Reynolds Number Dependency of the Heat and Mass Transfer in Mixed Convective Duct Flow with Condensation at a Cooled Wall

Author(s):  
Christian Brückner ◽  
Philipp Bahavar ◽  
Andreas Westhoff ◽  
Claus Wagner
2013 ◽  
Vol 68 (12) ◽  
pp. 751-758 ◽  
Author(s):  
Tasawar Hayat ◽  
Saima Noreen ◽  
Muhammad Qasim

In this paper, we discuss the effects of heat and mass transfer on the peristaltic flow in the presence of an induced magnetic field. Constitutive equations of a Phan-Thien-Tanner fluid are utilized in the mathematical description. Mathematical modelling is based upon the laws of mass, linear momentum, energy, and concentration. Relevant equations are simplified using long wavelength and low Reynolds number assumptions. A series solution is presented for small Weissenberg number. Variations of emerging parameters embedded in the flow system are discussed.


1963 ◽  
Vol 17 (1) ◽  
pp. 105-112 ◽  
Author(s):  
C. L. Tien ◽  
D. T. Campbell

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.


1991 ◽  
Vol 113 (4) ◽  
pp. 874-882 ◽  
Author(s):  
Y.-X. Tao ◽  
M. Kaviany

Simultaneous heat and mass transfer from partially liquid-covered surfaces is examined experimentally using a surface made of cylinders with the voids filled with liquid. The steady-state evaporation rate, surface temperature of the liquid and exposed solid, and location of meniscus are measured for various ambient air velocities and temperatures. Using these, we examine the effect of the extent to which the liquid covers the surface on the evaporation mass transfer rate resulting from the convective heat transfer from the ambient gas to this surface. The results show strong Bond and Reynolds number effects. For small Bond and Reynolds numbers, the presence of dry (exposed solid) surface does not influence the mass transfer rate. As the Bond or Reynolds number increases, a critical liquid coverage is found below which the mass transfer begins to decrease. Heat transfer from the exposed solid to the liquid is also examined using the measured surface temperature, a conduction model, and an estimate of the liquid and solid surface areas (using a static formation for the liquid meniscus). The results show that at the liquid surface an analogy between heat and mass transfer does not exist.


Author(s):  
Saja Al-rifai ◽  
Cheng-Xian Lin

Abstract In this study, a numerical analysis of turbulent flow heat and mass transfer in the cross-flow transport membrane condenser (TMC) based heat exchange was carried out. The heat exchanger under investigation was designed to recover both sensible and latent heat due to transport of heat and mass through a nanoporous ceramic membrane in the bundle of tubes of the heat exchanger. The shear stress transport SST k-ω turbulence model was used to model the turbulent flow of the flue gas mixture. The condensation rate of the water vapor from the flue gas were calculated using a mixed condensation model. The mixed model was based on the capillary condensation and wall condensation in the membrane tube. The numerical study was focused on the investigation of the impact of the turbulence intensity of the flue gas at various inlet conditions, such as Reynolds numbers and temperatures, on the heat and mass transfer and pressure drop characteristics. The numerical results were validated against the experimental results reported in the literature. Different tube diameters were used in the simulation, with the Reynolds number varied from 3000 to 10000. The results showed that an increase in turbulence intensity led to a significant increase in the turbulent kinetic energy, condensation rate, average convective Nusselt number and change on the pressure drop in the heat exchanger. The effects of inlet flow Reynolds number and tube diameter on the heat and mass transfer were also presented and discussed.


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