Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

JET IMPINGEMENT IN AN UNGLAZED SOLAR AIR COLLECTOR

Get access (open in a dialog) DOI: 10.1615/IHTC13.p24.160
13 pages

Abstrakt

Jet impingement in a solar air collector is associated with low jet Reynolds numbers and focused on improving the heat gained to the heat transfer fluid. Studies have shown that jet impingement can marginally improve the thermal efficiency of a glazed collector. However, little attention has been placed on applying jet impingement to an unglazed solar air collector. An unglazed roof integrated solar air collector has been developed, which is based on corrugated steel roofing. The application of jet impingement involves jets of air induced under negative pressure to impinge on the corrugated absorber. A flow distribution and thermal model of the collector were developed. The models identified that a crucial factor in determining the efficiency was mixing. Since the jets are drawn into the duct, the jet Reynolds number increases along the collector length. Mixing describes the amount of flow through the downstream holes which mixes with the downstream fluid within the duct. It was determined that the more mixing the lower the thermal efficiency. Low levels of mixing occurred in collectors of short length, and an experimental investigation was undertaken to investigate this effect. The experiments confirmed the results from the models, and identified that jet impingement could increase the thermal efficiency of the roof integrated collector by 39%.