Experimentally validated 3D simulation and performance optimization of a solar air duct with modified conical vortex generators

摘要

Providing flow-disturbing components on the effective heat transfer area of the absorber plate is the most efficient thermohydraulic performance enhancement technique employed in a solar air heater. The present investigation aims at finding the optimal set of geometrical parameters for a solar air heater with modified conical vortex generators. Optimization approach is adopted considering the thermohydraulic performance of the proposed design of the solar air heater. Experimentally validated numerical simulations for different parameters of the vortex generators like relative pitch ratio of 8 to 15, relative vortex generator height ratio of 0.17 to 0.34 and Reynolds number range of 3000 to 16,000 are optimized using Grey relational analysis and Overall evaluation criteria. Performance of solar air heater under different investigated parameters is analysed using performance indices like Nusselt number, friction factor, thermal performance enhancement factor, friction enhancement factor and thermo-hydraulic enhancement factor. A maximum Nusselt number of 142.4 is observed for relative pitch ratio of 8 and relative vortex generator height ratio of 0.34. Optimized geometrical parameters are predicted for different percentage weightage set on thermal and hydraulic performances. Correlation equations for Nusselt number and friction factor are developed for the overall range of investigated parameters.