Improving thermal power of a cylindrical solar cooker via novel micro/nano porous absorbers: A thermodynamic analysis with experimental validation

Abstract

In this paper, cylindrical solar cookers with microporous absorbers are experimentally and numerically investigated in terms of thermodynamic performance figures. For a typical spring day in Bayburt, which is a good example of continental climate in Turkey, a comprehensive thermal performance analysis is done for a cylindrical solar cooker. A mathematical model is developed to verify the accuracy of the measurements, which is applied to a solar cooker with conventional absorber, and a good accordance is achieved between numerical and experimental data. Afterwards, the model is utilised to analyse the impacts of porous absorbers on thermal performance parameters of cylindrical solar cooker with different porosity characteristics. In this respect, three porosity configurations (triangular, semi-circular and trapezoidal) are considered on the absorber surface, and the enhancement in thermal performance figures are evaluated through a computer code written in MATLAB. The results reveal that microporous absorbers play a key role in improving thermodynamic performance parameters of cylindrical solar cooker. According to the experimental results, energy and exergy efficiency of cylindrical solar cooker with ordinary absorber is found to be in the range of 27.7–17.0 and 17.9–11.5%, respectively. On the other hand, the said figures are enhanced to 30.4–18.7 and 19.9–12.8% with triangular porosity, 33.2–20.4 and 21.7–14.0% with semi-circular porosity, 34.6–21.2 and 22.6–14.6% with trapezoidal porosity. The time to boiling is also noticeably reduced via microporous absorbers, which is justified through a dynamic regression analysis.