Comparisons between Experiments and a Theoretical Model of Heat and Mass Transfer in Rotary Regenerators with Nonsorbing Matrices

1981 ◽  
Vol 103 (2) ◽  
pp. 189-195 ◽  
Author(s):  
J. G. van Leersum ◽  
C. W. Ambrose
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Theoretical Model ◽  
Heat And Mass Transfer ◽  
Equilibrium Model ◽  
Experimental Facility ◽  
Heat And Moisture ◽  
Good Agreement

A mathematical model of condensation, evaporation and heat transfer in a regenerator having a non sorbing matrix is derived. Good agreement between heat and moisture effectivities predicted by a simulation of the model, and corresponding results from an independently derived equilibrium model is shown for a particular case. Details of an experimental facility for testing the performance of a rotary regenerator are given, and a comparison between results obtained from the facility and those produced by the model are given.

Heat and mass transfer from rotating cones

1963 ◽  
Vol 17 (1) ◽  
pp. 105-112 ◽  
Author(s):  
C. L. Tien ◽  
D. T. Campbell
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Heat And Mass Transfer ◽  
Flow Characteristics ◽  
Sublimation Rate ◽  
Semi Empirical ◽  
Good Agreement

Heat transfer by convection from isothermal rotating cones is investigated experimentally by measuring the sublimation rate from naphthalene-coated cones and using the analogy between heat and mass transfer. Measurements are made for a range of conditions from entirely laminar flow to conditions when the outer 70% of the surface area is covered by turbulent flow. Mass-transfer measurements for laminar flow over cones of vertex angles 180°, 150°, 120° and 90° are in good agreement with the theoretical prediction. For turbulent flow, experimental results for cones of the above vertex angles also agree very well with the semi-empirical analogy calculations for the disk case. A different heat- and mass-transfer relationship with the rotational Reynolds number is observed in the measurements on the 60° cone, and is believed to be due to a change of flow characteristics. The instability and the transition of flows over different cone models are also discussed.

scholarly journals Characteristics of supercritical heat transfer during filmboiling of nanofluids on a vertical heated wall

2018 ◽  
pp. 29-35
Author(s):  
А. Avramenko ◽  
M. Kovetskaya ◽  
A. Tyrinov ◽  
Yu. Kovetska
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Heat Flux ◽  
High Temperature ◽  
Heat And Mass Transfer ◽  
Heated Surface ◽  
Heated Wall ◽  
Film Boiling

Nanofluid using for intensification of heat transfer during boiling are analyzed. The using boiling nanofluids for cooling high-temperature surfaces allows significantly intensify heat transfer process by increasing the heat transfer coefficient of a nanofluid in comparison with a pure liquid. The properties of nanoparticles, their concentration in the liquid, the underheating of the liquid to the saturation temperature have significant effect on the rate of heat transfer during boiling of the nanofluid. Increasing critical heat flux during boiling of nanofluids is associated with the formation of deposition layer of nanoparticles on heated surface, which contributes changing in the microcharacteristics of heat exchange surface. An increase in the critical heat flux during boiling of nanofluids is associated with the formation of a layer of deposition of nanoparticles on the surface, which contributes to a change in the microcharacteristics of the heat transfer of the surface. Mathematical model and results of calculation of film boiling characteristics of nanofluid on vertical heated wall are presented. It is shown that the greatest influence on the processes of heat and mass transfer during film boiling of the nanofluid is exerted by wall overheating, the ratio of temperature and Brownian diffusion and the concentration of nanoparticles in the liquid. The mathematical model does not take into account the effect changing structure of the heated surface on heat transfer processes but it allows to evaluate the effect of various thermophysical parameters on intensity of deposition of nanoparticles on heated wall. The obtained results allow to evaluate the effect of nanofluid physical properties on heat and mass transfer at cooling of high-temperature surfaces. The using nanofluids as cooling liquids for heat transfer equipment in the regime of supercritical heat transfer promotes an increase in heat transfer and accelerates the cooling process of high-temperature surfaces. Because of low thermal conductivity of vapor in comparison with the thermal conductivity of the liquid, an increase in the concentration of nanoparticles in the vapor contributes to greater growth in heat transfer in the case of supercritical heat transfer.

On the development of a model of coupled heat and moisture transfer in unsaturated soil

1992 ◽  
Vol 29 (6) ◽  
pp. 1107-1112 ◽  
Author(s):  
H. R. Thomas
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Unsaturated Soil ◽  
Moisture Transfer ◽  
Complex Model ◽  
Spatial Discretisation ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

The salient characteristics of a model of coupled heat and mass transfer in unsaturated soil are presented as a subset of a more complex model of the thermal–hydraulic–mechanical behaviour of unsaturated soil currently under development. Liquid and vapour flow continuity are considered separately before combining the two into a conservation of mass equation. Heat transfer by means of conduction, latent heat of vaporisation effects, and sensible heat transfer are included. A numerical simulation of the complete formulation is achieved via the use of the finite element method for spatial discretisation, with the time varying behaviour accommodated by a finite difference technique. An application of the model to the simulation of well-controlled laboratory experiments of heat and mass transfer in nondeforming medium sand is presented. Good correlation is obtained. Confidence in the approach developed is therefore achieved before proceeding to simulate the combination of the above flow processes with the deformation of engineered clay barriers. Key words : temperature, heat transfer, moisture flow, unsaturated soil, numerical model, experimental results, numerical simulation.

scholarly journals Convective Heat and Mass Transfer of Two Fluids in a Vertical Channel

2020 ◽  
Author(s):  
Suresh Babu Baluguri ◽  
G. Srinivas
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Convective Heat ◽  
Vertical Channel ◽  
Immiscible Fluids ◽  
Boundary Layer Equations ◽  
Two Fluids

A mathematical model for convective heat and mass transfer of two immiscible fluids in a vertical channel of variable width with thermo-diffusion, diffusion-thermal effects is presented. The governing boundary layer equations generated for momentum, angular momentum, energy and species concentration are solved with appropriate boundary conditions using Galeriken finite element method. The effects of the pertinent parameters are studied in detail. Furthermore, the rate of heat transfer, mass transfer and shear stress near both walls is analyzed.

scholarly journals Modelling of Coupled Heat and Mass Transfer in a Water-Cooled Falling-Film Absorber Working with an Aqueous Alkaline Nitrate Solution

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1804
Author(s):  
María E. Álvarez ◽  
Mahmoud Bourouis
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Theoretical Model ◽  
Flow Regime ◽  
Heat And Mass Transfer ◽  
Nitrate Solution ◽  
Droplet Formation ◽  
Solution Temperature ◽  
Falling Film ◽  
The Mathematical Model

A theoretical model was developed to investigate a falling-film absorber on horizontal tubes with an aqueous alkaline nitrate solution as working fluid. The absorbent, composed of an aqueous solution of nitrates (Li, K, Na) in salt mass percentages of 53%, 28%, and 19% respectively, offers favourable thermal stability, corrosiveness, and heat and mass transfer conditions which can be appropriate for absorption cooling cycles driven by high-temperature heat sources. The mathematical model developed characterises the heat and mass transfer processes and the flow regime effect (droplet-formation, droplet-fall, and falling-film) on the falling-film absorber. The results show the importance of the falling-film and droplet-formation flow regimes in the absorption process. The solution temperature and concentration profiles inside the absorber were established together with their values at the exit. The results obtained by the theoretical model were well in agreement with the experimental data obtained by the authors in a previous study. Deviations in predicting the solution and cooling water temperatures at the absorber exit were around 1 °C and for the concentration of the solution leaving the absorber, around 0.49%. The mathematical model also predicts the absorption rate at 4.7 g·m−2·s−1 for the absorber design and operating conditions used in the present work. This value is 22% higher than the experimental value obtained by the authors in their previous experimental work. The deviation is attributed to approximations incorporated into the model, especially as regards surface wettability and calculation of the mass transfer coefficients for each flow regime.

Method for Determining Overall Performances of Solar Kilns

1987 ◽  
Vol 109 (1) ◽  
pp. 26-29 ◽  
Author(s):  
J. A. Guzman ◽  
A. Lauterbach ◽  
R. Jordan
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Theoretical Model ◽  
Heat And Mass Transfer ◽  
Drying Process ◽  
Solar Kiln ◽  
Model Based ◽  
Transfer Equations

A theoretical model based on heat and mass transfer equations was developed for determining a reliable comparison between different solar kiln designs. It involves dividing the drying process into two sequential steps, one in which only heat transfer occurs and a second one in which the actual drying process takes place. The model gives an equation for determining the evaporated water in function of the normal drying variables, together with a specially defined parameter which gives account for the air recirculation inside the kiln. The model was validated experimentally for a box-type collector solar kiln operating under constant and falling rate drying periods. It was found that although the model could be applied satisfactorily, the tested design proved to be a very inefficient one, giving low values for the recirculating parameter.

A Theoretical Model for Unsteady Coupled Heat and Mass Transfer Phenomena in Industrial Dryers

2011 ◽  
Vol 42 (5) ◽  
pp. 415-432
Author(s):  
Hossein Shokouhmand ◽  
Sajjad Bigham ◽  
Sajjad Yazdani
Keyword(s):  
Mass Transfer ◽  
Theoretical Model ◽  
Heat And Mass Transfer

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.

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