Comparative performance analysis of solar powered supercritical-transcritical CO2 based systems for hydrogen production and multigeneration

CO2 based power and refrigeration cycles have been developed and analyzed in different existing studies. However, the development of a CO2 based comprehensive energy system and its performance analysis have not been considered. In this study, the integration of a CO2 based solar parabolic trough collector system, a supercritical CO2 power cycle, a transcritical CO2 power cycle, and a CO2 based cascade refrigeration system for hydrogen production and multigeneration purpose is analyzed thermodynamically. This study aims to analyze and compare the difference in the thermodynamic performance of comprehensive energy systems when CO2 is used as the working fluid in all the cycles with a system that uses other working fluids. Therefore, two comprehensive energy systems with the same number of subsystems are designed to justify the comparison. The second comprehensive energy system uses liquid potassium instead of CO2 as a working fluid in the solar parabolic trough collector and a steam cycle is used to replace the transcritical CO2 power cycle. Results of the energy and exergy performance analysis of two comprehensive energy systems showed that the two systems can be used for the multigeneration purpose. However, the use of a steam cycle and potassium-based solar parabolic trough collector increases the comprehensive energy systems' overall energy and exergy efficiency by 41.9% and 26.7% respectively. Also, the use of liquid potassium as working fluid in the parabolic trough collectors increases the absorbed solar energy input by 419 kW and 2100 kW thereby resulting in a 23% and 90.7% increase in energetic and exergetic efficiency respectively. The carbon emission reduction potential of the two comprehensive energy systems modelled in this study is also analyzed. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study analyzed the thermodynamic performance of a CO2-based comprehensive energy system, comparing it with a system that uses other working fluids. Results showed that using a steam cycle and potassium-based solar parabolic trough collector increased the overall energy and exergy efficiency of the systems. Additionally, the use of liquid potassium in the collector significantly improved the energetic and exergetic efficiency.