Analytical and numerical schemes for thermodynamically balanced humidification-dehumidification desalination systems

Abstract

Thermodynamic balancing is a promising method to enhance the performance of heat and mass exchange devices. It is successfully tested for humidification-dehumidification (HDH) desalination systems using an implicit procedure based on tabulated thermodynamic properties (i.e., temperature and enthalpy) of saturated air. This numerical procedure is not robust and is cumbersome to implement thermodynamic balancing and to model hybrid, multi-stage, and complicated systems. This paper provides a robust, explicit, and innovative models that facilitate the utilization of a thermodynamic balancing concept. The present models are used to get a deep understanding of the performance of the closed-air open-water (CAOW) water-heated HDH system with and without extractions. The relation between temperature and specific enthalpy of saturated air on HDH modeling is simplified. Based on that, zero and infinity extraction systems are modeled analytically and pseudo-analytically. To handle more than one extraction, a simple numerical model is presented. The analytical and numerical results are compared with the reported results in the literature. The performance results show that the proposed methods are reliable and accurate.