Development of a Flow Distribution and Design Model for Transpired Solar Collectors

Unglazed, transpired solar collectors offer a low-cost, high-efficiency means for preheating outside air for ventilation and crop drying applications. Although large building wall applications for these collectors have generally performed well in the field, many have exhibited poor flow distribution which can prevent maximum efficiency from being achieved. The objective of this work was todevelop a computer model which would run quickly on a personal computer and allow designers of transpired collectors to easily adjust geometric parameters to achieve reasonable flow uniformities and to determine efficiencies. This paper describes how this model was developed and includes results from model runs. In order to allow the model to run quickly on the PC, pipe network methods were usedto develop a set of simultaneous equations in the unknown flow rates. Previous research results on heat exchange effectiveness, pressure drop, and wind heat loss were incorporated.