Thermodynamic Performance Evaluation of Concentrating Solar Collector with Supercritical Carbon Dioxide (sCO2) Base Nanofluids

Abstract

The use of supercritical carbon dioxide as a working fluid is an important alternative to enable the use of parabolic collectors in the high-temperature applications field. In the present paper, the effects of carbon black nanoparticles dispersed in supercritical carbon dioxide (sCO2) base fluid on the energetic and exergetic performance of parabolic trough collectors are theoretically investigated. Thermal modeling and performance analyses are performed through the developed model in the Engineering Equation Solver software. To present operating conditions of the system, all working fluids are tested under a pressure of 80 bar at a mass flow rate of 1.1 kg/s. In these analyses, the fluid inlet temperature, ambient temperature, and nanofluid concentration are determined as the variable indicators. Up to approximately working fluid inlet temperature of 705 K, the exergy efficiencies of the concentrating collectors using the sCO2 nanofluids are higher than that of the concentrating collector using the sCO2 base fluid. Additionally, the exergy efficiency increases in the systems using nanofluids with 2% and 4% concentration ratio are between 0.34–6.96% and 0.49–11.44%, respectively, according to the system using base fluid. Besides, at the working fluid inlet temperature values greater than 705 K, the exergy efficiency of the collector of using the sCO2 working fluid is found higher than the collectors using the nanofluids. However, at the same working fluid inlet temperatures, the fluid outlet temperatures of the collectors with the sCO2 nanofluids are higher than the system with sCO2 working fluid.