Optimization of receiver height in compound parabolic collector by optical analysis and experimental method

Abstract

The paper presents the method of finding an optimized location of a tubular receiver for the compound parabolic collector (CPC) with a low acceptance angle of 6°. Due to low acceptance angle, the reflected rays concentrate below the common focus of parabola in a definite pattern. Graphical ray tracing approach (GRT) is implemented to execute the optical analysis with and without manufacturing error in a parabolic shape. This analysis is performed on the collector – receiver combinations by varying receiver height below the focus and they are compared on the basis of the utilized area for collector and receiver and projection ratios. The ideal cases in which the collector – receiver combinations contribute a high utilization and projection ratio are selected and verified with the observations of camera target method (CTM) performed on the actual CPC set-up. This set-up is built for a water heater application to validate the results obtained from the GRT and CTM observations. Surface areal irradiance (SAI) method is used to determine the net heat added to the receiver at different heights. The optimum height at which the CPC performed with higher thermal efficiency is concluded as the best location for the tubular receiver for the presented CPC.