EXPERIMENTAL STUDY ON THERMAL AND MOISTURE CHARACTERISTICS OF SOIL AROUND BURIED PIPE UNDER INTERMITTENT OPERATION
The test platform of soil heat and humidity transfer around ground source heat pump buried pipe was built.The influences of initial water content,waterproof layer,insulation layer and phase change backfill on soil heat and humidity transfer were investigated.Sandbox experiment results show that the heat of vertical buried pipe will cause the heat and humidity transfer of the surrounding soil.The increase of soil initial water content is beneficial to temperature recovery and heat transfer.The peak temperature during system operation decreases with the increase of initial water content.Waterproof layer,insulation layer and phase change backfill materials also have an impact on the temperature peak and temperature recovery.Temperature gradient and hydraulic gradient are the main factors causing water migration.At an initial moisture content of 15%,the temperature gradient dominates,driving the water radially out far away.At the initial moisture content of 25%,the hydraulic gradient dominates,causing water permeates down the depth.
ground source heat pumpsoil temperaturesoil humidityphase change material
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