Pressure drop and heat transfer characteristics of air-rockbed thermal storage systems

Experiments were conducted to determine the pressure drop and heat transfer characteristics of rockbeds with air as the heat transfer medium. Both the pressure drop and the coefficient of volumetric heat transfer between the air and the rockbeds were found to depend upon the rock size and the air flow rate. In addition, the pressure drop also exhibited dependence on the rockbed porosity. The data, however; did not suggest any influence of rockbed porosity and inlet air and initial rockbed temperatures on the volumetric heat transfer coefficient. Relationships are proposed to estimate the pressure drop and volumetric heat transfer coefficients in rockbeds for the range of variables encountered in low temperature storage applications.