Experimental flow characteristics of multi-pipe earth-to-air heat exchangers

The paper presents experimentally obtained flow characteristics of earth-to-air multi-pipe heat exchanger models. Investigation submerged exchangers consisted of 3, 5 and 7 parallel branches connected to the main pipe with the angles of 45° and 90°. The total pressure losses and flow division between the exchanger branches have been presented in figures. Significant flow non-uniformity (non uniform division of air between the exchanger pipes) and considerable pressure losses differences between 45° and 90° structures have been observed and discussed.