scholarly journals Measuring REA-based drying kinetics through temperature-moisture content relationship

2018 ◽  
Author(s):  
Xiao Dong Chen ◽  
Aditya Putranto
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Mass Transfer ◽  
Moisture Content ◽  
Mass Balance ◽  
Reaction Engineering ◽  
New Approach ◽  
Engineering Approach ◽  
Relative Activation ◽  
Drying Conditions

The reaction engineering approach (REA) has been proposed and implemented for modeling a number of challenging drying cases. While the modeling is simple and accurate, it is effective to generate the drying parameters. The relative activation energy is the fingerprint of the REA which describes the changes of internal behaviors inside the materials during drying. In this paper, a new method, based on combined heat and mass balance, is proposed and implemented to retrieve the relative activation energy of flat materials. The results indicate that the new approach can be used to retrieve well the activation energy of flat materials. The relative activation energy retrieved by the new approach is independent on the external drying conditions. This new approach can also potentially be used to evaluate the change of surface area of materials during drying Keywords: reaction engineering approach (REA);, modeling; relative activation energy; mass transfer;, heat transfer 

Mathematical analysis of solar conduction dryer using reaction engineering approach

2020 ◽  
Vol 18 (5-6) ◽  
Author(s):  
Anand Chavan ◽  
Bhaskar Thorat
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Mass Transfer ◽  
Effective Diffusivity ◽  
Reaction Engineering ◽  
Agricultural Product ◽  
Heat Transfer Mechanism ◽  
Engineering Approach ◽  
Individual Mode ◽  
Relative Activation

AbstractSolar conduction dryer (SCD) utilizes all three modes of heat transfer, viz., conduction, convection, and radiation. The effect of individual mode of heat transfer in SCD on agricultural product drying was studied using drying kinetics and basic heat transfer calculations. It was observed that the order of influence of mode of heat transfer mechanism as conduction followed by radiation and then convection. The correlation for relative activation energy (∆Ev/∆Ev,∞) as a function of moisture content (X−X∞), effective diffusivity (Deff), and mass transfer coefficient (hm) were determined for each mode of heat transfer. It was observed that the reaction engineering approach (REA) is appropriate tool to understand the physics of drying mechanism in SCD.

scholarly journals Impact of Binary Chemical Reaction and Activation Energy on Heat and Mass Transfer of Marangoni Driven Boundary Layer Flow of a Non-Newtonian Nanofluid

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 702
Author(s):  
Ramanahalli Jayadevamurthy Punith Gowda ◽  
Rangaswamy Naveen Kumar ◽  
Anigere Marikempaiah Jyothi ◽  
Ballajja Chandrappa Prasannakumara ◽  
Ioannis E. Sarris
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Boundary Layer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Velocity Gradient ◽  
Boundary Layer Flow ◽  
Biological Fluids ◽  
Porosity Parameter ◽  
Layer Flow

The flow and heat transfer of non-Newtonian nanofluids has an extensive range of applications in oceanography, the cooling of metallic plates, melt-spinning, the movement of biological fluids, heat exchangers technology, coating and suspensions. In view of these applications, we studied the steady Marangoni driven boundary layer flow, heat and mass transfer characteristics of a nanofluid. A non-Newtonian second-grade liquid model is used to deliberate the effect of activation energy on the chemically reactive non-Newtonian nanofluid. By applying suitable similarity transformations, the system of governing equations is transformed into a set of ordinary differential equations. These reduced equations are tackled numerically using the Runge–Kutta–Fehlberg fourth-fifth order (RKF-45) method. The velocity, concentration, thermal fields and rate of heat transfer are explored for the embedded non-dimensional parameters graphically. Our results revealed that the escalating values of the Marangoni number improve the velocity gradient and reduce the heat transfer. As the values of the porosity parameter increase, the velocity gradient is reduced and the heat transfer is improved. Finally, the Nusselt number is found to decline as the porosity parameter increases.

Evaluation of Mass Transfer Properties in Convective Drying of Kiwi and Eggplant

2017 ◽  
Vol 13 (7) ◽  
Author(s):  
Raquel P. F. Guine ◽  
Mariana F. S. Brito ◽  
Jéssica R. P. Ribeiro
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Operating Temperature ◽  
Convective Drying ◽  
Convective Mass Transfer ◽  
Air Flow Rate ◽  
Plant Foods ◽  
Different Temperatures ◽  
Drying Conditions ◽  
Transfer Properties

AbstractThe present work aimed at studying the mass transfer properties of two plant foods, kiwi (a fruit) and eggplant (a vegetable). For this convective drying experiments were conducted at different temperatures (from 50 to 80 ºC) and an air flow rate of 0.5 m/s, using slices with 6 mm thickness for both products. For the mathematical modelling two different methods were used, one based on the thin layer model and the other based on the Fick’s second law of diffusion. The results obtained allowed concluding that different methodologies allowed to obtain different values of the mass transfer properties, so care must be taken when choosing an appropriate calculation method. Regarding the values of diffusivity and mass transfer coefficient, in all cases they were found to increase with increasing operating temperature. Both the activation energy and the activation energy for convective mass transfer were similar for kiwi and for eggplant, indicating that both foods behave in a very similar way when exposed to the drying conditions tested.

Mass Transfer Parameters and Modeling of Hot Air Drying Kinetics of Dill Leaves

2016 ◽  
Vol 12 (2) ◽  
Author(s):  
Hosain Darvishi ◽  
Zanyar Farhudi ◽  
Nasser Behroozi-Khazaei
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Moisture Content ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Transfer Model ◽  
Hot Air ◽  
Drying Behavior ◽  
Kinetics Of ◽  
Best Fit

Abstract Moisture diffusivity (Dem), mass transfer coefficient (hm), activation energy and drying kinetics of the dill leaves were studied and modeled as a function of temperature (40–70 °C) and moisture content (0.20–5.67 kg water/kg dry matter). Results showed that the Dem and hm significantly depend on the temperature and moisture content (p < 0.05). The average of Dem and hm varied between 4.02 × 10–9 to 9.65 × 10–9 m2/s, and 2.38 × 10–7 to 6.33 × 10–7 m/s, respectively. Activation energy showed a significant dependence on the moisture content and estimated as 16.84 kJ/mol for diffusion model and 28.70 kJ/mol for mass transfer model. Out of the six models considered, the logarithmic model showed the best fit to drying behavior of the dill leaves.

Numerical investigation of heat and mass transfer during hydrogen sorption in a mixture of AB2 – AB5 metal hydride for hydrogen storage

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mapula Lucey Moropeng ◽  
Andrei Kolesnikov ◽  
Mykhaylo Lototskyy ◽  
Avhafunani Mavhungu
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat And Mass Transfer ◽  
Metal Hydride ◽  
Sorption Process ◽  
Hydrogen Gas ◽  
Hydrogen Sorption

AbstractThis paper presents the investigation of a two dimensional coupled model of heat and mass transfer in a mixture of AB2 – AB5 metal hydride (MH) systems of a cylindrical configuration during hydrogen sorption using COMSOL 5.3a commercial software. The parametric study on the sorption process has been studied with variation of heat transfer coefficient (HTC), and activation energy (AE) to understand the effects they have on the reaction kinetics of the sorption process. The simulation results demonstrate the importance of mutual dependence between the temperature propagation in the body of metal hydride, the absorbed concentration of the hydrogen gas, and the gas pressure for the absorption of hydrogen gas in metal hydrides. The decrease in the activation energy is found to have significant effect on the dynamic performances of hydrogen absorption in the MH reactors with an increased amount of hydrogen conversion, whilst the variation of heat transfer coefficient displayed insignificant change in hydrogen conversion. The simulated results show good agreement with the experimental results obtained from HYSA Systems and were implemented for use in the STILL RX60-30L electric forklift fuel cell applications designed by HYSA Systems in the University of the Western Cape.

Flow and heat transfer over a permeable moving wedge in a hybrid nanofluid with activation energy and binary chemical reaction

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nurul Amira Zainal ◽  
Roslinda Nazar ◽  
Kohilavani Naganthran ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Mass Transfer ◽  
Chemical Reaction ◽  
Volume Fraction ◽  
Hybrid Nanofluid ◽  
Content Type ◽  
Transfer Rates ◽  
Flow And Heat Transfer ◽  
Moving Wedge

Purpose The analysis of boundary layers is needed to reflect the behaviour of fluid flows in current industrial processes and to improve the efficacy of products. Hence, this study aims to analyse the flow and heat transfer performance of hybrid alumina-copper/water (Al2O3-Cu/H2O) nanofluid with the inclusion of activation energy and binary chemical reaction effect towards a moving wedge. Design/methodology/approach The multivariable differential equations with partial derivatives are converted into a specific type of ordinary differential equations by using valid similarity transformations. The reduced mathematical model is elucidated in the MATLAB system by using the bvp4c procedure. This solution method is competent in delivering multiple solutions once appropriate assumptions are supplied. Findings The results of multiple control parameters have been studied, and the findings are verified to provide more than one solution. The coefficient of skin friction was discovered to be increased by adding nanoparticles volume fraction from 0% to 0.5% and 1%, by almost 1.6% and 3.2%. Besides, increasing the nanoparticles volume fraction improves heat transfer efficiency gradually. The inclusion of the activation energy factor displays a downward trend in the mass transfer rates, consequently reducing the concentration profile. In contrast, the increment of the binary reaction rate greatly facilitates the augmentation of mass transfer rates. There is a significant enhancement in the heat transfer rate, approximately 13.2%, when the suction effect dominates about 10% in the boundary layer flow. Additionally, the results revealed that as the activation energy rises, the temperature and concentration profiles rise as well. It is proved that the activation energy parameter boosts the concentration of chemical species in the boundary layer. A similar pattern emerges as the wedge angle parameter increases. The current effort aims to improve the thermal analysis process, particularly in real-world applications such as geothermal reservoirs, chemical engineering and food processing, which often encountered mass transfer phenomenon followed by chemical reactions with activation energy. Originality/value The present results are original and new for the study of flow and heat transfer over a permeable moving wedge in a hybrid nanofluid with activation energy and binary chemical reaction.

scholarly journals Model for Heat and Mass Transfer in Freeze-Drying of Pellets

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Ioan Cristian Trelea ◽  
Stéphanie Passot ◽  
Michèle Marin ◽  
Fernanda Fonseca
Keyword(s):  
Mass Transfer ◽  
Moisture Content ◽  
Product Quality ◽  
Heat And Mass Transfer ◽  
Freeze Drying ◽  
Chamber Pressure ◽  
Bulk Temperature ◽  
Slab Thickness ◽  
Drying Time ◽  
Drying Conditions

Lyophilizing frozen pellets, and especially spray freeze-drying, have been receiving growing interest. To design efficient and safe freeze-drying cycles, local temperature and moisture content in the product bed have to be known, but both are difficult to measure in the industry. Mathematical modeling of heat and mass transfer helps to determine local freeze-drying conditions and predict effects of operation policy, and equipment and recipe changes on drying time and product quality. Representative pellets situated at different positions in the product slab were considered. One-dimensional transfer in the slab and radial transfer in the pellets were assumed. Coupled heat and vapor transfer equations between the temperature-controlled shelf, the product bulk, the sublimation front inside the pellets, and the chamber were established and solved numerically. The model was validated based on bulk temperature measurement performed at two different locations in the product slab and on partial vapor pressure measurement in the freeze-drying chamber. Fair agreement between measured and calculated values was found. In contrast, a previously developed model for compact product layer was found inadequate in describing freeze-drying of pellets. The developed model represents a good starting basis for studying freeze-drying of pellets. It has to be further improved and validated for a variety of product types and freeze-drying conditions (shelf temperature, total chamber pressure, pellet size, slab thickness, etc.). It could be used to develop freeze-drying cycles based on product quality criteria such as local moisture content and glass transition temperature.

Modeling Pneumatic Conveyor Duct Wear: A New Approach

2005 ◽  
Author(s):  
Prem Chand ◽  
A. C. Saha ◽  
Prafull Chand
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Material Flow ◽  
Gas Flow ◽  
Gas Mixture ◽  
New Approach ◽  
Flow Phenomenon ◽  
Transfer Processes ◽  
Flow Through ◽  
Difficult Situations

It was shown in one of our recent works [1] that, the apparently disconnected items like solid-gas flow phenomenon, duct wear and particle degradation are in fact beautifully connected involving all the three components of transfer processes — heat transfer, mass transfer and momentum transfer. This paper which basically is an extension of our work on Fluid Energy Mill [2] aims at predicting duct wear while transporting solids-gas mixture in pneumatic conveyor even in most difficult situations like flow through bends under interference situation. The paper elaborates the methodology used for wear prediction and highlights the effect of several parameters like material flow rate etc. on the nature and extent of the duct wear.

Magnetohydrodynamic flow of Carreau liquid over a stretchable sheet with a variable thickness

2020 ◽  
Vol 16 (5) ◽  
pp. 1277-1293 ◽  
Author(s):  
B. Mahanthesh
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Activation Energy ◽  
Mass Transfer ◽  
Differential Equations ◽  
Chemical Reaction ◽  
Variable Thickness ◽  
Transfer Rate ◽  
Content Type ◽  
Biomedical Sensors

PurposeThe magnetohydrodynamic (MHD) flow problems are important in the field of biomedical applications such as magnetic resonance imaging, inductive heat treatment of tumours, MHD-derived biomedical sensors, micropumps for drug delivery, MHD micromixers, magnetorelaxometry and actuators. Therefore, there is the impact of the magnetic field on the transport of non-Newtonian Carreau fluid in the presence of binary chemical reaction and activation energy over an extendable surface having a variable thickness. The significance of irregular heat source/sink and cross-diffusion effects is also explored.Design/methodology/approachThe leading governing equations are constructed by retaining the effects of binary chemical reaction and activation energy. Suitable similarity transformations are used to transform the governing partial differential equations into ordinary differential equations. Subsequent nonlinear two-point boundary value problem is treated numerically by using the shooting method based on Runge–Kutta–Fehlberg. Graphical results are presented to analyze the behaviour of effective parameters involved in the problem. The numerical values of the mass transfer rate (Sherwood number) and heat transfer rate (Nusselt number) are also calculated. Furthermore, the slope of the linear regression line through the data points is determined in order to quantify the outcome.FindingsIt is established that the external magnetic field restricts the flow strongly and serves as a potential control mechanism. It can be concluded that an applied magnetic field will play a major role in applications like micropumps, actuators and biomedical sensors. The heat transfer rate is enhanced due to Arrhenius activation energy mechanism. The boundary layer thickness is suppressed by strengthening the thickness of the sheet, resulting in higher values of Nusselt and Sherwood numbers.Originality/valueThe effects of magnetic field, binary chemical reaction and activation energy on heat and mass transfer of non-Newtonian Carreau liquid over an extendable surface with variable thickness are investigated for the first time.

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