Abstract:

A certain scale underground permafrost is chronically existing in northeast certain regions, it can form a nature cold source and has a great influence on the application of groundwater source heat pump. In order to improve operational efficiency of groundwater source heat pump, the authors use laboratory and field tests and numerical simulatiion method to study influence rule of cold source on groundwater heat source pump. Thermal physical experiments and field thermal response tests of the cold source site for Jiagedaqi region are carried on. It has been shown that thermal physical parameters of sand and gravel such as specific heat capacity and thermal conductivity present discrete phenomenon with the depth in the region; thermal physical parameters of sandstone and granite have a little change; thermal conductivity of granite is the largest and sand and gravel is the smallest and sandstone is in the middle in these samples; specific heat capacity is obvious fluctuated with the depth, specially for sand and gravel layers. Based on geological conditions, a numerical model is constructed and numerical simulation of heat breakthrough and influence radius of pumping and injecting system of multiple well are studied. The results show that influence range of cold source is within 150 m and cold source has the greatest effect on water source heat pump within the range of not more than 75 m. The results will provide theoretical basis and reference for groundwater source heat pump designing and site selection.

Key words: geotechnical thermo-physical property test, groundwater source heat pump, nature cold source, numerical model, groundwater