Keywords: energy efficiency, exergy efficiency, solar air heaters, SAH, sub-collectors, series configuration, parallel configuration, collector aspect ratio, mass flow rate
Exergetic performance evaluation of a single solar air heater with N sub collectors arranged in series or parallel configuration
The energy and exergy efficiency of the solar air heater (SAH) collector array consisting of a number of sub-collectors (N) arranged either in series or in parallel configuration have been evaluated for various values of collector aspect ratio (AR), mass flow rate per unit collection area (G) of the SAH collector array and N either in series or in parallel configuration for a given total collection area of SAH collector array. The energy efficiency increases with increase of G, AR and N in series configuration, and it decreases with increase of duct depth (H) and N in parallel configuration. The exergy efficiency based evaluation criterion shows that performance is not monotonous function of N either in series configuration or in parallel configuration, G, AR and H. It has been found that for higher exergy efficiency there must be optimum G for any configuration, and sub-collectors should be arranged in parallel configuration if G is high.