical analysis, an assessment approach of shallow geothermal energy project is proposed. A case study on Chongqing is carried out to verify the methods. According to the theoretical calculation, the heat transfer power per meter of typical boreholes in Chongqing is 40 W/m for cooling and 50 W/m for heating. The numerical model of 100m borehole heat exchanger (BHE) of ground sourced heat pump (GSHP) system is built, two sets of heating and cooling loads are input to calculate the ground thermal response, the results show that the thermal unbalance ratio equals to 1.5 would ensure the safe and reliable long time operation of GSHP system. By comparing the single and group borehole model, the heat transfer efficiency of BHE is not influenced by adjacent boreholes with 6m drilling spacing, the temperature distribution among boreholes almost uniform after a year running, however, the increase of cumulative temperature of the ground reaches 2.2°C after five years running.

Keywords:

Assessment methodology, borehole heat exchanger, shallow geothermal energy, thermal unbalance.