scholarly journals A new method to predict temperature distribution on a tube at constant heat flux

2021 ◽  
Vol 11 (5) ◽  
pp. 363-372
Author(s):  
Ali Habeeb Askar ◽  
Hazim Albedran ◽  
Endre Kovács ◽  
Károly Jármai
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Optimization Algorithm ◽  
Linear Interpolation ◽  
Electric Heater ◽  
Spline Curve ◽  
Surface Temperature Distribution ◽  
Cubic Spline Curve

Surface temperature distribution on a tube is one of the main factors affecting the calculation of the heat transfer coefficient calculation. When an electric heater heats the tube, a magnetic flux is generated that affects the thermocouples readings; therefore, an efficient fitting technique is needed to represent these readings. This work proposes an interpolated spline method to mathematically represent experimental data of a thermal distribution on a tube with heat flux. Linear regression was compared with a double linear interpolation process with an optimization algorithm and cubic spline curve method on the proposed problem. The results show that the interpolated experimental data can highly improve the regression of the spline curve. Consequently, an interpolated spline curve gives better surface temperature distribution and better estimation for the average temperature. The interpolated points on spline segments are chosen by an optimization algorithm, which is particle swarm optimization, in a way that provides more minor errors.

scholarly journals Thermal conductivity of porous ice in hailstone shells

1996 ◽  
Vol 42 (141) ◽  
pp. 195-200
Author(s):  
Guoguang Zheng ◽  
Roland List
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Linear Dependence ◽  
Internal Heat ◽  
Density Range ◽  
Surface Temperature Distribution ◽  
Temperature Distributions ◽  
Evolving Surface

AbstractThe thermal conductivity and diffusivity of porous ice accreted on spherical and spheroidal hailstone models were measured over a density range of 620–915 kg m−3. By scanning the evolving surface temperature distributions during cooling in a cold airflow the thermal conductivity was varied in iterative fashion until the internal heat flux produced the correct surface temperature distribution. The results indicate a linear dependence of the thermal conductivity,ki, and diffusivity,αi, on density. For example, lowering the density by 10% lowerskiby 15%. Within the range of cloud conditions, the density variations affect the thermal parameters more than temperature does. The results also indicate a continuous decrease of the thermal conductivity from bulk ice via consolidated porous ice to loosely packed snow.

Considerations in Predicting Burnout of Cylinders in Flow Boiling

1992 ◽  
Vol 114 (1) ◽  
pp. 185-193 ◽  
Author(s):  
P. Sadasivan ◽  
J. H. Lienhard
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Flow Boiling ◽  
Heater Surface ◽  
Near Surface ◽  
Surface Temperature Distribution ◽  
Peak Heat Flux ◽  
Far Wake ◽  
Gravity Surface

Previous investigations of the critical heat flux in flow boiling have resulted in widely different hydrodynamic mechanisms for the occurrence of burnout. Results of the present study indicate that existing models are not completely realistic representations of the process. The present study sorts out the influences of the far-wake bubble breakoff and vapor sheet characteristics, gravity, surface wettability, and heater surface temperature distribution on the peak heat flux in flow boiling on cylindrical heaters. The results indicate that burnout is dictated by near-surface effects. The controlling factor appears to be the vapor escape pattern close to the heater surface. It is also shown that a deficiency of liquid at the downstream end of the heater surface is not the cause of burnout.

The Influence of Plasma Arc Behavior on Ingot Top Surface Temperature Distribution during PAM Process

2013 ◽  
Vol 709 ◽  
pp. 313-319 ◽  
Author(s):  
Hai Song Li ◽  
Hong Chao Kou ◽  
Feng Xu ◽  
Hui Chang
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Element Model ◽  
Plasma Arc ◽  
Temperature Changes ◽  
Surface Temperature Distribution ◽  
Regional Center ◽  
Arc Behavior ◽  
Arc Heating

A 3D finite element model was established to simulate the top surface temperature evolution of Ti45Al8Nb (at.%) alloy ingot under the effect of plasma arc behavior during plasma arc cold hearth melting (PAM) process. According to the model, the top surface temperature distribution and its evolution was analyzed under different heat flux densities. Simulation results show that the position of maximum top surface temperature changes with plasma arc motion, and always located in the plasma arc heating regional center, and it increases first with time elapse and then decreases in the rest of time within one cycle. The results also show that the top surface temperature is increased with the increase in heat flux densities, but the extent is not significant, and meanwhile the temperature distribution is more non-uniform and temperature gradient is greater with the increase in heat flux densities.

Thermal conductivity of porous ice in hailstone shells

1996 ◽  
Vol 42 (141) ◽  
pp. 195-200
Author(s):  
Guoguang Zheng ◽  
Roland List
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Linear Dependence ◽  
Internal Heat ◽  
Density Range ◽  
Surface Temperature Distribution ◽  
Temperature Distributions ◽  
Evolving Surface

AbstractThe thermal conductivity and diffusivity of porous ice accreted on spherical and spheroidal hailstone models were measured over a density range of 620–915 kg m−3. By scanning the evolving surface temperature distributions during cooling in a cold airflow the thermal conductivity was varied in iterative fashion until the internal heat flux produced the correct surface temperature distribution. The results indicate a linear dependence of the thermal conductivity, ki, and diffusivity, αi, on density. For example, lowering the density by 10% lowers ki by 15%. Within the range of cloud conditions, the density variations affect the thermal parameters more than temperature does. The results also indicate a continuous decrease of the thermal conductivity from bulk ice via consolidated porous ice to loosely packed snow.

scholarly journals Interpolated spline method for a thermal distribution of a pipe with a turbulent heat flow

2021 ◽  
Vol 11 (5) ◽  
pp. 353-362
Author(s):  
Hazim Albedran ◽  
Ali Habeeb Askar ◽  
Károly Jármai ◽  
Endre Kovács
Keyword(s):  
Experimental Data ◽  
Optimization Algorithm ◽  
Linear Interpolation ◽  
Cubic Spline ◽  
Turbulent Heat ◽  
Spline Method ◽  
Thermal Distribution ◽  
Spline Curves ◽  
Curve Method ◽  
Cubic Spline Curve

This work presents an interpolated spline method to mathematically represent experimental data of a thermal distribution on a tube with heat flux. Linear regression was compared with the double linear interpolation process with an optimization algorithm and cubic spline curve method with the proposed problem. The results show that the interpolated experimental data can highly improve the efficiency of the cubic spline curves and lead to a smooth empirical equation for the experiments. The optimization algorithm chooses the interpolated points in a way that provides more minor errors.

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