Investigation of ribs disturbed entrance effect of heat transfer and pressure drop in pin-fin array

2019 ◽  
Vol 162 ◽  
pp. 114214 ◽  
Author(s):  
Wandong Bai ◽  
Dong Liang ◽  
Wei Chen ◽  
Minking K. Chyu
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Entrance Effect ◽  
Pin Fin ◽  
Pin Fin Array

scholarly journals Effect of Pin Diameter Degressive Gradient on Heat Transfer in a Microreactor with Non-Uniform Pin-Fin Array under Low Reynolds Number Conditions

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2702
Author(s):  
Miao Qian ◽  
Jie Li ◽  
Zhong Xiang ◽  
Chao Yan ◽  
Xudong Hu
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Low Reynolds Number ◽  
Hydrodynamic Characteristics ◽  
Pin Fin ◽  
Low Reynolds ◽  
Pin Fin Array

To improve the efficiency of hydrogen-producing microreactors with non-uniform pin-fin array, the influence of the pin diameter degressive gradient of the non-uniform pin-fin array (NPFA) on heat transfer and pressure drop characteristics is analyzed in this study via numerical simulation under low Reynolds number conditions. Because correlations in prior studies cannot be used to predict the Nusselt number and pressure drop in the NPFA, new heat transfer and friction factor correlations are developed in this paper to account for the effect of the pin diameter degressive gradient, providing a method for the optimized design of the pin diameter degressive gradient for a microreactor with NPFA. The results show that the Nusselt number and friction factor under a low Reynolds number are quite sensitive to the pin diameter degressive gradient. Based on the new correlations, the exponents of the pin diameter degressive gradient for the friction factor and Nusselt number were 6.9 and 2.1, respectively, indicating the significant influence of the pin diameter degressive gradient on the thermal and hydrodynamic characteristics in the NPFA structure.

Heat Transfer and Pressure Drop Measurements in Constant and Converging Section Pin and Diamond Pedestal Arrays

2009 ◽  
Author(s):  
I. Jaswal ◽  
F. E. Ames
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Local Maximum ◽  
Characteristic Dimension ◽  
Channel Height ◽  
Channel Spacing ◽  
Pin Fin ◽  
Converging Channel ◽  
Pin Fin Array ◽  
Constant Section

High solidity pin and pedestal arrays are beneficial in reducing temperature gradients and distributing stress across double wall cooling channels such as trailing edge regions. In this study two high solidity (45%) cooling channel geometries were selected and tested in both constant channel height and converging channel configurations. One geometry consisted of a high solidity round pin fin array and the other geometry consisted of a rounded diamond pedestal array designed to minimize pressure drop. Heat transfer rates for both geometries were determined on a row by row basis for both the constant channel and converging channel configurations. Heat transfer and pressure drop measurements were acquired in a bench scale test rig. Reynolds numbers ranged from approximately 3000 to 60,000 for the constant channel arrays and 3500 to 100,000 for the converging arrays based on the characteristic dimension of the pin or pedestal and the local maximum average velocity across a row. The high solidity pin fin array had an axial spacing (X/D) of 1.043 and a cross channel spacing (Z/D) of 1.674. The high solidity diamond pedestal array had an axial spacing of 1.00 and a cross channel spacing of 1.93. The constant section pin fin array had a channel height to diameter of 0.95 while the constant section diamond pedestal array had a height to characteristic dimension of 0.96. The converging pin fin array had an inlet to exit convergence ratio of 2.87 over five heated rows while the converging pedestal array had an inlet to exit convergence ratio of 3.53 over seven heated rows. The constant channel height internal cooling schemes have shown that the high solidity pin fin and the rounded diamond pedestal arrays produce comparable heat transfer and array pressure drop. Both the converging channel arrays show a noticeable (5% to 7%) reduction in heat transfer compared with the constant height channels. Array pressure drop for the two converging geometries was found to be quite consistent.

Thermal and Hydrodynamic Characteristics of Single-Phase Flow and Flow Boiling in a Staggered Micro-Pin-Fin Array

2008 ◽  
Author(s):  
Weilin Qu
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Single Phase ◽  
Flow Boiling ◽  
Hydrodynamic Characteristics ◽  
Inlet Temperature ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Pin Fin ◽  
Pin Fin Array

This study concerns thermal and hydrodynamic characteristics of water single-phase flow and flow boiling in a micro-pin-fin array. An array of 1950 staggered square micro-pin-fins with a 200×200 μm2 cross-section by a 670 μm height were fabricated into a copper heat sink test section. Two inlet temperatures of 30 °C and 60 °C, and six maximum mass velocities for each inlet temperature, ranging from 183 to 420 kg/m2s, were tested. The corresponding inlet Reynolds number ranged from 45.9 to 179.6. General characteristics of single-phase flow and flow boiling were described. Predictive tools were proposed for single-phase heat transfer coefficient and pressure drop. Unique features of flow boiling heat transfer in the micro-pin-fin array were identified. The classic Lockhart-Martinelli correlation incorporating a single-phase micro-pin-fin friction factor correlation and the laminar liquid–laminar vapor combination assumption was used to predict two-phase pressure drop in the micro-pin-fin array. The predictions agreed well with the experimental data.

Heat Transfer and Pressure Drop Measurements in Constant and Converging Section Pin and Diamond Pedestal Arrays

2009 ◽  
Vol 1 (1) ◽  
Author(s):  
I. Jaswal ◽  
F. E. Ames
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Local Maximum ◽  
Characteristic Dimension ◽  
Channel Height ◽  
Channel Spacing ◽  
Pin Fin ◽  
Converging Channel ◽  
Pin Fin Array ◽  
Constant Section

High solidity pin and pedestal arrays are beneficial in reducing temperature gradients and distributing stress across double wall cooling channels such as trailing edge regions. In this study two high solidity (45%) cooling channel geometries were selected and tested in both constant channel height and converging channel configurations. One geometry consisted of a high solidity round pin fin array and the other geometry consisted of a rounded diamond pedestal array designed to minimize pressure drop. Heat transfer rates for both geometries were determined on a row by row basis for both the constant channel and converging channel configurations. Heat transfer and pressure drop measurements were acquired in a bench scale test rig. Reynolds numbers ranged from approximately 3000 to 60,000 for the constant channel arrays and 3500 to 100,000 for the converging arrays based on the characteristic dimension of the pin or pedestal and the local maximum average velocity across a row. The high solidity pin fin array had an axial spacing (X/D) of 1.043 and a cross channel spacing (Z/D) of 1.674. The high solidity diamond pedestal array had an axial spacing of 1.00 and a cross channel spacing of 1.93. The constant section pin fin array had a channel height to diameter of 0.95 while the constant section diamond pedestal array had a height to characteristic dimension of 0.96. The converging pin fin array had an inlet to exit convergence ratio of 2.87 over five heated rows while the converging pedestal array had an inlet to exit convergence ratio of 3.53 over seven heated rows. The constant channel height internal cooling schemes have shown that the high solidity pin fin and the rounded diamond pedestal arrays produce comparable heat transfer and array pressure drop. Both the converging channel arrays show a noticeable (5–7%) reduction in heat transfer compared with the constant height channels. Array pressure drop for the two converging geometries was found to be quite consistent.

Assessment of heat transfer and pressure drop of metal foam-pin-fin heat sink

2021 ◽  
Vol 170 ◽  
pp. 107109
Author(s):  
Mohanad A. Alfellag ◽  
Hamdi E. Ahmed ◽  
Mohammed Gh. Jehad ◽  
Marwan Hameed
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
Metal Foam ◽  
Pin Fin

Experimental Investigation Into the Influence of Varying Stagger on the Performance of a Pin-Fin Array

2008 ◽  
Author(s):  
W. D. Allan ◽  
S. A. Andrews ◽  
M. LaViolette
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Pressure Loss ◽  
Reynolds Numbers ◽  
Design Criterion ◽  
Transfer Enhancement ◽  
Pin Fin ◽  
Line Array ◽  
Array Performance ◽  
Pin Fin Array

A six row pin-fin array was constructed with a spanwise spacing of 2.5 diameters, streamwise spacing of 1.5 diameters and a height to diameter ratio of 1. The streamwise stagger of alternate rows was continuously varied from fully in-line to fully staggered. Tests were carried out at Reynolds numbers of 2.7 × 104 and 2.3 × 104, corresponding to maximum velocities, in the low subsonic range, of 21 m/s and 18 m/s respectively. These results showed that the array averaged heat transfer was greatest from a fully staggered array and had a minimum at a stagger slightly greater than fully in-line. However, with increasing stagger, the array-averaged friction factor grew at a greater rate than the heat transfer. The ensuing analysis of the total array performance, considering both the magnitude of heat transfer and the losses within the array, showed that the fully in-line array had the highest ratio of heat transfer enhancement to friction factor enhancement. Therefore, if pressure loss was a design criterion, the fully in-line array was preferable. However, if pressure loss was not a constraint, then the staggered array was preferable.

A Study on Flow Boiling in Microchannel With Piranha Pin Fin

2015 ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Flow Boiling ◽  
Transfer Performance ◽  
Flow Conditions ◽  
Pin Fin ◽  
Flow And Heat Transfer

In this paper we reported an advanced structure, the Piranha Pin Fin (PPF), for microchannel flow boiling. Fluid flow and heat transfer performance were evaluated in detail with HFE7000 as working fluid. Surface temperature, pressure drop, heat transfer coefficient and critical heat flux (CHF) were experimentally obtained and discussed. Furthermore, microchannels with different PPF geometrical configurations were investigated. At the same time, tests for different flow conditions were conducted and analyzed. It turned out that microchannel with PPF can realize high-heat flux dissipation with reasonable pressure drop. Both flow conditions and PPF configuration played important roles for both fluid flow and heat transfer performance. This study provided useful reference for further PPF design in microchannel for flow boiling.

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