scholarly journals Investigation of Single-Phase Flow Characteristics in an Inline Pin-Fins Complex Geometry

2021 ◽  
Vol 1879 (3) ◽  
pp. 032118
Author(s):  
R. Shakir
Keyword(s):  
Single Phase ◽  
Complex Geometry ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Pin Fins

scholarly journals INVESTIGATION OF SINGLE-PHASE FLOW CHARACTERISTICS IN A STAGGER PIN-FINS COMPLEX GEOMETRY

2021 ◽  
Vol 25 (6) ◽  
pp. 74-81
Author(s):  
R. Shakir ◽  
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Complex Geometry ◽  
Flow Characteristics ◽  
Inlet Temperature ◽  
Phase Flow ◽  
Fluid Temperature ◽  
Single Phase Flow ◽  
Pin Fins ◽  
Micro Pin Fins

The cooling equipment project must use electrical and electronic equipment because of the need to remove the heat generated by this equipment. Investigation; R-113 single-phase flow heat transfer; (50 x 50 mm2) cross-section and (5 mm) height; used in a series of stagger-square micro-pin fins. Inlet temperature of (25 °C); (6) Mass flow rate at this temperature, the recommended range is (0. 0025 -0.01 kg/sec) the inlet and outlet pressures are approximately (1-1.10 bar), and through (25- 225 watts) applied heat. The iterative process is used to obtain the heat flow characteristics, for example; the single-phase heat transfer coefficient is completely laminar flow developing, in this flow, guesses the wall temperature, guess the fluid temperature. The possible mechanism of heat transfer has been discussed

Single Phase Flow in the Randomly Packed Bed With Spheres: Simulation and Experimental Validation

2016 ◽  
Author(s):  
Nan Zhang ◽  
Zhongning Sun ◽  
Ming Ding
Keyword(s):  
Single Phase ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Particle Diameter ◽  
Flow Characteristics ◽  
Packed Bed ◽  
Spherical Particles ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Local Flow

A computational fluid dynamic (CFD) model for single phase flow in the three dimensional randomly packed bed with spherical particles has been developed and validated with experimental results. The flow characteristics within this complex geometry are very complicated. In order to obtain insight into the interior and local flow characteristics, Three-dimensional simulation is required. First, we constructed the randomly packed bed with spherical particle, using Discrete Element Method (DEM) based on the integration of Newton’s laws of motion. To validate the DEM simulations the global bed porosity and the radial porosity distribution were compared with empirical correlation from literature. Second, the complex geometrical properties of random packed bed make it difficult to produce a fine mesh. Herein, the bridge method for meshing the particle-particle and particle-wall contact points in the packed bed was applied. The contact zones are modified and then partitioned into several regular parts, so the structure gird was meshed. Finally, the simulation of water flow in the randomly packed bed with a tube-to-particle diameter ratio of 6.325 has been carried out by the commercial CFD code. A comparison with previously published correlations and experimental data shows that the relationship proposed by KTA agree well with the measured pressure drop. Furthermore the results of simulation for distribution of velocity in the bed were analyzed and discussed.

Flow Patterns During Flow Boiling Instability in Silicon-Based Pin-Fin Microchannels

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Fayao Xu ◽  
Huiying Wu ◽  
Zhenyu Liu
Keyword(s):  
Single Phase ◽  
Flow Instability ◽  
Flow Boiling ◽  
Flow Patterns ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Pin Fin ◽  
Short Period ◽  
Pin Fins ◽  
Amplitude Mode

In this paper, the flow patterns during water flow boiling instability in pin-fin microchannels were experimentally studied. Three types of pin-fin arrays (in-line/circular pin-fins, staggered/circular pin-fins, and staggered/square pin-fins) were used in the study. The flow instability started to occur as the outlet water reached the saturation temperature. Before the unstable boiling, a wider range of stable boiling existed in the pin-fin microchannels compared to that in the plain microchannels. Two flow instability modes for the temperature and pressure oscillations, which were long-period/large-amplitude mode and short-period/small-amplitude mode, were identified. The temperature variation during the oscillation period of the long-period/large-amplitude mode can be divided into two stages: increasing stage and decreasing stage. In the increasing stage, bubbly flow, vapor-slug flow, stratified flow, and wispy flow occurred sequentially with time for the in-line pin-fin microchannels; liquid single-phase flow, aforementioned four kinds of two-phase flow patterns, and vapor single-phase flow occurred sequentially with time for the staggered pin-fin microchannel. The flow pattern transitions in the decreasing stage were the inverse of those in the increasing stage for both in-line and staggered pin-fin microchannels. For the short-period/small-amplitude oscillation mode, only the wispy flow occurred. With the increase of heat flux, the wispy flow and the vapor single-phase flow occupied more and more time ratio during an oscillation period in the in-line and staggered pin-fin microchannels.

A numerical investigation on single-phase flow characteristics and frictional pressure drop in helical pipes

2020 ◽  
Vol 52 (4) ◽  
pp. 045505
Author(s):  
Pengxin Cheng ◽  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
Shengyao Jiang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Numerical Investigation ◽  
Single Phase ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Frictional Pressure Drop

An Experimental Investigation of Gas-Liquid Heat Transfer in Rectangular Micro-Channels

2013 ◽  
Author(s):  
Sira Saisorn ◽  
Somchai Wongwises ◽  
Piyawat Kuaseng ◽  
Chompunut Nuibutr ◽  
Wattana Chanphan
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Camera System ◽  
Micro Channels ◽  
Flow Mechanisms

The investigations of heat transfer and fluid flow characteristics of non-boiling air-water flow in micro-channels are experimentally studied. The gas-liquid mixture from y-shape mixer is forced to flow in the 21 parallel rectangular microchannels with 40 mm long in the flow direction. Each channel has a width and a depth of 0.45 and 0.41 mm, respectively. Flow visualization is feasible by incorporating the stereozoom microscope into the camera system and different flow patterns are recorded. The experiments are performed under low superficial velocities. Two-phase heat transfer gives better results when compared with the single-phase flow. It is found from the experiment that heat transfer enhancement up to 53% is obtained over the single-phase flow. Also, the change in the configuration of the inlet plenum can result in the different two-phase flow mechanisms.

Thermal and Flow Characteristics of Water–Nitrogen Taylor Flow Inside Vertical Circular Tubes

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Jingzhi Zhang ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Flow Characteristics ◽  
Numerical Data ◽  
Bond Number ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Pressure Drops ◽  
Taylor Flow ◽  
Bubble Rising Velocity

Heat transfer and flow characteristics of Taylor flows in vertical capillaries with tube diameters ranging from 0.5 mm to 2 mm were studied numerically with the volume of fluid (VOF) method. Streamlines, bubble shapes, pressure drops, and heat transfer characteristics of the fully developed gas–liquid Taylor flow were investigated in detail. The numerical data fitted well with experimental results and with the predicted values of empirical correlations. The results indicate that the dimensionless liquid film thickness and bubble rising velocity increase with increasing capillary number. Pressure drops in liquid slug region are higher than the single-phase flow because of the Laplace pressure drop. The flow pattern dependent model and modified flow separation model which takes Bond number and Reynolds number into account can predict the numerical pressure drops well. Compared with the single-phase flow, less time is needed for the Taylor flow to reach a thermal fully developed status. The Nusselt number of Taylor flow is about 1.16–3.5 times of the fully developed single-phase flow with a constant wall heat flux. The recirculation regions in the liquid and gas slugs can enhance the heat transfer coefficient and accelerate the development of the thermal boundary layer.

Flow characteristics of single-phase flow in narrow annular channels

2008 ◽  
Vol 2 (4) ◽  
pp. 466-470 ◽  
Author(s):  
Heyi Zeng ◽  
Suizheng Qiu ◽  
Guanghui Su ◽  
Dounan Jia
Keyword(s):  
Single Phase ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Annular Channels
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