Laminar Fully Developed Flow and Heat Transfer in Triangular Plate-Fin Ducts

1986 ◽  
Vol 108 (1) ◽  
pp. 24-32 ◽  
Author(s):  
B. R. Baliga ◽  
R. R. Azrak
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Cross Section ◽  
Heat Exchangers ◽  
Conjugate Problem ◽  
Fully Developed Flow ◽  
Compact Heat Exchangers ◽  
Flow And Heat Transfer ◽  
Conductance Parameter ◽  
Local Results

This paper presents a numerical investigation of fully developed flow and heat transfer in triangular cross section plate-fin ducts encountered in compact heat exchangers. Heat conduction in the fin and convection in the fluid are analyzed simultaneously as a conjugate problem. Overall and local results are presented for representative values of the duct aspect ratio and a fin conductance parameter.

Study of Compact Heat Exchangers Operating In Self-Sustained Oscillatory Flows

2020 ◽  
pp. 1-37
Author(s):  
Tracy Fullerton ◽  
N. K. Anand
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchangers ◽  
Control Volume ◽  
Flow Analysis ◽  
Compact Heat Exchangers ◽  
Flow And Heat Transfer ◽  
Turbulent Flow Regime ◽  
Flat Tubes ◽  
Computer Codes

Abstract Computer codes were developed to study the performance of compact heat exchangers (CHEs) operating in self-sustained oscillatory flow (SSOF) regimes. The methods were based on a Control Volume Based Finite Volume (CVFVM) method for geometric discretization and the Explicit first stage, Single diagonal coefficient, Diagonally Implicit, Runge-Kutta (ESDIRK) method for temporal discretization. The developed codes were validated for both steady and unsteady cases. A study of nine geometrically related domains of flat tubes in staggered configurations was performed. Grid independence was established subject to double cyclic conditions – periodically fully developed flow and heat transfer in the stream-wise direction and cyclic or repeating flow and heat transfer in the cross-stream direction. The maximum Reynolds number was established at approximately 2,000 for the cases studied to avoid the turbulent flow regime. Parameters of interest like Nusselt number, friction factor, and pumping power were calculated for steady and SSOF regimes. An approach was proposed to determine critical Reynolds number (Recrit) for the SSOFs such that for Reynolds number below Recrit the flow remains steady and above Recrit the flow exhibits the characteristics of SSOFs before finally transitioning to fully turbulent conditions. The results indicated a sensitivity of performance parameters to transverse spacing but not to longitudinal spacing. The relative magnitudes of errors associated with simulating an SSOF with a steady flow analysis were also documented.

Numerical analysis of compact plate-fin heat exchangers for aerospace applications

2018 ◽  
Vol 28 (2) ◽  
pp. 395-412 ◽  
Author(s):  
Ranganayakulu Chennu
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Conduction ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Design Data ◽  
Content Type ◽  
Compact Heat Exchangers ◽  
Performance Deterioration

Purpose The purpose of this study is to find the thermo-hydraulic performances of compact heat exchangers (CHE’s), which are strongly depending upon the prediction of performance of various types of heat transfer surfaces such as offset strip fins, wavy fins, rectangular fins, triangular fins, triangular and rectangular perforated fins in terms of Colburn “j” and Fanning friction “f” factors. Design/methodology/approach Numerical methods play a major role for analysis of compact plate-fin heat exchangers, which are cost-effective and fast. This paper presents the on-going research and work carried out earlier for single-phase steady-state heat transfer and pressure drop analysis on CHE passages and fins. An analysis of a cross-flow plate-fin compact heat exchanger, accounting for the individual effects of two-dimensional longitudinal heat conduction through the exchanger wall, inlet fluid flow maldistribution and inlet temperature non-uniformity are carried out using a Finite Element Method (FEM). Findings The performance deterioration of high-efficiency cross-flow plate-fin compact heat exchangers have been reviewed with the combined effects of wall longitudinal heat conduction and inlet fluid flow/temperature non-uniformity using a dedicated FEM analysis. It is found that the performance deterioration is quite significant in some typical applications due to the effects of wall longitudinal heat conduction and inlet fluid flow non-uniformity on cross-flow plate-fin heat exchangers. A Computational Fluid Dynamics (CFD) program FLUENT has been used to predict the design data in terms of “j” and “f” factors for plate-fin heat exchanger fins. The suitable design data are generated using CFD analysis covering the laminar, transition and turbulent flow regimes for various types of fins. Originality/value The correlations for the friction factor “f” and Colburn factor “j” have been found to be good. The correlations can be used by the heat exchanger designers and can reduce the number of tests and modification of the prototype to a minimum for similar applications and types of fins.

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