Performances evaluation of a mid-/low-temperature solar thermochemical system with cooling, heating and power production

Abstract

Abstract A novel solar-assisted combined cooling, heating and power (CCHP) system is developed for improving the energy conversion efficiency in this work. Solar thermal energy (250-350℃) collected by the parabolic trough solar collector is used to drive a thermochemical reaction of methanol decomposition, then the generated solar fuel of syngas is fed into an internal combustion engine (ICE) to generate electricity. The high-temperature exhaust gas released from the ICE is used to produce cooling and heating energies via a double-effect LiBr-H2O absorption refrigerator and heat exchangers. The introduced solar energy is converted to chemical form of syngas and replaces a part of fossil fuel. The numerical simulation of the novel CCHP system is carried out, and the system energy efficiency and exergy efficiency at the designate condition are 77.69% and 55.94%, respectively. The system off-design performances are investigated by deploying it to a shopping center building, and the system annual efficiency reaches to 49.29% with the solar fraction of 11.58%. As compared with the typical CCHP systems with direct methanol combustion, the annual methanol consumption of the proposed system decreases to 895.15 tons, with the fuel saving ratio of 6.11%. The research findings provide a promising way for the cascade utilization of solar energy, and broaden its applications in distributed energy systems.