Flow and Heat Transfer Mechanisms in Plate-and-Frame Heat Exchangers

1999 ◽  
pp. 185-206 ◽  
Author(s):  
Bengt Sundén
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Flow And Heat Transfer ◽  
Transfer Mechanisms

scholarly journals Effect of the size of graded baffles on the performance of channel heat exchangers

2020 ◽  
Vol 24 (2 Part A) ◽  
pp. 767-775 ◽  
Author(s):  
Djamel Sahel ◽  
Houari Ameur ◽  
Touhami Baki
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchangers ◽  
Computer Code ◽  
Channel Length ◽  
Heat Transfer Characteristics ◽  
Enhancement Of Heat Transfer ◽  
Transfer Rates ◽  
Flow And Heat Transfer ◽  
Friction Factors

The baffling technique is well-known for its efficiency in terms of enhancement of heat transfer rates throught channels. However, the baffles insert is accompanied by an increase in the friction factor. This issue remains a great challenge for the designers of heat exchangers. To overcome this issue, we suggest in the present paper a new design of baffles which is here called graded baffle-design. The baffles have an up- or down-graded height along the channel length. This geometry is characterized by two ratios: up-graded baffle ratio and down-graded baffle ratio which are varied from 0-0.08. For a range of Reynolds number varying from 104 to 2 ? 104, the turbulent flow and heat transfer characteristics of a heat exchanger channel are numerically studied by the computer code FLUENT. The obtained results revealed an enhancement in the thermohydraulic performance offered by the new suggested design. For the channel with a down-graded baffle ratio equal to 0.08, the friction factors decreased by 4-8%

The Curvature Effect on the Heat Transfer at the End of a Bayonet Tube With Laminar Flows

2004 ◽  
Author(s):  
F. Sun ◽  
H. Li ◽  
J. Drummond ◽  
G.-X. Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Average Nusselt Number ◽  
Heat Transfer Performance ◽  
Laminar Flows ◽  
Transfer Performance ◽  
Curvature Effect ◽  
Flow And Heat Transfer ◽  
Cooling Agent ◽  
Annular Section

Bayonet tubes, simple refluent heat exchangers, are widely used to heat or cool a media when the heating/cooling agent is readily accessible from one side only. Many studies have been conducted to evaluate the heat transfer performance of bayonet tubes. The majority of these studies focus on the heat transfer in the annular section and little on the end surface. This paper presents a numerical simulation of the laminar flow and heat transfer in a bayonet tube. The simulation is first validated by the experimental data in the literature. The flow and heat transfer in bayonet tubes are then investigated with both flat and curved end surfaces. Both local and average Nusselt number on the end surfaces are calculated under various Re and geometry conditions. Effect of the end surface curvature is studied by comparing the performances of the flat and curved ended bayonet tubes.

State of the art on flow and heat transfer performance of compact fin-and-tube heat exchangers

2019 ◽  
Vol 139 (4) ◽  
pp. 2739-2768 ◽  
Author(s):  
A. Y. Adam ◽  
A. N. Oumer ◽  
G. Najafi ◽  
M. Ishak ◽  
M. Firdaus ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
State Of The Art ◽  
Transfer Performance ◽  
Flow And Heat Transfer

Experimental Study of Convective Heat Transfer in Standard and Cross-Drilled Brake Discs With Radial Vane and X-Lattice Cores

2018 ◽  
Author(s):  
Hongbin Yan ◽  
Shangsheng Feng ◽  
Wei-Tao Wu ◽  
Tian Jian Lu ◽  
Gongnan Xie
Keyword(s):  
Heat Transfer ◽  
Experimental Comparison ◽  
Brake Disc ◽  
Disc Brake ◽  
Cooling Performance ◽  
Flow And Heat Transfer ◽  
Brake Discs ◽  
Flow Through ◽  
The Cross ◽  
Transfer Mechanisms

To improve the cooling performance of disc brake systems, cross-drilled holes penetrating across the rubbing discs are separately introduced into a commercial radial vane brake disc (as reference) and a novel X-lattice cored brake disc. Prototype samples of both the reference and cross-drilled brake discs are fabricated. A rotating test rig is designed and constructed to characterize and compare the cooling performance of the brake discs with infrared thermography. Within the typical operating range of a vehicle, e.g., 200–1000 rpm, the experimental results show that the introduction of cross-drilled holes can substantially enhance brake disc cooling. For the radial vane brake disc, the overall Nusselt number is enhanced by 31%–44%; for the X-lattice cored brake disc, the cross-drilled holes only lead to 9%–18% enhancement. As the radial vane brake disc and the X-lattice cored brake disc with cross-drilled holes exhibit similar cooling performance, flow through the cross-drilled holes has a more prominent effect on the former than the latter. Corresponding fluid flow and heat transfer mechanisms underlying the enhanced heat transfer by cross-drilled holes and the different effects of cross-drilled holes on the two distinct brake discs are explored. The experimental comparison and the thermo-fluidic physics presented in this paper are beneficial for engineers to further improve disc brake cooling.

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.

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