Entropy Generation Minimization for Reverse Water Gas Shift (RWGS) Reactors

Abstract

Thermal design and optimization for reverse water gas shift (RWGS) reactors is particularly important to fuel synthesis in naval or commercial scenarios. The RWGS reactor with irreversibilities of heat transfer, chemical reaction and viscous flow is studied based on finite time thermodynamics or entropy generation minimization theory in this paper. The total entropy generation rate (EGR) in the RWGS reactor with different boundary conditions is minimized subject to specific feed compositions and chemical conversion using optimal control theory, and the optimal configurations obtained are compared with three reference reactors with linear, constant reservoir temperature and constant heat flux operations, which are commonly used in engineering. The results show that a drastic EGR reduction of up to 23% can be achieved by optimizing the reservoir temperature profile, the inlet temperature of feed gas and the reactor length simultaneously, compared to that of the reference reactor with the linear reservoir temperature. These optimization efforts are mainly achieved by reducing the irreversibility of heat transfer. Optimal paths have subsections of relatively constant thermal force, chemical force and local EGR. A conceptual optimal design of sandwich structure for the compact modular reactor is proposed, without elaborate control tools or excessive interstage equipment. The results can provide guidelines for designing industrial RWGS reactors in naval or commercial scenarios.

Entropy Generation Rate Minimization for Methanol Synthesis via a CO2 Hydrogenation Reactor

“…In the chemical industrial production, two reactions generally reacts in a suit of catalyst-filled tubes, which are placed inside a tubular heat exchanger. In order to simplify the model, this paper will study one such tube, and establish a one-dimensional pseudo-homogeneous plug flow reactor model as shown in Figure 1 [ 15 , 35 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ].…”

“…Chen et al [ 52 ] established a hollow fiber membrane contactor model for extracting CO 2 from seawater and obtained the analytical formulae of the CO 2 extraction rate and the EGR of the process. Zhang et al [ 53 ] established a reverse water-gas shift reaction (RWGS) reactor model based on the experimental data and obtained the optimal configuration for the minimum total EGR of the reactor.…”

Performance of Universal Reciprocating Heat-Engine Cycle with Variable Specific Heats Ratio of Working Fluid

“…Using finite time thermodynamics (FTT) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ] to optimize the performances of practical cycles and processes, a series of achievements were made, including Novikov heat engines [ 17 , 18 , 19 , 20 , 21 ], Curzon–Ahlborn heat engines [ 22 , 23 , 24 ], solar-driven engines [ 25 , 26 ], Maisotaenko cycle [ 27 , 28 , 29 ], OTEC systems [ 30 , 31 , 32 ], Kalina cycle [ 33 ], thermoelectric devices [ 34 , 35 , 36 , 37 , 38 , 39 ], dissipative heat engine [ 40 ], refrigeration cycle [ 41 ], earth [ 42 ], quantum systems [ 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ], economic systems [ 51 , 52 ], chemical systems [ …”

Improving Fe/Al2O3 Catalysts for the Reverse Water-Gas Shift Reaction: On the Effect of Cs as Activity/Selectivity Promoter

“…At lower temperatures, the equilibrium will increasingly favour the water-gas shift reaction-WGS (reverse of Equation (1)) and methanation (Equation (2)) reactions, given their exothermic nature. Due to the stoichiometry of the reaction, altering pressure has no significant effect on the reaction activity or the position of the equilibrium [8,9].…”