The Experts below are selected from a list of 7887 Experts worldwide ranked by ideXlab platform
Haocui Zhang - One of the best experts on this subject based on the ideXlab platform.
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Flow pattern and break-up of liquid Film in single-channel Falling Film microreactors
Chemical Engineering Journal, 2010Co-Authors: Haocui Zhang, Guangwe Chen, Quan YuanAbstract:This paper concerns an experimental investigation into the flow pattern transition and break-up mechanism of liquid Film in single-channel Falling Film microreactors. Three major flow patterns were observed to be ‘corner rivulet flow’, ‘Falling Film flow with dry patches’, and ‘complete Falling Film flow’. The critical flow rate associated with the transition between each flow pattern was determined. Hysteresis was found, as the critical flow rate was higher when the flow pattern shifted from ‘Falling Film flow with dry patches’ to ‘complete Falling Film flow’ than it was when the flow pattern shifted in the opposite direction. There existed a minimum wetting flow rate (MWF) in order to the complete Falling Film flow pattern to be present. MWF was observed to increase with the width or depth of microchannel and could not be well predicted by traditional Falling Film correlations. Based on the obtained data, an empirical correlation has been proposed for the prediction of MWF in Falling Film microreactors, where the influence of fluid physical properties and channel dimension is revealed.
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hydrodynamics and mass transfer of gas liquid flow in a Falling Film microreactor
Aiche Journal, 2009Co-Authors: Haocui Zhang, Guangwen Chen, Quan YuanAbstract:In this article, flow pattern of liquid Film and flooding phenomena of a Falling Film microreactor (FFMR) were investigated using high-speed CCD camera. Three flow regimes were identified as ‘‘corner rivulet flow,’’ ‘‘Falling Film flow with dry patches,’’ and ‘‘complete Falling Film flow’’ when liquid flow rate increased gradually. Besides liquid Film flow in microchannels, a flooding presented as the flow of liquid along the side wall of gas chamber in FFMR was found at high liquid flow rate. Moreover, the flooding could be initiated at lower flow rate with the reduction of the depth of the gas chamber. CO2 absorption was then investigated under the complete Falling flow regime in FFMR, where the effects of liquid viscosity and surface tension on mass transfer were demonstrated. The experimental results indicate that kL is in the range of 5.83 to 13.4 � 10 � 5 ms � 1 and an empirical correlation was proposed to predict kL in FFMR.
Quan Yuan - One of the best experts on this subject based on the ideXlab platform.
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Flow pattern and break-up of liquid Film in single-channel Falling Film microreactors
Chemical Engineering Journal, 2010Co-Authors: Haocui Zhang, Guangwe Chen, Quan YuanAbstract:This paper concerns an experimental investigation into the flow pattern transition and break-up mechanism of liquid Film in single-channel Falling Film microreactors. Three major flow patterns were observed to be ‘corner rivulet flow’, ‘Falling Film flow with dry patches’, and ‘complete Falling Film flow’. The critical flow rate associated with the transition between each flow pattern was determined. Hysteresis was found, as the critical flow rate was higher when the flow pattern shifted from ‘Falling Film flow with dry patches’ to ‘complete Falling Film flow’ than it was when the flow pattern shifted in the opposite direction. There existed a minimum wetting flow rate (MWF) in order to the complete Falling Film flow pattern to be present. MWF was observed to increase with the width or depth of microchannel and could not be well predicted by traditional Falling Film correlations. Based on the obtained data, an empirical correlation has been proposed for the prediction of MWF in Falling Film microreactors, where the influence of fluid physical properties and channel dimension is revealed.
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hydrodynamics and mass transfer of gas liquid flow in a Falling Film microreactor
Aiche Journal, 2009Co-Authors: Haocui Zhang, Guangwen Chen, Quan YuanAbstract:In this article, flow pattern of liquid Film and flooding phenomena of a Falling Film microreactor (FFMR) were investigated using high-speed CCD camera. Three flow regimes were identified as ‘‘corner rivulet flow,’’ ‘‘Falling Film flow with dry patches,’’ and ‘‘complete Falling Film flow’’ when liquid flow rate increased gradually. Besides liquid Film flow in microchannels, a flooding presented as the flow of liquid along the side wall of gas chamber in FFMR was found at high liquid flow rate. Moreover, the flooding could be initiated at lower flow rate with the reduction of the depth of the gas chamber. CO2 absorption was then investigated under the complete Falling flow regime in FFMR, where the effects of liquid viscosity and surface tension on mass transfer were demonstrated. The experimental results indicate that kL is in the range of 5.83 to 13.4 � 10 � 5 ms � 1 and an empirical correlation was proposed to predict kL in FFMR.
N E Wijeysundera - One of the best experts on this subject based on the ideXlab platform.
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mass transfer across the Falling Film simulations and experiments
Chemical Engineering Science, 2008Co-Authors: Z F Xu, B C Khoo, N E WijeysunderaAbstract:Abstract Mass transfer across the thin Falling Film gas–liquid interface is a very important process as in chemical engineering and other fields, and yet there is still a lack of general predictability of the transfer quantity based on basic hydrodynamic parameters and independent of the geometrical setup. In this work, a numerical simulation is carried out for a vertical Falling Film arrangement. The wave dynamics and the associated mass transfer phenomena are discussed and compared with previous experimental empirical relationships. Based on the validity of the simulated results for wave parameters, numerical experiments for mass transfer were carried out with the aim of comparing to the empirical relation based on a single hydrodynamic parameter β (the gradient of the vertical fluctuating velocity at the interface) established previously by Law and Khoo [2002. Transport across a turbulent gas–liquid interface. A.I.Ch.E. Journal 48(9), 1856–1868.] and Xu et al. [2006. Mass transfer across the turbulence gas–water interface. A.I.Ch.E. Journal 52, 3363–3374] with various non-Falling Film experiments. Separately, experiments in an inclined plate thin Falling Film apparatus were carried out to determine the β distribution and associated mass transfer. It is found that there is reasonable concurrence with the mentioned empirical relation, hence suggesting the general applicability of β characterizing the scalar transport across the gas–liquid interface independent of the means of turbulence generation.
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performance study of a Falling Film absorber with a Film inverting configuration
International Journal of Refrigeration-revue Internationale Du Froid, 2003Co-Authors: Raisul Islam, N E Wijeysundera, J C HoAbstract:This paper describes the development of a novel Film-inverting design concept for Falling-Film absorbers. The solid surface of the absorber is segmented so that both surfaces of the Falling-Film are alternatively cooled in a periodic manner. A conventional tubular absorber is modified by introducing Film-guiding fins between tubes to produce a Film-inverting arrangement. A maximum increase in vapour absorption rate of about 100% is obtained with the Film-inverting design compared to the tubular absorber. The numerical simulation indicates that the vapour absorption rate can be increased by using a large number of Film-inverting segments in the absorber.
Binglu Ruan - One of the best experts on this subject based on the ideXlab platform.
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Vapor Shear Effects on Falling-Film Mode Transitions Between Horizontal Tubes
2020Co-Authors: Binglu Ruan, Anthony M. Jacobi, Liansheng LiAbstract:A liquid Falling between horizontal tubes can take the form of droplets, jets, or a continuous sheet mode, depending on the flow rate. The so-called Falling-Film flow regime is important to heat and mass transfer, and to maintaining wetted-surface conditions in a Falling-Film tube bundle, and the performance of such tube bundles is important in many air-conditioning systems. In this paper, we review prior work on Falling Film mode transitions between horizontal tubes and investigate vapor shear effects on the mode transitions. It is shown that vapor shear effects on mode transitions depend on liquid properties. Mode transition hysteresis is reduced by an increasing gas flow velocity. It is also found that the liquid feeding length can have an impact on Falling-Film mode transitions.
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effects of a countercurrent gas flow on Falling Film mode transitions between horizontal tubes
Experimental Thermal and Fluid Science, 2009Co-Authors: Binglu Ruan, Anthony M. Jacobi, Liansheng LiAbstract:Abstract A liquid Film Falling between horizontal tubes is known to take the form of droplets, jets or sheets, depending on the liquid flow rate; the form of the flow is the so-called “Falling-Film mode”. Although previously neglected in studies of mode transition, a countercurrent gas flow often exists in Falling-Film heat exchangers, and its effect on the liquid flow might be important: it could impact the flow regime, lead to local “dryout,” and decrease the heat transfer rate. Experiments are conducted to explore the effects of a countercurrent gas flow and liquid feeding length on Falling-Film mode transitions for a liquid flowing over horizontal tubes. The effects on mode transition are shown to depend on fluid properties and are explained in terms of unsteadiness and Film thickness. In general, transition hysteresis is reduced with an increasing gas velocity. A correlation is developed to predict the countercurrent gas flow effects on Falling-Film mode transitions. The liquid feeding length can affect mode transitions in quiescent surroundings and when a countercurrent gas flow imposed.
J C Ho - One of the best experts on this subject based on the ideXlab platform.
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performance study of a Falling Film absorber with a Film inverting configuration
International Journal of Refrigeration-revue Internationale Du Froid, 2003Co-Authors: Raisul Islam, N E Wijeysundera, J C HoAbstract:This paper describes the development of a novel Film-inverting design concept for Falling-Film absorbers. The solid surface of the absorber is segmented so that both surfaces of the Falling-Film are alternatively cooled in a periodic manner. A conventional tubular absorber is modified by introducing Film-guiding fins between tubes to produce a Film-inverting arrangement. A maximum increase in vapour absorption rate of about 100% is obtained with the Film-inverting design compared to the tubular absorber. The numerical simulation indicates that the vapour absorption rate can be increased by using a large number of Film-inverting segments in the absorber.