Thermodynamic and exergy analysis of a hydrogen and permeate water production process by a solar-driven transcritical CO_2 power cycle with liquefied natural gas heat sink

摘要

A novel solar power, water and hydrogen cogeneration plant with recovery of cryogenic energy is proposed in this paper to produce hydrogen and permeate water by gasification of Liquefied Natural Gas (LNG). A mathematical model is developed to simulate the system and an exergy and thermodynamic parametric analysis is carried out to investigate the effect of several thermodynamic parameters on overall system performance. A dynamic Reverse Osmosis (RO) desalination model is introduced to produce different permeate and feed water mass flow rates. By the results, about 26.8% of net produced power is recovered by a turbine locating in RO brine discharge. The exergy analysis showed that the maximum exergy is destructed by collectors and condenser, respectively. Also, among output streams, natural gas ejected by Natural Gas (NG) turbine has the maximum exergy output. Furthermore, CO2 turbine inlet pressure has an optimum value aimed to produce maximum production and net output power. The net output power, moreover, increases by rising the boiler and turbine inlet temperatures and NG inlet pressure, while it decreases by increasing condensation temperature. It is noteworthy that by increasing recovery ratio of RO unit, the permeate water production increases and hydrogen production rate decreases, by contrast. (C) 2017 Elsevier Ltd. All rights reserved.