Modeling of a Solar Driven HD (Humidification-Dehumidification) Desalination System (original) (raw)
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A Theoretical Model For A Humidification Dehumidification (Hd) Solar Desalination Unit
2015
A theoretical study of a humidification<br> dehumidification solar desalination unit has been carried out to<br> increase understanding the effect of weather conditions on the unit<br> productivity. A humidification-dehumidification (HD) solar<br> desalination unit has been designed to provide fresh water for<br> population in remote arid areas. It consists of solar water collector<br> and air collector; to provide the hot water and air to the desalination<br> chamber. The desalination chamber is divided into humidification<br> and dehumidification towers. The circulation of air between the two<br> towers is maintained by the forced convection. A mathematical<br> model has been formulated, in which the thermodynamic relations<br> were used to study the flow, heat and mass transfer inside the<br> humidifier and dehumidifier. The present technique is performed in<br> order to increase the unit performance. H...
2014
A humidification-dehumidification (HD) solar desalination unit was designed. It seems to be suitable to provide drinking water for population or remote arid areas. Solar water and solar air collectors were designed to provide the hot water and air to the desalination chamber. The desalination chamber was divided into humidifier and dehumidifier towers. The circulation of air in the two towers was maintained by the forced convection. Theoretical and experimental works were done at different environmental conditions. A mathematical model was formulated, in which the thermodynamic relations were used to study the flow, heat and mass transfer inside the humidifier and dehumidifier. Such a technique was performed in order to increase the unit performance. Heat and mass balance was done and a set of governing equations was solved using the finite difference technique. The solar intensity was measured along the working day during the summer and winter months and a comparison between the theoretical and experimental results were performed. The average accumulative productivity of the system in November, December and January was ranged between 2 to 3.5 kg / m day while the average summer productivity was found between 6 to 8 kg/m day in June and 7.26 to 11 2 2 kg/m day in July and August.
2014
Abstract: A humidification-dehumidification (HD) solar desalination unit was designed. It seems to be suitable to provide drinking water for population or remote arid areas. Solar water and solar air collectors were designed to provide the hot water and air to the desalination chamber. The desalination chamber was divided into humidifier and dehumidifier towers. The circulation of air in the two towers was maintained by the forced convection. Theoretical and experimental works were done at different environmental conditions. A mathematical model was formulated, in which the thermodynamic relations were used to study the flow, heat and mass transfer inside the humidifier and dehumidifier. Such a technique was performed in order to increase the unit performance. Heat and mass balance was done and a set of governing equations was solved using the finite difference technique. The solar intensity was measured along the working day during the summer and winter months and a comparison betw...
Experimental investigation of a solar powered humidification-dehumidification desalination unit
DESALINATION AND WATER TREATMENT, 2017
The present work deals with an experimental study of a solar desalination unit using the humidification-dehumidification (HDH) process. A bench-scale desalination unit was designed and tested in Bizerte, Tunisia. Humidification is achieved through a humidifier with saline water falling on its absorber plate, and dehumidification is realized by means of a tubular heat-exchanger condenser. The desalination unit operates with open-water and open-air cycles. Thermal performances as well as fresh water production of the HDH desalination unit were evaluated via measurements of air and water temperatures and flow rates. Measurements were conducted in free and forced convection. Special attention was focused on the influence of air velocity on the fresh water production of the desalination unit. The optimal air velocity, corresponding to the maximum of fresh water production, was found to be 3.34 m/s.
Energy Conversion and Management, 2004
A numerical investigation of a humidification dehumidification desalination (HDD) process using solar energy is presented. The HDD system consists mainly of a concentrating solar water heating collector, flat plate solar air heating collector, humidifying tower and dehumidifying exchanger. Two separate circulating loops constitute the HDD system, the first for heating the feed water and the second for heating air. A mathematical model is developed, simulating the HDD system, to study the influence of the different system configurations, weather and operating conditions on the system productivity. The model validity is examined by comparing the theoretical and experimental results of the same authors. It is found that the results of the developed mathematical model are in good agreement with the experimental results and other published works. The results show also that the productivity of the unit is strongly influenced by the air flow rate, cooling water flow rate and total solar energy incident through the day. Wind speed and ambient temperature variations show a very small effect on the system productivity. In addition, the obtained results indicate that the solar water collector area strongly affects the system productivity, more so than the solar air collector area.
Air humidification–dehumidification for a water desalination system using solar energy
Desalination, 2007
This paper presents a theoretical study of a solar desalination system with humidification-dehumidification which is a promising technique of production of fresh water at small scale (few m 3 /d). A general model based on heat and mass transfer balances in each component of the system was developed and used to optimize the system's nondimensional characteristics. The daily production of fresh water depends on the ratio between the salt water and the air mass flow rates. It was shown that, if this ratio is continuously adjusted for optimum performance, it is possible to produce more than 40 L of fresh water daily per square meter of solar collector surface on a typical July day in Tunisia. Annual performances for open and closed air loop systems are also presented.
Performance Evaluation of a Solar Humidification-Dehumidification Desalination Unit
2015
This paper is to investigate the use of solar energy in desalination by humidification and dehumid-ification process (HD). Here, a proposal for the desalination unit has been come out with cylindrical shape containing the evaporator in the middle and surrounded by the condenser. The hot feed water coming from the solar thermal system is sprayed at the top of the evaporator where the air flows from the bottom. In the evaporator the air is humidified until it gets out saturated, then introduced to the condenser, where it is dehumidified to obtain the fresh water and circulated back to the evaporator. Practically there are many parameters influence on the performance of this desalination unit, which are environmental, design and operational. In the current study these parameters are taken in consideration to formulate mathematical models which govern the performance of the main components of this unit, which are the evaporator, the condenser and the solar thermal system. The deduced ma...
Renewable Energy, 2010
This paper tackles an experimental investigation of a new solar desalination prototype using the humidification dehumidification principle at the weather conditions of Sfax City, Tunisia. The prototype is designed and constructed at the national engineering school of Sfax to conduct this experimental investigation under different meteorological and operating parameters. It is composed of a flat plate solar air collector, a flat plate solar water collector, a humidifier, an evaporation tower and a condensation tower. An economic analysis was conducted, since it affects the final cost of produced water, to determine both the cost of fresh water production and the payback period of the experimental setup. Although a system may be technically very efficient, it may not be economic. The experimental investigation of the dynamic behaviour of the solar desalination unit during summer season (June, July and August) and during a typical day in July was carried to study the temporal evolutions of the temperature of air and water and the relative humidity at the inlet and the outlet of each component of the system.
Solar Desalination by Humidification-Dehumidification of Air
MATEC Web of Conferences, 2018
The importance of supplying potable water can hardly be overstressed. In many arid zones, coastal or inlands, seawater or brackish water desalination may be the only solution to the shortage of fresh water. The process based on humidification-dehumidification of air (HDH) principle mimic the natural water cycle. HDH technique has been subjected to many studies in recent years due to the low temperature, renewable energy use, simplicity, low cost installation and operation. An experimental test setup has been fabricated and assembled. The prototype equipped with appropriate measuring and controlling devices. Detailed experiments have been carried out at various operating conditions. The heat and mass transfer coefficients have been obtained experimentally. The results of the investigation have shown that the system productivity increases with the increase in the mass flow rate of water through the unit. Water temperature at condenser exit increases linearly with water temperature at humidifier inlet and it decreases as water flow rate increases. HDH desalination systems realised on also work at atmospheric pressure; hence they do not need mechanical energy except for circulation pumps and fans. These kinds of systems are suitable for developing countries. The system is modular, it is possible to increase productivity with additional solar collectors and additional HDH cycles.