Energetic and exergetic efficiency analysis of a v-corrugated solar air heater integrated with twisted tape inserts

Abstract

The present study provides an analytical and numerical investigation of the energy and exergy analysis of a v-corrugated solar air heater (VCSAH) integrated with twisted tape insert (TTI). The TTI is placed in the air passages formed by the absorber and backplates. The effect of design parameters such as twisted tape ratio (Y) and the number of channels (N) on the thermo-hydraulic performance is examined for a wide range of Reynolds number (Re) under realistic weather conditions data. The results reveal that as the Y decreases, the thermo-hydraulic efficiency of VCSAH-TTI is first rises to a specific value of Re to reach the peak value, and then drops down. The optimal number of channels that provides maximum thermo-hydraulic efficiency is N = 5 when the TTI is implemented. The maximum thermal and thermo-hydraulic efficiencies of VCSAH-TTI observed are 17.5 and 17%, respectively, compared to the VCSAH without TTI. Besides, the thermal efficiency is directly proportional to the number of channels. At Re = 10,000, the thermal efficiency is found to be 69.3% and 76.7% for N = 4 and N = 14, respectively. The accumulated useful heat gain of the proposed design is 17% higher than VCSAH without TTI.