Detailed performance analysis of parabolic trough collectors including geometric effect

Abstract

Parabolic trough collectors (PTCs) have been known for years as one of the leading methods for extracting energy from the sun. In the present work, the performance of PTCs was investigated. However, its performance needs some improvement to be integrated in more and wide range of applications. This idea motivated the author to investigate the performance of parabolic trough collectors in detail. Thus, in the present work, the performance of parabolic trough collectors is investigated. The effect of eight geometric and inlet variables on the PTC performance was evaluated. Two performance factors , the temperature difference and thermal efficiency, were selected. The effect of inlet condition, including inlet mass flow rate and inlet flow temperature reflector geometry, including reflector length and width,receiver diameters, including inlet and outlet reciever diameters, and cover diameters, including the inlet and outlet cover diameters on these PFs was assessed. Eight thermal working fluids were considered. A non-linear mathematical model was developed for PTC and implemented into MATLAB code where an iterative technique was used to conduct the present analyses. Level curves were generated to study the PTC key performance parameters. The curves revealed that the maximum values of the PFs and maximum range of change in these PFs occurred when the inlet conditions were varied. Changes in the inlet temperature, and changes in the reflector geometry yielded the highest and second-highest values. The cover geometry had the minimum effect on the PFs. Moreover, the best maximum efficiency, best maximum temperature difference, and maximum range of efficiency change were obtained for water, air, and carbon dioxide, respectively. The effect of inlet temperature is more significant than the mass flow rate effect on the thermal efficiency, whereas this effect is reversed in case of the temperature difference, by which the mass flow rate exerts the least influence on the temperature difference.