Experimental study on single-phase flow in horizontal internal helically-finned tubes: The critical Reynolds number for turbulent flow

2018 ◽  
Vol 92 ◽  
pp. 402-408 ◽  
Author(s):  
Yong-Hui Wang ◽  
Ji-Li Zhang ◽  
Zhi-Xian Ma
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Turbulent Flow ◽  
Single Phase ◽  
Critical Reynolds Number ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Finned Tubes

An Experimental Study of Friction Factor in the Transition Region for Single Phase Flow in Mini- and Micro-Tubes

2008 ◽  
Author(s):  
Afshin J. Ghajar ◽  
Rahul P. Rao ◽  
Wendell L. Cook ◽  
Clement C. Tang
Keyword(s):  
Experimental Study ◽  
Friction Factor ◽  
Transition Region ◽  
Pressure Transducer ◽  
Single Phase ◽  
Tube Diameter ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Steel Tubes ◽  
Pressure Sensing

A systematic and accurate experimental investigation of friction factor in the transition region for single phase flow in mini- and micro-tubes has been performed for eight stainless steel tubes with diameters ranging from 2083 μm to 667 μm. The pressure drop measurements were carefully performed by paying particular attention to the sensitivity of the pressure-sensing diaphragms used in the pressure transducer. Experimental results indicated that the start and end of the transition region was influenced by varying the tube diameter. The friction factor profile was not significantly affected for the tube diameters between 2083 μm and 1372 μm. However, the influence of the tube diameter on the friction factor profile became noticeable as the diameter decreased from 1372 μm to 667 μm.

Experimental Study and Numerical Analysis of Water Single-Phase Pressure Drop Across a Micro-Pin-Fin Array

2010 ◽  
Author(s):  
Christopher A. Konishi ◽  
Ruey Hwu ◽  
Weilin Qu ◽  
Frank E. Pfefferkorn
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Numerical Analysis ◽  
Single Phase ◽  
Inlet Temperature ◽  
Equivalent Diameter ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Pin Fin ◽  
Pin Fin Array

This study investigates the hydraulic performance of a copper micro-pin-fin array subjected to water liquid single-phase flow conditions. The test section contains an array of 1950 staggered square micro-pin-fins with 200 micron × 200 micron cross-section by 670 micron height. The ratios of longitudinal pitch and transverse pitch to pin-fin equivalent diameter are equal to 2. Seven water inlet temperatures from 22°C to 80°C, and seventeen maximum mass velocities for each inlet temperature, ranging from 181 to 1649 kg/m2s, were tested. The test module was well insulated to maintain adiabatic conditions. Comparison of predictions of eleven existing friction factor correlations with the experimental data show relatively large discrepancies. The experimental study was complemented with a numerical analysis of single-phase flow in the micro-pin-fin array. Numerical results show excellent agreement with experimental data for Reynolds numbers below 700.

Frictional Pressure Drop Correlations for Single-Phase Flow, Condensation, and Evaporation in Microfin Tubes

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Zan Wu ◽  
Bengt Sundén
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Single Phase ◽  
Flow Boiling ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Frictional Pressure Drop ◽  
Friction Factors ◽  
Flow Condensation ◽  
Microfin Tubes

Experimental single-phase, condensation, and evaporation (flow boiling) pressure drop data from the literature and our previous studies were collected to evaluate previous frictional pressure drop correlations for horizontal microfin tubes of different geometries. The modified Ravigururajan and Bergles correlation, by adopting the Churchill model to calculate the smooth-tube friction factor and by using the hydraulic diameter in the Reynolds number, can predict single-phase turbulent frictional pressure drop data relatively well. Eleven pressure drop correlations were evaluated by the collected database for condensation and evaporation. Correlations originally developed for condensation and evaporation in smooth tubes can be suitable for microfin tubes if the friction factors in the correlations were calculated by the Churchill model to include microfin effects. The three most accurate correlations were recommended for condensation and evaporation in microfin tubes. The Cavallini et al. correlation and the modified Friedel correlation can give good predictions for both condensation and evaporation. However, some inconsistencies were found, even for the recommended correlations.

scholarly journals Experimental Study of Single Phase Flow in a Closed-Loop Cooling System with Integrated Mini-Channel Heat Sink

Entropy ◽  
2016 ◽  
Vol 18 (6) ◽  
pp. 128 ◽  
Author(s):  
Lei Ma ◽  
Xuxin Zhao ◽  
Hongyuan Sun ◽  
Qixing Wu ◽  
Wei Liu
Keyword(s):  
Experimental Study ◽  
Heat Sink ◽  
Single Phase ◽  
Closed Loop ◽  
Cooling System ◽  
Phase Flow ◽  
Single Phase Flow

scholarly journals Modeling the influence of forming fabric structure on vacuum box dewatering

TAPPI Journal ◽  
2017 ◽  
Vol 16 (08) ◽  
pp. 477-483 ◽  
Author(s):  
Bjorn Sjostrand ◽  
Christophe Barbier ◽  
Lars Nilsson
Keyword(s):  
Experimental Study ◽  
Single Phase ◽  
Numerical Models ◽  
High Vacuum ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Vacuum Suction ◽  
Fabric Structure ◽  
Fabric Structures

This investigation used numerical models to describe forming section sheet dewatering at the high vacuum suction boxes. Three different fabric structures were examined with numerical models for single-phase flow of air and for two-phase flow of air and water. This was done to evaluate how forming fabric structure influences sheet dewatering. The numerical models were compared with an experimental study of the same fabrics investigated on a laboratory suction box. The small differences in dewatering rate in the experimental study could be simulated with the models, which confirmed the validity of the models. This implies that these numerical models can be used to describe new fabrics and how they will respond in the papermaking process.

scholarly journals Micro-orifice single-phase flow at very high Reynolds number

2018 ◽  
Vol 91 ◽  
pp. 35-40 ◽  
Author(s):  
Andrea Cioncolini ◽  
Stefano Cassineri ◽  
Jonathan Duff ◽  
Michele Curioni ◽  
Fabio Scenini
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Single Phase ◽  
Phase Flow ◽  
Single Phase Flow ◽  
High Reynolds ◽  
Very High

Heat Transfer Augmentation in 3D Inner Finned Helical Tube

Volume 3 ◽  
2004 ◽  
Author(s):  
Longjian Li ◽  
Wenzhi Cui ◽  
Quan Liao ◽  
Mingdao Xin ◽  
Tien-Chien Jen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Boiling Heat Transfer ◽  
Flow Resistance ◽  
Single Phase ◽  
Flow Boiling ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Helical Tube ◽  
Helical Tubes

Experiments were performed to investigate the performance enhancement of single-phase flow and boiling heat transfer in the 3D inner finned helical tubes. The tests for single-phase flow and heat transfer were carried out in the helical tubes with a curvature of 0.0663 and a length of 1.15m, the range of the Reynolds number examined varies from 1000 to 8500. In comparison to the smooth helical tube, the experimental results of two finned helical tubes with different inner fin geometry showed that the heat transfer and flow resistance in the 3D inner finned helical tube gains greater augmentation. Within the measured range of Reynolds number, the average augmentation ratio of heat transfer of the two finned tubes are 71% and 103%, compared with the smooth helical tube, and 90% and 140% for flow resistance, respectively. The tests for flow boiling heat transfer was carried out in the 3D inner finned helical tube with a curvature of 0.0605 and a length of 0.668m. Compared with that in the smooth helical tube, the boiling heat transfer coefficient in the 3D inner finned helical tube is increased by 40%∼120% under varied mass flow rate and wall heat flux conditions, meanwhile, the flow resistance coefficient increased by 18%∼119%.

Liquid Single-Phase Flow in an Array of Micro-Pin-Fins—Part I: Heat Transfer Characteristics

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
Weilin Qu ◽  
Abel Siu-Ho
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Single Phase ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Pin Fin ◽  
Pin Fins ◽  
Micro Pin Fins

This is Paper I of a two-part study concerning thermal and hydrodynamic characteristics of liquid single-phase flow in an array of micro-pin-fins. This paper reports the heat transfer results of the study. An array of 1950 staggered square micro-pin-fins with 200×200 μm2 cross-section by 670 μm height were fabricated into a copper test section. De-ionized water was used as the cooling liquid. Two coolant inlet temperatures of 30°C and 60°C and six maximum mass velocities for each inlet temperature ranging from 183 to 420 kg/m2 s were tested. The corresponding inlet Reynolds number ranged from 45.9 to 179.6. General characteristics of average and local heat transfer were described. Six previous conventional long and intermediate pin-fin correlations and two micro-pin-fin correlations were examined and were found to overpredict the average Nusselt number data. Two new heat transfer correlations were proposed for the average heat transfer based on the present data, in which the average Nusselt number is correlated with the average Reynolds number by power law. Values of the exponent m of the Reynolds number for the two new correlations are fairly close to those for the two previous micro-pin-fin correlations but substantially higher than those for the previous conventional pin-fin correlations, indicating a stronger dependence of the Nusselt number on the Reynolds number in micro-pin-fin arrays. The correlations developed for the average Nusselt number can adequately predict the local Nusselt number data.

Sign in / Sign up

Export Citation Format

Share Document