New thermal-hydraulic correlations for printed circuit heat exchangers (PCHEs) with zigzag channels under high Reynolds numbers

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Carolina P. Naveira-Cotta ◽  
Jian Su ◽  
Paulo Lucena Kreppel Paes ◽  
Philippe R. Egmont ◽  
Rodrigo P. M. Moreira ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Design Parameters ◽  
Channel Diameter ◽  
Content Type ◽  
Printed Circuit ◽  
High Reynolds Numbers ◽  
High Reynolds ◽  
The Impact

Purpose The purpose of this paper is to investigate the impact of semi-circular zigzag-channel printed circuit heat exchanger (PCHE) design parameters on heat transfer and pressure drop of flows under high Reynolds numbers and provide new thermal-hydraulic correlations relevant to conditions encountered in natural gas processing plants. Design/methodology/approach The correlations were developed using three-dimensional steady-state computational fluid dynamics simulations with varying semicircular channel diameter (from 1 to 5 mm), zigzag angle (from 15° to 45°) and Reynolds number (from 40,000 to 100,000). The simulation results were validated by comparison with experimental results and existing correlations. Findings The results revealed that the thermal-hydraulic performance was mostly affected by the zigzag angle, followed by the ratio of the zigzag channel length to the hydraulic diameter. Overall, smaller zigzag angles favored heat transfer intensification while keeping reasonably low pressure drops. Originality/value This study is, to date, the only one providing thermal-hydraulic correlations for PCHEs with zigzag channels under high Reynolds numbers. Besides, the broad range of parameters considered makes the proposed correlations valuable PCHE design tools.

An Experimental and Numerical Study of Heat Transfer and Pressure Loss in a Rectangular Channel With V-Shaped Ribs

2006 ◽  
Author(s):  
Michael Maurer ◽  
Jens von Wolfersdorf ◽  
Michael Gritsch
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Pressure Loss ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Transfer Enhancement ◽  
High Reynolds Numbers ◽  
High Reynolds

An experimental and numerical study was conducted to determine the thermal performance of V-shaped ribs in a rectangular channel with an aspect ratio of 2:1. Local heat transfer coefficients were measured using the steady state thermochromic liquid crystal technique. Periodic pressure losses were obtained with pressure taps along the smooth channel sidewall. Reynolds numbers from 95,000 to 500,000 were investigated with V-shaped ribs located on one side or on both sides of the test channel. The rib height-to-hydraulic diameter ratios (e/Dh) were 0.0625 and 0.02, and the rib pitch-to-height ratio (P/e) was 10. In addition, all test cases were investigated numerically. The commercial software FLUENT™ was used with a two-layer k-ε turbulence model. Numerically and experimentally obtained data were compared. It was determined that the heat transfer enhancement based on the heat transfer of a smooth wall levels off for Reynolds numbers over 200,000. The introduction of a second ribbed sidewall slightly increased the heat transfer enhancement whereas the pressure penalty was approximately doubled. Diminishing the rib height at high Reynolds numbers had the disadvantage of a slightly decreased heat transfer enhancement, but benefits in a significantly reduced pressure loss. At high Reynolds numbers small-scale ribs in a one-sided ribbed channel were shown to have the best thermal performance.

Temperature Control of Blow-Down, Supersonic Tunnels

1956 ◽  
Vol 60 (541) ◽  
pp. 67-70
Author(s):  
T. A. Thomson
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Mach Number ◽  
Reynolds Numbers ◽  
Stagnation Temperature ◽  
Blow Down ◽  
High Reynolds Numbers ◽  
Experimental Errors ◽  
High Reynolds

The blow-down type of intermittent, supersonic tunnel is attractive because of its simplicity and because relatively high Reynolds numbers can be obtained for a given size of test section. An adverse characteristic, however, is the fall of stagnation temperature during runs, which can affect experiments in several ways. The Reynolds number varies and the absolute velocity is not constant, even if the Mach number and pressure are; heat-transfer cannot be studied under controlled conditions and the experimental errors arising from the effect of heat-transfer on the boundary layer vary in time. These effects can become significant in quantitative experiments if the tunnel is large and the variation of temperature very rapid; the expense required to eliminate them might then be justified.

A Parametric Study on Fluid Flow and Heat Transfer in a Printed Circuit Heat Exchanger

2011 ◽  
Author(s):  
Sang-Moon Lee ◽  
Kwang-Yong Kim
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Design Parameters ◽  
Printed Circuit ◽  
Reference Shape ◽  
Shear Stress Transport Model

Numerical analyses for pressure drop and heat transfer in the flow channels of a printed circuit heat exchanger have been performed numerically. Three-dimensional Reynolds-averaged Navier-Stokes equations have been solved in conjunction with the shear stress transport model as a turbulence closure. The numerical solutions are validated with the available experimental results of the reference shape. The effects of two design parameters, namely, the channel angle and the ellipse aspect ratio of the cold channel, on the heat transfer and the friction performance have been evaluated.

How Turbulence Models Perform in Simulating Pipeflow Response to Targeted Wall-Shapes?

2021 ◽  
Author(s):  
Mehran Masoumifar ◽  
Suyash Verma ◽  
Arman Hemmati
Keyword(s):  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Flow Response ◽  
High Reynolds Numbers ◽  
Flow Features ◽  
Rans Models ◽  
Response And Recovery ◽  
High Reynolds

Abstract This study evaluates how Reynolds-Averaged-Navier-Stokes (RANS) models perform in simulating the characteristics of mean three-dimensional perturbed flows in pipes with targeted wall-shapes. Capturing such flow features using turbulence models is still challenging at high Reynolds numbers. The principal objective of this investigation is to evaluate which of the well-established RANS models can best predict the flow response and recovery characteristics in perturbed pipes at moderate and high Reynolds numbers (10000-158000). First, the flow profiles at various axial locations are compared between simulations and experiments. This is followed by assessing the well-known mean pipeflow scaling relations. The good agreement between our computationally predicted data using Standard k-epsilon model and those of experiments indicated that this model can accurately capture the pipeflow characteristics in response to introduced perturbation with smooth sinusoidal axial variations.

Heat Transfer Coefficient Distribution of W and Broken W Turbulators At High Reynolds Numbers

2021 ◽  
pp. 1-29
Author(s):  
Sam Ghazi-Hesami ◽  
Dylan Wise ◽  
Keith Taylor ◽  
Étienne Robert ◽  
Peter Ireland
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Reynolds Numbers ◽  
High Reynolds Numbers ◽  
Smooth Channel ◽  
Wide Range ◽  
High Reynolds

Abstract An experimental and numerical study of the convective heat transfer enhancement provided by two rib families (W and Broken W) is presented, covering Reynolds numbers (Re) between 300,000 to 900,000 in a straight channel with a rectangular cross section (AR=1.29). These high Reynolds numbers were selected for the current study since most data in the available literature typically pertain to investigations at lower Reynolds numbers. The objective of this study is to assess the local heat transfer coefficient (HTC) enhancement (compared with a smooth channel) and the overall thermal performance, taking into account the effect of increased roughness on the friction factor, of a group of W shaped turbulators over a wide range of Reynolds numbers. Furthermore, the effects of increasing the rib spacing on the thermal performance of the Broken W configuration are presented and discussed. The numerical results are compared against heat transfer measurements obtained using the Transient Liquid Crystal (TLC) method. The research shows that for the Broken W turbulators, increasing the Reynolds number is associated with an overall decrease of the thermal performance while the thermal performance of the W configuration is relatively insensitive to Reynolds number. Nevertheless, the Broken W configuration delivers higher thermal performance and heat transfer compared with the W configuration for the range of Re investigated. The Broken W configuration with a pitch spacing of 10 times the rib height was shown to provide the optimal thermal performance in the configurations investigated here.

Computational fluid dynamics and laminar heat transfer of water/Cu nanofluid in ribbed microchannel with a two-phase approach

2019 ◽  
Vol 29 (5) ◽  
pp. 1563-1589 ◽  
Author(s):  
Navid Ahmadi Cheloii ◽  
Omid Ali Akbari ◽  
Davood Toghraie
Keyword(s):  
Heat Transfer ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Two Phase ◽  
Rectangular Microchannel ◽  
Content Type ◽  
Performance Evaluation Criterion ◽  
Phase Mixture ◽  
Three Dimensional Space

Purpose This study aims to numerically investigate the heat transfer and laminar forced and two-phase flow of Water/Cu nanofluid in a rectangular microchannel with oblique ribs with angle of attacks equal to 0-45°. This simulation was conducted in the range of Reynolds numbers of 5-120 in volume fractions of 0, 2 and 4 per cent of solid nanoparticles in three-dimensional space. Design/methodology/approach This study investigates the effect of the changes of angle of attack of rectangular rib on heat transfer and hydrodynamics of two-phase flow. This study was done in three-dimensional space and simulation was done with finite volume method. SIMPLEC algorithm and second-order discretization of equations were used to increase the accuracy of results. The usage of nanofluid, application of rips with different angles of attacks and using the two-phase mixture method is the distinction of this paper compared with other studies. Findings The results of this research revealed that the changing angle of attack of ribs is an effective factor in heat transfer enhancement. On the other hand, the existence of rib on the internal surfaces of a microchannel increases friction coefficient. By increasing the volume fraction of nanoparticles, due to the augmentation of fluid density and viscosity, the pressure drop increases significantly. For all of the angle of attacks studied in this paper, the maximum rate of performance evaluation criterion has been obtained in Reynolds number of 30 and the minimum amount of performance evaluation criterion was been obtained in Reynolds numbers of 5 and 120. Originality/value Many studies have been done in the field of heat transfer in ribbed microchannel. In this paper, the laminar flow in the ribbed microchannel Water/Cu nanofluid in a rectangular microchannel by using two-phase mixture method is numerically investigated with different volume fractions (0-4 per cent), Reynolds numbers (5-120) and angle of attacks of rectangular rib in the indented microchannel (0-45°).

Influence of Rotation on Heat Transfer in a Two-Pass Channel With Impingement Under High Reynolds Number

2015 ◽  
Author(s):  
Li Yang ◽  
Kartikeya Tyagi ◽  
Srinath Ekkad ◽  
Jing Ren
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Coriolis Force ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Internal Cooling ◽  
Channel Diameter ◽  
Turbine Cooling ◽  
High Reynolds ◽  
The Impact

Effect of rotation on turbine blade internal cooling is an important factor in gas turbine cooling systems. In order to minimize the impact from the Coriolis force, cooling structures with less rotation-dependent cooling effectiveness are needed. This study presents an impingement design in a two pass channel to reduce impact of rotational forces on non-uniform heat transfer behavior inside these complex channels. A Transient Liquid Crystal(TLC) method was employed to obtain local heat transfer coefficient measurements in a rotating environment. The channel Reynolds number based on the channel diameter ranges from 25,000 to 100,000. The rotation number ranges from 0 to 0.14. A series of computational simulations with the SST model were also utilized to understand the flow field behavior that impacts the heat transfer distributions on the walls. A 1-D correlation of zone averaged Nusselt number distribution was derived from the measurements. Results show that rotation reduces the heat transfer on both sides of the impingement, which is due to the Coriolis force and the pressure redistribution. The local change in the present study is about 25%. Rotation significantly enhances the heat transfer near the closed end because of the centrifugal force and the ‘pumping’ effect. Within the parameters of this test, the magnitude of enhancement is 25% to 75%. Compared to U-bended two pass channel, impingement channel has advantages in the upstream channel and the end region, but performance is not beneficial on the leading side of the downstream channel.

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