AN EXPERIMENTAL & NUMERICAL INVESTIGATION OF HEAT LOSSES FROM SPHERICAL CAVITY SOLAR RECEIVER

Mechanical Engineering

NATIONAL CONFERENCE ON TECHNOLOGICAL ADVANCEMENTS IN ENGINEERING

Different shaped cavity receivers of solar collectors and heat loss in them are always been an interesting topic for the researchers. Experimental and numerical observation on this field has always been a tool for technologies utilizing solar energy. A numerical & experimental analysis was conducted on a spherical cavity solar receiver to analyze its losses. Numerical analysis was carried out using ANSYS FLUENT software. Heat losses are analyzed with and without glazing at the opening and also by varying the inclination angles (0o, 45o, 90o). The cavity receiver was made of copper tube of 6mm inside diameter winded in the form of a sphere with an opening ratio 0.5. In the numerical analysis the inner wall was assumed to be isothermal and adiabatic condition was given to the outer wall and also boussinesq approximation was assumed. The exhaust to the surrounding is taken as pressure outlet. The flow was taken laminar and effect of radiation is neglected. In the experimental analysis constant heat source is obtained by allowing water at different temperatures to pass through the copper tube and readings are taken using thermocouples fitted inside. From the analysis maximum heat loss was observed at 0o inclination of the spherical cavity receiver and minimum loss at 90o inclination. The stagnation temperature is lesser at 0o and larger at 90o. Also, experimental and numerical investigation has been conducted to study the effect of glazing and it is found that flux rate through glazing material is much lesser than the unglazed model.

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