An experimental study of a solar water desalination using an air bubble column humidifier is investigated. The characteristics of the generated bubbles are modified by using a different sieve plate ...with different hole size. The effect of water temperature, air flow rate, water height, and sieve's hole diameter on desalination performance is studied. The results showed that the daily productivity, efficiency and gain output ratio are 21kg, 63%, and 0.53 respectively; at inlet water temperature is 62°C. The change in the temperature difference along the column is less than 2.5°C for all measurements. The best performance is observed from sieve with 1mm hole diameter at which the outlet air from the bubble columns is always saturated. The air bubble column achieves higher performance than that for the conventional humidifier.
•Desalination using an air bubble column humidifier is investigated.•Effect of water temperature and height, air flow rate and hole diameter is studied.•At inlet water is 62 °C, productivity, efficiency and GOR are 21kg, 63%, and 0.53.•Air bubble column achieves higher performance than that conventional humidifier.•Temperature difference along air column is less than 2.5°C for all measurements.
► Water desalinated in a humidification/dehumidification unit. ► Experiment and theoretical model agree for distillate production and temperature. ► Enthalpy of condensation recovered as sensible ...heat up to 85% .
A desalination system based on the humidification and dehumidification of air is studied. The evaporator unit is based on a treated cellulose paper substratum through which water flows, and which has a large area to favor evaporation. The condenser unit is a liquid–gas heat exchanger, where water vapor is condensed and the enthalpy of condensation is recovered to preheat the water. The mathematical model and experimental results are presented and it is shown that they present a good agreement. Some operating conditions for better heat recovery are presented.
Due to the increase in human population, there is an ever-increasing demand for energy in different sectors which leads to environmental problems like climate change, rise in temperature, and global ...catastrophes. Cooling systems have become a very essential element in recent decades for mankind. The present system focuses on the design and fabrication of a counter-flow humidification setup which uses biomass-based charcoal as the packing material. Air velocity and water flow rate have been varied along with the density of charcoal. Output parameters such as a change in pressure (ΔP), Coefficient of performance (COP), evaporation rate (ER), humidification efficiency (HE), specific cooling capacity (SCC), and energy consumption (EC) are evaluated. Performance parameters obtained for charcoal are compared with that of standard Celdek Packing. Through experiments, it is found that humidification efficiencies for Celdek and charcoal packing are 77.45% and 57.40% respectively. The overall coefficient of performance obtained is 1.41 for charcoal and 3.17 for Celdek packing. Among the three densities which were considered, charcoal packing with a density of 400 kg/m3 exhibited higher performance with respect to COP, HE, ER, and SCC. Similarly, a water flow rate of 0.4 lpm gave a maximum performance and 0.7 lpm gave the least. It is concluded that charcoal can be considered one of the highly efficient biomass-based materials contributing to sustainable energy related to cooling applications.
In this paper, an anodic gas diffusion layer (GDL) with a gradient hydrophobic structured microporous layer (MPL) was prepared using a spraying method. The hydrophobicity of the MPL was changed by ...adding polyvinylpyrrolidone to the MPL close to the catalyst layer side to obtain a bilayer MPL with a gradient hydrophobic structure. By performing the above operation, we designed a double‐layer MPL structure with different hydrophobic gradients. In this study, we analyzed the effect of the gradient hydrophobic structure of bilayer MPL on the electrochemical performance of proton exchange membrane fuel cell by characterizing the physical properties, such as water contact angle, of anode self‐humidified GDL prepared in the laboratory. The study compared the limiting power density of the laboratory‐prepared GDL sample 10% with that of the commercial GDL29BC. The limiting power density of the sample 10% is 1.59, 1.5, and 1.49 W/cm2 under three humidity conditions of 40%, 60%, and 100%, respectively, which improve the performance by 19.5%, 17.2%, and 23.1% over that of the commercial GDL29BC. The anode GDL samples prepared in the laboratory showed good self‐wetting effect, which play a positive role in the improvement of fuel cell performance.
Preparation process and performance characterization of self‐humidifying anode gas diffusion layer.
•State of the art studies on HDH desalination cycles were reported.•Different HDH-based refrigeration, power and multi-generation cycles were reviewed.•Integration of reported HDH cycles with various ...desalination methods were examined.•A detailed comparison was drawn in terms of performance criteria of these systems.
Water and energy supply are two of the key issues human beings must address to attain sustainable development. Humidification-dehumidification technology has been proven to be a cost-effective approach to fulfill the freshwater demand. Particular attention has been given to coupling the humidification-dehumidification cycles with refrigeration, power and other desalination technologies with the aim of enhancing the performance of the combined cycle as well as increasing the amount of produced freshwater, cooling effect, power, etc. This paper provides a comprehensive review of the state-of-the-art investigations in terms of humidification-dehumidification technologies and their integration with the aforementioned cycles. In other words, an attempt has been made to categorize and discuss the various combined cycles based on humidification-dehumidification technology. A detailed comparison has been drawn regarding the performance criteria of the coupled cycles in terms of freshwater production, gained output ratio, and cost per liter. This comprehensive review lays the groundwork for future research concentrating on humidification-dehumidification based energy cycles.
•Coupled Adsorption and humidification-dehumidification technologies are investigated.•The coupled system has the capability of producing both cooling capacity and freshwater.•A thermoeconomic model ...for the system is developed to explore the system features.•The cost of freshwater produced is estimated at around 1.15 ȼ/liter, while the GOR is 2.50.•Considerable saving in the freshwater cost (between 30% and 40%) is attained.
Adsorption desalination (AD) and humidification-dehumidification desalination (HDH) technologies are attractive since they can be powered by low-grade energy sources and can be constructed on a small scale. This paper adopts a novel hybrid AD-(water-heated) HDH system to produce freshwater and cooling power, simultaneously. The system is mainly powered by a low-grade energy source (natural gas), while photovoltaic (PV) panels are used to run the auxiliary components such as pumps, and blowers. A detailed thermoeconomic model is developed to explore the effect of different parameters on the system performance and products’ cost. This analysis reveals that the system can deliver, at its optimal operating conditions, 21.75 kg of freshwater per hour for 1.15 ȼ/liter with a gained output ratio (GOR) of 2.50. The coefficient of performance (COP) and the cooling capacity of the proposed system are recorded at 0.46 and 2.53 kW, respectively. Besides, a comparison between the proposed hybrid system and a traditional standalone water-heated HDH unit is performed. This comparison shows that the GOR value of the hybrid system is always higher than that of the standalone HDH (about 350% increase). This trend indicates that the proposed system significantly improves overall performance. Considerable saving in the freshwater cost (from 30 to 40%) is also attained.
•A new PV-powered hybrid HDH-RO desalination system was theoretically assessed.•Thermal energy recovery unit and preheating solar collectors were involved.•Five coupled models were driven, solved, ...and validated.•As result, the system is feasible for high freshwater production with low power consumption.•Productivity (192–200 L/h), and specific power consumption (1.22–1.24 kWh/m3) were achieved.
Recently, constructing a high productive desalination unit with low power consumption has been a challenge. Along with that, this study aimed to simulate a new hybrid desalination unit merging two common techniques of high freshwater production: humidification-dehumidification (HDH), and reverse osmosis (RO). For low power consumption, the hybrid HDH-RO unit was powered with a photovoltaic (PV) systems. The system was provided with thermal energy recovery (TER) units, double-pass solar air collectors (SACs), and evacuated tube solar water collectors (SWCs). The TER units were parallel connected to the backside of PV panels for dual function: enhancing the PV conversion performance by cooling and preheating the seawater before entering the SWC. Both SAC and SWC were proposed to improve the evaporation rate inside the humidifier of the HDH unit. For a comprehensive analysis of the HDH-RO system, five coupled theoretical models were derived and solved, which all were validated by previous experimental data from the literature. All results confirmed that the proposed system can be a good choice for producing freshwater with low power consumption. The maximum hourly freshwater production of the new hybrid HDH-RO desalination system varied between 192 and 200 L, with a water recovery ratio ranged between 48 and 49.8%. Also, its specific power consumption (SPC) ranged between 1.22 and 1.24 kWh/m3, with an average saving a range between 14.7 and 65% compared to previous techniques of RO desalination system.
•Experimental study of the humidification of air in bubble columns.•An optically accessible bubble column is used for characterizing the flow.•The impact of operational parameters on the system ...productivity is evaluated.•The impacts on the performances of humidifier and dehumidifier are quantified.•Cross-influences are eliminated by a modified test setup and calculations.
The humidification-dehumidification process (HDH) for desalination is a promising technology to address water scarcity issues in rural regions. However, a low humidifier efficiency is a weakness of the process. Bubble column humidifiers (BCH) are promising for HDH, as they provide enhanced heat and mass transfer and have low maintenance requirements. Previous studies of HDH-systems with BCHs draw different conclusions regarding the impact of superficial air velocity and liquid height on the humidification. Furthermore, the impact of flow characteristics has never been investigated systematically at all. In this study, an optimized BCH test setup that allows for optical analysis of the humidifier is used and evaluated. Our test setup is validated, since the influence of water temperature on the humidification, which is exponential, is reproduced. Measurements with seawater show that the normalised system productivity is increased by about 56% with an increase in superficial air velocity from 0.5cm/s to 5cm/s. Furthermore, the system productivity is increased by around 29% with an increase in liquid height from 60mm to 378mm. While the impact of superficial air velocity can be traced back to temperature changes at the humidifier and dehumidifier outlets, the impact of liquid height is shown to be caused by a smaller heat loss surface in the humidifier with an increase in liquid height. For the impact of sieve plate orifice diameter, a clear influence on the humidification is not apparent, this parameter needs to be investigated further. Finally, our new test setup allows for analysing the humidification of air (1) in a systematic way, (2) in relevant measurement ranges and (3) in comparison with optical analyses of the flow characteristics.
In this communication, a new Humidification De-Humidification process desalination technology is identified which has some advantages (such as: high energy performance, high recovery flow rate, ...energy recovery and so on) in comparison with other similar methods; this technology is named “Humidification Compression”. This method is simulated by a commercial process simulation software and the results are compared with two conventional methods. It is seen that, gain output ratio (GOR) for proposed method is higher than conventional methods; also capital cost per product for proposed method is lower than two others.
•A new process with higher efficiency is synthesized and developed.•By combination of well-known processes the efficiency of HDH systems was increased.•The water recovery from humid air is carried out by use of a polytropic compressor.
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•A multigeneration system fueled by a geothermal source is proposed.•Absorption heat transformer and chiller have the highest irreversibilities.•The overall system performance in ...winter is better than that of summer.•The system has considerably high heating, cooling, and freshwater capacities.•Thermoeconomic indexes are significantly lower compared to similar systems.
Population growth, economic challenges, and the environmental crisis force scientists and designers to pay more attention to clean, sustainable, and renewable-based energy systems. In this regard, due to the unlimited geothermal potential in many countries, the geothermal energy resource can be an economical alternative. Therefore, in the present work, a novel multi-generation system, based on a 100% geothermal resource, for power, cooling, heating, and desalination has been designed and analyzed, thoroughly. The system is evaluated from the energy, exergy, and thermo-economic viewpoints, and providing high heating/cooling potentials while reducing the thermoeconomic indexes is the major achievement of this study. The results demonstrate that the system's net power output, freshwater production rate, heating, and cooling capacities are 78.47 kW, 92.1 m3/day, 6251 kW, and 4991 kW, respectively. Moreover, the highest amount of exergy destruction occurs in the absorption heat transformer (42%) and the absorption chiller (35%), respectively. In addition, the chiller’s absorber has the highest cost rate of exergy destruction, and the turbine and the evaporator of the organic Rankine cycle have the highest investment costs. It is found that energy and exergy efficiencies are 60.55% and 17.05%, respectively for summer, and 70.58% and 43.59%, respectively for winter, and the system's total cost rate is 44.12 $/h with the payback period of 5.63 years. Furthermore, the parametric study shows that increasing the ambient temperature and decreasing the terminal temperature difference of the heat transformer’s evaporator lead to higher exergy efficiency and lower total system cost rate.
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