Unglazed transpired solar collectors: Heat loss theory

Journal Article · Sun Aug 01 00:00:00 EDT 1993 · Journal of Solar Energy Engineering; (United States)

DOI:https://doi.org/10.1115/1.2930047· OSTI ID:6013703

Kutscher, C F; Christensen, C B; Barker, G M ^[1]

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1. National Renewable Energy Lab., Golden, CO (United States)

Unglazed transpired solar collectors offer a potentially low cost, high-efficiency option for once-through applications such as preheating air for ventilation, crop drying, and desiccant regeneration. This paper examines the major heat loss mechanisms associated with this concept. Radiation heat loss is determined by considering losses to both the sky and the ground. Convective heat losses are obtained by integrating the product of the temperature and velocity profiles in the boundary layer at the downwind edge of the collector. This convective heat loss is then expressed in terms of the thermal equivalent length of irradiated absorber, and analysis shows that this loss can be very low for large collectors event under windy conditions. These results are incorporated into a simple computer model which predicts collector efficiency as a function of suction velocity, wind speed, ambient temperature, and radiation. Remaining research issues are discussed.

• OSTI ID: 6013703
• Journal Information: Journal of Solar Energy Engineering; (United States), Journal Name: Journal of Solar Energy Engineering; (United States) Vol. 115:3; ISSN JSEEDO; ISSN 0199-6231
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
141000* -- Solar Collectors & Concentrators
AMBIENT TEMPERATURE
CONVECTION
CROPS
DESICCANTS
DRYERS
EFFICIENCY
ENERGY LOSSES
ENERGY TRANSFER
EQUIPMENT
HEAT LOSSES
HEAT TRANSFER
LOSSES
MASS TRANSFER
PERFORMANCE
RADIANT HEAT TRANSFER
RADIATIONS
REGENERATION
SOLAR COLLECTORS
SOLAR DRYERS
SOLAR EQUIPMENT
SOLAR RADIATION
STELLAR RADIATION
THERMAL EFFICIENCY
UNGLAZED SOLAR COLLECTORS
VELOCITY
VENTILATION
WIND