China
Africa
Explore chapters and articles related to this topic
Organics, Salts, Metals, and Nutrient Removal
Published in David H.F. Liu, Béla G. Lipták, Wastewater Treatment, 2020
R. David Holbrook, Sun-Nan Hong, Derk T.A. Huibers, Francis X. McGarvey, Chakra J. Santhanam
Multistage flash evaporation systems have been used commercially in desalination for many years. Conceptual designs for 1000-mgd plants are based on the flash principle. In the multistage flash process (see Figure 8.3.1), after the influent water has the SS removed and is deaerated, it is pumped through heat transfer units in several stages of the distillation system. Evaporating influent water condenses on the outside of the tubes. The concentrated waste water cascades from one stage to the next as a result of the pressure differential maintained. In each stage, the flashed water condenses on the tubes and is collected in trays (see Figure 8.3.1). When the concentrated wastewater reaches the lowest pressure stage, it is pumped out.
Deposition Methods
Published in Andrew Sarangan, Optical Thin Film Design, 2020
A major disadvantage of thermal evaporation is the difficulty in maintaining stoichiometry, especially with alloys. Many compounds will disintegrate when raised to high temperatures, and each component of the mixture will evaporate separately at different rates leading to a completely different stoichiometry at the substrate surface. As a result, only the most stable compounds can be deposited using thermal evaporation. Fortunately, most oxides and nitrides used in optical thin films are stable enough to be deposited using evaporation. These include SiO2, MgF2, Al2O3, Ta2O5, and Si3N4. Alloys such as ITO and GST cannot be easily deposited by thermal evaporation because their components will evaporate separately at different rates. Flash evaporation is a type of evaporation that can be used to evaporate components with different vapor pressures. The source material, usually in powder form, is dispensed at a controlled rate into a heated crucible to produce rapid evaporation. Since the temperature of the crucible is usually much higher than that required for normal evaporation, all species evaporate rapidly at similar rates (similar to PLD).
Numerical Study of Growth of a Vapor Bubble in Superheated Seawater with Time-Varying Pressure
Published in Heat Transfer Engineering, 2023
Flash evaporation (FE) is of importance in numerous applications such as seawater desalination, spray flash evaporation, nuclear reactor safety analysis, and in space applications for thermal control system of air vehicles, propelling system of microsatellites, and fuel mixing with air in the combustion engines [1]. During FE, pressure decreases abruptly and at some point, falls below the saturation pressure at the local temperature; consequently, liquid becomes superheated and intense evaporation and the subsequent bubble growth (BG) begin to occur. This gives rise to mechanical and thermal non-equilibrium, a phenomenon that arises due to liquid being superheated. The non-equilibrium heat and mass transfer, and the resulting rapid vapor generation in flashing process greatly influence the BG, void fraction, flow characteristics, and thermal performance. As a result, an appropriate description of BG in both mechanical and thermal non-equilibrium is essential to accurately predict the onset of FE and distribution of vapor in the system.
Comparative analysis of the use of flash evaporator and solar still with a solar desalination system
Published in International Journal of Ambient Energy, 2022
Hemin Thakkar, Kishor kumar Sadasivuni, P. V. Ramana, Hitesh Panchal, M. Suresh, Mohammad Israr, Medhat Elklawy, Hagar AlmElDin
The present research investigation shows the comparison between the use of solar still and the flash evaporator in the solar desalination system. From the seven days of research works, the following points are obtained: The flash evaporation system is a promising technology for solar desalination technologies.Distillate output of the solar desalination system with the use of the solar still was an average of 4.29 kg.Distillate output of the solar desalination system with the use of flash evaporator was 13.95 kg.Distillate output of the solar desalination system with the use of flash evaporator is the most promising application to improve the distillate output.
Advances and challenges in solar-powered wastewater treatment technologies for sustainable development: a comprehensive review
Published in International Journal of Ambient Energy, 2022
Alsehli, Choi, and Aljuhan (2017) presented the new design of the solar-driven MSF desalination unit having an array of solar concentrators and storage tanks. Circulation of brine solution through array eliminated the requirements of the heat exchanger and the fluid medium. A dynamic heat and mass transfer model was used to simulate the working performance of the desalination plant. Daily water production capacity and water production cost estimated to be 2230 m3 and 2.72 $/m3, respectively. Sharaf Eldean and Fath (2013) performed exergy and thermo-economic analyses of multi-stage desalination which involved two different techniques. The first technique was considered only for desalination purposes, while the second technique was considered for both desalination and electric power generation. Direct and indirect vapour generation processes were used for water stream and therminol-VP1, respectively. Furthermore, the total water productivity calculated for MSF brine recycle plant was 5000 m3/d. Nafey et al. (2007) experimentally studied the integrated flash evaporation process for water desalination. A mathematical model was developed to estimate the daily water productivity varying from 1.04 to 1.45 kg/m3 during low sunshine days. However, the higher daily water productivity of 4.2–7 kg/m3 was obtained during high sunshine days. Lu, Walton, and Swift (2001) investigated the thermal performance and economic viability of multi-effect multi-stage flash distillation unit driven by thermal energy obtained from salinity-gradient solar pond. The higher vapour temperature influenced the performance ratio and water productivity of the system. The increased temperature gradient between stages (first to fourth) increased the production rate, while it decreased the performance ratio. The results thus obtained were also compared with the data collected for spin flash unit having 24 stages. The summary of various studies on solar-powered MSF desalination is given in Table 6.