Effect of Plate Characteristics on Axial Dispersion and Heat Transfer in Plate Heat Exchangers

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
K. Shaji ◽  
Sarit K. Das
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Exchangers ◽  
Peclet Number ◽  
Axial Dispersion ◽  
Outlet Temperature ◽  
Plate Heat ◽  
Péclet Number ◽  
Back Mixing ◽  
Two Fluid

A new mathematical model of single-blow transient testing technique is proposed for the determination of heat transfer and dispersion coefficients in plate heat exchangers (PHEs) in which the flow maldisrtibution effects are separated from the fluid back-mixing. The fluid axial dispersion is used to characterize the back-mixing and other deviations from plug flow. Single-blow experiments are carried out with different number of plates for various flow rates with three different plate geometries of 30 deg, 60 deg, and mixed (30 deg/60 deg) chevron angles. The outlet temperature response to an exponential inlet temperature variation is solved numerically using finite difference method. In the present work, the whole curve matching technique is used to determine the values of Nusselt number and dispersive Peclet number. Since the maldistribution effects are separated, these data are independent of test conditions and hence using a regression analysis, general correlations are developed for Nusselt number and Peclet number of the present plate heat exchangers. The applicability of the single-blow test data is validated using a two-fluid experiment. Two-fluid experiments are conducted on the same plate heat exchanger with smaller and larger number of plates and the results have been compared with its simulation which used the Nusselt number and Peclet number correlations developed by the new model of single-blow test as the inputs.

scholarly journals Heat transfer from a moving fluid sphere with internal heat generation

2014 ◽  
Vol 18 (4) ◽  
pp. 1213-1222
Author(s):  
Silvia Alexandrova ◽  
Maria Karsheva ◽  
Abdellah Saboni ◽  
Christophe Gourdon
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Generation ◽  
Peclet Number ◽  
Average Nusselt Number ◽  
Viscosity Ratio ◽  
Fluid Sphere ◽  
Péclet Number ◽  
Convection Equation

In this work, we solve numerically the unsteady conduction-convection equation including heat generation inside a fluid sphere. The results of a numerical study in which the Nusselt numbers from a spherical fluid volume were computed for different ranges of Reynolds number (0<Re<100), Peclet number (0<Pe<10000) and viscosity ratio (0<k<10), are presented. For a circulating drop with Re?0, steady creeping flow is assumed around and inside the sphere. In this case, the average temperatures computed from our numerical analysis are compared with those from literature and a very good agreement is found. For higher Reynolds number (0<Re<100), the Navier-Stokes equations are solved inside and outside the fluid sphere as well as the unsteady conduction-convection equation including heat generation inside the fluid sphere. It is proved that the viscosity ratio k (k = ?d/?c) influences significantly the heat transfer from the sphere. The average Nusselt number decreases with increasing k for a fixed Peclet number and a given Reynolds number. It is also observed that the average Nusselt number is increasing as Peclet number increases for a fixed Re and a fixed k.

Low Knudsen Number Heat Transfer From Two Spheres in Contact

1974 ◽  
Vol 96 (4) ◽  
pp. 478-482 ◽  
Author(s):  
F. A. Morrison ◽  
L. D. Reed
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Knudsen Number ◽  
Peclet Number ◽  
Temperature Jump ◽  
Péclet Number

Heat transfer from an acrosol aggregate composed of two touching spheres is investigated analytically. In the range of interest, the Knudsen number is small and the Peclet number negligible. The Nusselt number of a sphere is found to be reduced by the presence of a neighbor and by temperature jump. Expressions for the Nusselt number are obtained.

Heat transfer at high Péclet number from a small sphere freely rotating in a simple shear field

1971 ◽  
Vol 46 (2) ◽  
pp. 233-240 ◽  
Author(s):  
Andreas Acrivos
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Simple Shear ◽  
Peclet Number ◽  
Reynolds Numbers ◽  
Small Sphere ◽  
Péclet Number ◽  
Shear Field ◽  
Method Of Solution ◽  
Small Shear

The problem of heat transfer at high Péclet number Pe from a sphere freely rotating in a simple shear field is considered theoretically for the case of small shear Reynolds numbers. It is shown that the present problem is in many respects similar to that of heat transfer past a freely rotating cylinder which was recently solved by Frankel & Acrivos (1968). By taking advantage of the close analogy between these two problems, an approximate method of solution is developed according to which the asymptotic Nusselt number for Pe → ∞ is 9, i.e. 4½ times its value for pure conduction. As in the corresponding case of the cylinder, the fact that the asymptotic Nusselt number is independent of Pe results from the presence of a region of closed streamlines which completely surrounds the rotating sphere.

Effect of the Chevron Angle on Cooling Heat Transfer Characteristics of Supercritical Pressure Fluids in Plate Heat Exchangers

2018 ◽  
Vol 40 (12) ◽  
pp. 1007-1022 ◽  
Author(s):  
Kazushi Miyata ◽  
Hideo Mori ◽  
Takahiro Taniguchi ◽  
Shuichi Umezawa ◽  
Katsuhiko Sugita
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Supercritical Pressure ◽  
Heat Transfer Characteristics ◽  
Plate Heat ◽  
Transfer Characteristics

Analisis Perbandingan Jenis Material Penukar Kalor Plat Datar Aliran Silang Untuk Proses Pengeringan Kayu

2021 ◽  
Vol 9 (1) ◽  
pp. 60-71
Author(s):  
Abeth Novria Sonjaya ◽  
Marhaenanto Marhaenanto ◽  
Mokhamad Eka Faiq ◽  
La Ode M Firman
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flat Plate ◽  
Heat Exchangers ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Plate Heat ◽  
Dry Air ◽  
Copper Material ◽  
Plate Type

The processed wood industry urgently needs a dryer to improve the quality of its production. One of the important components in a dryer is a heat exchanger. To support a durable heat transfer process, a superior material is needed. The aim of the study was to analyze the effectiveness of the application of cross-flow flat plate heat exchangers to be used in wood dryers and compare the materials used and simulate heat transfer on cross-flow flat plate heat exchangers using Computational Fluid Dynamic simulations. The results showed that there was a variation in the temperature out of dry air and gas on the flat plate heat exchanger and copper material had a better heat delivery by reaching the temperature out of dry air and gas on the flat plate type heat exchanger of successive cross flow and.   overall heat transfer coefficient value and the effectiveness value of the heat exchanger of the heat transfer characteristics that occur with the cross-flow flat plate type heat exchanger in copper material of 251.74725 W/K and 0.25.

Heat transfer enhancement in fin-plate heat exchangers by wing type vortex generators

1989 ◽  
Vol 12 (1) ◽  
pp. 288-294 ◽  
Author(s):  
Udo Brockmeier ◽  
Martin Fiebig ◽  
Thomas Güntermann ◽  
Nimai K. Mitra
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Exchangers ◽  
Vortex Generators ◽  
Transfer Enhancement ◽  
Plate Heat

CFD SIMULATION OF A PLATE HEAT EXCHANGER WITH TRAPEZOIDAL CHEVRON

2016 ◽  
Vol 78 (8-4) ◽  
Author(s):  
Chin Yung Shin ◽  
Normah Mohd-Ghazali
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Friction Factor ◽  
Cfd Simulation ◽  
General Pattern ◽  
Plate Heat Exchanger ◽  
Plate Heat ◽  
Flow Configuration ◽  
Heat Transfer Capacity

In this research, the trapezoidal shaped chevron plate heat exchanger (PHE) is simulated using computational fluid dynamics (CFD) software to determine its heat transfer capacity and friction factor. The PHE is modelled with chevron angles from 30° to 60°, and also the performances are compared with the plain PHE. The validation is done by comparing simulation result with published references using 30° trapezoidal chevron PHE. The Nusselt number and friction factor obtained from simulation model is plotted against different chevron angles. The Nusselt number and friction factor is also compared with available references, which some of the references used sinusoidal chevron PHE. The general pattern of Nusselt number and friction factor with increasing chevron angle agrees with the references. The heat transfer capacity found in current study is higher than the references used, and at the same time, the friction factor also increased. Besides this, it is also found that the counter flow configuration has better heat transfer capacity performance than the parallel flow configuration.

scholarly journals Analysis of transient mixed convection in a horizontal channel partially heated from below

2021 ◽  
Vol 4 (8(112)) ◽  
pp. 16-22
Author(s):  
Mahmoud A. Mashkour
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Source ◽  
Local Nusselt Number ◽  
Richardson Number ◽  
Stokes Equations ◽  
Heat Convection ◽  
Horizontal Channel ◽  
Outlet Temperature

The heat convection phenomenon has been investigated numerically (mathematically) for a channel located horizontally and partially heated at a uniform heat flux with forced and free heat convection. The investigated horizontal channel with a fluid inlet and the enclosure was exposed to the heat source from the bottom while the channel upper side was kept with a constant temperature equal to fluid outlet temperature. Transient, laminar, incompressible and mixed convective flow is assumed within the channel. Therefore, the flow field is estimated using Navier Stokes equations, which involves the Boussinesq approximation. While the temperature field is calculated using the standard energy model, where, Re, Pr, Ri are Reynolds number, Prandtl number, and Richardson number, respectively. Reynolds number (Re) was changed during the test from 1 to 50 (1, 10, 25, and 50) for each case study, Richardson (Ri) number was changed during the test from 1 to 25 (1, 5, 10, 15, 20, and, 25). The average Nusselt number (Nuav) increases exponentially with the Reynold number for each Richardson number and the local Nusselt number (NuI) rises in the heating point. Then gradually stabilized until reaching the endpoint of the channel while the local Nusselt number increases with a decrease in the Reynolds number over there. In addition, the streamlines and isotherms patterns in case of the very low value of the Reynolds number indicate very low convective heat transfer with all values of Richardson number. Furthermore, near the heat source, the fluid flow rate rise increases the convection heat transfer that clarified the Nusselt number behavior with Reynolds number indicating that maximum Nu No. are 6, 12, 27 and 31 for Re No. 1, 10, 25 and 50, respectively

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