Abstract
To efficiently convert and utilize intermittent solar energy, a novel solar-driven ethanol steam reforming (ESR) system integrated with a membrane reactor is proposed. It has the potential to convert low-grade solar thermal energy into high energy level chemical energy. Driven by chemical potential, hydrogen permeation membranes (HPM) can separate the generated hydrogen and shift the ESR equilibrium forward to increase conversion and thermodynamic efficiency. The thermodynamic and environmental performances are analyzed via numerical simulation under a reaction temperature range of 100–400 °C with permeate pressures of 0.01–0.75 bar. The highest theoretical conversion rate is 98.3% at 100 °C and 0.01 bar, while the highest first-law efficiency, solar-to-fuel efficiency, and exergy efficiency are 82.3%, 45.3%, and 70.4% at 215 °C and 0.20 bar. The standard coal saving rate (SCSR) and carbon dioxide reduction rate (CDRR) are maximums of 101 g·m−2·h−1 and 247 g·m−2·h−1 at 200 °C and 0.20 bar with a hydrogen generation rate of 22.4 mol·m−2·h−1. This study illustrates the feasibility of solar-driven ESR integrated with a membrane reactor and distinguishes a novel approach for distributed hydrogen generation and solar energy utilization and upgradation.
Highlights
The combustion of fossil fuels worldwide is releasing an enormous quantity of CO2 into the atmosphere that is considered largely responsible for environmental problems
Hydrogen can be produced by several solar thermochemical reactions [5,6,7], wherein the fuel reforming process driven by solar energy can generate hydrogen efficiently [8,9]
Giaconia [33] studied methane steam reforming using a membrane reactor driven by concentrated solar power and achieved a conversion rate twice that of a conventional reformer operating at thermodynamic equilibrium
Summary
The combustion of fossil fuels worldwide is releasing an enormous quantity of CO2 into the atmosphere that is considered largely responsible for environmental problems (e.g., global warming, NOx and SOx pollution). Giaconia [33] studied methane steam reforming using a membrane reactor driven by concentrated solar power and achieved a conversion rate twice that of a conventional reformer operating at thermodynamic equilibrium. He et al [5] modeled propane dehydrogenation using a trough solar collector combined with a membrane reactor and observed a maximum propane conversion rate and propylene yield. A novel solar-driven ESR system combined with an HPM reactor is proposed and analyzed This system allows for the conversion of intermittent low-grade solar thermal energy into high-grade chemical energy. The packed-bed (feed side) consists of a commercial nickel-based catalyst [35] to catalyze the ESR reaction, while the perme4atoefs1id e is connected to a vacuum pump that maintains a pressure conducive for hydrogen separation
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