The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Junjie Yan - One of the best experts on this subject based on the ideXlab platform.
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Experimental study on transient heat/mass transfer characteristics during static Flash of aqueous NaCl solution
International Journal of Heat and Mass Transfer, 2020Co-Authors: Dan Zhang, Qingzhong Yang, Xiaoqu Han, Huihui Wang, Junjie YanAbstract:Abstract The instant height/temperature of waterfilm were selected as a pair of characteristic parameters to study the transient heat/mass transfer properties during static film Flash of aqueous NaCl solution though experiments with waterfilm concentration ranging between 0 and 0.15 (mass fraction), superheat between 5.1 and 35.0 K, and initial height of waterfilm between 0.10 and 0.20 m. The heat transfer mainly happened at bubble interface within waterfilm. The mass transfer included two steps of vaporization at bubble interface and vapor overflow from top free surface. The transient intensity of heat transfer was measured by volumetric evaporation coefficient. It shared the same experience with volumetric void fraction of quick increase to a peak value and gradual falling back. But its change always lagged behind that of void fraction. The transient intensity of overflow was measured by overflow speed of Flash vapor. It was found to increase with rising superheat or initial height of waterfilm, but dropped significantly with increasing waterfilm concentration. On basis of these results, a calculation model for static film Flash was set up. The evolution of waterfilm temperature/height could be computed simultaneously from given evolution of Flash Chamber pressure and other necessary initial conditions.
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Experimental study on evolutions of temperature and height of waterfilm during static Flash
International Journal of Heat and Mass Transfer, 2018Co-Authors: Dan Zhang, Qingzhong Yang, Ting Liang, Junjie YanAbstract:Abstract The temperature and height of waterfilm were a pair of coupled characteristic parameters indicating the instant heat/mass transfer during static film Flash of pure water. Their evolutions and interactions were studied through experiments with initial height of waterfilm ranging between 0.15 and 0.3 m, initial temperature between 80.2 and 93.0 °C, initial pressure of vacuum Chamber between 0.013 and 0.061 MPa. Results suggested both height and decrease rate of temperature of waterfilm experienced a rapid increase to peak value and a gradual decline after that. Considering most of heat transfer happened within waterfilm, volumetric evaporation coefficient was introduced as the total heat flux transferred through all bubble interfaces within unit volume of waterfilm under unit superheat. This coefficient increased significantly with rising volumetric void fraction of waterfilm. Except vapor generation, mass transfer during static Flash also included the overflowing of vapor. Its overflowing speed increased with initial height of waterfilm. According to these results, a model was set up to calculate the evolutions of temperature and height of waterfilm from given evolution of saturation temperature corresponding to the pressure of Flash Chamber.
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Experimental investigation on heat transfer characteristics in circulatory Flash vaporization of aqueous NaCl solution.
Desalination, 2018Co-Authors: Yu Wang, Qingzhong Yang, Junjie YanAbstract:Abstract In this work, a series of experiments on circulatory Flash vaporization of 10% and 20% NaCl solution was performed. The heat transfer characteristics in circulatory Flash vaporization under different experimental conditions were presented. The non-equilibrium fraction of circulatory Flash vaporization (NEF) was adopted to describe the extent of Flash vaporization process completion. A volumetric heat transfer coefficient of circulatory Flash vaporization (hv) was introduced in the present study to evaluate the heat flux evolution from per unit volume of liquid pool under unit superheat degree. Moreover, the influences of superheat degree, pressure of Flash evaporator, initial liquid level, circulating flow rate and concentration of NaCl solution on the volumetric heat transfer coefficient were also analyzed. Results suggested that the volumetric heat transfer coefficient increased with the superheat degree and Flash Chamber pressure. Lowering the initial liquid level and brine concentration promoted the heat transfer intensity. And Nusselt number of circulatory Flash vaporization NuA was proposed to describe the heat transfer performance of circulatory Flash vaporization according to the definition of volumetric heat transfer coefficient. Moreover, a correlation between Nusselt number of circulatory Flash vaporization and dimensionless parameters was obtained with the relative error between −31.1% and 32.8% for 1.5 ≤ ΔT ≤ 20 K, 400≤Q≤1200 L h−1, 7.4 ≤ Pf ≤ 31.2 kPa and 0.05 ≤ fm ≤ 0.2.
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Experimental study on energy transformation and separation characteristic of circulatory Flash evaporation
International Journal of Heat and Mass Transfer, 2016Co-Authors: Yousen Zhang, Jinshi Wang, Junjie Yan, Daotong Chong, Jiping LiuAbstract:Abstract Flash evaporation efficiency and steam-carrying ratio under low superheat were introduced to investigate energy transformation and separation characteristic of circulatory Flash evaporation in present paper. Experiments were carried out with flow rates of 400, 600, 800, 1000, 1200 L·h −1 , initial water film heights ranging from 100 to 300 mm, initial water film concentration of 0, 5%, 10% and at pressures of 7.4, 12.3, 19.9, 31.2, 47.4 kPa, respectively. Results indicated that Flash evaporation efficiency increased with increasing flow rate and Flash Chamber pressure, but decreased with increasing initial water film height and initial water film concentration. Since upward steam carries the droplets out of the Flash Chamber, the value of experimental Flash vapor mass was larger than the theoretical one which not considering the steam-carrying effect. Steam-carrying ratio under low superheat decreased with increasing of superheat and mass flow rate, but increased with increasing water film height. Moreover, there was a peak value in steam-carrying ratio curve for static Flash evaporation while the steam-carrying ratio for circulatory Flash evaporation decreased monotonically.
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Experimental study on circulatory Flash speed of aqueous NaCl solution circulatory Flash evaporation
Desalination, 2016Co-Authors: Yu Wang, Yousen Zhang, Dan Zhang, Qingzhong Yang, Junjie YanAbstract:Abstract In present paper, a series of experiments on circulatory Flash evaporation of 15% aqueous NaCl solution was carried out under various main experimental parameters. Circulatory Flash speed, which represented the superheated energy consumed in unit time in Flash Chamber, was defined as average change rate of the non-equilibrium fraction during the residence time in Flash Chamber. It indicated the intensity of Flash evaporation. The experiment results showed that circulatory Flash speed quickly decreased to a lowest point, then increased monotonously with the increasing superheat and finally became flat. Influence of parameters, such as flow rate, initial height of water film and equilibrium pressure on circulatory Flash speed was also investigated. As circulatory Flash speed increased, NEF had a minimum value. At the same circulatory Flash speed, NEF decreased when superheat degree and equilibrium pressure increased. And comparative study on Flash speed between static and circulatory Flash evaporation was also conducted. Both theoretical and experimental results of volumetric heat transfer coefficient showed a linear relationship with circulatory Flash speed. However, the experimental values were greater than the calculated values due to the liquid droplets entrainment.
D. Yogi Goswami - One of the best experts on this subject based on the ideXlab platform.
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Theoretical and experimental simulation of passive vacuum solar Flash desalination
Journal of Solar Energy Engineering, 2013Co-Authors: Mohammad Abutayeh, D. Yogi Goswami, Elias K. StefanakosAbstract:Experimental and theoretical simulations of a novel sustainable desalination process have been carried out. The simulated process consists of pumping seawater through a solar heater before Flashing it under vacuum in an elevated Chamber. Vacuum is passively created and then maintained by the hydrostatic balance between pressure inside the elevated Flash Chamber and outdoor atmospheric pressure. Experimental simulations were carried out using a pilot unit built to depict the proposed desalination system. Theoretical simulations were performed using a detailed computer code employing fundamental physical and thermodynamic laws to describe the separation process, complimented by experimentally based correlations to estimate physical properties of the involved species and operational parameters of the proposed system setting it apart from previous empirical desalination models. Experimental and theoretical simulation results matched well, validating the developed model. Feasibility of the proposed system rapidly increased with Flash temperature due to increased fresh water production and improved heat recovery. In addition, the proposed desalination system is naturally sustainable by solar radiation and gravity, making it very energy efficient.
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Sustainable Desalination Process Simulation
Volume 5: Energy Systems Analysis Thermodynamics and Sustainability; NanoEngineering for Energy; Engineering to Address Climate Change Parts A and B, 2010Co-Authors: Mohammad Abutayeh, D. Yogi Goswami, Elias K. StefanakosAbstract:Experimental and theoretical simulations of a novel sustainable desalination process have been carried out. The simulated process consists of pumping seawater through a solar heater before Flashing it under vacuum in an elevated Chamber. The vacuum is passively created and then maintained by the hydrostatic balance between pressure inside the elevated Flash Chamber and outdoor atmospheric pressure. The experimental simulations were carried out using a pilot unit built to depict the proposed desalination system. Theoretical simulations were performed using a detailed computer code employing fundamental physical and thermodynamic laws to describe the separation process, complimented by experimentally based correlations to estimate physical properties of the involved species and operational parameters of the proposed system setting it apart from previous empirical desalination models. Experimental and theoretical simulation results matched well with one another, validating the developed model. Feasibility of the proposed system rapidly increased with Flash temperature due to increased fresh water production and improved heat recovery. In addition, the proposed desalination system is naturally sustainable by solar radiation and gravity, making it very energy efficient.Copyright © 2010 by ASME
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Passive vacuum solar Flash desalination
Aiche Journal, 2009Co-Authors: Mohammad Abutayeh, D. Yogi GoswamiAbstract:A model for a sustainable desalination process has been developed. The simulated process consists of pumping seawater through a solar heater before Flashing it under a passively created vacuum in an elevated Chamber. The vacuum enhances evaporation and is maintained by the balance between the hydrostatic pressure inside the elevated Flash Chamber and the atmospheric pressure. The developed model uses theoretical thermodynamic relations to describe the process setting it apart from previous empirical correlations. © 2009 American Institute of Chemical Engineers AIChE J, 2010
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Solar Flash Desalination Under Hydrostatically Sustained Vacuum
Journal of Solar Energy Engineering, 2009Co-Authors: Mohammad Abutayeh, D. Yogi GoswamiAbstract:A new desalination scheme has been proposed. The system consists of a saline water tank, a concentrated brine tank, and a fresh water tank placed on ground level plus an evaporator and a condenser located several meters above the ground. The evaporator-condenser assembly, or Flash Chamber, is initially filled with saline water that later drops by gravity, creating a vacuum above the water surface in the unit without a vacuum pump. The vacuum is maintained by the internal hydrostatic pressure balanced by the atmospheric pressure. The ground tanks are open to the atmosphere, while the Flash Chamber is insulated and sealed to retain both heat and vacuum. A theoretical simulation of the proposed model was carried out using a detailed model built by employing the fundamental physical and thermodynamic relationships to describe the process and was complimented by reliable empirical correlations to estimate the physical properties of the involved species and the operational parameters of the proposed system. The simulation results show that running the system at higher ,Flash temperatures with a fixed Flash Chamber size will result in faster vacuum erosion leading to less overall evaporation.
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Solar Flash Desalination Under Hydrostatically Sustained Vacuum
ASME 2008 2nd International Conference on Energy Sustainability Volume 2, 2008Co-Authors: Mohammad Abutayeh, D. Yogi GoswamiAbstract:Creating vacuum conditions above liquids increases their evaporation rates. This phenomenon can be integrated into a practical continuous desalination process by repeatedly Flashing seawater in vacuumed Chambers to produce water vapor that condenses afterwards producing fresh water. Gravity can be used to balance the hydrostatic pressure inside the Flash Chambers with the outdoor atmospheric pressure to maintain that vacuum, while low grade solar radiation can be used to add heat to seawater before Flashing. The proposed desalination system consists of a saline water tank, a concentrated brine tank, and a fresh water tank placed on ground level plus an evaporator and a condenser located several meters above ground. The evaporator-condenser assembly, or Flash Chamber, is initially filled with saline water that later drops by gravity creating a vacuum above the water surface in the unit without a vacuum pump. The vacuum is maintained by the internal hydrostatic pressure balanced by the atmospheric pressure. The ground tanks are open to the atmosphere, while the Flash Chamber is insulated and sealed to retain both heat and vacuum.Copyright © 2008 by ASME
Qingzhong Yang - One of the best experts on this subject based on the ideXlab platform.
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Experimental study on transient heat/mass transfer characteristics during static Flash of aqueous NaCl solution
International Journal of Heat and Mass Transfer, 2020Co-Authors: Dan Zhang, Qingzhong Yang, Xiaoqu Han, Huihui Wang, Junjie YanAbstract:Abstract The instant height/temperature of waterfilm were selected as a pair of characteristic parameters to study the transient heat/mass transfer properties during static film Flash of aqueous NaCl solution though experiments with waterfilm concentration ranging between 0 and 0.15 (mass fraction), superheat between 5.1 and 35.0 K, and initial height of waterfilm between 0.10 and 0.20 m. The heat transfer mainly happened at bubble interface within waterfilm. The mass transfer included two steps of vaporization at bubble interface and vapor overflow from top free surface. The transient intensity of heat transfer was measured by volumetric evaporation coefficient. It shared the same experience with volumetric void fraction of quick increase to a peak value and gradual falling back. But its change always lagged behind that of void fraction. The transient intensity of overflow was measured by overflow speed of Flash vapor. It was found to increase with rising superheat or initial height of waterfilm, but dropped significantly with increasing waterfilm concentration. On basis of these results, a calculation model for static film Flash was set up. The evolution of waterfilm temperature/height could be computed simultaneously from given evolution of Flash Chamber pressure and other necessary initial conditions.
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Experimental study on evolutions of temperature and height of waterfilm during static Flash
International Journal of Heat and Mass Transfer, 2018Co-Authors: Dan Zhang, Qingzhong Yang, Ting Liang, Junjie YanAbstract:Abstract The temperature and height of waterfilm were a pair of coupled characteristic parameters indicating the instant heat/mass transfer during static film Flash of pure water. Their evolutions and interactions were studied through experiments with initial height of waterfilm ranging between 0.15 and 0.3 m, initial temperature between 80.2 and 93.0 °C, initial pressure of vacuum Chamber between 0.013 and 0.061 MPa. Results suggested both height and decrease rate of temperature of waterfilm experienced a rapid increase to peak value and a gradual decline after that. Considering most of heat transfer happened within waterfilm, volumetric evaporation coefficient was introduced as the total heat flux transferred through all bubble interfaces within unit volume of waterfilm under unit superheat. This coefficient increased significantly with rising volumetric void fraction of waterfilm. Except vapor generation, mass transfer during static Flash also included the overflowing of vapor. Its overflowing speed increased with initial height of waterfilm. According to these results, a model was set up to calculate the evolutions of temperature and height of waterfilm from given evolution of saturation temperature corresponding to the pressure of Flash Chamber.
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Experimental investigation on heat transfer characteristics in circulatory Flash vaporization of aqueous NaCl solution.
Desalination, 2018Co-Authors: Yu Wang, Qingzhong Yang, Junjie YanAbstract:Abstract In this work, a series of experiments on circulatory Flash vaporization of 10% and 20% NaCl solution was performed. The heat transfer characteristics in circulatory Flash vaporization under different experimental conditions were presented. The non-equilibrium fraction of circulatory Flash vaporization (NEF) was adopted to describe the extent of Flash vaporization process completion. A volumetric heat transfer coefficient of circulatory Flash vaporization (hv) was introduced in the present study to evaluate the heat flux evolution from per unit volume of liquid pool under unit superheat degree. Moreover, the influences of superheat degree, pressure of Flash evaporator, initial liquid level, circulating flow rate and concentration of NaCl solution on the volumetric heat transfer coefficient were also analyzed. Results suggested that the volumetric heat transfer coefficient increased with the superheat degree and Flash Chamber pressure. Lowering the initial liquid level and brine concentration promoted the heat transfer intensity. And Nusselt number of circulatory Flash vaporization NuA was proposed to describe the heat transfer performance of circulatory Flash vaporization according to the definition of volumetric heat transfer coefficient. Moreover, a correlation between Nusselt number of circulatory Flash vaporization and dimensionless parameters was obtained with the relative error between −31.1% and 32.8% for 1.5 ≤ ΔT ≤ 20 K, 400≤Q≤1200 L h−1, 7.4 ≤ Pf ≤ 31.2 kPa and 0.05 ≤ fm ≤ 0.2.
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Experimental study on circulatory Flash speed of aqueous NaCl solution circulatory Flash evaporation
Desalination, 2016Co-Authors: Yu Wang, Yousen Zhang, Dan Zhang, Qingzhong Yang, Junjie YanAbstract:Abstract In present paper, a series of experiments on circulatory Flash evaporation of 15% aqueous NaCl solution was carried out under various main experimental parameters. Circulatory Flash speed, which represented the superheated energy consumed in unit time in Flash Chamber, was defined as average change rate of the non-equilibrium fraction during the residence time in Flash Chamber. It indicated the intensity of Flash evaporation. The experiment results showed that circulatory Flash speed quickly decreased to a lowest point, then increased monotonously with the increasing superheat and finally became flat. Influence of parameters, such as flow rate, initial height of water film and equilibrium pressure on circulatory Flash speed was also investigated. As circulatory Flash speed increased, NEF had a minimum value. At the same circulatory Flash speed, NEF decreased when superheat degree and equilibrium pressure increased. And comparative study on Flash speed between static and circulatory Flash evaporation was also conducted. Both theoretical and experimental results of volumetric heat transfer coefficient showed a linear relationship with circulatory Flash speed. However, the experimental values were greater than the calculated values due to the liquid droplets entrainment.
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experimental study on equilibrium waterfilm concentration in static Flash evaporation of aqueous nacl solution
Desalination, 2014Co-Authors: Bingchao Zhao, Qingzhong Yang, Dan Zhang, Junjie YanAbstract:Abstract Experimental study on equilibrium waterfilm concentration in static Flash evaporation of aqueous NaCl solution was presented. Equilibrium waterfilm concentration was defined as the concentration of aqueous NaCl solution in a Flash Chamber at equilibrium time after each Flash. Experiments were carried out with the initial waterfilm concentration varied from 0 to 0.264 (saturation), separating height from 0.115 to 0.415 m, and superheat from 1.8 to 43.4 K. Results indicated that both evaporation and steam-carrying effect influenced the change of equilibrium waterfilm concentration. Equilibrium waterfilm concentration gradually increased with rising superheat until saturation. Meanwhile, minimum crystallization superheat was defined as the minimum superheat that made NaCl crystals separated out from waterfilm during the process of static Flash evaporation when the equilibrium waterfilm concentration was in a saturated state. Results showed that the minimum crystallization superheat decreased with the rising initial waterfilm concentration or the decreasing separating height. Finally, a calculating formula of equilibrium waterfilm concentration with an empirical constraint was set up, and the relative error between experimental and calculating equilibrium waterfilm concentrations varied between − 14.6% and 8.7%.
Mohammad Abutayeh - One of the best experts on this subject based on the ideXlab platform.
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Theoretical and experimental simulation of passive vacuum solar Flash desalination
Journal of Solar Energy Engineering, 2013Co-Authors: Mohammad Abutayeh, D. Yogi Goswami, Elias K. StefanakosAbstract:Experimental and theoretical simulations of a novel sustainable desalination process have been carried out. The simulated process consists of pumping seawater through a solar heater before Flashing it under vacuum in an elevated Chamber. Vacuum is passively created and then maintained by the hydrostatic balance between pressure inside the elevated Flash Chamber and outdoor atmospheric pressure. Experimental simulations were carried out using a pilot unit built to depict the proposed desalination system. Theoretical simulations were performed using a detailed computer code employing fundamental physical and thermodynamic laws to describe the separation process, complimented by experimentally based correlations to estimate physical properties of the involved species and operational parameters of the proposed system setting it apart from previous empirical desalination models. Experimental and theoretical simulation results matched well, validating the developed model. Feasibility of the proposed system rapidly increased with Flash temperature due to increased fresh water production and improved heat recovery. In addition, the proposed desalination system is naturally sustainable by solar radiation and gravity, making it very energy efficient.
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Sustainable Desalination Process Simulation
Volume 5: Energy Systems Analysis Thermodynamics and Sustainability; NanoEngineering for Energy; Engineering to Address Climate Change Parts A and B, 2010Co-Authors: Mohammad Abutayeh, D. Yogi Goswami, Elias K. StefanakosAbstract:Experimental and theoretical simulations of a novel sustainable desalination process have been carried out. The simulated process consists of pumping seawater through a solar heater before Flashing it under vacuum in an elevated Chamber. The vacuum is passively created and then maintained by the hydrostatic balance between pressure inside the elevated Flash Chamber and outdoor atmospheric pressure. The experimental simulations were carried out using a pilot unit built to depict the proposed desalination system. Theoretical simulations were performed using a detailed computer code employing fundamental physical and thermodynamic laws to describe the separation process, complimented by experimentally based correlations to estimate physical properties of the involved species and operational parameters of the proposed system setting it apart from previous empirical desalination models. Experimental and theoretical simulation results matched well with one another, validating the developed model. Feasibility of the proposed system rapidly increased with Flash temperature due to increased fresh water production and improved heat recovery. In addition, the proposed desalination system is naturally sustainable by solar radiation and gravity, making it very energy efficient.Copyright © 2010 by ASME
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Passive vacuum solar Flash desalination
Aiche Journal, 2009Co-Authors: Mohammad Abutayeh, D. Yogi GoswamiAbstract:A model for a sustainable desalination process has been developed. The simulated process consists of pumping seawater through a solar heater before Flashing it under a passively created vacuum in an elevated Chamber. The vacuum enhances evaporation and is maintained by the balance between the hydrostatic pressure inside the elevated Flash Chamber and the atmospheric pressure. The developed model uses theoretical thermodynamic relations to describe the process setting it apart from previous empirical correlations. © 2009 American Institute of Chemical Engineers AIChE J, 2010
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Solar Flash Desalination Under Hydrostatically Sustained Vacuum
Journal of Solar Energy Engineering, 2009Co-Authors: Mohammad Abutayeh, D. Yogi GoswamiAbstract:A new desalination scheme has been proposed. The system consists of a saline water tank, a concentrated brine tank, and a fresh water tank placed on ground level plus an evaporator and a condenser located several meters above the ground. The evaporator-condenser assembly, or Flash Chamber, is initially filled with saline water that later drops by gravity, creating a vacuum above the water surface in the unit without a vacuum pump. The vacuum is maintained by the internal hydrostatic pressure balanced by the atmospheric pressure. The ground tanks are open to the atmosphere, while the Flash Chamber is insulated and sealed to retain both heat and vacuum. A theoretical simulation of the proposed model was carried out using a detailed model built by employing the fundamental physical and thermodynamic relationships to describe the process and was complimented by reliable empirical correlations to estimate the physical properties of the involved species and the operational parameters of the proposed system. The simulation results show that running the system at higher ,Flash temperatures with a fixed Flash Chamber size will result in faster vacuum erosion leading to less overall evaporation.
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Solar Flash Desalination Under Hydrostatically Sustained Vacuum
ASME 2008 2nd International Conference on Energy Sustainability Volume 2, 2008Co-Authors: Mohammad Abutayeh, D. Yogi GoswamiAbstract:Creating vacuum conditions above liquids increases their evaporation rates. This phenomenon can be integrated into a practical continuous desalination process by repeatedly Flashing seawater in vacuumed Chambers to produce water vapor that condenses afterwards producing fresh water. Gravity can be used to balance the hydrostatic pressure inside the Flash Chambers with the outdoor atmospheric pressure to maintain that vacuum, while low grade solar radiation can be used to add heat to seawater before Flashing. The proposed desalination system consists of a saline water tank, a concentrated brine tank, and a fresh water tank placed on ground level plus an evaporator and a condenser located several meters above ground. The evaporator-condenser assembly, or Flash Chamber, is initially filled with saline water that later drops by gravity creating a vacuum above the water surface in the unit without a vacuum pump. The vacuum is maintained by the internal hydrostatic pressure balanced by the atmospheric pressure. The ground tanks are open to the atmosphere, while the Flash Chamber is insulated and sealed to retain both heat and vacuum.Copyright © 2008 by ASME
Hassan E.s. Fath - One of the best experts on this subject based on the ideXlab platform.
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Comparative study for different demister locations in multistage Flash (MSF) Flash Chamber (FC)
Desalination and Water Treatment, 2013Co-Authors: M. Khamis Mansour, Hassan E.s. FathAbstract:ABSTRACTMultistage Flash (MSF) is a widely used technology in large capacity salted water desalination plants. The enhancement in the thermal performance of this technology is still prospective and promising. In this research, vapor flow through the Flash Chamber (FC) was studied. Flow development in 2D simulation model of a real FC was investigated. Trajectory of liquid droplets was calculated using Lagrange approach. The continuity and Navier–Stokes equations for the continuous phase “vapor” were solved simultaneously with the particle equation using two equations k–ϵ turbulence model. The computational model was verified by comparing the predicated results (vapor pressure drop through the FC demister and moist separation efficiency) with those obtained from the published experimental data. The comparison showed a good agreement between both results with maximum deviation of less than −19.16%, however, most of the disagreement between both results is fewer than 10%. Four different demister locations wer...
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numerical simulation of vapor flow and pressure drop across the demister of msf desalination plant
Energy Conversion and Management, 2013Co-Authors: Isam Janajreh, Ashraf Hasania, Hassan E.s. FathAbstract:This paper presents a numerical simulation of the water vapor flow in an MSF Flash Chamber along with the pressure drop across the demister. The demister is a simple porous blanket of metal wires mesh (usually made of stainless steel wires) which retains liquid droplets entrained by the vapor momentum to enhance the quality of the product water. Two main areas of concern in wire mesh mist eliminators are; (i) the pressure drop and (ii) the mist removal efficiency. The present simulation focuses only on the pressure drop across the demister. The simulation is carried out considering a full scale Flashing Chamber of a typical operational MSF desalination plant and of a real industrial demister dimensions. The study simulates the demister as porous media flow. It takes into account the vapor velocity, the dimension of the demister, its porosity and wire thickness. The obtained pressure drop was found to be within a reasonable agreement with the published literature data and it follows a trend compatible with Ergun’s equation as well as the empirical correlation of Svendsen. 2012 Published by Elsevier Ltd.
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Numerical simulation of Flashing process in MSF Flash Chamber
Desalination and Water Treatment, 2013Co-Authors: M. Khamis Mansour, Hassan E.s. FathAbstract:abstract Multistage Flash (MSF) technology is widely used in saline water desalination particularly in Middle East and North Africa and Gulf Cooperation Council countries. Enhancement in the thermal performance of this technology in different plant sections and processes including the brine Flashing process is still promising. This study addresses the optimal position of jumping plate (weir) location and its number inside the MSF Chamber. The optimization exercise has been carried out in terms of maximum Flashing vapor production and lower pressure drop using commercial computational fluid dynamics software ANSYS CFX 12.1. The Eulerian–Eulerian (free surface flow) two-phase model was adopted while a k–ϵ model was used a turbulent flow model. The theoretical model was verified by comparing the predicated results with those obtained from the reference case study. The maximum deviation between both results was found to be within 8.3%. Prediction of velocity vectors, phase volume fraction, and temperature pro...
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the non equilibrium factor and the Flashing evaporation rate inside the Flash Chamber of a multi stage Flash desalination plant
Desalination, 1997Co-Authors: Hassan E.s. FathAbstract:A study was undertaken to measure the non-equilibrium factor and to correlate the Flashing evaporation rate inside the Flash Chamber of a multi-stage Flash (MSF) desalination plant. A computer code was developed to quantitatively simulate the MSF desalination plant operation and solve the mass, heat and salt balance equations. The simulator was tested against an MSF pilot plant with a four-stage heat recovery section and a two-stage heat rejection section, and then used to technically evaluate the Flash Chamber performance. For a constant top brine temperature of 112°C, the results indicated that (1) the non-equilibrium factor (1-β) varies between 0.24 to 0.66 (low values of Flash Chamber effectiveness, β). In order to reach thermodynamic equilibrium, the Flashing evaporation process should be enhanced through increasing the brine superheat, Flashing surface area, number of active nucleation sites, and brine residence time inside the Flash Chamber; (2) the average Flashing heat flux ranges from 100 to 200 kW/m2 and increases with the brine superheat and the stage pressure. Similar to the surface nucleate boiling, the Flashing heat flux could be correlated as: Q″ = 0.055(Tb(av)−Tsat)3.