화학공학소재연구정보센터
International Journal of Heat and Mass Transfer, Vol.89, 1258-1276, 2015
Numerical modeling of fluid flow and coupled heat and mass transfer in a counter-cross-flow parallel-plate liquid-to-air membrane energy exchanger
In this paper, a numerical model is developed and applied to investigate the fluid flow and heat and mass transfer in a counter-cross-flow liquid-to-air membrane energy exchanger (LAMEE). An iterative finite-difference method is used to solve two-dimensional steady-state flow field and the coupled heat and moisture transfer equations for the liquid desiccant and air streams. The model is validated with experimental data, and the agreement is within +/- 10%. The results of the numerical model show that the phase change energy plays a key role in the establishment of the temperature and moisture content distributions in the LAMEE. In the process of air cooling and dehumidification, the liquid desiccant temperature is increased not only by the sensible heat transfer, but also by the moisture transfer. Also, the capacity of the liquid desiccant to absorb moisture from the air is shown to be affected by the sensible energy transfer between the two fluids. Moreover, it is shown that the counter-cross-flow LAMEE effectiveness is between the effectiveness of pure counter-flow and pure cross-flow LAMEEs with the same membrane area. It is recommended for a practical design that the aspect ratio and entrance ratio should be less than 0.2 and 0.1 respectively, in order to achieve a high performance of the counter-cross-flow design that approaches within 2% the performance of a counter-flow design. Alternately, the membrane area of the practical design can be increased slightly (by 10%) so that the counter-cross-flow LAMEE has the same performance as a counter-flow LAMEE. (C) 2015 Elsevier Ltd. All rights reserved.