Design, fabrication and investigations of natural convection step serrated fin plate integrated trough array low-cost collector for solar air heating: An application to agricultural crop drying

Abstract

This paper establishes the design modification procedure for flat plate solar thermal collector and investigates the performance by incorporating a specially designed low-cost Step Serrated Fin Plate Integrated Trough Array (SSFPT) on the sun-facing side of the collector. The idea of integrating trough profile on the step serration is for concentrating heat radiations with a latent heat storing copper pipe at its focal point filled with phase change material, giving tremendous improvements and high thermal and exergy efficiencies. Also, the step serrated fins increase air stagnation and heat acquisition. The performance of the SSFPT collector solar air heater is experimentally investigated and compared with the conventional Flat Plate Collector Solar Air Heater (FPC SAH) of the same collector area by natural convection. The average outlet temperature of SSFPT collector SAH and FPC SAH varies from 44.5 to 74.5 °C and 38.0–48.2 °C and the average stagnation temperature lies between 43.1 and 74.4 °C and 38.5–48.5 °C. The maximum thermal and exergy efficiency of SSFPT SAH is 66.32 % and 23.06 %. This proposed collector achieves a maximum Nusselt number of ∼ 7.11 at Rayleigh number ∼ 441.5 × 103 and a better augmenting effect with a thermo-hydraulic performance factor of 1.4 after 4 h of operational time. The thorough economic analysis yields cost per kWh of the SSFPT collector is 0.10$ which is 0.18$ lesser than conventional FPC SAH.