Thermal Analysis and Simulation of an Uncovered Flat-plate Solar Collector with Parallel Tubes

Abstract

The use of low-temperature solar thermal energy is of vital importance to households both in temperate zones for heating and in Sahelian zones for domestic hot water. This study focuses on the thermal analysis and simulation of an uncovered flat plate collector with parallel tubes using water as the heat transfer fluid. It is based on the analysis of the thermal performance and the careful selection of each component of the system, namely the coating, the absorber, and the insulator, to obtain optimal operation of the solar collector. The equations are presented in such a way that they can be easily solved by programming in the structured language MATLAB. The Newton-Raphson method was used to determine the temperature of the absorber wall after obtaining a nonlinear equation. Unlike stainless steel and Aluminum, the copper absorber does not store enough energy in itself, but transmits most of the energy flow to the heat transfer fluid, resulting in outlet temperatures of 82.62°C from a 2m tube, making copper the most suitable material for an absorber. TINOX and black chrome are better quality coatings, with a tube outlet temperature of 82.9°C, while that of the selective black plate is 80.12°C. The study also involved a comparative analysis of the thermal system with four types of insulation at the tube outlet. The water temperature ranged from 81.56°C to 82.32°C with insulation, meanwhile it was 73.37°C without insulation. As the fluid inlet temperature approaches ambient temperature, collector efficiency increases until it attains a maximum value of 62%.