Three-Dimensional Numerical Simulation on the Laminar Flow and Heat Transfer in Four Basic Fins of Plate-Fin Heat Exchangers

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Yinhai Zhu ◽  
Yanzhong Li
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Heat Exchangers ◽  
Flow Direction ◽  
Three Dimensional ◽  
Entry Length ◽  
Flow And Heat Transfer ◽  
F Factor ◽  
The One ◽  
Data Reduction Method

In this paper, four basic fins of the plate-fin heat exchangers, rectangular plain fin, strip offset fin, perforated fin, and wavy fin, are modeled and simulated by taking account of fin thickness, thermal entry effect, and end effect. Three-dimensional numerical simulations on the flow and heat transfer in the four fins are investigated and carried out at laminar flow regime. Validity of the modeling technique is verified by comparing computational results with both corresponding experimental data and three empirical correlations from literatures. Global average Colburn factor (j factor) and friction factor (f factor) and their local 1D streamwise-average distributions along the fins are presented by introducing data reduction method. The heat transfer behaviors in both the developing and developed regions are analyzed by examining variations of the local Nusselt number along the flow direction. It is found that the thermal entry length of the four fins might be expressed in the format of Le=c1 Rec2 Pr Dh, which has the same form as the one in a circular tube.

scholarly journals The Effect of Geometrical Parameters on Heat Transfer Characteristics of Compact Heat Exchanger with Louvered Fins

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
P. Gunnasegaran ◽  
N. H. Shuaib ◽  
M. F. Abdul Jalal
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
Cross Flow ◽  
Geometrical Parameters ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Drop Flow ◽  
Louvered Fins

Compact heat exchangers (CHEs) have been widely used in various applications in thermal fluid systems including automotive thermal management systems. Among the different types of heat exchangers for engine cooling applications, cross-flow CHEs with louvered fins are of special interest because of their higher heat rejection capability with the lower flow resistance. In this study, the effects of geometrical parameters such as louver angle and fin pitch on air flow and heat transfer characteristics on CHEs are numerically investigated. Numerical investigations using five different cases with increased and decreased louver angles (+2°, +4°, −2°, −4°, and uniform angle 20°), with a fixed fin pitch and using three different fin pitches (1.0 mm, 2.0 mm, and 4.0 mm), and with the fixed louver angle are examined. The three-dimensional (3D) governing equations for the fluid flow and heat transfer are solved using a standard finite-volume method (FVM) for the range of Reynolds number between 100 and 1000. The computational model is used to study the variations of pressure drop, flow temperature, and Nusselt number.

Aspects of Flow and Heat Transfer in Louver-Fin Round-Tube Heat Exchangers

2005 ◽  
Author(s):  
Hailing Wu ◽  
Ying Gong ◽  
Xiaobo Zhu
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
Flow Region ◽  
Recirculation Region ◽  
Round Tube ◽  
Flow And Heat Transfer ◽  
Representative Cell ◽  
Conjugated Heat Transfer ◽  
Good Agreement

Experimental and numerical investigations on flow and heat transfer were conducted for louver-fin round-tube two-row heat exchangers. The airflow velocity ranged from 1 m/s to 3 m/s. A three-dimensional numerical method was developed by modeling representative cell units with fluid-solid conjugated heat transfer. Results of three-dimensional numerical simulations were in good agreement with the experimental data. A stagnant flow region exists behind the round tubes, and results in diminished local convective heat transfer. For two-row heat exchangers operating at Reynolds number, Re<300, the first row dominates the heat transfer rate. With Re increasing, the heat transfer contribution of both rows tends to be more uniform. The flow pattern shows a recirculation region downstream of the heat exchanger at higher Re flows, which may be induced by a vortex-shedding instability from the tube and louver bank.

Prediction of Turbulent Flow and Heat Transfer in a Ribbed Rectangular Duct With and Without Rotation

1993 ◽  
Author(s):  
C. Prakash ◽  
R. Zerkle
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Turbulent Flow ◽  
Flow Direction ◽  
Three Dimensional ◽  
Stationary Case ◽  
Rectangular Duct ◽  
Wall Functions ◽  
Flow And Heat Transfer ◽  
Smooth Channel

The present study deals with the numerical prediction of turbulent flow and heat transfer in a 2:1 aspect ratio rectangular duct with ribs on the two shorter sides. The ribs are of square cross–section, staggered and aligned normal (90–deg) to the main flow direction. The ratio of rib height to duct hydraulic diameter equals 0.063, and the ratio of rib spacing to rib height equals 10. The duct may be stationary or rotating. The axis of rotation is normal to the axis of the duct and parallel to the ribbed walls (i.e., the ribbed walls form the leading and the trailing faces). The problem is three–dimensional and fully elliptic; hence, for computational economy, the present analysis deals only with a periodically–fully–developed situation where the calculation domain is limited to the region between two adjacent ribs. Turbulence is modelled with the k–epsilon model in conjunction with wall–functions. However, since the rib height is small, use of wall–functions necessitates that the Reynolds number be kept high. (Attempts to use a two–layer model that permits integration to the wall did not yield satisfactory results and such modelling issues are discussed at length). Computations are made here for Reynolds number in the range (30,000–100,000) and for Rotation number=0 (stationary), 0.06, and 0.12. For the stationary case, the predicted heat transfer agrees well with the experimental correlations. Due to the Coriolis induced secondary flow, rotation is found to enhance heat transfer from the trailing and the side walls, while decreasing heat transfer from the leading face. Relative to the corresponding stationary case, the effect of rotation is found to be less for a ribbed channel as compared to a smooth channel.

Effect of Cylinder Aspect Ratio and Channel Dimensions on the Fluid Flow and Heat Transfer in Parallel-Plate Channel Heat Exchangers

2002 ◽  
Author(s):  
A. K. Saha ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Heat Exchangers ◽  
Parallel Plate ◽  
Numerical Study ◽  
Three Dimensional ◽  
Channel Height ◽  
Flow And Heat Transfer ◽  
Plate Channel

A comparative numerical study has been carried out to analyze the unsteady three-dimensional flow and heat transfer in a parallel-plate channel heat exchangers with in-line arrays of periodically mounted square cylinders (pins) at various Reynolds number and geometrical configurations. The geometry considered represents the narrow trailing edge region of the blade where pin fins are used to serve both a structural and a heat transfer role. 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 (corresponding to water). Conjugate heat transfer calculations have been employed to account for the conduction in the solid cylinder and convection in the fluid. The thermal performance factor (TPF) increases significantly when the flow becomes unsteady. The choice of aspect ratio of the cylinders is judged by their relative increase in friction factor and heat transfer at transitional Reynolds number. The TPF is found to increase with the increase in pitch of the cylinders. The increase in channel height enhances the TPF though the heat transfer decreases at higher channel height.

Numerical Simulation and Experimental Validation of Flow and Heat Transfer in Flat-Tube Heat Exchangers

2007 ◽  
Author(s):  
Jiuyang Yu ◽  
Wenwu Xia ◽  
Xingkui Feng
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
Flat Tube ◽  
Flow Energy ◽  
Flow Parameters ◽  
Flow And Heat Transfer ◽  
Measured Flow

A three dimensional numerical simulation study has been carried out to predict air flow and temperature distribution in flat-tube heat exchangers. Due to the symmetry in geometrical construction, a section of heat exchanger has been considered for CFD analysis by using PHOENICS software. The k-ε turbulence model has been used to solve the transport equations for turbulent flow energy and the dissipation rate. In order to check the validity of the computational modeling, the results were compared with the measured flow parameters such as pressure and velocity distribution. It is found that both the heat transfer coefficient and the pressure drop for the shell-side are in good arrangement with experimental results. Comparing with circular-tube heat exchangers, the simulation result shows that the pressure drop of flat-tube heat exchangers decreases 12%∼20%, and the coefficient of integral performance Nu/ζ0.29 has an increment, which is between 22%∼34%.

Influence of Thermo-Physical Properties on the Flow and Heat Transfer in Rectangular Micro-Channels

2011 ◽  
Vol 347-353 ◽  
pp. 2640-2644 ◽  
Author(s):  
Xue Tao Duan ◽  
Bin Xu ◽  
Hao Luo
Keyword(s):  
Heat Transfer ◽  
Physical Properties ◽  
Flow Direction ◽  
Three Dimensional ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Flux Boundary Condition ◽  
Flow And Heat Transfer ◽  
Friction Factors ◽  
Micro Channels

This paper investigated the behaviors of flow and heat transfer of single-phase in rectangular micro-channels with three-dimensional numerical analysis. The single micro-channel is 200μm deep, 50μm wide. Deionized water was used as the working fluid. The fluid physical properties varying with temperature and Re number were studied. Comparisons were made among the results obtained from experiments, numerical simulations, and from those in the literature. The results indicated that the friction factors decreasing along the flow direction were ascribed to the fluid temperature rising under the unified heat flux boundary condition. It was found that influence of viscosity variation with temperature and viscous dissipation effect could be too significant to be neglected.

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