Subcooled-Boiling and Convective Heat Transfer for Heptane Flowing Inside an Annulus and Past a Coiled Wire: Part II—Correlation of Data

1986 ◽  
Vol 108 (4) ◽  
pp. 928-933 ◽  
Author(s):  
H. Mu¨ller-Steinhagen ◽  
N. Epstein ◽  
A. P. Watkinson
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Subcooled Boiling ◽  
Transfer Data ◽  
Satisfactory Accuracy ◽  
Flow Past

In Part I of this paper, the authors reported an extensive series of heat transfer data for subcooled boiling of heptane in turbulent flow in an annulus, and in laminar flow past a coiled wire. These data plus some new measurements for laminar flow in the annulus were compared to the predictions of some 12 correlations from the literature. The applicability of these correlations to the present data is determined and a combination of correlations proposed to predict heat transfer with satisfactory accuracy.

Free Convection Effects on Laminar Forced Convective Heat Transfer in a Horizontal Isothermal Tube

1982 ◽  
Vol 104 (1) ◽  
pp. 145-152 ◽  
Author(s):  
W. W. Yousef ◽  
J. D. Tarasuk
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Free Convection ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Temperature Difference ◽  
Reynolds Numbers ◽  
Transfer Data ◽  
Forced Convective Heat Transfer ◽  
Nusselt Numbers

The influence of free convection due to buoyancy on forced laminar flow of air in the entrance region of a horizontal isothermal tube was investigated. The Graetz numbers ranged form 2.5 to 110.0, the Reynolds numbers ranged from 120 to 1200, the Grashof numbers ranged from 0.8 × 104 to 8.7 × 104, and the ratio L/D was varied from 6 up to 46. The average Nusselt numbers based on the log-mean temperature difference, ranged from 2.0 to 25.9. The heat transfer data were correlated according to the influence of free convection which was found to have a significant effect at points close to the entrance to the tube.

scholarly journals Convective Heat Transfer Enhancement in Nanofluids: Real Anomaly or Analysis Artifact?

2011 ◽  
Author(s):  
Naveen Prabhat ◽  
Jacopo Buongiorno ◽  
Lin-wen Hu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Transfer Coefficient ◽  
Temperature Dependence ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Transfer Enhancement

The nanofluid literature contains many claims of anomalous convective heat transfer enhancement in both turbulent and laminar flow. To put such claims to the test, we have performed a critical detailed analysis of the database reported in 12 nanofluid papers (8 on laminar flow and 4 on turbulent flow). The methodology accounted for both modeling and experimental uncertainties in the following way. The heat transfer coefficient for any given data set was calculated according to the established correlations (Dittus-Boelter’s for turbulent flow and Shah’s for laminar flow). The uncertainty in the correlation input parameters (i.e. nanofluid thermo-physical properties and flow rate) was propagated to get the uncertainty on the predicted heat transfer coefficient. The predicted and measured heat transfer coefficient values were then compared to each other. If they differed by more than their respective uncertainties, we judged the deviation anomalous. According to this methodology, it was found that in nanofluid laminar flow in fact there seems to be anomalous heat transfer enhancement in the entrance region, while the data are in agreement (within uncertainties) with the Shah’s correlation in the fully developed region. On the other hand, the turbulent flow data could be reconciled (within uncertainties) with the Dittus-Boelter’s correlation, once the temperature dependence of viscosity was included in the prediction of the Reynolds number. While this finding is plausible, it could not be conclusively confirmed, because most papers do not report information about the temperature dependence of the viscosity for their nanofluids.

scholarly journals Study of Convective Heat Transfer in Grinding Applied to Tool Carbide

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Lei Zhang ◽  
W. Brian Rowe
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Model ◽  
Cemented Carbide ◽  
Transfer Model ◽  
Grinding Temperature ◽  
Temperature Prediction

Abstract The grinding temperature is of great importance for the quality and integrity of machined cemented carbide tool. Tool edge surfaces may be damaged by softening or being stressed, hardened, burned, or cracked. Former research on grinding temperature prediction often made assumptions to simplify heat convection due to the grinding fluid. However, these simplifying assumptions can sometimes undermine the mathematical relationships between grinding conditions and surface temperature, particularly in low-temperature grinding where fluid convection is most important. This paper is an attempt to provide an improved comprehensive thermal model for the prediction of contact temperatures and for monitoring and control of thermal damage. Based on previous thermal model research, this paper tackles a key element of the thermal model for temperature prediction. It proposes a convective heat transfer model based on the classic theory of turbulent flow passing a plate. Theoretical predictions from the thermal model of turbulent flow developed in this paper are compared with experimental values. Predictions are further compared with values from a previously published laminar flow model. And it is shown that the new model leads to a significant reduction in predicted temperatures. The results suggest that the thermal model for the turbulent flow provides a reasonable estimate of predicted temperature values within the region of the fluid boiling temperature. The estimates appear to be an improvement compared with the laminar flow thermal model. The turbulent flow thermal model is considered to improve estimates of background contact temperatures in grinding cemented carbide.

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