Topic
Multiple-effect humidification
About: Multiple-effect humidification is a research topic. Over the lifetime, 202 publications have been published within this topic receiving 6207 citations. The topic is also known as: MEH.
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TL;DR: In this article, a model for the operation of proton exchange membrane fuel cells (PEMFC) with internal humidification of the gases is presented and the range of operating conditions for a PEMFC using dry H 2 /air was investigated, which predicts that dry air, entering at the cathode, can be fully internally humidified by the water produced by the electrochemical reaction at temperatures up to 70°C.
Abstract: Operation of proton exchange membrane fuel cells (PEMFC) without external humidification of the reactant gases is advantageous for the PEMFC system, because it eliminates the need of a gas-humidification subsystem. The gas-humidification subsystem is a burden in the fuel cell system with respect to weight, complexity, cost, and parasitic power. A model for the operation of PEMFC with internal humidification of the gases is presented and the range of operating conditions for a PEMFC using dry H 2 /air was investigated. The model predicts that dry air, entering at the cathode, can be fully internally humidified by the water produced by the electrochemical reaction at temperatures up to 70°C. This model was experimentally verified for cell temperatures up to 60°C by long-term operation of a PEMFC with dry gases for up to 1800 h. The current densities, obtained at 0.6 V, were 20 to 40% lower than those measured when both gases were humidified. The water distribution in the cell, while operating with dry gases, was investigated by measuring the amount of product water on the anode and cathode sides. It was found that the back-diffusion of product water to the anode is the dominant process for water management in the cell over a wide range of operating conditions. The dominating water back-diffusion also allows internal humidification of the hydrogen reactant and prevents drying out of the anode.
371 citations
TL;DR: In this article, a comprehensive review of the state-of-the-art in one of the most promising of these technologies, solar-driven humidification-dehumidification (HDH) desalination, is provided.
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 state-of-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.
362 citations
TL;DR: In this article, the authors analyzed the thermodynamic performance of various HDH cycles by way of a theoretical cycle analysis and proposed novel high-performance variations on those cycles, such as multi-extraction, multi-pressure and thermal vapor compression cycles.
Abstract: Humidification dehumidification desalination (HDH) is a promising technology for small-scale water production applications. There are several embodiments of this technology which have been investigated by researchers around the world. However, from a previous literature [1], we have found that no study carried out a detailed thermodynamic analysis in order to improve and/or optimize the system performance. In this paper, we analyze the thermodynamic performance of various HDH cycles by way of a theoretical cycle analysis. In addition, we propose novel high-performance variations on those cycles. These high-performance cycles include multi-extraction, multi-pressure and thermal vapor compression cycles. It is predicted that the systems based on these novel cycles will have gained-output ratio in excess of 5 and will outperform existing HDH systems.
250 citations
01 Dec 2009
TL;DR: In this paper, the authors analyzed the thermodynamic performance of various HDH cycles by way of a theoretical cycle analysis and proposed novel high-performance variations on those cycles, such as multi-extraction, multi-pressure and thermal vapor compression cycles.
Abstract: Humidification dehumidification desalination (HDH) is a promising technology for small-scale water production applications. There are several embodiments of this technology which have been investigated by researchers around the world. However, from a previous literature [1], we have found that no study carried out a detailed thermodynamic analysis in order to improve and/or optimize the system performance. In this paper, we analyze the thermodynamic performance of various HDH cycles by way of a theoretical cycle analysis. In addition, we propose novel high-performance variations on those cycles. These high-performance cycles include multi-extraction, multi-pressure and thermal vapor compression cycles. It is predicted that the systems based on these novel cycles will have gained-output ratio in excess of 5 and will outperform existing HDH systems.
206 citations
TL;DR: In this article, the closed air cycle humidification-dehumidification process was used for water desalination using solar energy, where the circulated air by natural or forced convection was heated by the hot water obtained either from a flat plate solar collector or from an electrical heater.
188 citations