Convective heat transfer in louvered solar collectors

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6761945

Christopher, D M

The first theoretical model is based on an algebraic formulation of the conversion equations. It accounts for conduction, convection, and thermal and solar band radiation exchange. The second theoretical model is a differential formulation and numerical solution of the two-dimensional conservation equations. The analysis includes variable properties, buoyancy, and radiative transfer between surfaces. The multiply-connected computational region lies between the lower cover plate and the backplate and contains the absorber, which is made of overlapping, opaque louvers. The experimental and differential models are used to determine the convective heat transfer coefficient along the louver surfaces. The thermal efficiency of the louvered collector is determined from the experimental results and from the algebraic model. Parametric studies are performed to determine the effects that collector and louver geometry and several operating parameters have on the louver Nusselt number and the collector thermal efficiency. The local Nusselt number along the louver is shown to be proportional to the inlet temperature. The collector tilt is shown to have little influence on the Nusselt number; however, the buoyancy forces do cause greater mass flow rate between the louvers near the entrance than between louvers near the exit. Finally, the collector design containing ten 12 cm louvers per meter of collector length will retain the high convective heat transfer rate inherent in the louvered design. For this design, the thermal efficiency of the louvered solar collector was found to be at least 20% greater than that of a comparable flat-plate collector.

• OSTI ID: 6761945
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
141000* -- Solar Collectors & Concentrators
CONVECTION
DESIGN
EFFICIENCY
ENERGY TRANSFER
EQUIPMENT
GEOMETRY
HEAT FLOW
HEAT TRANSFER
INCIDENCE ANGLE
MATHEMATICAL MODELS
MATHEMATICS
MECHANICAL PROPERTIES
OPERATION
PARAMETRIC ANALYSIS
PHYSICAL PROPERTIES
RADIANT HEAT TRANSFER
SOLAR ABSORBERS
SOLAR COLLECTORS
SOLAR EQUIPMENT
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES