Thermal properties of a variable cavity wall

An experimental investigation of heat transfer through a variable aspect ratio cavity wall has been conducted with the aid of a guarded hot box. A block and brick cavity wall measuring 1.2×1.2 m2 was tested at cavity depths of 78, 60 and 40 mm. The influence of cavity flow upon the rate of heat transfer was established by correlation of convective cavity flows, measured by means of laser Doppler anemometry and by measuring surface temperatures on the four cavity faces. The experimental results show that with increasing aspect ratio, flow magnitude falls, circulation intensity reduces and the thermal resistance of the air cavity is thereby increased. Computational predictions were also used for the purpose of gaining an insight into cavity heat transfer and extrapolating models for further configurations.