Estimation of Heat Transfer Coefficient from Universal Expression of Tangential Velocity at Boundary Layer Edge on Side Wall of a Fully Turbulent Agitated Vessel

2008 ◽  
Vol 41 (3) ◽  
pp. 145-154 ◽  
Author(s):  
Katsumi Shiobara ◽  
Setsuro Hiraoka ◽  
Yoshihito Kato ◽  
Shuichi Iwata ◽  
Yutaka Tada ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Tangential Velocity ◽  
Side Wall ◽  
Agitated Vessel ◽  
Universal Expression ◽  
Boundary Layer Edge

Freestream Flow Effects on Film Effectiveness and Heat Transfer Coefficient Augmentation for Compound Angle Shaped Holes

2017 ◽  
Author(s):  
Joshua B. Anderson ◽  
John W. McClintic ◽  
David G. Bogard ◽  
Thomas E. Dyson ◽  
Zachary Webster
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Layer Thickness ◽  
Film Cooling ◽  
Gas Turbines ◽  
Boundary Layer Thickness ◽  
Adiabatic Effectiveness ◽  
Compound Angle

The use of compound-angled shaped film cooling holes in gas turbines provides a method for cooling regions of extreme curvature on turbine blades or vanes. These configurations have received surprisingly little attention in the film cooling literature. In this study, a row of laid-back fanshaped holes based on an open-literature design, were oriented at a 45-degree compound angle to the approaching freestream flow. In this study, the influence of the approach flow boundary layer thickness and character were experimentally investigated. A trip wire and turbulence generator were used to vary the boundary layer thickness and freestream conditions from a thin laminar boundary layer flow to a fully turbulent boundary layer and freestream at the hole breakout location. Steady-state adiabatic effectiveness and heat transfer coefficient augmentation were measured using high-resolution IR thermography, which allowed the use of an elevated density ratio of DR = 1.20. The results show adiabatic effectiveness was generally lower than for axially-oriented holes of the same geometry, and that boundary layer thickness was an important parameter in predicting effectiveness of the holes. Heat transfer coefficient augmentation was highly dependent on the freestream turbulence levels as well as boundary layer thickness, and significant spatial variations were observed.

Investigating the Effect of Fuel Rate Variation in an Industrial Thermal Cracking Furnace With Alternative Arrangement of Wall Burners Using Computational Fluid Dynamics Simulation

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
Hossein Mohammad Ghasemi ◽  
Neda Gilani ◽  
Jafar Towfighi Daryan
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Side Wall ◽  
Base Flow ◽  
Dynamics Simulation ◽  
Rate Variation ◽  
Fuel Rate

A new arrangement of side-wall burners of an industrial furnace was studied by three-dimensional computational fluid dynamics (CFD) simulation. This simulation was conducted on ten calculation domain. Finite rate/eddy dissipation model was used as a combustion model. Discrete ordinate model (DOM) was considered as radiation model. Furthermore, weighted sum of gray gas model (WSGGM) was used to calculate radiative gas properties. Tube skin temperature and heat flux profiles were obtained by solving mass, momentum, and energy equations. Moreover, fuel rate variation was considered as an effective parameter. A base flow rate of fuel (m˙=0.0695kg/s) was assigned and different ratios (0.25 m˙, 0.5 m˙, 2 m˙, and 4 m˙) were assigned to investigate the heat distribution over the furnace. Resulted temperature and heat profiles were obtained in nonuniform mode using the proposed wall burner arrangement. According to the results, despite increased heat transfer coefficient of about 34% for m˙–4 m˙, temperature profile for this rate is too high and is harmful for tube metallurgy. Also, the proper range for fuel rate variation was determined as 0.5–2 m˙. In this range, heat transfer coefficient and Nusselt number for m˙–2 m˙ were increased by 21% and for m˙–0.25 m˙ were decreased by about 28%.

Heat Transfer to the Turbulent Separated Flow of Air Downstream of a Step in the Surface of a Plate

1964 ◽  
Vol 86 (2) ◽  
pp. 259-264 ◽  
Author(s):  
R. A. Seban
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Separated Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Suction Or Injection ◽  
Turbulent Separated Flow

Experiments on a system in which separation of a turbulent boundary layer occurred at a downward step in the surface of a plate and reattached on the plate downstream of the step have produced additional results for the local heat-transfer coefficient and for the velocity and temperature distribution in the separated and reattached regions of the flow. In neither region was there found the kind of similarity near the wall that characterizes flows that are dominated by the friction at the wall, so that even this first element of the usual rationalization of the heat transfer is unavailable for the interpretation of the results. The effect of suction or injection through a slot at the base of the step is also indicated and this demonstrates relatively small effects on both the pressure distribution and the local heat-transfer coefficient.

Effects of Channel Height and Bulk Temperature Considerations on Heat Transfer Coefficient of Wetted Surfaces in a Single Inline Row Impingement Channel

2008 ◽  
Author(s):  
Mark Ricklick ◽  
Stephanie Kersten ◽  
V. Krishnan ◽  
J. S. Kapat
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Side Wall ◽  
Bulk Temperature ◽  
Channel Height ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Jet Impact ◽  
Side Walls

High performance turbine airfoils are typically cooled with a combination of internal cooling channels and impingement/film cooling. In such applications, the jets impinge against a target surface, and then exit along the channel formed by the jet plate, target plate, and side walls. Local convection coefficients are the result of both the jet impact, as well as the channel flow produced from the exiting jets. Numerous studies have explored the effects of jet array and channel configurations on both target and jet plate heat transfer coefficients. However, little work has been done in examining effects on the channel side walls, which may be a major contributor to heat transfer in real world applications. This paper examines the local and averaged effects of channel height and on heat transfer coefficients, with special attention given to the channel side walls. The effects on heat transfer results due to bulk temperature variations were also investigated. High resolution local heat transfer coefficient distributions on target and side wall surfaces were measured using temperature sensitive paint and recorded via a scientific grade charge-coupled device (CCD) camera. Streamwise pressure distributions for both the target and side walls was recorded and used to explain heat transfer trends. Results are presented for average jet based Reynolds numbers between 17,000 and 45,000. All experiments were carried out on a large scale single row, 15 hole impingement channel, with X/D of 5, Y/D of 4, and Z/D of 1, 3 and 5. The results obtained from this investigation will aid in the validation of predictive tools and development of physics-based models.

Distribution of local heat transfer coefficient values in the wall region of an agitated vessel

2008 ◽  
Vol 62 (1) ◽  
Author(s):  
Magdalena Cudak ◽  
Joanna Karcz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Turbulent Regime ◽  
Transfer Coefficients ◽  
Measuring Point ◽  
Agitated Vessel ◽  
Heat Transfer Coefficients

AbstractExperimentally found local heat transfer coefficients are analyzed as a function of the measuring point on the heat transfer surface area of the agitated vessel wall and of the impeller eccentricity. Eccentric Rushton turbine and A 315 impeller are considered. Local heat transfer coefficients were measured by means of the computer-aided electrochemical method. The measurements were performed in an agitated vessel with inner diameter 0.3 m, filled with liquid up to the height equal to the vessel diameter. The experiments were carried out within the turbulent regime of the Newtonian liquid flow in the agitated vessel. The results were compared with the data obtained for the agitated vessel equipped with an eccentrically located axial flow propeller or an HE 3 impeller. Experimental studies show that the distributions of the heat transfer coefficient values depend on the impeller eccentricity, impeller type and the direction of the liquid circulation in the agitated vessel.

scholarly journals Heat transfer coefficient in agitated vessel with perforated screw mixer.

1990 ◽  
Vol 16 (1) ◽  
pp. 46-50
Author(s):  
Toshiyuki Kobashi ◽  
Teruo Takahashi ◽  
Yoshiro Kitamura
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Agitated Vessel ◽  
Screw Mixer

Universal Expression of Tangential Velocity Distribution near Side Wall of a Fully Turbulent Agitated Vessel without Baffles

2007 ◽  
Vol 40 (8) ◽  
pp. 666-672 ◽  
Author(s):  
Setsuro Hiraoka ◽  
Katsumi Shiobara ◽  
Yoshihito Kato ◽  
Shuichi Iwata ◽  
Yutaka Tada ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Tangential Velocity ◽  
Side Wall ◽  
Agitated Vessel ◽  
Universal Expression

Analysis of Passive Tube Condensation With Non-Condensable Gas Using Heat and Mass Analogy Model

2021 ◽  
Author(s):  
Ugur Cotul ◽  
Shripad T. Revankar
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Liquid Film ◽  
Transfer Coefficient ◽  
Condensation Heat Transfer ◽  
Vapor Flow ◽  
Vapor Mixture ◽  
Condenser Tube ◽  
Numerical Predictions

Abstract In this study, we used the heat and mass analogy model to be able to predict the heat transfer properties of a condenser tube operating in passive mode. The most important advantage of analogy model comparing boundary layer model is simplicity and fast computation, that’s why it can be applied to various engineering problems for many cases. The heat and mass analogy model is based on the heat transfer balance between liquid film and gas mixture area. The main problem for the liquid film region is the heat transfer coefficient (HTC) which is affected negatively in the presence of non-condensable gas. Therefore, our main goal is to increase the HTC and condensation heat transfer rate by updating the analogy code. In the gas-vapor mixture region, heat transfer mainly occurred as latent condensation and sensible heat transfer. In order to maintain this balance between the mixture and liquid film, the interface temperature is iterated. After defining a specified tolerance value of the heat and mass analogy model codes, this iteration process was started to be used at the entrance of a condenser tube. The gas and vapor mixture is considered to be saturated at the liquid/gas interface in the heat and mass transfer analogy model. Via boundary layer study of species concentration and energy balance, the non-condensable gas effect on condensation is added into the equation. For the condensation heat transfer coefficient of turbulent vapor flow associated with laminar condensate, numerical predictions were made and they were satisfactory. The predictions were compared with the experimental data from the literature to be able to test the model. Non-condensable gas mass fraction and vapor-non-condensable mixture temperature were presented in the form of radial and axial profiles.

Two Target Parameters, the Heat Transfer Qmix/B and the Drag Force Fdmix/C are Susceptible to the Molar Gas Composition W of the Six Gas–Gas Mixtures in the W-Domain [0, 1]

2010 ◽  
Author(s):  
Mohammad Reza Mobinipouya
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Prandtl Number ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Thermophysical Properties ◽  
Gas Mixtures ◽  
Average Heat Transfer Coefficient ◽  
Average Heat

This paper addresses the laminar boundary layer flow of selected binary gas mixtures along a heated flat plate. To form the binary gas mixtures, light helium (He) is the primary gas and the heavier secondary gases are nitrogen (N2), oxygen (O2), xenon (Xe), carbon dioxide (CO2), methane (CH4), tetrafluoromethane (CF4) and sulfur hexafluoride (SF6). The central objective in the work is to investigate the potential of this group of binary gas mixtures for heat transfer intensification. From fluid physics, two thermophysical properties: viscosity η and density ρ influence the fluid flow, whereas four thermophysical properties: viscosity η, thermal conductivity λ, density ρ, and heat capacity at constant pressure Cp affect the forced convective heat transfer. The heat transfer augmentation from the flat plate is pursued by stimulating the forced convection mode as a whole. In this regard, it became necessary to construct a specific correlation equation to handle binary gas mixtures owing Prandtl number Pr ∈ (0.1, 1). The rate of heat transfer Q between a heated plate and a cold fluid is calculated with: Qmix/B=λmix0.623ρmix0.500Cp,mix0.377ηmix0.123(1) If the surface area of the plate A and the temperature difference Tw–T∞ are specified, the only possible way for intensifying the rate of heat transfer Q is by enlarging the magnitude of the average heat transfer coefficient h. This is precisely the main goal to be pursued in the present paper. The average heat transfer coefficient h in laminar boundary layer flows of incompressible, viscous fluids along heated flat plates depends on the dimensionless fluid temperature gradient at the plate θ′(0). It is given by the Prandtl number function f (Pr).

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