Maximum energy output chemical pump configuration with an infinite-low- and a finite-high-chemical potential mass reservoirs

Abstract

The chemical pumps widely exist in various chemical systems, such as mass exchangers, desalination systems, biological systems, electrochemical systems, photochemical systems, solid-state devices, fuel pumps for solar-energy conversion systems, absorption and carbon pumps for material capture systems, etc. Therefore, performance improvements of the chemical systems become an urgent and important problem, which can be solved by optimizing the cycle configurations of the chemical pumps. Based on this consideration, an isothermal endoreversible chemical pump model is built in this paper, which operates between an infinite-low- and a finite-high-chemical potential mass reservoirs. Based on finite time thermodynamic theory, two mass transfer laws, i.e., the linear law and diffusive law are considered. When the cycle work input and operating time are specified, the optimal cycle configuration with maximum energy output is gained. For the linear law, with the optimal chemical pump configuration, the chemical potentials in the finite-high-chemical potential mass reservoir and the working substance nonlinearly vary with the operating time, meanwhile their ratio stays invariant. When both the chemical potential mass reservoirs are infinite ones, the dimensionless energy pumping rate and dimensionless entropy generation rate under the optimal time decrease with the increases of coefficient of performance and exergy efficiency. For the diffusive law, the optimal cycle configuration is quite different with that gained from the linear law. For the linear or diffusive law, the optimal chemical pump configuration with infinite-chemical potential mass reservoirs is made up of two invariant chemical potential branches along with two instant invariant mass-flux branches. The gained results can offer new references for the practical chemical pump designs.