Modelling and analysis of parameters of vacuum tube solar collector with U-shaped tube for different climates

Abstract In this study, based on the energy balance for different components of a double-layered vacuum-tube solar collector with U-tube, thermal performance unit is investigated separately using an analytical and quasi-dynamic method. The model used in study determines temperature distribution longitudinal radial directions. research, effects physical parameters heat transfer including size collector, thermal-loss coefficient, absorption mass flow resistance air layer under climate conditions have been evaluated collector. results showed that by increasing diameter tube constant length, annual efficiency increased. Also, fixed-diameter tube, increases, but increase meagre lengths >1.5 m. optimal rate maximum has obtained cities climates. According to results, climates values can be optimized as relationship between average radiation annually symbol flow.