Experimental investigation and numerical modelling on the performance assessments of evacuated U – Tube solar collector systems

Abstract

Abstract In this paper, an experimental investigation for predicting the performance of evacuated U – tube solar collector is presented. A simplified numerical model is developed for predicting the working fluid outlet temperature of a single evacuated U – tube solar collector and also for the whole solar collector system. The model predictions are compared with the experimental data and noticed a good agreement exists between them. It is observed from the experimental and numerical analyses that evacuated U – tube solar collector manifolds connected in series provides higher temperature rise of working fluid at higher solar intensities and lower working fluid inlet temperatures and flow rates. The working fluid transition time in an evacuated U – tube solar collector is defined for analysing the time taken by a working fluid to attain a steady state condition. Based on experimental analysis, three empirical correlations for predicting working fluid transition time, energy efficiency and exergy efficiency are developed as the function of operating parameters and ambient temperature. Data predicted from these correlations match with the experimental data with maximum errors of ± 12.7%, ± 6.9% and ± 7.8% for working fluid transition time, energy efficiency and exergy efficiency of an evacuated U – tube solar collector, respectively.