Optimization for a Thermochemical Energy Storage-reactor based on Entransy Dissipation Minimization

In this paper, a thermochemical energy storage-reactor (TESR) is optimized based on entransy theory to reduce the irreversibility of heat transfer and reaction. Two types of optimization problems including fixed chemical energy conversion and fixed total heat flux are discussed detail. Firstly, the formula of entransy dissipation for the process of TTES is derived based on the entransy balance equation, then a casing TTES with methane-water reforming is optimized for entransy dissipation minimization (EDM). The optimized results based on EDM are also compared with that based on entropy production minimization (EPM). The results show that: there are some similarities and differences between EDM and EPM for optimizing the TESR. The similarity is that the heating temperature along the reaction flow should be non-linear, to decrease the total irreversibility. The difference is that the EDM is focused on decreasing the irreversibility of heat transfer, and the EPM is focused on decreasing the irreversibility of reaction. The total heat consumption based on EDM is lower than that based on EPM when the chemical energy conversion is certain, and the chemical energy conversion based on EDM is higher than that based on EPM when the total heat flux is certain.