Turbulent flow analysis of a flattened tube in- plane curved solar collector using Titanium oxide nanofluid

Abstract

The present study deals with the experimental investigation on the performance of a solar water heater consisting of a flattened tube absorber with a spiral configuration. The analysis is carried out by using water and Titanium oxide nanofluid of 0.1% concentration as the working fluid adopting forced circulation for various flow rates of 0.05 kg/s, 0.066 kg/s, 0.083 kg/s. The effect of mass flow rate on the flatness of the tube and spiral configuration of the absorber is investigated. The outlet fluid temperature, instantaneous efficiency, Reynolds number, Nusselt number, and heat transfer coefficient, friction factor, and Dean number are the parameters considered in this analysis. The results show that there is a significant increase in heat transfer coefficient of 22% for TiO2 (φ = 0.1) nanofluid compared to water. The results indicate that the instantaneous efficiency increases by 7.5% for TiO2 nanofluid. The highest outlet temperature of 67 °C was obtained for a mass flow rate of 0.066 kg/s. The removal energy parameter FRUL increases by 20% and the absorbed energy parameter FR(τα) increases by 5% for TiO2 nanofluid comparing with water. The values of the Nusselt number, friction factor and dean number obtained experimentally are compared with numerical correlation and the deviation is found to be within ±3% to ±8%. The Dean number is calculated for different curvature ratio of κ1 = 0.141, κ2 = 0.070 and κ3 = 0.047.Increase dean number of 18% with increase in curvature ratio is found.