Energy and exergy analyses of a nanofluid based solar cooling and hydrogen production combined system

Abstract A nanofluid is used as working fluid in a solar parabolic trough collector (PTC) for solar cooling and hydrogen production. The combined system is composed of five sub-systems including PTC, Rankine cycle, thermal energy storage, triple effect absorption cooling system (TEACS), and proton exchange membrane (PEM) electrolyzer. The results of the thermodynamic model for the hybrid PTC/Rankine cycle, TEACS and PEM electrolyzer subsystem are validated. Furthermore, the effects of ambient temperature, solar irradiation and nanofluid volume fraction on the hydrogen production, COP and exergy efficiency of TEACS, and the overall energy and exergy efficiency of the hybrid system are examined. We found that the rate of hydrogen production increases at higher solar radiation intensity because the Rankine cycle delivers more power to the PEM electrolyzer. Exergy analysis reveals that the efficiency of the hybrid system increases approximately by 9% by increase of ambient temperature from 5 to 40 °C. The power generation by Rankine cycle and hydrogen production by electrolyzer increases using higher volume fraction of nanoparticles. The overall energy and exergy efficiency of the hybrid system with the nanoparticles volume fraction of 0 are 1.55 and 1.4 times more than the nanoparticles volume fraction of 0.03 at solar intensity of 600 W m −2 .