Night sky cooling for concentrating solar power plants

Concentrating solar power (CSP) plants are currently designed with either cooling towers or air-cooled condensers. These two alternatives have a trade off: cooling tower evaporative cooling systems use water, which is a scarce resource in the desert environments where CSP is implemented, but air-cooling results in decreased power plant performance. In this paper, a radiation-enhanced cooling system for thermal power plants is analyzed with a detailed heat transfer model and shown to be feasible for CSP. The proposed system consumes no water and has the potential to out-perform air-cooling. Heat transfer occurs by convection and radiation to the cold night temperatures of desert environments. The radiators are uncovered black panels with tubes of cooling fluid circulated to a cold storage system. The radiators' performance is modeled using a two-dimensional finite difference model and the complete power plant system is modeled on an hourly basis using a standard power plant with thermal energy storage. If the night sky cooling system is the same size as the solar collector field, annual simulation shows that the system can provide over 90% of the required cooling. In addition, performance is improved compared to traditional air-cooling because the parasitic load for circulating water in the radiator system is about 1% of gross energy production while the parasitic load for an air-cooled power plant is about 4%. The night sky cooling system is a potential solution to the water issues that face CSP power plants and other power plants located in desert environments.