Performance of an adiabatic pre-cooling system for concentrating solar power plants in arid areas

Abstract

An adiabatic pre-cooling (AP) mechanical draft system for concentrating solar power (CSP) plants in arid regions is investigated. The cooling system amalgamates advantages of both dry and adiabatic cooling into a single system. We aim to demonstrate the system’s potentially advantageous spray water consumption characteristics and cooling performance, as it compares to conventional dry and wet-cooling, for arid-area CSP plants. This is done by investigating the AP system’s performance in isolation, via simulation and experimental validation, and a case study simulating performance of a 100 MW arid-area CSP plant with AP, dry and wet-cooling. Our primary contributions entail: analysing AP, dry and wet-cooling and CSP performance with hourly temporal resolution, from which annual hourly statistical summaries are presented, and quantifying AP and CSP performance in response to AP target saturation levels. Our performance assessment ambit includes: power cycle thermal efficiency, cooling or spray water consumption, gross output, parasitic consumption, plant capacity factor and intensive capital expenditure. Our main results show that: increased AP saturation beyond ≈80 % yields insignificant power cycle thermal efficiency enhancement, with gross output stabilising at >70 % saturation. Nonetheless, at 99 % saturation, AP boosts power cycle thermal efficiency by 1.61 % above dry-cooling, consumes 14.61 % less water than wet-cooling, and can increase power block capital cost by 14.19 % before the plant’s intensive capital expenditure equals that with dry-cooling. Furthermore, a 10 percentage point increase in AP saturation level increases the intensive cooling water consumption by ≈26.75 % on average, reduces the cooling parasitic energy consumption by ≈5.37 % on average, and raises the plant capacity factor by ≈0.35 % on average.