A Two-Dimensional Multiphysics Coupling Model of a Middle and Low Temperature Solar Receiver/Reactor for Methanol Decomposition

Yanjuan Wang,Jing Lei,Qibin Liu,Can Chen,Jiwei Li

doi:10.3390/en10111705

Abstract

In this paper, the endothermic methanol decomposition reaction is used to obtain syngas by transforming middle and low temperature solar energy into chemical energy. A two-dimensional multiphysics coupling model of a middle and low temperature of 150~300 °C solar receiver/reactor was developed, which couples momentum equation in porous catalyst bed, the governing mass conservation with chemical reaction, and energy conservation incorporating conduction/convection/radiation heat transfer. The complex thermochemical conversion process of the middle and low temperature solar receiver/reactor (MLTSRR) system was analyzed. The numerical finite element method (FEM) model was validated by comparing it with the experimental data and a good agreement was obtained, revealing that the numerical FEM model is reliable. The characteristics of chemical reaction, coupled heat transfer, the components of reaction products, and the temperature fields in the receiver/reactor were also revealed and discussed. The effects of the annulus vacuum space and the glass tube on the performance of the solar receiver/reactor were further studied. It was revealed that when the direct normal irradiation increases from 200 W/m2 to 800 W/m2, the theoretical efficiency of solar energy transformed into chemical energy can reach 0.14–0.75. When the methanol feeding rate is 13 kg/h, the solar flux increases from 500 W/m2 to 1000 W/m2, methanol conversion can fall by 6.8–8.9% with air in the annulus, and methanol conversion can decrease by 21.8–28.9% when the glass is removed from the receiver/reactor.

Highlights

Solar thermochemical processes can be used to obtain chemical fuel by transforming middle and low temperature solar energy into chemical energy of the syngas for storing and transporting solar energy
A scalable and simple solar reactor, which uses porous ceria as catalyst was proposed by Chueh et al The porous ceria was directly exposed to the high-temperature concentrated solar energy, which improves the heat transfer performance of catalyst
To validate that the numerical program can deal with the methanol conversion in the middle and low temperature solar receiver/reactor (MLTSRR), the numerical finite element method (FEM) model is validated by comparing the experimental data from Liu et al The numerical conditions are the same as the experiment conditions

Summary

Introduction

Solar thermochemical processes can be used to obtain chemical fuel by transforming middle and low temperature solar energy into chemical energy of the syngas for storing and transporting solar energy. A scalable and simple solar reactor, which uses porous ceria as catalyst was proposed by Chueh et al The porous ceria was directly exposed to the high-temperature concentrated solar energy, which improves the heat transfer performance of catalyst. They investigated the viability of a thermochemical cycle driven by solar energy for dissociating water and carbon dioxide using nonstoichiometric ceria.

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Results

Conclusion