Research on the thermal conductivity and moisture migration characteristics of Shanghai mucky clay. I: Experimental modeling

Abstract

With the development and exploitation of geothermal energy ground source heat pump (GSHP) sys- tems are being utilized all over Shanghai due to its unique energy advantages. A model experiment is designed and carried out to simulate an alternately-running GSHP sys- tem in summer and winter. It aims to study the character- istics of thermal conductivity and moisture migration of saturated soft clay (Shanghai mucky clay) with respect to thermal balance during the operation of a GSHP system by a series of laboratory modeling experiments. Thermal conductivity is an essential thermo-physical parameter for designing a GSHP system and is calculated (1.3680 W/(m C)) rather than obtained via the expensive and time consuming in situ thermal response test. The value mea- sured in laboratory experiments (1.1200 W/(m C)) by transient probes did not comply well with in situ data. The Thermal conduction and moisture migration characteristics of Shanghai mucky clay indicate it is a geo-material with good heat storage but poor heat release based on a com- parison between summer and winter conditions. All results provide reference for further discussion regarding the environmental effect of thermal balance surrounding a GSHP system. They are essential and valuable for the development of GSHP systems in Shanghai.