Minimization of entropy generation rate in reverse water gas shift reactor with linear phenomenological heat transfer law

Abstract

The reverse water gas shift (RWGS) reaction can convert CO₂ into useful industrial raw materials, which meets the requirement and trend of carbon-neutral energy development. For the one-dimensional tubular plug flow RWGS reactor, the heat transfer process was assumed to obey the linear phenomenological heat transfer law &lang;<i>q</i>&prop;&Delta;(&Tau;^-1)&rang;. Under the conditions that all of the CO yield, inlet temperature, inlet pressure and inlet compositions were given and the temperature of the heat source outside the tube was fully controllable, the minimum total entropy generation rate (EGR) of the RWGS reactor and the corresponding optimal temperature distribution of the heat source outside the tube were solved by applying finite time thermodynamics and optimal control theory. The optimization results were further compared to the performances of two reference reactors with the constant and the linear heat source temperatures and those for the case with Newtonian heat transfer law &lang;<i>q</i>&prop;&Delta;(&Tau;)&rang;. The results show that optimizing the heat-source temperature distribution could reduce the total EGR of the RWGS reactor by more than 48% compared to those of the two reference reactors, and the main reduction is the EGR in heat transfer and chemical reaction processes; heat transfer laws have significant effects on the minimum total EGR of the RWGS reactor and the corresponding optimal temperature distribution of the heat source outside the tube. The obtained results in this paper have certain guiding significance for the design of RWGS reactors in actual engineering.