Investigation of the Flow Phenomenon Inside Gas Ejectors With Moist Gas Entrainment

2016 ◽  
Vol 9 (1) ◽  
Author(s):  
Yuping Wang ◽  
Mark Pellerin ◽  
Pravansu Mohanty ◽  
Subrata Sengupta
Keyword(s):  
Water Vapor ◽  
Phase Change ◽  
Gas Flow ◽  
Phase Distribution ◽  
Light Attenuation ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Second Phase ◽  
Symmetric Model ◽  
Design And Optimization

This paper focuses on the gas flow study of an ejector used in applications where moist gases are being entrained. Two parts of work are presented. In the first part, characteristics of gas flow inside an ejector, as well as the ejector's performance under various operating and geometric configurations, were studied with a three-dimensional computational model. Measurements were also performed for validation of the model. In the second part, focus was given to the potential condensation or desublimation phenomena that may occur inside an ejector when water vapor is included in the entrained stream. Experiments using light-attenuation method were performed to verify the presence of a second phase; then, the onset of phase change and the phase distribution were obtained numerically. A two-dimensional axis-symmetric model was developed based on the model used in the first part. User-defined functions were used to implement the phase-change criteria and particle prediction. A series of simulations were performed with various amounts of water vapor added into the entrained flow. It was found that both frost particles and water condensate could form inside the mixing tube depending on the operating conditions and water vapor concentrations. When the concentration exceeds 3% by mass, water vapor could condense throughout the mixing tube. Some preliminary results of the second phase particles formed, e.g., critical sizes and distributions, were also obtained to assist with the design and optimization of gas ejectors used in similar applications.

Numerical and Experimental Study of Flow Phenomenon Inside Gas Ejectors With Moist Gases Entrainment

2015 ◽  
Author(s):  
Yuping Wang ◽  
Mark Pellerin ◽  
Pravansu Mohanty ◽  
Subrata Sengupta
Keyword(s):  
Water Vapor ◽  
Gas Flow ◽  
Phase Distribution ◽  
Light Attenuation ◽  
Measurement Data ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Second Phase ◽  
Symmetric Model ◽  
Wide Range

Gas ejectors can be found in a wide range of applications such as refrigeration and thrust augmentation. This paper focuses on the study of an ejector used in applications where moist gases are being entrained. In the first part of this work, the gas flow characteristics inside an ejector, as well as the ejector’s performance under various operating and geometric configurations, were studied with a three-dimensional computational model, which was validated against measurement data. In the second part, focus was given to the potential condensation or de-sublimation phenomena that may occur inside an ejector when water vapor is included in the entrained stream. An experiment using light-attenuation method was performed to verify the presence of a second phase, then the onset of phase change and the phase distribution were obtained numerically. A two-dimensional axis-symmetric model was developed based on the model used in the first part. A series of simulations were performed with various amounts of water vapor added into the entrained flow. It was found that both frost particles and water condensate could form inside the mixing tube depending on the operating conditions and water vapor concentrations. When the concentration exceeds 3%, water vapor could condense throughout the mixing tube. Some preliminary results of the second phase particles formed, e.g. critical sizes and distributions, were also obtained to assist with the design and optimization of gas ejectors used in similar applications.

Numerical Simulations of the Fluid Flow and Heat Transfer during a Solidification Phase Change of a Polymer in a Die

2010 ◽  
Vol 97-101 ◽  
pp. 2736-2743
Author(s):  
Shi Xiong Ren ◽  
Sha Sha Dang ◽  
Tao Lu ◽  
Kui Sheng Wang
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Liquid Volume ◽  
Liquid Volume Fraction ◽  
Three Dimensional Models ◽  
Lower Temperature ◽  
Thermal Oil

Three-dimensional models of heat transfer have been established and numerically solved using a commercial software package, Fluent, in order to obtain distributions of temperature, velocity, pressure, and liquid volume fraction of the polymer. The influences of the boundary conditions on the phase change of the polymer and the temperature distribution in the die have been evaluated. The results show that the temperature of the region close to the pelletizing surface is relatively low due to the cooling effect of the cool water, while the temperature deeper inside the die is higher, with a lower temperature gradient, as a result of the heating effect of the hot thermal oil and the polymer. A solidification phase change of the polymer occurs near the polymer outlet due to heat loss from the polymer to the water, while deeper inside the hole the polymer remains fluid without solidification, due to heating by the thermal oil. Numerical simulation provides a reliable method to optimize the design of the die, the choice of metallic material for the die, and the operating conditions of the polymer pelletizing under water.

On the Coupling of Inverse Design and Optimization Techniques for Turbomachinery Blade Design

2006 ◽  
Author(s):  
Duccio Bonaiuti ◽  
Mehrdad Zangeneh
Keyword(s):  
Mechanical Design ◽  
Design Method ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Optimization Techniques ◽  
Operating Conditions ◽  
Inverse Design ◽  
Design Parameters ◽  
Optimization Strategy ◽  
Design And Optimization

Optimization strategies have been used in recent years for the aerodynamic and mechanical design of turbomachine components. One crucial aspect in the use of such methodologies is the choice of the geometrical parameterization, which determines the complexity of the objective function to be optimized. In the present paper, an optimization strategy for the aerodynamic design of turbomachines is presented, where the blade parameterization is based on the use of a three-dimensional inverse design method. The blade geometry is described by means of aerodynamic parameters, like the blade loading, which are closely related to the aerodynamic performance to be optimized, thus leading to a simple shape of the optimization function. On the basis of this consideration, it is possible to use simple approximation functions for describing the correlations between the input design parameters and the performance ones. The Response Surface Methodology coupled with the Design of Experiments (DOE) technique was used for this purpose. CFD analyses were run to evaluate the configurations required by the DOE to generate the database. Optimization algorithms were then applied to the approximated functions in order to determine the optimal configuration or the set of optimal ones (Pareto front). The method was applied for the aerodynamic redesign of two different turbomachine components: a centrifugal compressor stage and a single-stage axial compressor. In both cases, both design and off-design operating conditions were analyzed and optimized.

PEM Fuel Cell Dynamic Model With Phase Change Effect

2005 ◽  
Vol 2 (4) ◽  
pp. 274-283 ◽  
Author(s):  
X. Xue ◽  
J. Tang
Keyword(s):  
Phase Change ◽  
Dynamic Model ◽  
Gas Flow ◽  
Dynamic Control ◽  
Transient Behavior ◽  
Operating Conditions ◽  
System Level ◽  
Change Effect ◽  
Flow Phase ◽  
Higher Temperature

In this research, a system-level dynamic model accounting for the phase change effect is developed for polymer electrolyte fuel cells (PEMFCs). This model can illustrate the complicated transient behavior of temperature, gas flow, phase change in the anode and cathode channels, and membrane humidification under operating conditions. Simulation indicates that vapor in the cathode channel is more likely to be in the over saturated state and phase change (condensation under large load current situation) then takes place, which leads to higher temperature at cathode channel due to latent heat generation. In the anode channel, on the other hand, the phase change is less likely to occur even if the inlet hydrogen is humidified with a high relative humidity value. The model is partially validated using the experimental data from open literature. A series of analyses are carried out to investigate the underlying physical mechanisms. This model can be used in the optimal design and dynamic control of PEMFCs.

scholarly journals Design and Optimization of Chemical Mixing System for Vacuum Chambers: Simulation Results

2014 ◽  
Vol 5 ◽  
Author(s):  
Faruk Unker ◽  
Erdar Kaplan ◽  
Olkan Cuvalci
Keyword(s):  
Gas Flow ◽  
Flow Behavior ◽  
Atomic Layer ◽  
Flow Patterns ◽  
Operating Conditions ◽  
Tantalum Nitride ◽  
Ansys Fluent ◽  
Design And Optimization ◽  
Parametric Investigation ◽  
Process Gas

Computational fluid dynamics (CFD) is widely used in device design to determine gas flow patterns and turbulence levels.  CFD is also used to simulate particles and droplets, which are subjected to various forces, turbulence and wall interactions. These studies can now be performed routinely because of the availability of commercial software containing high quality turbulence and particle models. In order to understand how the gas is brought down to wafer, it is necessary to have a knowledge of the gas flow behavior very early in the design spiral of the Tantalum nitride-Atomic layer deposition(TaN-ALD) chamber by undertaking parametric investigation of the interaction effect between gas flow and the funnel structure. This paper presents such a  parametric  investigation on a generic TaN-ALD chamber using CFD. The results presented have been analyzed for a total of 11 different cases by varying neck and nozzle angles for a process gas. The gas flow was mainly investigated for the nozzle angles of  4.5◦,  9◦,  12◦  and  20◦ and the film thickness results were compared with numerical flow patterns. CFD simulations using the turbulence model in ANSYS Fluent v.13 are undertaken. The parametric study has demonstrated that CFD is a powerful tool to study the problem of gas flow-structure interaction on funnel and is capable of providing a means of visualizing the path of the gas under different operating conditions

scholarly journals Dehydration Simulation of Natural Gas by using Tri Ethylene Glycol

2018 ◽  
Vol 7 (1) ◽  
pp. 11-18
Author(s):  
Eric Farda
Keyword(s):  
Water Vapor ◽  
Natural Gas ◽  
Ethylene Glycol ◽  
Water Content ◽  
Flow Rate ◽  
Gas Flow ◽  
Operating Conditions ◽  
Aspen Hysys ◽  
Natural Gas Dehydration ◽  
Content Specification

Water content in natural gas poses threat to process facilities such as column distillation. Natural gas from reservoirs usually contains water vapor, the presence of water vapor in gas processing causes bad impact to process facilities. Dry Gas composition data was taken from Salamander Energy. Optimization of natural gas dehydration using Tri Ethylene Glycol was carried out using Aspen HYSYS V8.6 with Peng-Robinson fluid package. The natural gas dehydrating plant was designed with operating conditions of 394 bar and 460C and 10 MMSCFD and 6.8 MMSCFD gas flow rate were inputted. Results obtained from HYSYS simulation shows. Three different TEG flowrates were used for this simulation. Results obtained from simulation that . For the purpose of running the plant economically, the minimum flow rate of TEG which will reduce the water content to within the limit of pipeline specification, is very important and the result obtained showed that a minimum of 3 m3/h of TEG is required to reduce the water content of a gas stream of 10MMSCFD to 6.8lb/MMSCFD, which is within the limit of 6-7lb/MMSCFD, this value when compare to gas plant which uses 15m3/h for the gas stream of 10MMSCFD to achieve the same water  content  specification is far lower.  Values below  this flow  rate  (3.5m3/h)  may not reduce the water content to the specified limit.

Three-Dimensional Numerical Study on Freezing Phase Change Heat Transfer in Biological Tissue Embedded With Two Cryoprobes

2011 ◽  
Author(s):  
Fang Zhao ◽  
Zhenqian Chen ◽  
Mingheng Shi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Biological Tissue ◽  
Numerical Study ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Freezing Process ◽  
Ice Crystal ◽  
Obvious Effect ◽  
Phase Change Heat Transfer

A mathematical model for phase change heat transfer in cryosurgery was established. In this model, a fractal tree-like branched network was used to describe the complicated geometrical frame of blood vessel. The temperature distribution and ice crystal growth process in biological tissue including normal tissue and tumor embedded with two cryoprobes were numerically simulated. The effects of cooling rate, initial temperature and distance of two cryoprobes on freezing process of tissue were also studied. The results show that the ice crystal grows more rapidly in the initial freezing stage and then slows down in the following process, and the pre-cooling of cryoprobes has no obvious effect on freezing rate of tissue. It also can be seen that the distance of 10 mm between two cryoprobes is the most appropriate choice for operation effect in the range of operating conditions presented in this study.

Development of an Exhaust Gas Recirculation Distribution Prediction Method Using Three-Dimensional Flow Analysis and Its Application

2003 ◽  
Vol 125 (4) ◽  
pp. 1066-1074 ◽  
Author(s):  
K. Yoshizawa ◽  
K. Mori ◽  
Y. Matayoshi ◽  
S. Kimura
Keyword(s):  
Gas Flow ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Flow Region ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Spiral Flow ◽  
Gas Recirculation

A multidimensional computational fluid dynamics (CFD) method has been used to improve the exhaust gas recirculation (EGR) distribution in the intake manifold. Since gas flow in the intake system is affected by intake pulsation caused by the gas exchange process, a pulsation flow simulation is used. A one-dimensional gas exchange calculation is combined with three-dimensional intake gas flow calculation to simulate pulsation flow. This pulsation flow simulation makes it possible to predict the EGR distribution. The gas flow in the intake system was analyzed in detail. It was found that a reverse flow region formed downstream of the throttle valve. The size and shape of the reverse flow region greatly depend on the engine operating conditions. With a conventional EGR system, it is difficult to distribute EGR uniformly under various engine operating conditions. A new EGR system that uses a spiral flow to mix the fresh air and EGR gas has been developed to obtain a uniform EGR distribution. As a result of adopting this system, a uniform EGR distribution is obtained regardless of the engine operating conditions. This spiral flow EGR system was applied to a low-emission vehicle (LEV) put on the Japanese market.

Development of an EGR Distribution Prediction Method Using Three-Dimensional Flow Analysis and its Application

2001 ◽  
Author(s):  
Koudai Yoshizawa ◽  
Kouji Mori ◽  
Yutaka Matayoshi ◽  
Shuji Kimura
Keyword(s):  
Gas Exchange ◽  
Gas Flow ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Flow Region ◽  
Operating Conditions ◽  
Intake Manifold ◽  
Spiral Flow ◽  
Intake System

Abstract A multidimensional computational fluid dynamics (CED) method has been used to improve the exhaust gas recirculation (EGR) distribution in the intake manifold. Since gas flow in the intake system is affected by intake pulsation caused by the gas exchange process, a pulsation flow simulation is used. A one-dimensional gas exchange calculation is combined with three-dimensional intake gas flow to simulate pulsation flow. This pulsation flow simulation makes it possible to predict the EGR distribution. The gas flow in the intake system was analyzed in detail. It was found that a reverse flow region formed downstream of the throttle valve. The size and shape of the reverse flow region greatly depend on the engine operating conditions. With a conventional EGR system, it is difficult to distribute EGR uniformly under various engine operating conditions. A new EGR system that uses a spiral flow to mix the fresh air and EGR gas has been developed to obtain a uniform EGR distribution. As a result of adopting this system, a uniform EGR distribution is obtained regardless of the engine operating conditions. This spiral flow EGR system was applied to a low-emission vehicle (LEV) put on the Japanese market.

Simulation of Rapid Thermal Processing Equipment and Processes

1993 ◽  
Vol 303 ◽  
Author(s):  
Kun-Ho Lie ◽  
Tushar P. Merchant ◽  
Klavs F. Jensen
Keyword(s):  
Heat Transfer ◽  
Thermal Processing ◽  
Gas Flow ◽  
Transient Flow ◽  
Radiation Heat Transfer ◽  
Rapid Thermal Processing ◽  
Operating Conditions ◽  
Multiple Reflections ◽  
Design And Optimization ◽  
Process Gas

ABSTRACTWe present finite element simulations of fluid flow, heat transfer, and chemical reactions in axisymmetric rapid thermal processing (RTP) configurations. A new approach to simulating radiation heat transfer between lamps, substrates, and system walls is described. The method accounts for multiple reflections and readily allows the inclusion of temperature, radiation wavelength, and materials specific emissivity parameters. The influence of system geometry, lamp power profile, substrate and wall emissivity parameters, and process gas flow upon RTP performance characteristics is illustrated through examples. Transient flow and heat transfer simulations are used to identify operating conditions where flow recirculations are avoided. The further use of physically based models in the design and optimization of RTP systems is discussed.

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