CFD modelling of R410A flow through an expansion valve using equilibrium and modified relaxation models

2021 ◽  
Vol 185 ◽  
pp. 116442
Author(s):  
Michal Loska ◽  
Jacek Smolka ◽  
Michal Haida ◽  
Ekaterini E. Kriezi ◽  
Krzysztof Banasiak
Keyword(s):  
Cfd Modelling ◽  
Expansion Valve ◽  
Flow Through ◽  
Relaxation Models

Numerical Investigation of Flow Through an Ultra-Micro Scale Gas Turbine

2017 ◽  
Author(s):  
Rohann D’souza ◽  
Rajnish Sharma
Keyword(s):  
Gas Turbine ◽  
Leading Edge ◽  
Integrated System ◽  
Tip Clearance ◽  
Cfd Modelling ◽  
3 Dimensional ◽  
Micro Scale ◽  
Viscous Heat ◽  
Flow Through ◽  
Nozzle Guide

The ultra-micro scale gas turbine (UMGT) is an ongoing area of research, as an alternate power source for portable electronic devices. To advance our understanding that will help in its development, this paper focuses on a numerical analysis via computational fluid dynamics (CFD) of flow through a 3 dimensional (3D) blade profiled UMGT turbine. CFD modelling was based off an integrated turbine that consists of a volute, nozzle guide vanes (NGV) and rotor. Firstly, the flow through the integrated system as well as each component was analyzed. Secondly, the turbine was simulated under three different isothermal conditions and compared to the adiabatic situation, in order to understand the loss mechanisms. Lastly, the effect of tip clearance was studied, where it was varied between 0–10% of the blade height. CFD results showed, the flow through the turbine was quite well behaved, however separation of flow at the NGV leading edge, and residual swirl at the rotor trailing edge, were observed. The effects of the isothermal wall boundary condition was very pronounced at the volute and NGV, resulting in a large amount of good heat to be conducted away, at the rotor however conduction was only a percentage of the viscous heat generated. Lastly tip clearance proved to have a linearly detrimental effect on power.

Impact of Area Contact Between Sensor Bulb and Evaporator Return Line on Modular Refrigeration Unit: Computational and Experimental

2005 ◽  
Vol 127 (1) ◽  
pp. 95-100 ◽  
Author(s):  
Saket Karajgikar ◽  
Nikhil Lakhkar ◽  
Dereje Agonafer ◽  
Roger Schmidt
Keyword(s):  
Mechanical Analysis ◽  
Evaporator Temperature ◽  
Thermally Induced ◽  
The Past ◽  
Refrigeration Unit ◽  
Expansion Valve ◽  
Flow Through ◽  
The Stability ◽  
Experimental Bench ◽  
Server System

In the past, virtually all commercial computers were designed to operate at temperatures above the ambient and were primarily air-cooled. However, researchers have always known the advantages of operating electronics at low temperatures. This facilitates faster switching time of semiconductor devices, increased circuit speeds due to lower electrical resistance of interconnecting materials, and reduction in thermally induced failures of devices and components. Depending on the doping characteristics of the chip, performance improvement ranges from 1% to 3% for every 10°C lower transistor temperature can be realized. The IBM S/390 high-end server system is the first IBM design which uses a conventional refrigeration system to maintain the chip temperatures below that of comparable air-cooled systems, but well above cryogenic temperature. In previous work, the focus was to study the effect of variation of evaporator outlet superheat on the flow through thermostatic expansion valve at varying evaporator temperature. The effect of change in bulb location and effect of bulb time constant on the hunting at the evaporator has been reported. The effect of area contact on the stability of the system is been predicted theoretically. Mechanical analysis is performed in order to check the stresses induced. The evaporator return line and the sensor bulb are simply attached. The effect of area contact is further studied experimentally on an experimental bench.

3D CFD Investigation of Air Flow Behind a Porous Fence Using Different Turbulence Models

2014 ◽  
Author(s):  
Yizhong Xu ◽  
Mohamad Y. Mustafa ◽  
Geanette Polanco
Keyword(s):  
Velocity Profile ◽  
Turbulence Model ◽  
Air Flow ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulence Structure ◽  
Cfd Modelling ◽  
Lack Of Information ◽  
Vertical Velocity Profile ◽  
Flow Through

Even after many years of the application of numerical CFD techniques to flow through porous fences, still there is disagreement between researchers regarding the best turbulence model to be implemented in this field. Moreover, different sources claim to have achieved good agreement between numerical results and experimental data; however, it is not always possible to compare numerical and experimental results due to the lack of information or variations in test conditions. In this paper, five different turbulence models namely; K-ε models (standard, RNG and Realizable) and K-ω models (Standard and SST), have been applied through a 3D CFD model to investigate air flow behind a porous panel, under the same conditions (boundary conditions and numerical schemes). Results are compared with wind tunnel experiments. Comparison is based on the vertical velocity profile at a location 925 mm downstream of the fence along its center line. All models were capable of reproducing the velocity profile, however, some turbulence models over-predicted the reduction of velocity while it was under-predicted by other models, however, discrepancy between CFD modelling and experimental results was kept around 20%. Comprehensive description of the turbulence structure and the streamlines highlight the fact that the criterion for selecting the best turbulence model cannot rely only on the velocity comparison at one location, it must also include other variables.

scholarly journals Reduction of Noise Caused by Gas-Liquid Two-Phase Refrigerant Flow through an Expansion Valve.

1993 ◽  
Vol 59 (557) ◽  
pp. 243-248 ◽  
Author(s):  
Tomomi Umeda ◽  
Shozo Nakamura ◽  
Kensaku Oguni ◽  
Toshihiko Fukushima ◽  
Shin-Ichi Shimode ◽  
...  
Keyword(s):  
Two Phase ◽  
Expansion Valve ◽  
Flow Through

scholarly journals 3D Transient CFD Modelling of Blood Flow through Coronary Artery

2019 ◽  
Vol 9 (2) ◽  
pp. 1335-1340
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Vascular System ◽  
Hemodynamic Parameters ◽  
Cfd Modelling ◽  
The Past ◽  
Diastolic Phase ◽  
Flow Through ◽  
Artery Disease ◽  
The Many

Over the past few decades, stroke has become one of the most common cause deaths. The heart muscle, like every other organ or tissue in our body, needs oxygen-rich blood to survive. Coronary artery disease means narrowing of the coronary arteries. This narrowing is due to a buildup of plaque in the walls of the arteries. Computational simulations provide invaluable information that is extremely difficult to obtain experimentally and is one of the many CFD sample applications in the biomedical area in which blood flow through an abnormal artery can be predicted. CFD analysis is increasingly performed to study fluid phenomena inside the human vascular system. In this paper, the study is to develop 3D CFD model of the Coronary artery to observe the blood flow through artery and estimate some of the hemodynamic parameters of blood during systolic and diastolic phase with plaque formation in artery. Hemodynamic parameters were quantified and flow patterns are visualized in the presence of plaques by using CFD.

scholarly journals CFD Modelling of Multiphase Flow through T Junction

2016 ◽  
Vol 24 ◽  
pp. 325-331 ◽  
Author(s):  
A.S. Athulya ◽  
R. Miji Cherian
Keyword(s):  
Multiphase Flow ◽  
Cfd Modelling ◽  
Flow Through

Experimental analysis of R22 and R407c flow through electronic expansion valve

2006 ◽  
Vol 47 (5) ◽  
pp. 529-544 ◽  
Author(s):  
Chuan Zhang ◽  
Shanwei Ma ◽  
Jiangpin Chen ◽  
Zhijiu Chen
Keyword(s):  
Experimental Analysis ◽  
Expansion Valve ◽  
Flow Through

scholarly journals Detailed CFD Modelling of Open Refrigerated Display Cabinets

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Pedro Dinis Gaspar ◽  
L. C. Carrilho Gonçalves ◽  
R. A. Pitarma
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Thermal Response ◽  
Experimental Tests ◽  
Cfd Modelling ◽  
Humidity Effect ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Parametric Studies ◽  
Flow Through

A comprehensive and detailed computational fluid dynamics (CFDs) modelling of air flow and heat transfer in an open refrigerated display cabinet (ORDC) is performed in this study. The physical-mathematical model considers the flow through the internal ducts, across fans and evaporator, and includes the thermal response of food products. The air humidity effect and thermal radiation heat transfer between surfaces are taken into account. Experimental tests were performed to characterize the phenomena near physical extremities and to validate the numerical predictions of air temperature, relative humidity, and velocity. Numerical and experimental results comparison reveals the predictive capabilities of the computational model for the optimized conception and development of this type of equipments. Numerical predictions are used to propose geometrical and functional parametric studies that improve thermal performance of the ORDC and consequently food safety.

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