scholarly journals Simulation of Thermal Transfer Through the Polyamide Intake Manifold

2019 ◽  
Vol 56 (1) ◽  
pp. 190-193
Author(s):  
Corneliu Birtok-Baneasa ◽  
Adina Budiul-Berghian ◽  
Virginia Ana Socalici ◽  
Robert Bucevschi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Boundary Layer ◽  
Numerical Model ◽  
Air Temperature ◽  
Wall Temperature ◽  
Thermal Boundary Layer ◽  
Intake Manifold ◽  
Thermal Transfer ◽  
Steady Heat

The aim of the present study is to model the steady heat transfer of the engine polyamide intake manifold. Under the condition of a steady flow, the intake manifold wall temperature and the intake air temperature were measured to examine the effect of the thermal boundary layer on the heat transfer. Experimental data is used to generate the numerical model of airflow simulation through the intake manifold.

scholarly journals Thermal-Boundary-Layer Response to Convected Far-Field Fluid Temperature Changes

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
Hongwei Li ◽  
M. Razi Nalim
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Temperature Difference ◽  
Wall Temperature ◽  
Thermal Boundary Layer ◽  
Steady State Solution ◽  
Step Change ◽  
Far Field ◽  
Fluid Temperature ◽  
Constant Wall Temperature

Fluid flows of varying temperature occur in heat exchangers, nuclear reactors, nonsteady-flow devices, and combustion engines, among other applications with heat transfer processes that influence energy conversion efficiency. A general numerical method was developed with the capability to predict the transient laminar thermal-boundary-layer response for similar or nonsimilar flow and thermal behaviors. The method was tested for the step change in the far-field flow temperature of a two-dimensional semi-infinite flat plate with steady hydrodynamic boundary layer and constant wall temperature assumptions. Changes in the magnitude and sign of the fluid-wall temperature difference were considered, including flow with no initial temperature difference and built-up thermal boundary layer. The equations for momentum and energy were solved based on the Keller-box finite-difference method. The accuracy of the method was verified by comparing with related transient solutions, the steady-state solution, and by grid independence tests. The existence of a similarity solution is shown for a step change in the far-field temperature and is verified by the computed general solution. Transient heat transfer correlations are presented, which indicate that both magnitude and direction of heat transfer can be significantly different from predictions by quasisteady models commonly used. The deviation is greater and lasts longer for large Prandtl number fluids.

Laminar Heat Transfer for Gas-Liquid Segmented Flows in Circular and Non-Circular Ducts With Constant Wall Temperature

2014 ◽  
Author(s):  
Y. S. Muzychka
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Wall Temperature ◽  
Thermal Boundary Layer ◽  
Additional Parameter ◽  
Residence Times ◽  
Constant Wall Temperature ◽  
Fully Developed Flow ◽  
New Model ◽  
Layer Flow

A new model is developed for gas-liquid segmented flows in ducts and channels. This model is an improvement of an earlier analysis presented and published by the author. In the present work, it is shown that for constant wall temperature, the dimensionless mean wall flux has two characteristic behaviours: thermal boundary layer flow and fully developed flow. These can also be viewed as short and long residence times as the plug train moves through the tube or channel. The boundary layer limit is dominant for short residence times while fully developed flow occurs for longer residence times. An additional parameter, the plug length to duct length ratio, (Ls/L), is shown to have significant impact on the rate of heat transfer. This parameter has the limits 0 < Ls/L < 1. The new model is compared with data from several published studies in which the variables were well controlled. It is also shown that careful experiments must be undertaken to demonstrate the characteristics of this type of flow under constant wall temperature conditions.

Heat transfer from surfaces of non-uniform temperature

1958 ◽  
Vol 4 (1) ◽  
pp. 22-32 ◽  
Author(s):  
D. B. Spalding
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Boundary Layer Thickness ◽  
Thermal Boundary Layer ◽  
Total Heat Flux ◽  
Uniform Temperature ◽  
Steady Heat ◽  
Arbitrary Velocity

The paper deals with the calculation of steady heat transfer from a surface of arbitrary temperature distribution to a laminar semi-infinite stream of arbitrary velocity distribution. Lighthill's method is improved by a correction which accounts for the departures from linearity of the velocity profile within the thermal boundary layer, and which comprehends the influences of Prandtl number, pressure gradient, body forces, and non-coincident start of velocity and thermal layers. Methods are given for evaluating the total heat flux directly, and for integrating the differential equations for the growth of the boundary layer thickness by means of quadratures.

Thermal Boundary Layer Response to Far-Field Flow Temperature Transitions

2007 ◽  
Author(s):  
Hongwei Li ◽  
M. Razi Nalim
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Temperature Difference ◽  
Wall Temperature ◽  
Thermal Boundary Layer ◽  
Far Field ◽  
Fluid Temperature ◽  
Transfer Coefficients ◽  
Flow Temperature ◽  
Constant Wall Temperature

Gas flows of varying temperature occur in heat exchangers, nuclear reactors, non-steady flow devices, and combustion engines, among other applications with heat transfer processes that influence energy conversion efficiency. A general numerical method is developed for predicting the transient laminar thermal boundary layer response to arbitrarily prescribed changes in the bulk far-field fluid temperature. The method is tested for the step change of the far-field flow temperature of a two-dimensional semi-infinite flat plate with steady hydrodynamic boundary layer and constant wall temperature assumptions. Changes of the fluid-wall temperature difference in magnitude and sign are considered, including flow with no initial temperature difference and built-up thermal boundary layer. The governing differential equations for momentum and energy are solved based on the Keller-Box finite difference method. The accuracy of the solutions is verified through comparing with the steady state solution. Transient heat transfer coefficients are presented, which indicate that both magnitude and direction of heat transfer can be significantly different from quasi-steady models commonly used.

The Effects of Conjugate Heat Transfer on the Thermal Field Above a Film Cooled Wall

2011 ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Wall Temperature ◽  
Film Cooling ◽  
Thermal Boundary Layer ◽  
Heat Transfer Analysis ◽  
Gas Temperature ◽  
Adiabatic Wall ◽  
Thermal Fields ◽  
Conducting Wall

Common gas turbine heat transfer analysis methods rely on the assumption that the driving temperature for heat transfer to a film cooled wall can be approximated by the adiabatic wall temperature. This assumption implies that the gas temperature above a film cooled adiabatic wall is representative of the overlying gas temperature on a film cooled conducting wall. This assumption has never been evaluated experimentally. In order for the adiabatic wall temperature as driving temperature for heat transfer assumption to be valid, the developing thermal boundary layer that exists above a conducting wall must not significantly affect the overriding gas temperature. In this paper, thermal fields above conducting and adiabatic walls of identical geometry and at the same experimental conditions were measured. These measurements allow for a direct comparison of the thermal fields above each wall in order to determine the validity of the adiabatic wall temperature as driving temperature for heat transfer assumption. In cases where the film cooling jet was detached, a very clear effect of the developing thermal boundary layer on the gas temperature above the wall was measured. In this case, the temperatures above the wall were clearly not well represented by the adiabatic wall temperature. For cases where the film cooling jet remained attached, differences in the thermal fields above the adiabatic and conducting wall were small, indicating a very thin thermal boundary layer existed beneath the coolant jet.

Effect of Nanofluid on Heat Transfer Enhancement for Mixed Convection Flow Over a Corrugated Surface

2020 ◽  
Vol 45 (4) ◽  
pp. 373-383
Author(s):  
Nepal Chandra Roy ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Local Nusselt Number ◽  
Richardson Number ◽  
Thermal Boundary Layer ◽  
Volume Fraction ◽  
Convection Flow ◽  
Mixed Convection Flow

AbstractA mathematical model for mixed convection flow of a nanofluid along a vertical wavy surface has been studied. Numerical results reveal the effects of the volume fraction of nanoparticles, the axial distribution, the Richardson number, and the amplitude/wavelength ratio on the heat transfer of Al2O3-water nanofluid. By increasing the volume fraction of nanoparticles, the local Nusselt number and the thermal boundary layer increases significantly. In case of \mathrm{Ri}=1.0, the inclusion of 2 % and 5 % nanoparticles in the pure fluid augments the local Nusselt number, measured at the axial position 6.0, by 6.6 % and 16.3 % for a flat plate and by 5.9 % and 14.5 %, and 5.4 % and 13.3 % for the wavy surfaces with an amplitude/wavelength ratio of 0.1 and 0.2, respectively. However, when the Richardson number is increased, the local Nusselt number is found to increase but the thermal boundary layer decreases. For small values of the amplitude/wavelength ratio, the two harmonics pattern of the energy field cannot be detected by the local Nusselt number curve, however the isotherms clearly demonstrate this characteristic. The pressure leads to the first harmonic, and the buoyancy, diffusion, and inertia forces produce the second harmonic.

Experimental Study of Heat Transfer to Supercritical Pressure Water Flowing in a 2×2 Rod Bundle

2014 ◽  
Author(s):  
Han Wang ◽  
Qincheng Bi ◽  
Linchuan Wang ◽  
Haicai Lv ◽  
Laurence K. H. Leung
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Pressure Drop ◽  
Wall Temperature ◽  
Mass Flux ◽  
Heat Fluxes ◽  
Outer Diameter ◽  
Square Channel ◽  
Rod Bundle

An experiment has recently been performed at Xi’an Jiaotong University to study the wall temperature and pressure drop at supercritical pressures with upward flow of water inside a 2×2 rod bundle. A fuel-assembly simulator with four heated rods was installed inside a square channel with rounded corner. The outer diameter of each heated rod is 8 mm with an effective heated length of 600 mm. Experimental parameters covered the pressure of 23–28 MPa, mass flux of 350–1000 kg/m2s and heat flux on the rod surface of 200–1000 kW/m2. According to the experimental data, it was found that the circumferential wall temperature distribution of a heated rod is not uniform. The temperature difference between the maximum and the minimum varies with heat flux and/or mass flux. Heat transfer characteristics of supercritical water in bundle were discussed with respect to various heat fluxes. The effect of heat flux on heat transfer in rod bundles is similar with that in tubes or annuli. In addition, flow resistance reflected in the form of pressure loss has also been studied. Experimental results showed that the total pressure drop increases with bulk enthalpy and mass flux. Four heat transfer correlations developed for supercritical pressures water were compared with the present test data. Predictions of Jackson correlation agrees closely with the experimental data.

Vortex-Induced Vibration for Heat Transfer Enhancement

2014 ◽  
Author(s):  
Junxiang Shi ◽  
Steven R. Schafer ◽  
Chung-Lung (C. L. ) Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Enhancement ◽  
Natural Frequency ◽  
Vortex Shedding ◽  
Pressure Loss ◽  
Thermal Boundary Layer ◽  
Transfer Enhancement ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

A passive, self-agitating method which takes advantage of vortex-induced vibration (VIV) is presented to disrupt the thermal boundary layer and thereby enhance the convective heat transfer performance of a channel. A flexible cylinder is placed at centerline of a channel. The vortex shedding due to the presence of the cylinder generates a periodic lift force and the consequent vibration of the cylinder. The fluid-structure-interaction (FSI) due to the vibration strengthens the disruption of the thermal boundary layer by reinforcing vortex interaction with the walls, and improves the mixing process. This novel concept is demonstrated by a three-dimensional modeling study in different channels. The fluid dynamics and thermal performance are discussed in terms of the vortex dynamics, disruption of the thermal boundary layer, local and average Nusselt numbers (Nu), and pressure loss. At different conditions (Reynolds numbers, channel geometries, material properties), the channel with the VIV is seen to significantly increase the convective heat transfer coefficient. When the Reynolds number is 168, the channel with the VIV improves the average Nu by 234.8% and 51.4% in comparison with a clean channel and a channel with a stationary cylinder, respectively. The cylinder with the natural frequency close to the vortex shedding frequency is proved to have the maximum heat transfer enhancement. When the natural frequency is different from the vortex shedding frequency, the lower natural frequency shows a higher heat transfer rate and lower pressure loss than the larger one.

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