Three dimensional numerical analysis of conjugate heat transfer for enhancement of thermal performance using finned tubes in an economical unglazed solar flat plate collector

Flat plate solar collectors are the most common thermal collectors used among the various solar collectors for domestic and industrial purposes. This is mainly due to simple design as well as low maintenance cost. But an attempt is being made in this paper to design low cost but comparatively efficient, maintenance free flat plate collector. The greater affordability in terms of cost is the most important objective of the present paper. In general, flat plate collectors have lower efficiency as large heat losses occur from the collector surface by convection and re-radiation. In the present work an unglazed solar collector is designed with an innovative serrated fined tube design as well as another designing with diametrically placed planar fin bifurcating the absorber tube passage. The idea behind these two designs is that greater heat transfer by convection is possible from the unglazed collector to the absorber tubes. The numerical results obtained using Computational fluid dynamics by employing conjugate heat transfer show that for lower flow rates the heat transfer flux increases as compared to the base model for both the configurations.