NUSSELT NUMBER EXPERIMENTAL CORRELATION FOR FORCED CONVECTION IN FINNED ASTM TUBES

2020 ◽  
Author(s):  
Rodrigo Ducatti Marson ◽  
José Alexandre Matelli ◽  
Alex Bimbato
Keyword(s):  
Nusselt Number ◽  
Forced Convection ◽  
Experimental Correlation

Three-Dimensional Forced Convection in Plane Symmetric Sudden Expansion

2004 ◽  
Vol 126 (5) ◽  
pp. 836-839 ◽  
Author(s):  
J. H. Nie and ◽  
B. F. Armaly
Keyword(s):  
Nusselt Number ◽  
Forced Convection ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Flow Region ◽  
Outer Edge ◽  
Sudden Expansion ◽  
Recirculation Flow ◽  
Plane Symmetric ◽  
Laminar Forced Convection

Simulations of three-dimensional laminar forced convection in a plane symmetric sudden expansion are presented for Reynolds numbers where the flow is steady and symmetric. A swirling “jetlike” flow develops near the sidewalls in the separating shear layer, and its impingement on the stepped wall is responsible for the maximum that develops in the Nusselt number adjacent to the sidewalls and for the reverse flow that develops in that region. The maximum Nusselt number on the stepped wall is located inside the primary recirculation flow region and its location does not coincide with the jetlike flow impingement region. The results reveal that the location where the streamwise component of wall shear stress is zero on the stepped walls does not coincide with the outer edge of the primary recirculation flow region near the sidewalls.

Forced Convection in a Channel Partly Occupied by a Bidisperse Porous Medium: Symmetric Case

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
D. A. Nield ◽  
A. V. Kuznetsov
Keyword(s):  
Porous Medium ◽  
Nusselt Number ◽  
Forced Convection ◽  
Analytic Solution ◽  
Solid Material ◽  
Symmetric Case ◽  
Interface Condition ◽  
Temperature Model ◽  
The Core ◽  
Two Temperature

An analytic solution is obtained for the problem of fully developed forced convection in a channel between parallel plane walls, partly occupied by a bidisperse porous medium (BDPM) and partly by a fluid clear of solid material, the distribution of material being symmetrical with the BDPM forming either the core or the sheath portion of the channel. The case of uniform flux boundaries is considered. For the porous medium, a two-velocity two-temperature model based on Darcy’s law is employed and the Beavers–Joseph interface condition is imposed. In each case, Nusselt number values are obtained in terms of various parameters.

Transient Internal Forced Convection Under Arbitrary Time-Dependent Heat Flux

2013 ◽  
Author(s):  
M. Fakoor-Pakdaman ◽  
M. Andisheh-Tadbir ◽  
Majid Bahrami
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Forced Convection ◽  
Analytical Model ◽  
Time Dependent ◽  
Bulk Temperature ◽  
Fluid Temperature ◽  
Flux Boundary Condition ◽  
Arbitrary Time

A new all-time model is developed to predict transient laminar forced convection heat transfer inside a circular tube under arbitrary time-dependent heat flux. Slug flow condition is assumed for the velocity profile inside the tube. The solution to the time-dependent energy equation for a step heat flux boundary condition is generalized for arbitrary time variations in surface heat flux using a Duhamel’s integral technique. A cyclic time-dependent heat flux is considered and new compact closed-form relationships are proposed to predict: i) fluid temperature distribution inside the tube ii) fluid bulk temperature and iii) the Nusselt number. A new definition, cyclic fully-developed Nusselt number, is introduced and it is shown that in the thermally fully-developed region the Nusselt number is not a function of axial location, but it varies with time and the angular frequency of the imposed heat flux. Optimum conditions are found which maximize the heat transfer rate of the unsteady laminar forced-convective tube flow. We also performed an independent numerical simulation using ANSYS to validate the present analytical model. The comparison between the numerical and the present analytical model shows great agreement; a maximum relative difference less than 5.3%.

Empirical Heat Transfer Correlations during Frost Deposition on a Triangular Tube Banks Arrangement

2016 ◽  
Vol 366 ◽  
pp. 88-96
Author(s):  
Raquel da Cunha Ribeiro da Silva ◽  
Carlos Salinas Sedano ◽  
Kamal A.R. Ismail ◽  
Paúl Adrian Delgado Maldonado
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Numerical Study ◽  
Experimental Measurements ◽  
Empirical Correlations ◽  
Frost Formation ◽  
Cylindrical System ◽  
Experimental Correlation ◽  
Tube Banks ◽  
Dimensionless Correlations

An experimental study was reported earlier on the development of frost formation by humid flow passing over the cylinder. In this study, dimensionless correlations used in previous experimental data, and reported empirical correlations of the Nusselt number, were used. This paper reports results of an experimental and numerical investigation where the emphasis was placed on obtaining empirical correlation for the Nusselt number. In this work some experimental results of the frost thickness around every cylinder in a triangular arrangement are presented, an estimated experimental correlation to find Nusselt number. This correlation is based on the experimental measurements in a wind tunnel situated in the Laboratory of Thermal storage and Fluids in the Mechanical Engineering Faculty at Unicamp. A numerical study is performed to study the frost formation in the cylindrical system.

On the Nusselt Number for H2 Heat Transfer in Rectangular Ducts of Large Aspect Ratios

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
C. Y. Wang
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Aspect Ratio ◽  
Forced Convection ◽  
Parallel Plate ◽  
Convection Heat Transfer ◽  
Analytic Method ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Aspect Ratios

The H1 and H2 forced convection heat transfer in rectangular ducts are studied using an accurate, analytic method. It is confirmed that, as the aspect ratio tends to infinity, the Nusselt number for the H2 case approaches 2.9162, much lower than the parallel plate value of 8.2353 attained by the H1 case. The controversy about the H2 limit is thus settled. An explanation of the behavior is suggested.

Numerical Analysis of Laminar Forced Convection in Sinusoidal-Wavy-, Rounded-Ellipse-, and Rounded-Vee-Shaped Corrugated-Plate Channels

2010 ◽  
Author(s):  
Dean Ferley ◽  
Scott J. Ormiston
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Numerical Analysis ◽  
Prandtl Number ◽  
Friction Factor ◽  
Forced Convection ◽  
Reynolds Numbers ◽  
Ansys Cfx ◽  
Prandtl Numbers ◽  
Laminar Forced Convection

Numerical analysis of steady, two-dimensional, laminar forced convection in corrugated-plate channels is performed using a commercial CFD code: ANSYS CFX. The flow domain consists of six modules in each of three wall corrugations: sinusoidal-wavy-shaped (SWS), rounded-ellipse-shaped (RES), and rounded-vee-shaped (RVS). One ratio of minimum-to-maximum plate spacings and one module length-to-height ratio is considered. Fluid flow and heat transfer are repeating in the modules and the results are examined in a typical module in the fully-developed region for Reynolds numbers in the range of 25 to 300 for Prandtl numbers of 0.7 (air), 2.29 (water), and 34.6 (ethylene glycol). The RES corrugation produced the highest peak value of local Nusselt number as well as the highest friction factor. The SWS corrugation produced the highest average Nusselt number, except at a Prandtl number of 34.6 at higher Reynolds number where the RES corrugation had the highest value. The RVS corrugation had the lowest friction factor for the geometric configuration considered. The highest heat transfer rate per unit pumping power was found at the highest Prandtl number for the RES corrugation.

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