Developing an Empirical Co-Relation for Performance of a Schefflersolar Concentrator Using Dimensional Analysis

The present paper consists of arriving at an empirical correlation between the performances of the solar Scheffler Concentrator for Steam Generator (SCSG) with respect to various parameters. In order to reduce the complexity due to large number of dependent variables, dimensional analysis has been used to simplify the calculations. The interdependence of different parameters and the regression analysis has been performed using MATLAB. Multidimensional nonlinear multivariate fit is achieved using MATLAB function ‘nlinfit’, which gives multivariate relation between any two parameters. Extensive analysis of regression results shows system efficiency of solar concentrator increases with increase in UX parameter which signifies the importance of the overall heat transfer coefficient (U), the direct solar intensity (Ib) and temperature difference between solar receiver and ambient atmosphere in terms of a single dimensionless parameter and it is strongly dependent on steam pressure than concentration ratio. Further analysis to find the optimum point for maximum efficiency and heat gain gives a maximum efficiency of 44.74% at 5.6bar pressure for the SCSG of 6.5m2aperture area and 52.8% at 2bar for SCSGof 2.5m2aperture area. Keywords - Solar energy, concentration ratio, Scheffler collector, dimensional analysis, regression, efficiency.