Experimental investigation on heat transfer performance of solar collector with baffles and semicircular loops fins under varied air mass flow rates

Insertion of fins and turbulators is one of the effective approaches to augment the restricted heat transfer characteristics of an air-based flat plate solar collector and the creation of holes/perforations in baffles and fins further increase the degree of improvement. Therefore, the prime objective of the present study is the experimental assessment of temperature distribution, heat transfer coefficients and thermal efficiency of a solar air heater integrated with baffles and fins in the form of hollow semicircular loops. The plain absorber plate was modified with the continuous insertion of semicircular loops of 0.03 m radius, constructed with wire of 0.002 m thick in a staggered manner. The experiments were conducted for measurement of solar intensity and collector temperature at air mass flow rates ranging from 0.006 to 0.02 kg/s. Results indicated the temperature of the air to be lower than loops and absorber plate but surpassed the glass plate temperature. The average temperature rise of air in finned collector was ranging from 14.08 to 22.78 degrees C, remarkably higher than conventional flat plate solar collector. Air mass flow rate of 0.02 kg/s presented 109%, 80.72% and 62.56% augmented average heat transfer coefficient than 0.006, 0.01 and 0.015 kg/s, respectively and 22.03% enhanced thermal efficiency than 0.006 kg/s. Further, the finned collector at 0.02 kg/s yielded 19.73-34.3% superior average thermal efficiency and 37.38-66.05% escalated heat transfer coefficient over the smooth absorber plate solar collector. The solar collector with hollow fins and baffles will be suitable for domestic and industrial applications like agricultural products drying, greenhouse, and space heating.