The Experts below are selected from a list of 984 Experts worldwide ranked by ideXlab platform
Ho-ming Yeh - One of the best experts on this subject based on the ideXlab platform.
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Numerical Analysis on Heat Transfer in Parallel-Flow Rectangular Recuperators with Internal Recycle
淡江大學, 2016Co-Authors: Ho-ming YehAbstract:[[abstract]]Heat transfer in parallel-Flow rectangular recuperators with internal recycle has been investigated. In contrast to a single-pass device of same size without recycle, considerable improvement in performance is achievable if one of the Flow channels, either heated-fluid phase or cooled-fluid phase, is divided into two subchannels of same width with one performed as the Cocurrent-Flow operating subchannel and the other as the countercurrent-Flow reflux subchannel which provides the increase of fluid velocity, resulting in reduction of heat-transfer resistance. The improvement in performance by recycling operation increases as Flow rate and reflux ratio increase with negligible amount of hydraulic-dissipated energy[[notice]]補正完
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Recovery of deuterium from water-isotope mixture by thermal diffusion in countercurrent-Flow flat-plate Frazier scheme with optimum plate spacing
Progress in Nuclear Energy, 2010Co-Authors: Ho-ming YehAbstract:Abstract The effect of plate spacing on the degree of recovery and production rate for deuterium recovery from water–isotope mixture in flat-plate thermal diffusion columns of countercurrent-Flow Frazier scheme with fixed operation expense, has been investigated. The equations for estimating optimum plate spacing for maximum recovery and maximum production rate have been derived. Considerable improvement in performance is obtainable when thermal diffusion columns with optimum plate spacing are employed for operation. The fact that countercurrent-Flow operation is more effective than Cocurrent-Flow operation for the recovery of deuterium in a Frazier scheme, is also confirmed.
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deuterium recovery from water isotope mixture by thermal diffusion in countercurrent Flow frazier scheme inclined for improved performance
Fusion Engineering and Design, 2008Co-Authors: Ho-ming YehAbstract:The theory for recovery of deuterium from water isotope mixture by thermal diffusion in countercurrent-Flow inclined Frazier scheme has been developed and investigated. The equations for the optimal angles of inclination and the corresponding best performances were derived. Considerable improvement in performance is obtained when the Frazier scheme is operated at the optimal angle of inclination. Further improvement can be achieved if the operation is conducted in countercurrent Flow, instead of being in Cocurrent Flow.
Evgeny V Rebrov - One of the best experts on this subject based on the ideXlab platform.
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microwave assisted Flow synthesis coupling of electromagnetic and hydrodynamic phenomena
Aiche Journal, 2014Co-Authors: N G Patil, F Benaskar, J Meuldijk, L A Hulshof, Volker Hessel, J Jaap C Schouten, Erik D C Esveld, Evgeny V RebrovAbstract:This article describes the results of a modeling study performed to understand the microwave heating process in continuous-Flow reactors. It demonstrates the influence of liquid velocity profiles on temperature and microwave energy dissipation in a microwave integrated milli reactor-heat exchanger. Horizontal Cocurrent Flow of a strong microwave absorbing reaction mixture (ethanol + acetic acid, molar ratio 5:1) and a microwave transparent coolant (toluene) was established in a Teflon supported quartz tube (i.d.: 3 × 10−3 m and o.d.: 4 × 10−3 m) and shell (i.d.: 7 × 10−3 m and o.d.: 9 × 10−3 m), respectively. Modeling showed that the temperature rise of the highly microwave absorbing reaction mixture was up to four times higher in the almost stagnant liquid at the reactor walls than in the bulk liquid. The coolant Flow was ineffective in controlling the outlet reaction mixture temperature. However, at high Flow rates it limits the overheating of the stagnant liquid film of the reaction mixture at the reactor walls. It was also found that the stagnant layer around a fiber optic temperature probe, when inserted from the direction of the Flow, resulted in much higher temperatures than the bulk liquid. This was not the case when the probe was inserted from the opposite direction. The experimental validations of these modeling results proved that the temperature profiles depend more on the reaction mixture velocity profiles than on the microwave energy dissipation/electric field intensity. Thus, in Flow synthesis, particularly where a focused microwave field is applied over a small tubular Flow reactor, it is very important to understand the large (direct/indirect) influence of reactor internals on the microwave heating process. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3824–3832, 2014
Palghat A. Ramachandran - One of the best experts on this subject based on the ideXlab platform.
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A phenomenological model for pressure drop, liquid holdup, and Flow regime transition in gas-liquid trickle Flow
Chemical Engineering Science, 1992Co-Authors: R. A. Holub, Milorad P. Dudukovic, Palghat A. RamachandranAbstract:Abstract A phenomenological, pore-scale, hydrodynamic model is developed for representation of the uniform, two-phase, gas-liquid Cocurrent Flow in the low interaction regime in trickle bed reactors. The model provides improved predictions for both the pressure drop and liquid holdup using the parameters obtained exclusively from single phase Flow data. In addition, a new criterion for prediction of trickle to pulsing Flow regime transition is developed based on Kapitza's (1948) work on laminar film stability. Agreement with available data is good.
N G Patil - One of the best experts on this subject based on the ideXlab platform.
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microwave assisted Flow synthesis coupling of electromagnetic and hydrodynamic phenomena
Aiche Journal, 2014Co-Authors: N G Patil, F Benaskar, J Meuldijk, L A Hulshof, Volker Hessel, J Jaap C Schouten, Erik D C Esveld, Evgeny V RebrovAbstract:This article describes the results of a modeling study performed to understand the microwave heating process in continuous-Flow reactors. It demonstrates the influence of liquid velocity profiles on temperature and microwave energy dissipation in a microwave integrated milli reactor-heat exchanger. Horizontal Cocurrent Flow of a strong microwave absorbing reaction mixture (ethanol + acetic acid, molar ratio 5:1) and a microwave transparent coolant (toluene) was established in a Teflon supported quartz tube (i.d.: 3 × 10−3 m and o.d.: 4 × 10−3 m) and shell (i.d.: 7 × 10−3 m and o.d.: 9 × 10−3 m), respectively. Modeling showed that the temperature rise of the highly microwave absorbing reaction mixture was up to four times higher in the almost stagnant liquid at the reactor walls than in the bulk liquid. The coolant Flow was ineffective in controlling the outlet reaction mixture temperature. However, at high Flow rates it limits the overheating of the stagnant liquid film of the reaction mixture at the reactor walls. It was also found that the stagnant layer around a fiber optic temperature probe, when inserted from the direction of the Flow, resulted in much higher temperatures than the bulk liquid. This was not the case when the probe was inserted from the opposite direction. The experimental validations of these modeling results proved that the temperature profiles depend more on the reaction mixture velocity profiles than on the microwave energy dissipation/electric field intensity. Thus, in Flow synthesis, particularly where a focused microwave field is applied over a small tubular Flow reactor, it is very important to understand the large (direct/indirect) influence of reactor internals on the microwave heating process. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3824–3832, 2014
K D P Nigam - One of the best experts on this subject based on the ideXlab platform.
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investigation of liquid maldistribution in trickle bed reactors using porous media concept in cfd
Chemical Engineering Science, 2007Co-Authors: Arnab Atta, Shantanu Roy, K D P NigamAbstract:A three-dimensional CFD model for simulating two-phase Flow in trickle-bed reactors (TBRs) is presented. Based on porous media concept, a two-phase Eulerian model (rather than computationally demanding traditional three-phase Eulerian model) describing the Flow domain as porous region is presented to understand and forecast the liquid maldistribution in TBRs under cold-Flow conditions. The drag forces between phases have been accounted by employing the relative permeability concept [Saez, A. E., Carbonell, R. G., 1985. Hydrodynamic parameters for gas–liquid Cocurrent Flow in packed beds. A.I.Ch.E. Journal 31, 52–62]. The model predictions are validated against experimental data reported in literature, notably using the liquid distribution studies of Marcendelli [1999. Hydrodynamique, Transfert de Chaleur Particule-Fluide et Distribution des phases dans les Reacteurs a lit Fixe a Ecoulement a Co-courant Descendant de Gaz et de Liquide. Doctoral Thesis. INPL, Nancy, France]. Various distributor configurations reported therein have been recreated in the CFD model and sensitivity studies have been performed. Good agreement is obtained between the reported experimental results and this proposed first-principle based CFD model. Finally, the concept of distribution uniformity is discussed and applied to the CFD model predictions. The CFD model is subjected to a systematic sensitivity study in order to explore better liquid distribution alternatives.
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prediction of pressure drop and liquid holdup in trickle bed reactor using relative permeability concept in cfd
Chemical Engineering Science, 2007Co-Authors: Arnab Atta, Shantanu Roy, K D P NigamAbstract:Abstract A Computational Fluid Dynamics (CFD) model based on porous media concept is presented to model the hydrodynamics of two-phase Flow in trickle-bed reactors (TBRs). The aim of this study is to develop a comprehensive CFD based model for predicting hydrodynamic parameters in trickle-bed reactors under cold-Flow conditions. The two-phase Eulerian model describing the Flow domain as a porous region has been used to simulate the macroscale multiphase Flow in trickle beds operating under trickle Flow regime using FLUENT 6.2 software. The closure terms for phase interactions have been addressed by adopting the relative permeability concept [Saez, A.E., Carbonell, R.G., 1985. Hydrodynamic parameters for gas–liquid Cocurrent Flow in packed beds. A.I.Ch.E. Journal 31, 52–62]. The model has been evaluated by comparing predictions with the data (collected under a varied set of laboratory conditions) available in the open literature. It is shown that while being relatively simple in structure, this CFD model is flexible and predictive for a large body of experimental data presented in the open literature.