The potential of solar-driven humidification–dehumidification desalination for small-scale decentralized water production

Abstract

World-wide water scarcity, especially in the developing world, indicates a pressing need to develop inexpensive, decentralized small-scale desalination technologies which use renewable resources of energy. This paper provides a comprehensive review of the stateof-the-art in one of the most promising of these technologies, solar-driven humidification-dehumidification (HDH) desalination. Previous studies have investigated many different variations on the HDH cycle. In this paper, performance parameters which enable comparison of the various versions of the HDH cycle have been defined and evaluated. To better compare these cycles, each has been represented in psychometric coordinates. The principal components of the HDH system are also reviewed and compared, including the humidifier, solar heaters, and dehumidifiers. Particular attention is given to solar air heaters, for which design data is limited; and direct air heating is compared to direct water heating in the cycle assessments. Alternative processes based on the HDH concept are also reviewed and compared. Further, novel proposals for improvement of the HDH cycle are outlined. It is concluded that HDH technology has great promise for decentralized small-scale water production applications, although additional research and development is needed for improving system efficiency and reducing capital cost.

Entropy generation in condensation in the presence of high concentrations of noncondensable gases

“…A water heater between the humidifier and dehumidifier provides the heat input to the system. This particular embodiment of HDH is known as a closed air, open water (CAOW) cycle; there are several others that have been studied in detail [1,7], but will not be discussed further here.…”

Thermodynamic analysis of humidification dehumidification desalination cycles

“…From the literature cited above and a previous literature review [1], we have found no study which systematically attempts to improve and/or optimize the cycle performance by modifying the cycle itself. Hence, the objective of this paper is to analyze the thermodynamic performance of various HDH cycles in literature and to propose novel high-performance variations on those cycles.…”

Steam generation under one sun enabled by a floating structure with thermal concentration

“…Solar thermal technologies, i.e., the conversion of the sunlight to thermal energy, are being developed for many applications such as power generation, domestic water heating, desalination, and other industrial processes. [1][2][3][4][5][6][7] Steam and vapor generation is often desired in these applications, but the dilute solar flux (1000 W/m 2 ) does not provide enough power per unit area of the absorber to reach the required high temperatures and to compensate for the large latent heat of water vaporization. Optical…”