scholarly journals Intensification of heat transfer in the inlet of the convective stage of the recuperative-burner unit

2021 ◽  
Vol 2088 (1) ◽  
pp. 012024
Author(s):  
Yu L Leukhin ◽  
P D Alekseev
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Three Dimensional ◽  
Annular Channel ◽  
Initial Section ◽  
Stagnant Zone ◽  
Original Design ◽  
Ansys Fluent ◽  
Annular Gap ◽  
Burner Unit

Abstract The study of aerodynamics and heat transfer in the recuperator convective stage of the recuperative-burner unit with the jet leakage of the flue gas flow onto the outer cylindrical surface is carried out. Numerical modeling of the problem was carried out in a three-dimensional formulation using the ANSYS Fluent software package. It was found that in the original design of the recuperative-burner unit, there is a significant unevenness of heat transfer along the length and perimeter of the working surface of the convective stage. In the initial section of the annular gap, a stagnant zone with the lowest heat transfer rate is observed. To eliminate the stagnant zone and to intensify heat transfer on the surface in this area, it is proposed to make the entrance to the perforated pipe in the form of an inner quarter of a torus; to install smooth protrusions on its surface; to locate an annular flow divider on the inner surface of the heat transfer wall, which separates the front part of the annular channel with formation of a set of vortex chambers. The research results are presented.

Analysis of a Virtual Prototype First-Stage Rotor Blade Using Integrated Computer-Based Design Tools

2006 ◽  
Author(s):  
Michel Arnal ◽  
Christian Precht ◽  
Thomas Sprunk ◽  
Tobias Danninger ◽  
John Stokes
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Thermal Loading ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Life Assessment ◽  
Element Analysis ◽  
Pressure Losses ◽  
Cooling Channels ◽  
Internally Cooled

The present paper outlines a practical methodology for improved virtual prototyping, using as an example, the recently re-engineered, internally-cooled 1st stage blade of a 40 MW industrial gas turbine. Using the full 3-D CAD model of the blade, a CFD simulation that includes the hot gas flow around the blade, conjugate heat transfer from the fluid to the solid at the blade surface, heat conduction through the solid, and the coolant flow in the plenum is performed. The pressure losses through and heat transfer to the cooling channels inside the airfoil are captured with a 1-D code and the 1-D results are linked to the three-dimensional CFD analysis. The resultant three-dimensional temperature distribution through the blade provides the required thermal loading for the subsequent structural finite element analysis. The results of this analysis include the thermo-mechanical stress distribution, which is the basis for blade life assessment.

scholarly journals Investigation of aerodynamics and heat transfer of the modular jet recuperator

2021 ◽  
Vol 2039 (1) ◽  
pp. 012001
Author(s):  
P D Alekseev ◽  
Yu L Leukhin
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Annular Channel ◽  
Secondary Flows ◽  
Cocurrent Flow ◽  
Outlet Section ◽  
Entire Cross Section ◽  
Staggered Arrangement ◽  
Perforated Pipe ◽  
The Impact

Abstract A study of the aerodynamics and heat transfer of a jet modular recuperator with a change in its geometric characteristics has been carried out. The influence of the in-line and staggered arrangement of the blowing holes, as well as the diameter of the perforated pipe is considered. In all considered variants, the number of holes, their diameter and gas flow rate through the recuperator remained unchanged. Numerical modeling of the problem was carried out in a three-dimensional setting using the ANSYS Fluent 15.0 software package. It was found that with the in-line arrangement of the blowing holes, secondary flows are formed between their longitudinal rows in the form of swirling jets of opposite rotation directed towards the outlet section of the recuperative device, through which the main part of the heated air flows out. With the staggered arrangement of the blowing holes, the formation of spiral vortices is disturbed, the air flow is carried out along the entire cross section of the annular channel, increasing the drift effect of the flow on the impact jets, which leads to a decrease in the intensity of heat transfer and its uniformity along the length of the working surface. An increase in the diameter of the inner perforated pipe leads to a decrease in the drift effect of the cocurrent flow on the jets, an increase in the distribution uniformity of the heat flux along the length of the heat transfer surface, and an increase in the heat transfer coefficient.

Gas Flow and Heat Transfer Analysis for an Anode Duct in Reduced Temperature SOFCs

2003 ◽  
Author(s):  
Jinliang Yuan ◽  
Masoud Rokni ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Fuel Cell ◽  
Porous Layer ◽  
Gas Flow ◽  
Porous Electrode ◽  
Three Dimensional ◽  
Gas Permeation ◽  
Heat Transfer Analysis ◽  
Fuel Cell Performance ◽  
Flow And Heat Transfer

In this study, a fully three-dimensional calculation method has been further developed to simulate and analyze various processes in a thick anode duct. The composite duct consists of a porous layer, the flow duct and solid current connector. The analysis takes the electrochemical reactions into account. Momentum and heat transport together with gas species equations have been solved by coupled source terms and variable thermo-physical properties (such as density, viscosity, specific heat, etc.) of the fuel gases mixture. The unique fuel cell conditions such as the combined thermal boundary conditions on solid walls, mass transfer (generation and consumption) associated with the electrochemical reaction and gas permeation to / from the porous electrode are applied in the analysis. Results from this study are presented for various governing parameters in order to identify the important factors on the fuel cell performance. It is found that gas species convection has a significant contribution to the gas species transport from / to the active reaction site; consequently characteristics of both gas flow and heat transfer vary widely due to big permeation to the porous layer in the entrance region and species mass concentration related diffusion after a certain distance downstream the inlet.

Flowfield and Heat Transfer Numerical Analysis of a Stator Vane Endwall With High Freestream Turbulence

2015 ◽  
Author(s):  
A. Andreini ◽  
C. Bianchini ◽  
E. Burberi ◽  
B. Facchini ◽  
R. Abram ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Computational Methods ◽  
Gas Flow ◽  
Three Dimensional ◽  
Computational Procedure ◽  
Industrial Applications ◽  
Turbulence Modelling ◽  
Large Set ◽  
Present Contribution ◽  
Stator Vane

Among the different parts subjected to hot gas flow, endwall heat transfer evaluation is particularly challenging because the flow is strongly affected by secondary effects. Large three-dimensional flow structures introduce remarkable spatial variation of heat transfer, both along streamwise and spanwise directions, making the use of simplified modelling approaches questionable in terms of reliability, and at the same time increasing the challenge for high fidelity computational methods. The aim of the present contribution is to describe the work done in the assessment of computational methods for the estimate of high pressure vane endwall heat transfer for industrial applications. Efforts were first devoted to the development and validation of an accurate computational procedure against a large set of aerodynamic and heat transfer data, available from literature, for both airfoil and endwall of a low-pressure linear cascade with low and high inlet turbulence levels. The analysis, focused on steady state computations, is principally devoted to the turbulence modelling assessment, including non-linear turbulence closure as well as transition modelling. Obtained results showed that the aerodynamics of both passage and endwall are well captured independently of the turbulence modelling while a large impact on both pattern and averaged value is verified for the heat transfer.

Numerical Simulation on Process of Flow and Heat Transfer in Upright Magnesium Reducing Furnace

2011 ◽  
Vol 383-390 ◽  
pp. 6657-6662 ◽  
Author(s):  
Jun Xiao Feng ◽  
Qi Bo Cheng ◽  
Si Jing Yu
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Temperature Field ◽  
Flue Gas ◽  
Gas Flow ◽  
Three Dimensional ◽  
Reaction Heat ◽  
Flow And Heat Transfer ◽  
Major Factors ◽  
High Chemical Reaction

Based on the analysis of structural characteristic superiority, the process of combustion, flue gas flow and heat transfer in the upright magnesium reducing furnace, the three dimensional mathematical model is devoloped. And numerical simulation is performed further with the commercial software FLUENT. Finally, the flow and temperature field in furnace and temperature field in reducing pot have been obtained. The results indicate that the upright magnesium reducing furnace has perfect flue gas flow field and temperature field to meet the challenge of the magnesium reducing process; the major factors that affect the magnesium reducing reaction are the low thermal conductivity of slag and the high chemical reaction heat absorption.

Measurements and Numerical Simulations of Heat Transfer and Pressure Drop in a Duct With Smooth Walls

2017 ◽  
Author(s):  
Puxuan Li ◽  
Steve J. Eckels
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Numerical Models ◽  
Convective Heat Transfer Coefficient ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Inlet Temperature ◽  
Ansys Fluent

Accurate measurements of heat transfer and pressure drop play important roles in thermal designs in a variety of pipes and ducts. In this study, the convective heat transfer coefficient was measured with a semi-local surface average based on Newton’s Law of cooling. Flow and heat transfer data for different Reynolds numbers were collected and compared in a duct with smooth walls. Pressure drop was measured with a pressure transducer from OMEGA Engineering Inc. The experimental results were compared with numerical estimations generated in ANSYS Fluent. Fluent contains the broad physical modeling capabilities needed to model heat transfer and pressure drop in the duct. Thermal conduction and convection in the three-dimensional (3D) duct are simulated together. Special cares for selecting the viscosity models and the near-wall treatments are discussed. The goal of the paper is to find appropriate numerical models for simulating heat conduction, heat convection and pressure drop in the duct with different Reynolds numbers. The relationship between the heat transfer coefficient and Reynolds numbers is discussed. Heat flux and inlet temperature measured in the experiment are applied to the boundary conditions. The study provides the unique opportunity to verify the accuracy of numerical models on heat transfer and pressure drop in ANSYS Fluent.

Three-Dimensional Fluid Dynamics and Radiative Heat Transfer Modeling of a Small Particle Solar Receiver

2013 ◽  
Author(s):  
Pablo Fernández del Campo ◽  
Fletcher Miller ◽  
Adam Crocker
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Small Particle ◽  
Radiative Heat ◽  
Three Dimensional ◽  
Solar Irradiation ◽  
Ansys Fluent ◽  
Solar Receiver

We present an investigation of the effects of the solar irradiation and mass flow conditions on the behavior of a Small Particle Solar Receiver employing our new, three-dimensional coupled fluid flow and radiative heat transfer model. This research expands on previous work conducted by our group and utilizes improved software with a set of new features that allows performing more flexible simulations and obtaining more accurate results. For the first time, it is possible not only to accurately predict the overall efficiency and the wall temperature distribution of the solar receiver, but also to determine the effect on the receiver of the window, the outlet tube, real solar irradiation from a heliostat field, non-cylindrical geometries and 3-D effects. This way, a much better understanding of the receiver’s capabilities is obtained. While the previous models were useful to observe simple trends, this new software is flexible and accurate enough to eventually act as a design and optimization tool for the actual receiver. The solution procedure relies on the coupling of the CFD package ANSYS Fluent to our in-house Monte Carlo Ray Trace (MCRT) software. On the one hand, ANSYS Fluent is utilized as the mass-, momentum- and energy-equation solver and requires the divergence of the radiative heat flux, which constitutes a source term of the energy equation. On the other hand, the MCRT software calculates the radiation heat transfer in the solar receiver and needs the temperature field to do so. By virtue of the coupled nature of the problem, both codes should provide feed-back to each other and iterate until convergence. The coupling between ANSYS Fluent and our in-house MCRT code is done via User-Defined Functions. After developing the mathematical model, setting up and validating the software, and optimizing the coupled solution procedure, the receiver has been simulated under fifteen different solar irradiation and mass flow rate cross combinations. Among other results, the behavior of the receiver at different times of the day and the optimum mass flow rate as a function of the solar thermal input are presented. On an average day, the thermal efficiency of the receiver is found to be over 89% and the outlet temperature over 1250 K at all times from 7:30 AM to 4:00 PM (Albuquerque, NM) by properly adapting the mass flow rate. The origin of the losses and how to improve the efficiency of the Small Particle Solar Receiver are discussed as well.

scholarly journals Performance of drop shaped pin fin heat exchanger with four different fin dimensions

2020 ◽  
Vol 14 (2) ◽  
pp. 6934-6951
Author(s):  
A.A. Mohamed ◽  
Obai Younis
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Surface Area ◽  
Three Dimensional ◽  
Tail Length ◽  
Ansys Fluent ◽  
Frictional Loss ◽  
Pin Fin ◽  
Heating And Cooling ◽  
Wetted Surface Area

In engineering, there are two primary heat transfer procedures of fluids namely, heating and cooling within a conduit that are well recognized. The heat transfer literacy remains a core component to design the heat exchangers. The study aims to present the consequences of drop shaped pin fin hear exchanger performance with four different fin dimensions. A rectangular duct with different drop-shaped pin fins dimensions is present in the heat exchanger, having similar heat transfer wetted surface area. ANSYS FLUENT 14.5 conducted three-dimensional finite volume to select the optimum pin fin dimension. The numerical results for the four cases L/D 1, 1.25, 1.5 and 1.75 indicated heat transfer had no effect on the variations in pin tail length; however, it affected frictional losses or pressure drop. There is significant decrease in the frictional loss as the result of increase in the pin tail length. The pun fin drop showed significant decrease in friction power, unlike the round pins. The ratio of pin height to the cylindrical portion of the pin (H/D) had major impact on the wetted surface area, which affects the rate of heat transfer.  

Analysis of Transport Processes and Chemical Reaction in Combustion Duct of Compact Methane Reformer

2010 ◽  
Author(s):  
Guogang Yang ◽  
Wei Wei ◽  
Jinliang Yuan ◽  
Danting Yue ◽  
Xinrong Lv
Keyword(s):  
Heat Transfer ◽  
Chemical Reaction ◽  
Porous Layer ◽  
Catalytic Combustion ◽  
Gas Flow ◽  
Three Dimensional ◽  
Gas Permeation ◽  
Transport Processes ◽  
Fuel Gas ◽  
Porous Catalyst

A composite combustion duct in compact methane reformers consists of a gas flow channel, porous layer and solid plates. There are various transport processes appeared, such as gas flow in the channel, multi-component species convection/diffusion in the porous layer, and heat transfer. They are further coupled by methane catalytic combustion in the porous layer, which affects the reformer overall performance and reliability. By three dimensional CFD approach, the reacting gas flow and heat transfer processes were numerically studied. The reformer conditions such as mass balances associated with the chemical reaction and gas permeation to/from the porous layer are implemented in the calculation. The results reveal that the catalytic combustion reaction is confined in a thin porous catalyst area close to fuel gas flow duct. Transport processes of the fuel gas species and temperature distribution are significantly affected by the reactions.

Numerical Study of Nozzle Design on Cadmium Quenching Process in Thermochemical Splitting of Water

2009 ◽  
Author(s):  
Jianhu Nie ◽  
Yitung Chen ◽  
Bunsen Wong ◽  
Lloyd C. Brown
Keyword(s):  
Heat Transfer ◽  
Hydrogen Production ◽  
Gas Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Numerical Results ◽  
Nozzle Design ◽  
Flow And Heat Transfer ◽  
Quenching Process

Three-dimensional liquid-gas flow with condensation during cadmium quenching process for hydrogen production was numerically simulated in order to effectively guide the design of solar decomposer and vapor quencher. The mixture model was selected for modeling the multiphase flow, and the two-equation RNG k-ε model was used to model the turbulent flow and heat transfer. Numerical results including velocity, temperature, pressure, and mole fraction distributions were obtained for different nozzle designs. Numerical results showed that flow is relatively low in the decomposer and close to the bottom and the top inlets. The maximum velocity develops in the region near the entrance of the quenching nozzle as the nozzle angle is small. As the nozzle angle is large, the maximum velocity appears in the exit tube. Temperature, pressure and cadmium vapor distributions are also directly affected by the nozzle angle.

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