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.

scholarly journals Numerical study of gas dynamics and heat transfer in matrix channels at various rib angles

2021 ◽  
Vol 2057 (1) ◽  
pp. 012026
Author(s):  
A V Barsukov ◽  
V V Terekhov ◽  
V I Terekhov
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Gas Dynamics ◽  
Average Velocity ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Separation Flow ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Abstract The results of numerical simulation of the separation flow in matrix channels by the RANS method are presented. The simulation is performed at the Reynolds number Re = 12600, determined by the mass-average velocity and the height of the channel. The distribution of the local Nusselt number is obtained for various Reynolds numbers in the range of 5÷15⋅103 and several rib angles. It is shown that the temperature distribution on the surface is highly nonuniform; in particular, the maximum heat transfer value is observed near the upper edge facets, in the vicinity of which the greatest velocity gradient is observed.

Study of Flow and Convective Heat Transfer in a Simulated Scaled Up Low Emission Annular Combustor

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Sunil Patil ◽  
Teddy Sedalor ◽  
Danesh Tafti ◽  
Srinath Ekkad ◽  
Yong Kim ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat ◽  
Swirling Flow ◽  
Numerical Study ◽  
Swirl Number ◽  
Maximum Heat ◽  
Number Range ◽  
Maximum Heat Transfer ◽  
Annular Combustor

Modern dry low emissions (DLE) combustors are characterized by highly swirling and expanding flows that makes the convective heat load on the gas side difficult to predict and estimate. A coupled experimental–numerical study of swirling flow inside a DLE annular combustor model is used to determine the distribution of heat transfer on the liner walls. Three different Reynolds numbers are investigated in the range of 210,000–840,000 with a characteristic swirl number of 0.98. The maximum heat transfer coefficient enhancement ratio decreased from 6 to 3.6 as the flow Reynolds number increased from 210,000 to 840,000. This is attributed to a reduction in the normalized turbulent kinetic energy in the impinging shear layer, which is strongly dependent on the swirl number that remains constant at 0.98 for the Reynolds number range investigated. The location of peak heat transfer did not change with the increase in Reynolds number since the flow structures in the combustors did not change with Reynolds number. Results also showed that the heat transfer distributions in the annulus have slightly different characteristics for the concave and convex walls. A modified swirl number accounting for the step expansion ratio is defined to facilitate comparison between the heat transfer characteristics in the annular combustor with previous work in a can combustor. A higher modified swirl number in the annular combustor resulted in higher heat transfer augmentation and a slower decay with Reynolds number.

scholarly journals Evaluation of Heat Transfer Performance of a Multi-Disc Sorption Bed Dedicated for Adsorption Cooling Technology

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4660 ◽  
Author(s):  
Marcin Sosnowski
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Transfer Performance ◽  
Design Parameters ◽  
Transfer Performance ◽  
Sorption Model ◽  
Factors Influencing ◽  
Computational Fluid Dynamics Cfd ◽  
Cooling Technology

The possibility of implementing the innovative multi-disc sorption bed combined with the heat exchanger into the adsorption cooling technology is investigated experimentally and numerically in the paper. The developed in-house sorption model incorporated into the commercial computational fluid dynamics (CFD) code was applied within the analysis. The research allowed to define the design parameters of the proposed type of the sorption bed and correlate them with basic factors influencing the performance of the sorption bed and its dimensions. The designed multi-disc sorption bed is characterized by great scalability and allows to significantly expand the potential installation sites of the adsorption chillers.

An Experimental Investigation of Heat Transfer Enhancement by Pulsating Laminar Flow in a Triangular Grooved Channel

2012 ◽  
Vol 516-517 ◽  
pp. 249-252 ◽  
Author(s):  
Bing Chang Yang ◽  
Dong Xu Jin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Strouhal Number ◽  
Enhancement Factor ◽  
Pulsating Flow ◽  
Transfer Enhancement ◽  
Maximum Heat ◽  
Pulsation Amplitude ◽  
Maximum Heat Transfer

Heat transfer enhancement by pulsating flow in a triangular grooved channel has been experimentally investigated. Effects of Reynolds number Re, Strouhal number St, pulsation amplitude A on the heat transfer enhancement were studied. The experimental results show that, the pulsating flow can significantly enhance heat transfer compared to the steady flow case, for instance, an enhancement of 115% is achieved at Re=400, A=0.5 and St=0.3. There exists an optimal Strouhal number corresponding to the maximum heat transfer enhancement factor. The heat transfer enhancement factor increases with the increase of Reynolds number and pulsation amplitude.

Numerical Investigation on Pool Boiling Over a Vertical Tube Coupled With In-Tube Condensation

2019 ◽  
Author(s):  
Shuai Ren ◽  
Wenzhong Zhou
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Boiling Heat Transfer ◽  
Power Plants ◽  
Pool Boiling ◽  
Heat Removal ◽  
Vertical Tube ◽  
Two Phase ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Abstract Pool boiling and in-tube condensation phenomena have been investigated intensively during the past decades, due to the superior heat transfer capacity of the phase change process. In passive heat removal heat exchangers of nuclear power plants, the two phase-change phenomena usually occur simultaneously on both sides of the tube wall to achieve the maximum heat transfer efficiency. However, the studies on the effects of in-tube condensation on external pool boiling heat transfer are very limited, especially in numerical computation aspect. In the present study, the saturated pooling boiling over a vertical tube under the influences of in-tube steam condensation is investigated numerically. The Volume of Fluid (VOF) interface tracking method is employed based on the 2D axisymmetric Euler-Euler multiphase frame. The phase change model combining with a mathematical smoothing algorithm and a temporal relaxation procedure has been implemented into CFD platform by user defined functions (UDFs). The two-phase flow pattern and bubble behavior have been analyzed. The effects of inlet steam mass flow rate on boiling heat transfer are discussed.

Effect of Gap Distance on Confined Boiling Heat Transfer Over a Saturated Porous Structure

2005 ◽  
Author(s):  
M. J. Schertzer ◽  
M. Khammar ◽  
D. Ewing ◽  
C. Y. Ching ◽  
J. S. Chang
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
High Speed ◽  
Imaging System ◽  
Porous Plate ◽  
Heat Removal ◽  
Heat Fluxes ◽  
Maximum Heat ◽  
Porous Wick ◽  
Maximum Heat Transfer

An experimental investigation was performed to study the effect that the introduction of a gap between a heated fin and a porous media would have on the heat removal characteristics of a capillary evaporator. In these experiments, a thin stainless steel resistive foil stretched between two copper electrodes was used to heat a saturated porous plate with an effective pore size of 50 microns. The temperature distribution on a 10 mm wide simulated fin was measured by a high-speed infra-red thermal imaging system. The heat removal performance was investigated for gap distances of 0.00 to 1.00 mm and for heat fluxes of 17 to 180 kW/m2. These results showed that the maximum heat transfer rate that could be achieved before persistent hot spots were observed on the surface increased with gap distance. Local temperature measurements made using thermocouples embedded in the porous media indicate that vapour penetration into the porous wick is intermittent, and that there is no stable single phase blanket of vapour. For a gap distance of 0.00 mm, this penetration is more uniformly distributed across the width of the heated fin than at a gap distance of 0.50 mm. In the latter case, the vapour distribution is much higher near the edge of the heated fin.

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 Computational Fluid Dynamics Simulation and Experimental Study of Key Design Parameters of Solar Thermal Collectors

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
James Allan ◽  
Zahir Dehouche ◽  
Sinisa Stankovice ◽  
Alan Harries
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Thermal Efficiency ◽  
Thermal Contact ◽  
High Surface ◽  
Heat Removal ◽  
Solar Thermal ◽  
Dynamics Simulation ◽  
Low Flow ◽  
Design Parameters

Numerical simulation enables the optimization of a solar collector without the expense of building prototypes. This study details an approach using computational fluid dynamics (CFD) to simulate the performance of a solar thermal collector. Inputs to the simulation include; heat loss coefficient, irradiance, and ambient temperature. A simulated thermal efficiency was validated using experimental results by comparing the calculated heat removal factor. The validated methodology was then applied to five different inlet configurations of a header–riser collector. The most efficient designs had uniform flow through the risers. The worst performing configurations had low flow rates in the risers that led to high surface temperatures and poor thermal efficiency. The calculated heat removal factor differed by between 4.2% for the serpentine model and 12.1% for the header–riser. The discrepancies were attributed to differences in thermal contact between plate and tubes in the simulated and actual design.

Optimal Configuration of Vortex Generator for Heat Transfer Enhancement in a Plate-Fin Channel

2017 ◽  
Vol 10 (2) ◽  
Author(s):  
Tariq Amin Khan ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Three Dimensional ◽  
Vortex Generator ◽  
Design Parameters ◽  
Heat Transfer Characteristics ◽  
Maximum Heat ◽  
Transfer Characteristics ◽  
Maximum Heat Transfer ◽  
Independent Design

Heat transfer is a naturally occurring phenomenon and its augmentation is a vital research topic for many years. Although, vortex generators (VGs) are widely used to enhance the heat transfer of plate-fin type heat exchangers, few researches deal with its thermal optimization. This work is dedicated to the numerical investigation and optimization of VGs configuration in a plate-fin channel. Three-dimensional (3D) numerical simulations are performed to study the effect of angle of attack and attach angle (angle between VG and wall) and shape of VG on the fluid flow and heat transfer characteristics. The flow is assumed as steady-state, incompressible, and laminar within the range of studied Reynolds numbers (Re = 380–1140). Results are presented in the form average and local Nusselt number and friction factor. The effect of attach angle is highlighted and the results show that the attach angle of 90 deg may not be necessary for enhancing the heat transfer. The flow structure and heat transfer characteristics of certain cases are examined in detail. The parameters of VG are then optimized for maximum heat transfer and minimum pressure drop. The three independent design parameters are considered for the two objective functions. For this purpose, computation fluid dynamics (CFD) data, response surface methodology (RSM) and a multi-objective optimization algorithm (MOA) are combined. The data obtained from numerical simulations are used to train a Bayesian-regularized artificial neural network (BRANN). This in turn is used to drive a MOA to find the optimal parameters of VGs in the form of Pareto front. The optimal values of these parameters are finally presented.

scholarly journals Hybrid Al2O3-Cu/water nanofluid flow and heat transfer over vertical double forward-facing step

2021 ◽  
pp. 80-80
Author(s):  
Hussein Togun ◽  
Raadz Homod ◽  
T Tuqaabdulrazzaq
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Friction Coefficient ◽  
Transfer Coefficient ◽  
Skin Friction Coefficient ◽  
Average Heat Transfer Coefficient ◽  
Maximum Heat ◽  
Average Heat ◽  
Maximum Heat Transfer

Turbulent heat transfer and hybrid Al2O3-Cu/nanofluid over vertical double forward facing-stepis numerically conducted. K-? standard model based on finite volume method in two dimensional are applied to investigate the influences of Reynolds number, step height, volume fractions hybrid Al2O3-Cu/nanofluid on thermal performance. In this paper, different step heights for three cases of vertical double FFS are adopted by five different of volume fractions of hybrid (Al2O3-Cu/water) nanofluid varied for 0.1, 0.33, 0.75, 1, and 2, while the Reynolds number different between 10000 to 40000 with temperature is constant. The main findings revealed that rise in local heat transfer coefficients with raised Reynolds number and maximum heat transfer coefficient was noticed at Re=40000. Also rises in heat transfer coefficient detected with increased volume concentrations of hybrid (Al2O3-Cu/water) nanofluid and the maximum heat transfer coefficient found at hybrid Al2O3-Cu/water nanofluid of 2% in compared with others. It?s also found that rise in surface heat transfer coefficient at 1ststep-case 2 was greater than at 1ststep-case 1 and 3 while was higher at 2ndstep-case 3. Average heat transfer coefficient with Reynolds number for all cases are presented in this paper and found that the maximum average heat transfer coefficient was at case 2 compared with case 1 and 3. Gradually increases in skin friction coefficient remarked at 1stand 2ndsteps of the channel and drop in skin friction coefficient was obtained with increased of Reynolds number. Counter of velocity was presented to show the recirculation regions at first and second steps as clarified the enrichment in heat transfer rate. Furthermore, the counter of turbulence kinetic energy contour was displayed to provide demonstration for achieving thermal performance at second step for all cases.

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