scholarly journals Stationary temperature field in an unbounded cylinder with the heat transfer coefficient periodically varying along the perimeter

1961 ◽  
Vol 06 (4) ◽  
pp. 300-310
Author(s):  
Jiří Šimonek
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Stationary Temperature Field ◽  
Unbounded Cylinder ◽  
The Heat Transfer Coefficient

Heat-Transfer Coefficient of Inviscid Fluid Freezing Onto a Moving Heat Sink

1963 ◽  
Vol 85 (3) ◽  
pp. 246-256 ◽  
Author(s):  
H. Bueckner ◽  
G. Horvay
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Inviscid Fluid ◽  
Metal Bath ◽  
Sine Transform ◽  
Fourier Sine Transform ◽  
Simplifying Assumptions ◽  
The Heat Transfer Coefficient

When a cold slab travels at speed U through a liquid metal bath, it freezes out metal at the rate of V. It is shown that the problem of determining the heat-transfer coefficient h at the interface of the liquid and solid phases is equivalent—under certain simplifying assumptions—to solving the (time-independent) wave equation in a sector. For the case of α ≡ arctan V/U < π/4, treated in the present paper, the problem is reduced, through suitable changes of variables and a Fourier sine transform, to the solution of Dirichlet’s problem for the Laplace equation. The temperature field T(X, Y) is expressed as an inverse sine transform, involving a single integration (in the transform variable). One finds that at the entrance cross section to the bath, X = 0, the heat-transfer coefficient is zero, then it rapidly approaches the asymptotic (“fully developed”) value h = γcV cos α. The heat-transfer coefficient is determined in closed form for α = π/6, π/4, and asymptotic expressions of it are derived for very small and very large distances from the origin when α is arbitrary (0 < α < π/4). Numerical evaluation of the heat-transfer coefficient at the solid-liquid interface is carried out for α = π/36, π/12, π/4. Plots of the temperature field T for these angles are also shown, along rays ϑ = π/6, π/3, π/2 to the horizontal.

Numerical Simulation of Residual Stress in Quenching 2024 Honeycomb Aluminum Alloy Thin Plates

2011 ◽  
Vol 422 ◽  
pp. 818-823
Author(s):  
Li Jin ◽  
Jian Jun Wu ◽  
Tong Zhu ◽  
Yong Jun Wang ◽  
Shang Liang Li
Keyword(s):  
Heat Transfer ◽  
Residual Stress ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thin Plate ◽  
Air Cooling ◽  
Finite Element Software ◽  
Simulation Results ◽  
The Heat Transfer Coefficient

The heat transfer coefficient during the aluminum thin plate quenching is difficult to measure experimentally. In this paper, according to the warping deformation characteristics of the 2024 honeycombed aluminum thin plate quenching, the heat transfer coefficient is obtained using finite element software ABAQUS. During the calculation process of the heat transfer coefficient, the sheet practical quenching process of immersion and the air-cooling has been considered. Using the heat transfer coefficient above, the quenching temperature field is solved through the simulation. Based on the temperature field, the residual stress field is simulated. Depending on the simulation results, the magnitude and the distribution of the residual stress is obtained. By X - ray diffraction method, the simulation results have been compared to the experiment results and they are in better agreement. It proves that the simulation method is available and effectively.

Evaporation of lignin-lean black liquor

TAPPI Journal ◽  
2015 ◽  
Vol 14 (7) ◽  
pp. 441-450
Author(s):  
HENRIK WALLMO, ◽  
ULF ANDERSSON ◽  
MATHIAS GOURDON ◽  
MARTIN WIMBY
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Black Liquor ◽  
Salt Content ◽  
Solubility Limit ◽  
Lignin Removal ◽  
Kraft Black Liquor ◽  
Black Liquors ◽  
The Heat Transfer Coefficient

Many of the pulp mill biorefinery concepts recently presented include removal of lignin from black liquor. In this work, the aim was to study how the change in liquor chemistry affected the evaporation of kraft black liquor when lignin was removed using the LignoBoost process. Lignin was removed from a softwood kraft black liquor and four different black liquors were studied: one reference black liquor (with no lignin extracted); two ligninlean black liquors with a lignin removal rate of 5.5% and 21%, respectively; and one liquor with maximum lignin removal of 60%. Evaporation tests were carried out at the research evaporator in Chalmers University of Technology. Studied parameters were liquor viscosity, boiling point rise, heat transfer coefficient, scaling propensity, changes in liquor chemical composition, and tube incrustation. It was found that the solubility limit for incrustation changed towards lower dry solids for the lignin-lean black liquors due to an increased salt content. The scaling obtained on the tubes was easily cleaned with thin liquor at 105°C. It was also shown that the liquor viscosity decreased exponentially with increased lignin outtake and hence, the heat transfer coefficient increased with increased lignin outtake. Long term tests, operated about 6 percentage dry solids units above the solubility limit for incrustation for all liquors, showed that the heat transfer coefficient increased from 650 W/m2K for the reference liquor to 1500 W/m2K for the liquor with highest lignin separation degree, 60%.

scholarly journals Systematic heat transfer measurements in highly viscous binary fluids

2021 ◽  
Author(s):  
Ann-Christin Fleer ◽  
Markus Richter ◽  
Roland Span
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volatile Component ◽  
Test Tube ◽  
Heat Fluxes ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Low Viscosity ◽  
The Heat Transfer Coefficient

AbstractInvestigations of flow boiling in highly viscous fluids show that heat transfer mechanisms in such fluids are different from those in fluids of low viscosity like refrigerants or water. To gain a better understanding, a modified standard apparatus was developed; it was specifically designed for fluids of high viscosity up to 1000 Pa∙s and enables heat transfer measurements with a single horizontal test tube over a wide range of heat fluxes. Here, we present measurements of the heat transfer coefficient at pool boiling conditions in highly viscous binary mixtures of three different polydimethylsiloxanes (PDMS) and n-pentane, which is the volatile component in the mixture. Systematic measurements were carried out to investigate pool boiling in mixtures with a focus on the temperature, the viscosity of the non-volatile component and the fraction of the volatile component on the heat transfer coefficient. Furthermore, copper test tubes with polished and sanded surfaces were used to evaluate the influence of the surface structure on the heat transfer coefficient. The results show that viscosity and composition of the mixture have the strongest effect on the heat transfer coefficient in highly viscous mixtures, whereby the viscosity of the mixture depends on the base viscosity of the used PDMS, on the concentration of n-pentane in the mixture, and on the temperature. For nucleate boiling, the influence of the surface structure of the test tube is less pronounced than observed in boiling experiments with pure fluids of low viscosity, but the relative enhancement of the heat transfer coefficient is still significant. In particular for mixtures with high concentrations of the volatile component and at high pool temperature, heat transfer coefficients increase with heat flux until they reach a maximum. At further increased heat fluxes the heat transfer coefficients decrease again. Observed temperature differences between heating surface and pool are much larger than for boiling fluids with low viscosity. Temperature differences up to 137 K (for a mixture containing 5% n-pentane by mass at a heat flux of 13.6 kW/m2) were measured.

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