Comprehensive performance evaluation of the glass tube solar collector with relative single-axis tracking: solar collector design, mathematical model, experimental validation, numerical optimization and life cycle assessment

Abstract

This paper presents a comprehensive performance evaluation of the glass tube solar collector with relative single-axis tracking, incorporating various methods and approaches. In the first phase of the paper, a novel (unique, simple and compact) solar collector construction for single-stage (direct) water heating is presented. The performance (useful heat power, heat losses and thermal efficiency) of the mentioned solar collector is investigated mathematically (using a three-stage iterative calculation algorithm) in the second phase. Results of the experimental validation (using a specific useful heat power as a comparison indicator), in the third phase, showed that the average daily absolute measurement percentage error was 5.67 % (for clear-sky days) and 6.66 % (for cloudy-sky days). In the fourth phase, two (also novel) optimization criteria (one geometric and one thermal) were defined, which were then used in the Ansys Fluent software to numerically optimize the width of = the flat absorber plate (80 mm) and the mutual axial distance between them (99.3–103.51 mm, depending on the date). In the fifth and final phase, a simplified Life Cycle Assessment method is employed to critically analyze and evaluate the overall environmental impact of the solar collector if it were to be commercialized, as the authors believe it has potential for wider application in the future.