Transpired Solar Air Heaters. Volume 1. Investigation of Transpired Porous-Bed Solar Air Heaters. Final Report.

摘要

Tests were conducted to determine the thermal performance of a number of transpired porous-bed solar air heaters. Improvements were made to a reference double-glazed transpired solar air heater and the performance experimentally determined. An air heater incorporating two parallel glass-plate honeycombs for air heater incorporating two parallel glass-plate honeycombs for heat-loss control was also tested. The performance of the double-honeycomb collector proved to be superior to the reference solar air heater's due to the increased transmittance of the coverglass assembly. Both collectors exhibited performance greater than any current state-of-the-art collectors. Two steady-state performance models of the reference double-glazed solar air heater were formulated. One (reference model) incorporated the theoretical work of Edwards and Leung to predict the air temperature rise through the porous bed while the other assumed an isothermal bed with a heat-exchanger effectiveness of one. An energy balance was performed at each collector element, and the resultant system of nonlinear equations was solved iteratively to predict the collector's performance. Air recirculation above the porous bed was modeled using the reference formulation. Collector performance was predicted closely using the isothermal bed model. The reference model yielded close prediction using a recirculation rate of 20%. (ERA citation 08:031551)