역전기투석 스택 디자인 파라미터가 스택 성능에 미치는 영향

Abstract

Reverse electrodialysis is a technology to harvest renewable and clean salinity gradient energy through ion exchange membrane by mixing two solution streams of different concentrations. From an economic point of view power density(obtained power per total active membrane area), energy efficiency(the amount of energy produced from specified volumes of river and sea water in relation to the thermodynamic maximum) and pumping power are important stack performance evaluation items. These are complexly influenced by stack design parameters such as linear feed velocity, residence time and flow path length. This work experimentally investigate the effect of linear feed velocity, residence time and flow path length on power density, energy efficiency and pumping power in RED stack. Experiments were conducted at fixed linear feed velocity ( 0.5 , 1.0 , 1.5 and 2.0 cm/s ) with a stack of 50cells ( 7.2 cm x 10, 20 and 30 cm ). The parameters affecting the trade-off relationship of performance items are evaluated by multiplying two performance items. As a result, the trade-off relationship is confirmed experimentally. Optimal stack design parameters when the pressure is not considered are the linear velocity ( 2.5 cm/s ), the residence time ( 8 s ), flow path length ( 20 cm ). But considering pumping power, the optimum design parameters are linear velocity ( 0.44 cm/s ), residence time ( 23 s ), flow path length ( 10 cm ). The linear velocity is lowered, the residence time is longer and the flow path length is shortened. And these optimal stack design parameters are similar to that of paper performed cost-based optimization by modelling. So it can be presented as an optimal parameter and these values are verified experimentally.