جستجوی مقالات مرتبط با کلیدواژه « fresh water » در نشریات گروه « مکانیک »

Nowadays, one of the suitable technologies in terms of power generation and saving energy with high efficiency is using the multigeneration systems that renewable fuels are used as an alternative to fossil fuels. In the present study, a multigeneration system including biogas fired gas turbine, Organic Rankine Cycle (ORC), domestic water heater, Reverse Osmosis (RO) unit and Proton Exchange Membrane (PEM) electrolyzer. The proposed multigeneration system is assessed from energy and exergy viewpoints. After that, a comprehensive parametric study is carried out to show the effects of some key parameters (including pressure ratio of compressor, condenser pressure, evaporator temperature, preheater temperature and inlet temperature of gas turbine) on main performance criteria of the multigeneration system. Finally, the multi generation system is optimized from thermal efficiency point of view. The optimization results indicate that the thermal efficiency has optimum values for evaporator temperature and pressure ratio of compressor. Also, results show that the values of generated power, produced fresh water, thermal efficiency, exergy efficiency, produced hydrogen and total exergy destruction are calculated as 1192 kW, 5.584 kg/s, 55.74%, 30.56%, 1.455 kg/hr and 2827 kW, respectively.

Desalination of saline and seawater is one of the best ways to provide fresh water. This article provides an overview of different types of water desalination processes, with introduction of advantages, disadvantages and various techniques to increase their efficiency. The results of this study suggest that for saline waters with salts greater than 1.2% mass fraction, it is more economical to use reverse osmosis devices instead of electro-dialysis process. Furthermore, the resistance of electro-dialysis membranes is much higher than of reverse osmosis membranes. Multiple-effect distillation (MED) is the most important thermal process that can produce a large amount of fresh water. The vapor-compression (VC) method does not require an external heating source and is exerted by electricity, therefore, the method is suitable for populated areas that have access to electricity. Low energy consumption in the freezing method is the most important advantage of that in comparison to other methods. Because, most areas in need of fresh water have high solar irradiations, so solar water desalination is the best way to provide the required water. Passive solar desalinations are devices that do not require a variety of energy and pumping systems and work with the least peripheral equipment, therefore, are cost-effective than solar active desalinations. The advantage of a stepped-solar still is that by placing a small basin with phase change material at the bottom of the absorber plate, it is possible to use the benefits of a single basin solar still at all period of day and night.

Present paper has investigated the performance assessment of a humidificationdehumidification (HDH) desalination system connected to photovoltaic thermal (PV/T) collectors. The main components of the system include humidification, dehumidification and PV/T collectors. Problem governing equations are obtained by writing the energy balance for the system various components and solved numerically. The simulation results of the present study are in fair agreement with the experimental data of previous literatures. Paper results show that at least three PV/T collectors with total area 2.3 m2 is needed to supply the minimum solar energy for the startup of system. Also, there is a desired mass flow rate for brackish water and air which maximize the system energy efficiency. The desired values of mass flow rate of brackish water and air and the maximum energy efficiency are 0.025 kg/s, 0.03 kg/s and 65%, respectively. Furthermore, the increase of PV/T collectors number increases freshwater productivity and output electrical power and decreases the energy efficiency due to the increase of consumed pumping power. Due to the negative influence of the temperature increase of inlet brackish water on the performance of dehumidifier and PV/T collectors, it causes the decrease of freshwater productivity, electrical power and energy efficiency.

Due to the favorable properties of wide regions of the world and has developed a shortage of fresh water in dry areas that already face large-scale development has occurred Such as parts of North Africa and the Middle East, to produce fresh water by desalination to need a lot of energy and a lot of research studies for the development of solar desalination is being done by solar energy With the aim of identifying key technical challenges and potential opportunities for solar energy, A variety of technologies for the optimum amount of solar energy as well as various technologies for solar desalination system includes advanced technique for restoring energy is studied we conclude that the development of solar desalination system for cost-effective and energy-efficient in the near future may be grounds for water supply desert regions of the world. The effects of water cooling with two modes: simple desalination (passive) by installing cooling and desalination of water (active) examined and compared in terms of daily production has been tested. Tests in August (August) in geographical coordinates (N:35°34′,E:53°22′) carried on the basis of the results observed maximum production rate freshwater disabled 0.26 (kg / m2) per hour. Moreover, the daily output disable mode of 1.035 (kg / m2.day) daily 1.530 (kg / m2) reached in active mode.