Numerical study of heat transfer of laminar air flow in perforated trapezoidal corrugated plate-fin ducts

2021 ◽  
pp. 095440622110345
Author(s):  
Morteza Piradl ◽  
SM Pesteei
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Numerical Study ◽  
Perforated Plate ◽  
Temperature Fields ◽  
Unusual Behavior ◽  
Constant Wall Temperature ◽  
Wide Range ◽  
Goodness Factor

A novel trapezoidal corrugated perforated fin core is proposed in this study. The porosity of the fin surface, or perforations, is indicated to promote the unusual behavior of increasing the heat transfer coefficient, while reducing the friction factor with respect to its non-perforated counterpart, primarily due to surface transpiration, which leads to better flow mixing and successive boundary layer disturbances. This allows the heat exchanger to be built much more compact with a smaller volume and a front area. To highlight this, the results of the computational simulations for velocity and temperature fields in typical trapezoidal corrugated perforated plate-fin ducts are presented. Constant property, fully or periodically developed laminar airflow [Formula: see text] with Reynolds number [Formula: see text] passing through inter-fin passages, with fins at constant wall temperature T, in which the fin walls have perforations equally spaced along the length of the duct, is considered and a parametric study of the effects of the duct geometry, including the variation of the inclination angle [Formula: see text] of the diverging plane, the aspect ratio of the channel or period length and fin density effects [Formula: see text] and the converging-diverging ratio of the plate [Formula: see text], is performed. The results of the Fanning friction factor and the Nusselt number over the wide range of the Reynolds number, which was treated in this study, show the improved performance. The improvement is assessed quantitatively by the area goodness factor ( j/ f) relative to Re, comparison with simple flat channels. It is seen that increasing ϕ to [Formula: see text] improves the core performance; As ϕ increases beyond [Formula: see text], performance starts to decrease. j/ f increases with increasing λ; and λ = 3.6 acts as an inflection point. It is better to have a large λ value for lower Re range and vice versa. As ε increases, the performance increases; so, the highest area goodness factor value occurs at [Formula: see text]. In case 11, with [Formula: see text], [Formula: see text], and [Formula: see text] at Re = 200, compared to the non-perforated channel, the friction factor decreases about 11%, and the area goodness factor increases about 72%. Thus, the area goodness factor of the perforated case reaches 0.37.

scholarly journals Experimental and Numerical Study Effect of Using Nanofluids in Perforated Plate Fin Heat Sink for Electronics Cooling

2018 ◽  
Vol 24 (8) ◽  
pp. 1
Author(s):  
Kadhum Audaa Jehhef
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Volume Fraction ◽  
Numerical Study ◽  
Perforated Plate ◽  
Processing Unit ◽  
Transfer Enhancement

An experimental and numerical investigation of the effect of using two types of nanofluids with suspending of (Al2O3 and CuO) nanoparticles in deionized water with a volume fraction of (0.1% vol.), in addition to use three types of fin plate configurations of (smooth, perforated, and dimple plate) to study the heat transfer enhancement characteristics of commercial fin plate heat sink for cooling computer processing unit. All experimental tests under simulated conditions by using heat flux heater element with input power range of (5, 16, 35, 70, and 100 W). The experimental parameters calculated are such as water and nanofluid as coolant with Reynolds number of (7000, 8000, 9400 and 11300); the air is blown in the inlet duct across the heat sink with Reynolds number of (10500, 12300, 14200 and 16000). The distance fin-to-fin is kept constant at (2.00 mm), and the channel employed in this work has a square cross-section of (7 cm) inside. It was observed that the average effectiveness and Nusselt number of the nanofluids are higher compared with those of using conventional liquid cooling systems. However, the perforated fin plate showed higher air heat dissipation than the other configuration plate fin employed in this study. The experimental results were supported by numerical results which gave a good indication to heat transfer enhancement in studied ranges.  

A Numerical Simulation of Heat Transfer Enhancement Using Al2O3 Nanofluid

2020 ◽  
Vol 10 (5) ◽  
pp. 610-621
Author(s):  
Taliv Hussain ◽  
Mohammad T. Javed
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Friction Factor ◽  
Volume Concentration ◽  
Numerical Study ◽  
Pure Water ◽  
Maximum Deviation ◽  
Nanoparticle Concentration ◽  
Maximum Increase

Introduction: A numerical study is performed in which the friction factor and forced convection heat transfer is studied for Al2O3 nanoparticle dispersed in water as a base fluid. Methods: Four concentrations of nanofluids in the range of 0-2.5 vol% have been simulated. The Reynolds Number is varied in the range of 100-500 by varying inlet velocity. Cross flow of air is assumed over the pipe with air velocity of 2.2 m/s. Results: The results depict that the friction factor decreases with an increase in flow rate and increases with increase in volume concentration. The maximum deviation for friction factor obtained by simulation from that obtained using Darcy’s relation is about 21.5% for water. Nusselt number increases with increase in Reynolds Number and nanofluid volume concentration with a maximum of 7653.68 W/m2 at a nanoparticle concentration of 2.5% and Reynolds Number of 500. Heat transfer rate enhancement of upto 13.6% is obtained as compared to pure water. The maximum increase in Nusselt Number is about 13.07% for a nanoparticle concentration of 2.5%. Conclusion: The simulation results are compared with established relations obtained by other researchers and there is a good agreement in terms of trends obtained. The deviations from established relations are also depicted.

The Effect of Twisted-Tape Width on Heat Transfer and Pressure Drop for Fully Developed Laminar Flow

1996 ◽  
Vol 118 (3) ◽  
pp. 584-589 ◽  
Author(s):  
W. M. Chakroun ◽  
S. F. Al-Fahed
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Friction Factor ◽  
Twisted Tape ◽  
Constant Wall Temperature ◽  
Low Reynolds Number Flows ◽  
Temperature Boundary ◽  
Series Of Experiments

A series of experiments was conducted to study the effect of twisted-tape width on the heat transfer and pressure drop with laminar flow in tubes. Data for three twisted-tape wavelengths, each with five different widths, have been collected with constant wall temperature boundary condition. Correlations for the friction factor and Nusselt number are also available. The correlations predict the experimental data to within 10 to 15 percent for the heat transfer and friction factor, respectively. The presence of the twisted tape has caused the friction factor to increase by a factor of 3 to 7 depending on Reynolds number and the twisted-tape geometry. Heat transfer results have shown an increase of 1.5 to 3 times that of plain tubes depending on the flow conditions and the twisted-tape geometry. The width shows no effect on friction factor and heat transfer in the low range of Reynolds number but has a more pronounced effect on heat transfer at the higher range of Reynolds number. It is recommended to use loose-fit tapes for low Reynolds number flows instead of tight-fit in the design of heat exchangers because they are easier to install and remove for cleaning purposes.

Interaction of Natural Convection Wakes Arising From Thermal Sources on a Vertical Surface

1985 ◽  
Vol 107 (4) ◽  
pp. 883-892 ◽  
Author(s):  
Y. Jaluria
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Natural Convection ◽  
Numerical Study ◽  
Finite Difference Methods ◽  
Heat Removal ◽  
Temperature Fields ◽  
Electronic Components ◽  
Wide Range ◽  
Wall Plume

A numerical study of the interacting natural convection flows generated by isolated thermal energy sources, such as electronic components, located on a vertical adiabatic surface is carried out. Of particular interest were the effects of the wake on the heat transfer from and the flow over a downstream heat source and the nature of the wall plume far from the sources. This consideration is related to the positioning of finite-sized electronic components and the relevant heat removal process. A two-dimensional flow is considered, without making the boundary-layer assumptions. The full elliptic equations governing the flow are solved numerically, employing finite-difference methods. The results are compared with the boundary layer solutions, obtained in earlier studies, in order to determine the nonboundary-layer effects. This is an important consideration in several practical circumstances that involve small heat inputs, sources of relatively small heights, and small separation distances between the sources. It is found that the flow downstream rapidly approaches the characteristics of an idealized wall plume due to a line source. A boundary-layer flow arises far from the heat sources and this flow provides the boundary conditions for the elliptic problem. The nature of the velocity and temperature fields is studied in detail for a wide range of governing parameters and the heat transfer coefficients for the heated elements determined. The relevance of the results obtained to practical systems is outlined, particularly for small Grashof numbers which necessitate a solution of the full equations.

Numerical Study of Thermal Stratification in a Liquid Storage Tank With a Porous Manifold

Solar Energy ◽  
2006 ◽  
Author(s):  
N. M. Brown ◽  
F. C. Lai
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Storage Tank ◽  
Richardson Number ◽  
Thermal Stratification ◽  
Numerical Study ◽  
Temperature Fields ◽  
Liquid Storage ◽  
Wide Range ◽  
Liquid Storage Tank

A numerical model has been developed to study the effects of a porous manifold on thermal stratification in a storage tank. The model is used to predict the development of flow and temperature fields during a charging process. Computations have covered a wide range of the Grashof number (1.8 × 105 < Gr < 1.8 × 108) and Reynolds number (10 ≤ Re ≤ 104), or in terms of the Richardson number, 0.1 < Ri < 105. The results obtained compare favorably well with the experimental data. In addition, the present results have confirmed the effectiveness of porous manifold in the promotion of thermal stratification and provide useful information for the design of such system.

scholarly journals Numerical study of perforated plate convective heat transfer

2014 ◽  
Vol 18 (3) ◽  
pp. 949-956 ◽  
Author(s):  
Mladen Tomic ◽  
Predrag Zivkovic ◽  
Mica Vukic ◽  
Gradimir Ilic ◽  
Mladen Stojiljkovic
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Reynolds Number ◽  
Numerical Study ◽  
Plate Thickness ◽  
Perforated Plate ◽  
Diameter Ratio ◽  
Working Fluid ◽  
The Difference ◽  
The Heat Transfer Coefficient

Numerical simulations were performed to determine the heat transfer coefficient of a perforated plate with square arranged cylindrical perforations. Three parameters were varied in the study: plate porosity, pitch Reynolds number and working fluid, while perforation diameter and plate thickness were constant. The Reynolds number was varied in the range from 50 to 7000, and porosity in the range from 0.1 to 0.3. As working fluids, helium, air or carbon-dioxide were set, respectively. The Nusselt number was correlated in the function of the Reynolds number, the Prandtl number, and the pitch-to-diameter ratio. The comparison with other correlations is given at the end of the paper. The difference was found to be acceptable.

Simulation of Turbulent Heat Transfer in a Tube Fitted with Twisted Tape Placed Separately from the Tube Walls

2015 ◽  
Vol 751 ◽  
pp. 245-250 ◽  
Author(s):  
Niwat Piriyarungroj ◽  
Smith Eiamsa-ard ◽  
Pongjet Promvonge ◽  
Petpices Eiamsa-Ard ◽  
Chinaruk Thianpong
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Transfer Rate ◽  
Reynolds Numbers ◽  
Turbulent Heat Transfer ◽  
Twisted Tape ◽  
Turbulent Heat ◽  
Clearance Ratio ◽  
Constant Wall Temperature

The effects of loose-fit twisted tape (LFT) on the heat transfer rate, friction factor, fluid phenomena and thermal performance of a tube under constant wall temperature are examined. It is observed that apart from the rise of Reynolds number, the reduction of the clearance ratio (c/D) leads to an increase in the heat transfer and pressure loss. According to the numerical results, the heat transfer and friction factor in the tubes with loose-fit twisted tape (LFT) for the smallest clearance ratio of c/D = 0.05 are higher those other clearance ratios. In addition, the thermal performances of clearance ratio c/D = 0.05 are found to be higher than those other clearance ratios (c/D) for all Reynolds numbers examined.

Three-Dimensional Flow and Heat Transfer Calculations in Micro-Channel Heat Exchangers

2001 ◽  
Author(s):  
A. K. Saha ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Critical Reynolds Number ◽  
Numerical Study ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Plane Channel ◽  
Micro Channel ◽  
Flow And Heat Transfer

Abstract A three-dimensional numerical study has been carried out to analyze the unsteady flow and heat transfer in a micro-channel with an array of periodically mounted square cylinders. The current geometry represents a micro-heat exchanger and has potential applications in the cooling of turbine blades and electronic cooling. The cylinder dimensions are of the order of few microns. The three-dimensional unsteady Navier-Stokes and energy equations are solved using higher order temporal and spatial discretizations. The simulations have been carried out for a range of Reynolds number based on cylinder width (180–600) and a Prandtl number of 6.99. Conjugate heat transfer calculations have been employed to account for the conduction in the solid cylinder and convection in the fluid. The flow is found to become unsteady at a critical Reynolds number that falls between 250 and 400. The flow shows quasi-periodic behavior with multiple frequencies at a Reynolds number of 400. The heat transfer enhancement compared to a plane channel is marginal (1.1–1.4 times) for the steady flow cases whereas it is significant (12–15 times) when the flow is unsteady. The friction factor was found to decrease with Reynolds number in both the steady and unsteady regimes. However, the friction factor increases at the critical Reynolds number where it becomes unsteady in nature.

scholarly journals Numerical investigation for convective heat transfer and friction factor under pulsating flow conditions

2018 ◽  
Vol 240 ◽  
pp. 01003
Author(s):  
Erman Aslan ◽  
Mert Ozsaban ◽  
Guven Ozcelik ◽  
Hasan Riza Guven
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Friction Factor ◽  
Convective Heat ◽  
Numerical Study ◽  
Pulsating Flow ◽  
Channel Height ◽  
Corrugated Channel ◽  
Sst Model

For pulsating flow, the behaviours of the convective heat transfer and friction factor for a periodic corrugated channel are investigated numerically. The finite volume method is used in the numerical study. Three different Reynolds Averaged Numerical Simulation based turbulence models, namely the k-ω model, the Shear Stress Transport (SST) model and the transition SST model are used and compared. The results are also compared with the previous experiments for non-pulsating flow. Analyses are conducted for air flow through a corrugated channel which has sharp corrugation peaks with an inclination angle of 30° and a 5mm minimum channel height. Reynolds number is changed in the range 6294 to 7380, while keeping the Prandtl number constant at 0.70. A sinusoidal pulsatile flow condition which is F=400 and uA*=0.5 is used. Variations of the Nusselt number and the friction factor with the Reynolds number are studied. Non-pulsating flow results and pulsating flow results are compared with each other.

Performance Comparison of Nanofluids Through Plain Channel Considering the Effects of Uncertainties in Thermophysical Properties

2016 ◽  
Author(s):  
Ningbo Zhao ◽  
Qiang Wang ◽  
Shuying Li
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Brownian Motion ◽  
Thermophysical Properties ◽  
Volume Fraction ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Performance Comparison ◽  
Constant Wall Temperature

To compare and understand the laminar thermal-hydraulic performance of plate-fin channel with rectangle plain fin by using variable thermophysical properties of the most commonly used nanofluids (Al2O3-water), a three-dimensional numerical study is investigated by using the single-phase approach at a constant wall temperature boundary condition. Different models published in literatures are considered for the thermal conductivity and viscosity. On this basis, a parametric analysis is conducted to evaluate the effects of various pertinent parameters including nanoparticle volume fraction (0%–4%), Brownian motion of nanoparticle and Reynolds number (800–1500) on the heat transfer and flow characteristics of plain fin channel in detail. All the numerical results demonstrate that the addition of Al2O3 nanoparticle can enhance the heat transfer and flow pressure loss of base fluid because of the higher thermal conductivity and viscosity for nanofluids. And these enhancements are more obvious by increasing the volume fraction of nanoparticle, increasing Reynolds number, and considering the effects of nanoparticle Brownian motion. In addition, there are significantly differences in the thermal and flow fields for different nanofluids models at a fixed Reynolds number, which means that the effective theoretical formulas and empiric corrections for the nanofluids thrmophysical properties need to be studied extensively in the future.

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