scholarly journals Thermal Analysis and Optimization of Nano Coated Radiator Tubes Using Computational Fluid Dynamics and Taguchi Method

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 804
Author(s):  
Sudalai Suresh Pungaiah ◽  
Chidambara Kuttalam Kailasanathan
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Thermal Analysis ◽  
Computational Fluid Dynamics ◽  
Orthogonal Array ◽  
Heat Dissipation ◽  
Heat Removal ◽  
Taguchi Methods ◽  
Coolant Fluid ◽  
The Impact

Automotive heat removal levels are of high importance for maximizing fuel consumption. Current radiator designs are constrained by air-side impedance, and a large front field must meet the cooling requirements. The enormous demand for powerful engines in smaller hood areas has caused a lack of heat dissipation in the vehicle radiators. As a prediction, exceptional radiators are modest enough to understand coolness and demonstrate great sensitivity to cooling capacity. The working parameters of the nano-coated tubes are studied using Computational Fluid Dynamics (CFD) and Taguchi methods in this article. The CFD and Taguchi methods are used for the design of experiments to analyse the impact of nano-coated radiator parameters and the parameters having a significant impact on the efficiency of the radiator. The CFD and Taguchi methodology studies show that all of the above-mentioned parameters contribute equally to the rate of heat transfer, effectiveness, and overall heat transfer coefficient of the nanocoated radiator tubes. Experimental findings are examined to assess the adequacy of the proposed method. In this study, the coolant fluid was transmitted at three different mass flow rates, at three different coating thicknesses, and coated on the top surface of the radiator tubes. Thermal analysis is performed for three temperatures as heat input conditioning for CFD. The most important parameter for nanocoated radiator tubes is the orthogonal array, followed by the Signal-to-Noise Ratio (SNRA) and the variance analysis (ANOVA). A proper orthogonal array is then selected and tests are carried out. The findings of ANOVA showed 95% confidence and were confirmed in the most significant parameters. The optimal values of the parameters are obtained with the help of the graphs.

scholarly journals The Protect Air Film of an Exterior Window

2021 ◽  
Author(s):  
Sanaz Dianat
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Speed ◽  
Glass Temperature ◽  
Experimental Procedure ◽  
Wind Speeds ◽  
Computational Fluid Dynamics Cfd ◽  
Air Film ◽  
The Impact

The research paper investigates the impact of a window’s exterior air film on the assembly temperature. The exterior air film constitutes a vital portion of a window’s insulating values. The air film increases the temperature of the window exterior pane to a temperature above ambient temperature. The air film also rises the interior glass temperature and reduces the heat transfer from the interior surface. According to computational fluid dynamics (CFD), the air film is removed in windy conditions, decreasing the window temperature on the outside as well as on the inside. The idea behind the project is to carry out an experimental procedure on three different windows to validate the CFD results, which indicates the effect of various wind speeds. Keyword: Exterior air film, computational fluid dynamics, window assembly, wind speed

scholarly journals The Protect Air Film of an Exterior Window

2021 ◽  
Author(s):  
Sanaz Dianat
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Speed ◽  
Glass Temperature ◽  
Experimental Procedure ◽  
Wind Speeds ◽  
Computational Fluid Dynamics Cfd ◽  
Air Film ◽  
The Impact

The research paper investigates the impact of a window’s exterior air film on the assembly temperature. The exterior air film constitutes a vital portion of a window’s insulating values. The air film increases the temperature of the window exterior pane to a temperature above ambient temperature. The air film also rises the interior glass temperature and reduces the heat transfer from the interior surface. According to computational fluid dynamics (CFD), the air film is removed in windy conditions, decreasing the window temperature on the outside as well as on the inside. The idea behind the project is to carry out an experimental procedure on three different windows to validate the CFD results, which indicates the effect of various wind speeds. Keyword: Exterior air film, computational fluid dynamics, window assembly, wind speed

scholarly journals Heat dissipation from a stationary brake disc, Part 2: CFD modelling and experimental validations

2017 ◽  
Vol 232 (10) ◽  
pp. 1898-1924 ◽  
Author(s):  
Marko Tirovic ◽  
Kevin Stevens
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Dissipation ◽  
Axial Flow ◽  
Flow Visualisation ◽  
Brake Disc ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Static Conditions

Following from the analytical modelling presented in Part 1, this paper details a comprehensive computational fluid dynamics modelling of the three-dimensional flow field around, and heat dissipation from, a stationary brake disc. Four commonly used turbulence models were compared and the shear stress turbulence model was found to be most suitable for these studies. Inferior cooling of the anti-coning disc type is well known but the core cause in static conditions was only now established. The air flow exiting the lower vane channels at the inner rotor diameter changes direction and flows axially over the hat region. This axial flow acts as a blocker to the higher vane inlets, drastically reducing convective cooling from the upper half of the disc. The complexity of disc stationary cooling is further caused by the change of flow patterns during disc cooling. The above axial flow effects slowly vanish as the disc temperatures reduce. Consequently, convective heat transfer coefficients are affected by both, the change in the flow pattern and decrease in air velocities due to reduced air buoyancy as the disc cools down. As in Part 1, the special thermal rig was used to validate the computational fluid dynamics results quantitatively and qualitatively. The former used numerous thermocouples positioned strategically around the brake disc, with the latter introducing the concept of laser generated light plane combined with a smoke generator to enable flow visualisation. Predicted average heat transfer coefficients using computational fluid dynamics correlate well with the experimental values, and even two-dimensional analytical values (as presented in Part 1) reasonably closely follow the trends. The results present an important step in establishing cooling characteristics related to the electric parking brake application in commercial vehicles, with future publications detailing heat transfer from the entire brake assembly.

Lumped Capacitance and Three-Dimensional Computational Fluid Dynamics Conjugate Heat Transfer Modeling of an Automotive Turbocharger

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
R. D. Burke ◽  
C. D. Copeland ◽  
T. Duda ◽  
M. A. Rayes-Belmote
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Weak Link ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Inlet Temperature ◽  
Compression Process ◽  
The Impact

One-dimensional wave-action engine models have become an essential tool within engine development including stages of component selection, understanding system interactions, and control strategy development. Simple turbocharger models are seen as a weak link in the accuracy of these simulation tools, and advanced models have been proposed to account for phenomena including heat transfer. In order to run within a full engine code, these models are necessarily simple in structure yet are required to describe a highly complex 3D problem. This paper aims to assess the validity of one of the key assumptions in simple heat transfer models, namely, that the heat transfer between the compressor casing and intake air occurs only after the compression process. Initially, a sensitivity study was conducted on a simple lumped capacity thermal model of a turbocharger. A new partition parameter was introduced αA, which divides the internal wetted area of the compressor housing into pre- and postcompression. The sensitivity of heat fluxes to αA was quantified with respect to the sensitivity to turbine inlet temperature (TIT). At low speeds, the TIT was the dominant effect on compressor efficiency, whereas at high speed αA had a similar influence to TIT. However, modeling of the conduction within the compressor housing using an additional thermal resistance caused changes in heat flows of less than 10%. Three-dimensional computational fluid dynamics (CFD) analysis was undertaken using a number of cases approximating different values of αA. It was seen that when considering a case similar to αA = 0, meaning that heat transfer on the compressor side is considered to occur only after the compression process, significant temperature could build up in the impeller area of the compressor housing, indicating the importance of the precompression heat path. The 3D simulation was used to estimate a realistic value for αA which was suggested to be between 0.15 and 0.3. Using a value of this magnitude in the lumped capacitance model showed that at low speed there would be less than 1% point effect on apparent efficiency which would be negligible compared to the 8% point seen as a result of TIT. In contrast, at high speeds, the impact of αA was similar to that of TIT, both leading to approximately 1% point apparent efficiency error.

scholarly journals Computational Fluid Dynamics of Heat Transfer in Stirred Tank Reactors

2021 ◽  
Author(s):  
Chaitanya Moholkar ◽  
Punit Gharat ◽  
Vivek Vitankar ◽  
Channamallikarjun Mathpati ◽  
Jyeshtharaj Joshi
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Heat Removal ◽  
Design Parameters ◽  
Operational Parameters ◽  
Power Requirement ◽  
Maximum Heat ◽  
Maximum Heat Transfer

In the present work, computational fluid dynamics study of stirred tanks of three sizes (20L, 400L and 5000L) provided with helical coils has been carried out. Various design parameters (impeller diameter, type and clearance) and operational parameters (Reynolds Number and Power per unit volume) have been varied and their effect on process side heat transfer coefficient has been studied. CFD model is validated with experimental work of Cummings and West[9] and in house experimentation. Design settings of D/T=0.5, C/T=0.33 for PBTD450 resulted in maximum heat transfer (5440 W/m2K for P/V=1000 W/m3). For constant RPM and constant D/T (Constant Reynolds Number), Increasing the power number of impeller increased process side HTC at the cost of increased power requirement (decreasing efficiency). In such cases, proper selection of impeller system needs to be made based on the requirements of heat removal and optimizing parameters such as product yield, product quality etc.

Computational Fluid Dynamics and Thermal Analysis of Leaf Seals for Aero-engine Application

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Vincenzo Fico ◽  
Michael J. Pekris ◽  
Christopher J. Barnes ◽  
Rakesh Kumar Jha ◽  
David Gillespie
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Experimental Data ◽  
Thermal Analysis ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Boundary Conditions ◽  
Thermal Boundary Conditions ◽  
Leaf Pack ◽  
Aero Engine

Aero-engine gas turbine performance and efficiency can be improved through the application of compliant shaft seal types to certain sealing locations within the secondary air system. Leaf seals offer better performance than traditional labyrinth seals, giving lower leakage flows at design duties. However, for aero-engine applications, seal designs must be able to cope with relatively large off-design seal closures and closure uncertainties. The two-way coupling between temperatures of seal components and seal closures, through the frictional heat generated at the leaf–rotor interface when in contact, represents an important challenge for leaf seal analysis and design. This coupling can lead to leaf wear and loss, rotor overheating, and possibly to unstable sealing system behavior (thermal runaway). In this paper, we use computational fluid dynamics (CFD), finite element (FE) thermal analysis, and experimental data to characterize the thermal behavior of leaf seals. This sets the basis for a study of the coupled thermomechanical behavior. CFD is used to understand the fluid-mechanics of a leaf pack. The leaf seal tested at the Oxford Osney Laboratory is used for the study. Simulations for four seal axial Reynolds number are conducted; for each value of the Reynolds number, leaf tip-rotor contact, and clearance are considered. Distribution of mass flow within the leaf pack, distribution of heat transfer coefficient (HTC) at the leaf surface, and swirl velocity pick-up across the pack predicted using CFD are discussed. The experimental data obtained from the Oxford rig is used to develop a set of thermal boundary conditions for the leaf pack. An FE thermal model of the rig is devised, informed by the aforementioned CFD study. Four experiments are simulated; thermal boundary conditions are calibrated to match the predicted metal temperatures to those measured on the rig. A sensitivity analysis of the rotor temperature predictions to the heat transfer assumptions is carried out. The calibrated set of thermal boundary conditions is shown to accurately predict the measured rotor temperatures.

The Impact of Electrostatic Forces on the Dynamic and Heat Transfer Coefficient of Single Bubble Rising

2016 ◽  
Vol 5 (2) ◽  
pp. 35-46
Author(s):  
Mohammad Ali Salehi ◽  
Samaneh Poursaman
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Electric Field ◽  
Air Bubbles ◽  
Bubble Rising ◽  
The Impact

In this study, the effect of an applied electric field on the separation and rise of bubble was simulated by Computational Fluid dynamics and results were compared with experimental data. The numerical results showed proper agreement (10%) with experimental reports. The working fluids in the experiment were air, water, and oil. During the simulation, the effects of different voltages on the bubble, bubble ascent, Reynolds and Nusselt number were investigated. The results showed that the more polar air bubbles in the fluid changed and diverted its route. Applying an electric field, reduces separation time, resulting in the formation of bubbles and more bubbles generated at the same time that it increases the heat transfer.

Application of Computational Fluid Dynamics in the Simulation of a Radioactive Waste Vitrification Facility

2004 ◽  
Author(s):  
Chris Barringer ◽  
Jonathan Berkoe ◽  
Chris Rayner ◽  
Gene Huang
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Radioactive Waste ◽  
Waste Treatment ◽  
Ventilation System ◽  
Heat Removal ◽  
Local Environment ◽  
Operating Conditions ◽  
Department Of Energy

The Columbia River in Washington State is at risk of radioactive contamination — a legacy of the cold war. Two hundred thousand cubic meters (fifty-three million US gallons) of radioactive waste is stored in 177 underground tanks at the Hanford site. This waste, which is 60% of the nation’s radioactive waste, is a product of 50 years of plutonium production for national defense. Bechtel National, Inc. has been commissioned by the U.S. Department of Energy to design and build a vast complex of waste treatment facilities to convert this waste into stable glass using a proven vitrification process. In this vitrification process, radioactive waste is mixed with glass-forming materials, then melted at approximately 1200C, and then poured into stainless steel canisters. These canisters are then permanently stored at secure aboveground or belowground facilities. The vitrification process results in a large amount of heat being stored in the hot glass. This heat must be removed within production schedule constraints. In the vitrification facility this glass is cooled in a small room called the Pour Cave. The room contains insulation to protect the concrete, and ventilation and water-cooled cooling panels to facilitate heat removal. The canister heat release rate depends on the thermal properties of the glass (which varies as the glass recipe changes), and the local environment, which includes other hot glass canisters. The cooling process is extremely complex. It is strongly coupled, and is driven by radiation, forced convection, natural convection and conduction heat transfer. Computational fluid dynamics, CFD, was used to predict the heat load to the ventilation system, the cooling panels and to the insulated concrete walls for a variety of operating conditions, providing the data needed for the design of these systems. Of particular interest was the temperature of the concrete, and whether or not design limits would be exceeded. The paper describes the special techniques that were developed to simulate the Pour Cave. This includes description of the modeling of the pouring of the glass, buoyancy modeling, and initialization of the simulation. Results are presented which show the predicted heat transfer characteristics throughout the Pour Cave.

An Experimental Assessment of Computational Fluid Dynamics Predictive Accuracy for Electronic Component Operational Temperature

2003 ◽  
Author(s):  
Vale´rie Eveloy ◽  
Peter Rodgers ◽  
M. S. J. Hashmi
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Thermal Analysis ◽  
Computational Fluid Dynamics ◽  
Printed Circuit Boards ◽  
Turbulence Models ◽  
Electronic Component ◽  
Thermal Design ◽  
Junction Temperature ◽  
Temperature Prediction

The flow modeling approaches employed in Computational Fluid Dynamics (CFD) codes dedicated to the thermal analysis of electronic equipment are generally not specific for the analysis of forced airflows over populated Printed Circuit Boards. This limitation has been previously highlighted [1], with component junction temperature prediction errors of up to 35% reported. This study evaluates the predictive capability of candidate turbulence models more suited to the analysis of electronic component heat transfer. Significant improvements in component junction temperature prediction accuracy are obtained, relative to a standard high-Reynolds number k-e model, which are attributed to better prediction of both board leading edge heat transfer and component thermal interaction. Such improvements would enable parametric analysis of product thermal performance to be undertaken with greater confidence in the thermal design process, and the generation of more accurate temperature boundary conditions for use in Physics-of-Failure based reliability prediction methods. The case is made for vendors of CFD codes dedicated to the thermal analysis of electronics to consider the adoption of eddy viscosity turbulence models more suited to board-level analysis.

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