Design and Evaluation of a Compound Parabolic Concentrator for Heat Generation of Thermal Processes

Abstract

A solar concentrator was designed using a detailed one-dimensional numerical model previously developed to describe the heat and fluid-dynamic behavior inside a compound parabolic concentrator (CPC). The governing equations (continuity, momentum and energy) inside the CPC absorber tube, together with the energy equation in the tube wall and the thermal analysis in the solar concentrator were solved. Two CPC geometries were proposed based on numerical simulation and commercial availability of materials; one of this is tested in this work. A ray tracing analysis was made for this configuration to quantify optical energy losses due to truncation. Then, a module with aperture area of 2.1 m2 was constructed. The module has 12 CPCs, each one with real concentration ratio of 1.8, acceptance angle of 30°, and a tubular receiver covered by a selective surface. An experimental setup was designed and built to test different operational conditions for the module; for example mass flow rate and inlet temperature. The experimental setup has the following elements: The CPC, two water storage tanks, a recirculation pump, and a support structure that allows positioning the CPC at different angles. Experimental results obtained using the Mexican standard NMX-ES-001-NORMEX-2005 show that this technology could be able to supply stable temperatures for industrial processes. However, a new prototype is going to be developed and constructed in order to improve some manufacturing errors detected in these experimental tests.