scholarly journals Erratum: “Use of Streamwise Periodic Boundary Conditions for Problems in Heat and Mass Transfer” [Journal of Heat Transfer, 2007, 129(4), pp. 601–605]

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
S. B. Beale
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Boundary Conditions ◽  
Heat And Mass Transfer ◽  
Periodic Boundary ◽  
Periodic Boundary Conditions

Transient Heat Transfer of a Hollow Cylinder Subjected to Periodic Boundary Conditions

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Yujia Sun ◽  
Xiaobing Zhang
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Hollow Cylinder ◽  
Periodic Boundary ◽  
Periodic Boundary Conditions ◽  
Transient Heat Transfer ◽  
Maximum Temperature ◽  
Water Cooling ◽  
Chromium Plating ◽  
Inner Surface

The purpose of this paper is to study the transient temperature responses of a hollow cylinder subjected to periodic boundary conditions, which comprises with a short heating period (a few milliseconds) and a relative long cooling period (a few seconds). During the heating process, the inner surface is under complex convection heat transfer condition, which is not so easy to approximate. This paper first calculated the gas temperature history and the convective heat transfer coefficient history between the gas flow and the inner surface and then they were applied to the inner surface as boundary conditions. Finite element analysis was used to solve the transient heat transfer equations of the hollow cylinder. Results show that the inner surface is under strong thermal impact and large temperature gradient occurs in the region adjacent to the inner surface. Sometimes chromium plating and water cooling are used to relief the thermal shock of a tube under such thermal conditions. The effects of these methods are analyzed, and it indicates that the chromium plating can reduce the maximum temperature of the inner surface for the first cycle during periodic heating and the water cooling method can reduce the growth trend of the maximum temperature for sustained conditions. We also investigate the effects of different parameters on the maximum temperature of the inner surface, like chromium thickness, water velocity, channel diameter, and number of cooling channels.

Entropy Generation in Convective Heat Transfer and Isothermal Convective Mass Transfer

1987 ◽  
Vol 109 (3) ◽  
pp. 647-652 ◽  
Author(s):  
J. Y. San ◽  
W. M. Worek ◽  
Z. Lavan
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Boundary Conditions ◽  
Convective Heat Transfer ◽  
Heat And Mass Transfer ◽  
Convective Heat ◽  
Entropy Generation ◽  
Ideal Gas ◽  
Convective Mass Transfer ◽  
Plate Spacing

The irreversible generation of entropy for two limiting cases of combined forced-convection heat and mass transfer in a two-dimensional channel are investigated. First, convective heat transfer in a channel with either constant heat flux or constant surface temperature boundary conditions are considered for laminar and turbulent flow. The entropy generation is minimized to yield expressions for optimum plate spacing and optimum Reynolds numbers for both boundary conditions and flow regimes. Second, isothermal convective mass transfer in a channel is considered, assuming the diffusing substance to be an ideal gas with Lewis number equal to unity. The flow is considered to be either laminar or turbulent with boundary conditions at the channel walls of either constant concentration or constant mass flux. The analogy between heat and mass transfer is used to determine the entropy generation and the relations for optimum plate spacing and Reynolds number. The applicable range of the results for both limiting cases are then investigated by non-dimensionalizing the entropy generation equation.

A Simplified CFD Model With Multi-Periodic Boundary Conditions for Cross Wavy Channels

2011 ◽  
Author(s):  
L. X. Du ◽  
M. Zeng ◽  
Q. W. Wang
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Periodic Boundary ◽  
Flow Direction ◽  
Wave Length ◽  
Three Dimensional ◽  
Periodic Boundary Conditions ◽  
Navier Stokes ◽  
The Cross ◽  
Wavy Channels

The compact and efficient primary surface heat exchangers are often used as recuperators in microturbine regenerative cycle systems. In the present study, the flow and the heat transfer performance of the cross wavy (CW) ducts have been simulated by three-dimensional models. The hydrodynamic diameters of the models are 1.689mm. Navier-Stokes and energy equations are solved by COMSOL3.5. Because one single wavy cell will overlap more than one adjacent channel, multi-periodic boundary conditions are especially adopted to simplify the calculations. Multi-periodic boundary conditions have been proved to have more reasonable flow field and heat transfer coefficient compared with the literature results. A dimensionless parameter L/A (wave length L, internal height of the corrugation in flow direction A) is defined as the optimization target. The numerical results indicated that when L/A = 6, the CW channel has the best comprehensive performance in all the cases. The comprehensive performances of the CW ducts are evaluated by the j/f (heat transfer factor j and friction factor f). The flow and heat transfer characteristics are much more complex in the cross wavy channels, especially when L/A is small.

scholarly journals Use of Streamwise Periodic Boundary Conditions for Problems in Heat and Mass Transfer

2006 ◽  
Vol 129 (4) ◽  
pp. 601-605 ◽  
Author(s):  
Steven B. Beale
Keyword(s):  
Mass Transfer ◽  
Boundary Conditions ◽  
Periodic Boundary ◽  
Periodic Boundary Conditions ◽  
Robin Boundary Condition ◽  
Constant Heat Flux ◽  
Mathematical Basis ◽  
Constant Wall Temperature ◽  
Heat And Mass Exchange ◽  
Arbitrary Boundary

Fully developed periodic boundary conditions have frequently been employed to effect performance calculations for heat and mass exchange devices. In this paper a method is proposed, which is based on the use of primitive variables combined with the prescription of slip values. Either pressure difference or mass flow rate may be equivalently prescribed. Both constant wall temperature (Dirichlet) and constant heat flux (Neumann) conditions may be considered, as well as the intermediate linear (Robin) boundary condition. The example of an offset-fin plate-fin heat exchanger is used to illustrate the application of the procedure. The mathematical basis by which the method may be extended to the consideration of mass transfer problems with arbitrary boundary conditions, and associated continuity, momentum, and species sources and sinks is discussed.

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