Comprehensive study on solar air heater with circular and V-type turbulators attached on absorber plate

Performance enrichment in a single pass SAH (solar air heater) with circular and V-shape inserts are considered in this paper. Two identical SAH; conventional and modified SAH are tested with different Reynolds number ranging from 6000 to 12,000. Circular and V-shape turbulators are fixed in the absorber plate of modified SAH at six different configurations; inline arrangements with 4 x 4 (type-a), 5 x 4 (type-b), 6 x 4 (type-c) and 6 x 4 zigzag arrangement of circular inserts (type-d). Experiments are extended by introducing V-type inserts in convex (type-e) and concave shape (type-f) to create additional turbulence motion. Experiment results revealed that the system efficiency increases with Reynolds number and number of turbulators in absorber plate. Air temperature reaches an upper value of 66 degrees C in type-f with the mass flow rate of 57.7 kg/hr. Nusselt number increases with the Reynolds number and reaches the maximum of 210 for type-f turbulators at Reynolds number of 11615. Thermal enhancement factor decreases with increase in Reynolds number for all modifications. First law, thermohydraulic and second law efficiency increases up to 85%, 63% and 45% respectively for type-f at Reynolds number of 11615. Theoretical analysis also carried out and agrees well with experimental results. (C) 2015 Elsevier Ltd. All rights reserved.