Humidification and Dehumidification Processes: Advantages and Disadvantages

Abstract

Desalination systems based on the Humidification Dehumidification (HDH) process come in a large variety of forms. They all operate in very similar manners, all requiring the evaporation of salt water and the condensation of pure, distilled water, in the same way clouds are formed every day. As engineers we must pursue the processes that have the best possible efficiency for the specific situation we find ourselves in. The purpose of this paper is to explore the various Humidification Dehumidification desalination processes and thermodynamically compare them with one another in order to determine which one of these processes has the most potential in specific environmental situations. This paper explores the advantages and disadvantages of all HDH processes as well as compare them with more common desalination methods like reverse osmosis. An in depth study of available literature is conducted, listed and explained regarding these HDH processes and their specific characteristics, focusing on the key points of efficiency, limiting factors and environmental effects. In some cases these processes, especially those utilizing the open air cycle or solar collectors, can be severely affected by environmental situations. The environmental situations can include high humidity environments, high temperature environments, high rainfall environments and of course the polar opposites of these situations and any combination of them. The paper takes into account these environmental effects and makes recommendations based on different environmental situations that can be found around the world. The HDH processes can obtain the energy they need to operate from various sources. Recommendations are also made with this in mind. Recommendations are also made regarding possible processes and specific design areas, which, in the in the writers opinion, should be the focus of improvements made by future designers are noted. Considering the efficiency limiting areas that cause bottlenecks in the processes, the writer prescribes possible ways to limit the effects of these bottleneck areas. The writer’s own recommendations regarding possible processes and possible improvements are also stated, paying attention to the recommendations already found in literature.