Studying some of the earth tube heat exchanger and soils properties

In this paper the composition and thermal property of soil and pipe of earth tube heat exchanger are discussed. The main factors that impact the soil thermal properties and several commonly-used pipe materials are studied. The impact of soil thermal conductivity and pipe thermal conductivity on the soil temperature field around the buried pipe is very important. As an energy-saving and environment friendly air conditioning technology, earth tube heat exchanger has been utilized wildly for some years. It is necessary to study in detail soil properties and pipe materials for utilizing earth tube heat exchanger successfully. The thermal conductivity for sandy soil is higher than sandy clay loam soil  and heat exchange rate between air in metal pipe and soil achieve  more 5 time for PVC pipe and wet soil with 15% moisture achieve heat exchange rate to air in pipe by 5% more dry soil.