Performance Analysis and Optimization of Solar Thermochemical Water-Splitting Cycle with Single and Multiple Receivers

Abstract

Solar thermochemical water-splitting cycle models for hydrogen production with single and multiple receivers working between 1773 and 1173 K are developed. The receiver pressures and aperture sizes are optimized for maximum cycle efficiency. The efficiency of the cycle increases with the number of receivers because of the decrease in vacuum pump work. The solar-to-fuel efficiency is increased by 14% going from a one receiver system to a four-receiver system. The performance analyses of the cycles with varying direct normal irradiance (DNI) shows that the advantage of multiple receivers vanishes as DNI decreases because of the constant radiation losses from the receiver apertures. These radiation losses from the aperture can be lowered when a receiver with a variable aperture size is used. The efficiency of a two-receiver system increases by 48% at DNI 300 W m−2% and 15% at DNI 900 W m−2 using a variable aperture size. The performance of the multireceiver systems with variable aperture size is discussed using a linear regression model. In addition, the option of cogeneration of hydrogen and electricity in a multireceiver system is analyzed. The efficiencies of single-, two-, three-, and four-receiver systems for cogeneration are 19.6%, 20.0%, 20.57%, and 21.1%, respectively.