Kinetics of convective heat and mass transfer coefficient of green chilli during open-sun and greenhouse drying

Abstract Background In this research work, a coupled heat and mass transfer model was developed for salt recovery from concentrated brine water through an osmotic membrane distillation (OMD) process in a hollow fiber membrane contactor (HFMC).The model was built based on the resistance-in-series concept for water transport across the hydrophobic membrane. The model was adopted to incorporate the effects of polarization layers such as temperature and concentration polarization, as well as viscosity changes during concentration. Results The modeling equations were numerically simulated in MATLAB® and were successfully validated with experimental data from literature with a deviation within the range of 1–5%. The model was then applied to study the effects of key process parameters like feed concentrations, osmotic solution concentration, feed, and osmotic solution flow rates and feed temperature on the overall heat and mass transfer coefficient as well as on water transport flux to improve the process efficiency. The mass balance modeling was applied to calculate the membrane area based on the simulated mass transfer coefficient. Finally, a scale-up for the MD process for salt recovery on an industrial scale was proposed. Conclusions This study highlights the effect of key parameters for salt recovery from wastewater using the membrane distillation process. Further, the applicability of the OMD process for salt recovery on large scale was investigated. Sensitivity analysis was performed to identify the key parameters. From the results of this study, it is concluded that the OMD process can be promising in salt recovery from wastewater.

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Mass Transfer Coefficients during Steel Decarburization in a RH Degasser

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.273-276.679 ◽

2008 ◽

Vol 273-276 ◽

pp. 679-684

Author(s):

Roberto Parreiras Tavares ◽

André Afonso Nascimento ◽

Henrique Loures Vale Pujatti

Keyword(s):

Mass Transfer ◽

Reynolds Number ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Gas Flow ◽

Vacuum Chamber ◽

Volumetric Mass Transfer Coefficient ◽

Gas Flow Rate ◽

Rh Process ◽

Kinetics Of

The RH process is a secondary refining process that can simultaneously attain significant levels of removal of interstitial elements, such as carbon, nitrogen and hydrogen, from liquid steel. In the RH process, the decarburization rate plays a very important role in determining the productivity of the equipment. The kinetics of this reaction is controlled by mass transfer in the liquid phase. In the present work, a physical model of a RH degasser has been built and used in the study of the kinetics of decarburization. The effects of the gas flow rate and of the configurations of the nozzles used in the injection of the gas have been analyzed. The decarburization reaction of liquid steel was simulated using a reaction involving CO2 and caustic solutions. The concentration of CO2 in the solution was evaluated using pH measurements. Based on the experimental results, it was possible to estimate the reaction rate constant. A volumetric mass transfer coefficient was then calculated based on these rate constants and on the circulation rate of the liquid. The logarithm of the mass transfer coefficient showed a linear relationship with the logarithm of the gas flow rate. The slope of the line was found to vary according to the relevance of the reaction at the free surface in the vacuum chamber. A linear relationship between the volumetric mass transfer coefficient and the nozzle Reynolds number was also observed. The slopes of the lines changed according to the relative importance of the two reaction sites, gas-liquid interface in the upleg snorkel and in the vacuum. At higher Reynolds number, the reaction in the vacuum chamber tends to be more significant.

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An Inverse Method for Drying at High Mass Transfer Biot Number

Heat Transfer: Volume 3 ◽

10.1115/ht2003-47146 ◽

2003 ◽

Cited By ~ 2

Author(s):

Gligor H. Kanevce ◽

Ljubica P. Kanevce ◽

George S. Dulikravich ◽

Marcelo J. Colac¸o

Keyword(s):

Heat Transfer ◽

Mass Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Heat And Mass Transfer ◽

Biot Number ◽

Temperature Sensitivity ◽

Sensitivity Coefficient ◽

The Heat Transfer Coefficient

The inverse problem of using temperature measurements to estimate the moisture content and temperature-dependent moisture diffusivity together with the heat and mass transfer coefficients is analyzed in this paper. In the convective drying practice, usually the mass transfer Biot number is very high and the heat transfer Biot number is very small. This leads to a very small temperature sensitivity coefficient with respect to the mass transfer coefficient when compared to the temperature sensitivity coefficient with respect to the heat transfer coefficient. Under these conditions the relative error of the estimated mass transfer coefficient is high. To overcome this problem, in this paper the mass transfer coefficient is related to the heat transfer coefficient through the analogy between the heat and mass transfer processes in the boundary layer. The resulting parameter estimation problem is then solved by using a hybrid constrained optimization algorithm OPTRAN.

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Development of heat and mass transfer coefficient correlations for natural packings used in solar desalination process

10.5004/dwt.2019.24074 ◽

2019 ◽

Vol 153 ◽

pp. 46-53

Author(s):

K. Zhani ◽

S. Mejbri

Keyword(s):

Mass Transfer ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Heat And Mass Transfer ◽

Solar Desalination

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The effect of aeration conditions, characterized by the volumetric mass transfer coefficient KLa, on the fermentation kinetics of Bacillus thuringiensis kurstaki

Journal of Biotechnology ◽

10.1016/j.jbiotec.2015.06.387 ◽

2015 ◽

Vol 210 ◽

pp. 100-106 ◽

Cited By ~ 9

Author(s):

Jihane Rahbani Mounsef ◽

Dominique Salameh ◽

Nicolas Louka ◽

Cedric Brandam ◽

Roger Lteif

Keyword(s):

Mass Transfer ◽

Bacillus Thuringiensis ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Volumetric Mass Transfer Coefficient ◽

Fermentation Kinetics ◽

Bacillus Thuringiensis Kurstaki ◽

Aeration Conditions ◽

Kinetics Of

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Convective Mass Transfer Coefficient at Wooden Surface in Jet Drying of Veneer

Holzforschung ◽

10.1515/hf.1999.034 ◽

1999 ◽

Vol 53 (2) ◽

pp. 204-208 ◽

Cited By ~ 4

Author(s):

Antti Hukka ◽

Olli Oksanen

Keyword(s):

Mass Transfer ◽

Moisture Content ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Heat And Mass Transfer ◽

Correction Factor ◽

Average Moisture Content ◽

Correction Coefficient ◽

Convective Mass Transfer ◽

Wooden Surface

Summary The relationship between heat and mass transfer at wooden surface is investigated experimentally by drying 1.6 mm thick birch veneers in constant conditions in a laboratory-scale roller dryer. By intermediate weighing of the samples a drying curve is established for each specimen. The drying curves are formulated in a functional form to produce the drying rate as a function of wood moisture content. Based on that and the measured heat-transfer coefficient a correction factor is calculated for the mass transfer coefficient predicted by the boundary layer theory. The results show that the convective mass transfer coefficient for wooden surfaces substantially deviates from that given by the analogy between heat and mass transfer. The correction factor describing the internal resistance for evaporation is strongly dependent on wood temperature within the range 50–90°C, but for practical purposes not dependent on the average moisture content of the veneer (range 40–70%). The numerical value of the correction coefficient established is somewhat lower than published earlier by other researchers.

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