Optical efficiency and convective heat loss of a cylindrical-hemispherical receiver used in parabolic dish concentrator

The efficiency of the parabolic dish concentrator system is primarily affected by the geometrical parameters of the receiver. To understand these effects, optical and thermal analysis of a cylindrical-hemispherical cavity receiver is carried out in this paper. The optical efficiency of the receiver is evaluated for varying receiver height (h\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$h$$\end{document}) from 0.135 to 0.165 m and coil tube diameter (dt\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${d}_{{\text{t}}}$$\end{document}) from 0.009 to 0.012 m using the Monte Carlo Ray Tracing Method, and it is found that the optical efficiency is achieved to be 92.87% for the receiver having tube diameter of 0.012 m with height of 0.145 m. Thermal analysis of the receiver is also carried out to estimate the heat loss in both natural and forced convection modes using numerical modeling. The heat losses are analyzed for varying factors like receiver orientation (gamma = 0o to 90o), wind velocity (V = 0 to 6 m s-1) and receiver temperature (T = 600 and 700 K) with head-on wind and back-on wind directions. The results illustrate that the heat loss from the receiver is high at gamma = 60o for head-on wind direction; and for back-on wind direction, this is high at gamma = 90o. On the other hand, the minimum heat loss is observed at gamma = 30o for both directions of wind. Artificial Neural Network is also applied to estimate the convective heat loss from the receiver. Error matrices like average percentage error (APE), maximum correlation coefficient (R), and root mean square error (RMSE) are used to evaluate the model performance considering input variables like receiver aperture diameter (D\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{D}}$$\end{document}), receiver orientation (gamma\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upgamma$$\end{document}), surface temperature of the receiver (Ts\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{{\text{s}}}$$\end{document}), and wind velocity (V\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$V$$\end{document}). Also, the predicted values of ANN have been compared with the results obtained from numerical analysis to evaluate the error percentage.