scholarly journals Low Peclet Number Heat Transfer in a Laminar Tube Flow Subjected to Axially Varying Wall Heat Flux

1988 ◽  
Vol 110 (3) ◽  
pp. 796-798 ◽  
Author(s):  
A. J. Pearlstein ◽  
B. P. Dempsey
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Peclet Number ◽  
Wall Heat Flux ◽  
Tube Flow ◽  
Péclet Number ◽  
Laminar Tube Flow

Heat Transfer of Power Law Fluid at Low Peclet Number Flow

1983 ◽  
Vol 105 (3) ◽  
pp. 542-549 ◽  
Author(s):  
Vi-Duong Dang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Power Law ◽  
Peclet Number ◽  
Wall Heat Flux ◽  
Power Law Fluid ◽  
Axial Conduction ◽  
Péclet Number ◽  
Constant Wall Heat Flux ◽  
Number Flow

An exact solution is presented for the temperature distribution and local Nusselt number of power law fluid in conduit at low Peclet number flow by considering axial conduction in both the upstream and the downstream regions while keeping the wall at constant temperature. Solutions are also reported for the parallel plate geometry for the aforementioned heat transfer condition and for constant wall heat flux boundary condition. The order of importance of axial conduction is established for different geometries and different boundary conditions. The effect of axial conduction is more significant when power law model index, s, increases for constant wall heat flux case, but the effect changes with Peclet number for constant wall temperature case.

A Numerical Model for Heat Transfer in Dry and Wet Grinding Based on the Finite Difference Method and Jet Cooling

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
Mohammadreza Kadivar ◽  
Mohammadali Kadivar ◽  
Amir Daneshi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Peclet Number ◽  
Material Removal ◽  
Flux Flow ◽  
Péclet Number ◽  
Heat Partition ◽  
Simulation Results

Abstract Grinding is a promising machining method for finishing workpieces that need a smooth surface with tight tolerances. Due to the high thermal energy generated in the grinding zone, an accurate prediction of workpiece temperature plays a crucial role in the design and optimization of the grinding process. Finite difference method (FDM) is used for simulating the temperature distribution in a workpiece subjected to shallow grinding using a DuFort–Frankel explicit scheme. Moreover, two simple methods, one for modeling the effect of material removal in shallow grinding and the other for calculating the heat partition, are presented. A semi-empirical correlation of cooling jet is applied to calculate the convection heat transfer coefficient (CHTC) over the grinding surface. Experiments were carried out to verify the simulation results, and a good agreement was observed between the simulation and experimental data. An analysis of the results indicated that the misestimation of workpiece temperature could occur when the effect of the material removal rate is not considered in the simulation. The simulation results showed that the heat flux flow is one-dimensional for a high Peclet number, while a two-dimensional heat flux flow prevails for a low Peclet number. The results revealed that reducing the Peclet number and extending the depth of cut increase the heat partition. The study of wet grinding demonstrated that, for efficient cooling, the coolant should be applied directly to the contact zone. Moreover, using water-based emulsion as a coolant was more effective than palm and sunflower oils.

Liquid Flow Forced Convection in Rectangular Microchannels With Nonuniform Heating: Toward Analytical Modeling of Hotspots

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Milad Azari ◽  
Arman Sadeghi ◽  
Morteza Dejam
Keyword(s):  
Heat Flux ◽  
Peclet Number ◽  
Nonuniform Distribution ◽  
Heat Fluxes ◽  
Wall Heat Flux ◽  
Nonuniform Heating ◽  
Rectangular Microchannel ◽  
Péclet Number ◽  
Accurate Design ◽  
Realistic Situation

Abstract The heat generated by microprocessors has an extremely nonuniform spatial distribution with hotspots that have heat fluxes several times larger than the background flux. Hence, for an accurate design of microchannel heat sinks used for cooling of micro-electronic devices, models are required that can take such a nonuniform distribution of wall heat flux into account. In this study, analytical solutions are obtained for hydrodynamically fully developed but thermally developing mixed electro-osmotic and pressure-driven (PD) flow in a rectangular microchannel with a peripherally uniform but axially nonuniform distribution of the wall heat flux. It is assumed that the heat flux is applied over a finite length, to mimic a physically more realistic situation, and the Péclet number is small so that lateral temperature variations are negligible as compared to the axial variations of temperature. By comparing the results with those of full numerical simulations for exponential (EHF), sinusoidal (SHF), and stepwise (STHF) distributions of wall heat flux, it is demonstrated that the solutions obtained are accurate up to a Péclet number of 10. Fortunately, this value is larger than the maximum Péclet number of electro-osmotic microflows. Furthermore, it is shown that smoother distributions of wall heat flux give rise to higher heat transfer rates. The model developed in this study can pave the way for modeling of hotspots in more complicated microfluidic devices.

scholarly journals Maximum Temperature in Dry Surface Grinding for High Peclet Number and Arbitrary Heat Flux Profile

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
J. L. González-Santander
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Linear Regression ◽  
Peclet Number ◽  
Surface Grinding ◽  
Linear Case ◽  
Maximum Temperature ◽  
Péclet Number ◽  
Asymptotic Expressions ◽  
Flux Profile

Regarding heat transfer in dry surface grinding, simple asymptotic expressions of the maximum temperature for large Peclet numbers are derived. For this purpose, we consider the most common heat flux profiles reported in the literature, such as constant, linear, triangular, and parabolic. In the constant case, we provide a refinement of the expression given in the literature. In the linear case, we derive the same expression found in the literature, being the latter fitted by using a linear regression. The expressions for the triangular and parabolic cases are novel.

scholarly journals Experimental Heat Transfer Investigation of Stationary and Orthogonally Rotating Asymmetric and Symmetric Heated Smooth and Turbulated Channels

1992 ◽  
Author(s):  
H. A. El-Husayni ◽  
M. E. Taslim ◽  
D. M. Kercher
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Rotation Number ◽  
Symmetric Case ◽  
Wall Heat Flux ◽  
Heated Wall ◽  
Wall Heat Transfer ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Smooth Channel

An experimental investigation was conducted to determine the effects of variations in wall thermal boundary conditions on local heat transfer coefficients in stationary and orthogonally rotating smooth wall and two opposite-wall turbulated square channels. Results were obtained for three distributions of uniform wall heat flux: asymmetric, applied to the primary wall only; symmetric, applied to two opposite walls only; and fully-symmetric, applied to all four channel walls. Measured stationary and rotating smooth channel average heat transfer coefficients at channel location L/Dh = 9.53 were not significantly sensitive to wall heat flux distributions. Trailing side heat transfer generally increased with Rotation number whereas the leading wall results showed a decreasing trend at low Rotation numbers to a minimum and then an increasing trend with further increase in Rotation number. The stationary turbulated wall heat transfer coefficients did not vary markedly with the variations in wall heat flux distributions. Rotating leading wall heat transfer decreased with Rotation number and showed little sensitivity to heat flux distributions except for the fully-symmetric heated wall case at the highest Reynolds number tested. Trailing wall heat transfer coefficients were sensitive to the thermal wall distributions generally at all Reynolds numbers tested and particularly with increasing Rotation number. While the asymmetric case showed a slight deficit in trailing wall heat transfer coefficients due to rotation, the symmetric case indicated little change whereas the fully-symmetric case exhibited an enhancement.

scholarly journals HEAT EXCHANGE IN A PLANE CHANNEL IN A TURBULENT FLOW REGIME IN THE CASE OF SMALL VALUES OF PRANDTL NUMBER ACCORDING TO DATA OF DIRECT NUMERICAL SIMULATION

2021 ◽  
Vol 56 ◽  
pp. 57-60
Author(s):  
Yurii G. Chesnokov ◽  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Prandtl Number ◽  
Direct Numerical Simulation ◽  
Transfer Process ◽  
Peclet Number ◽  
Plane Channel ◽  
Heat Transfer Process ◽  
Flat Channel ◽  
Péclet Number

Using the results obtained by the method of direct numerical simulation of the heat transfer process in a flat channel by various authors, it is shown that at small values of Prandtl number quite a few characteristics of the heat transfer process in a flat channel depend not on Reynolds and Prandtl numbers separately, but on Peclet number. Peclet number is calculated from the so-called dynamic speed

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