Direct Contact Condensation Jet in Cross-Flow Using Computational Fluid Dynamics

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Bernardo Alan de Freitas Duarte ◽  
Ricardo Serfaty ◽  
Aristeu da Silveira Neto
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Phase Change ◽  
Computational Model ◽  
Direct Contact ◽  
Flow Behavior ◽  
Cross Flow ◽  
Complex Case ◽  
Eulerian Approach ◽  
Contact Condensation

The computational fluid dynamics is an important methodology to study the characteristics of flows in nature and in a number of engineering applications. Modeling nonisothermal flows may be useful to predict the main flow behavior allowing the improvement of equipment and industrial processes. In addition, investigations using computational models may provide key information about the fundamental characteristics of flow, developing theoretical groundwork of physical processes. In the last years, the topic of phase change has been intensively studied using computational fluid dynamics due to the computational and numerical advances reported in the literature. Among several issues related to the phase change topic, direct contact condensation (DCC) is widely studied in the literature since it is part of a number of industrial applications. In the present work, DCC was studied using a mathematical and computational model with an Eulerian approach. The homemade code MFSim was used to run all the computational simulations in the cluster of the Fluid Mechanics Laboratory from the Federal University of Uberlandia (UFU). The computational model was validated and showed results with high accuracy and low differences compared to previous works in the literature. A complex case study of DCC with cross-flow was then studied and the computational model provided accurate results compared to experimental data from the literature. The jet centerline was well represented and the interface dynamic was accurately captured during all the simulation time. The investigation of the velocity field provided information about the deeply transient characteristic of this flow. The v-velocity component presented the more large variations in time since the standard deviation was subjected to a variation of about 45% compared to the temporal average. In addition, the time history of the maximum resultant velocities observed presented magnitude from 29 m/s to 73 m/s. The importance of modeling three-dimensional (3D) effects was confirmed with the relevance of the velocity magnitudes in the third axis component. Therefore, the Eulerian phase change model used in the present study indicated the possibility to model even complex phenomena using an Eulerian approach.

Computational Fluid Dynamics Simulation of Direct-Contact Condensation Phenomenon of Vapor Jet in Subcooled Water Tank

2016 ◽  
Vol 2 (4) ◽  
Author(s):  
Yu Ji ◽  
Hao-Chun Zhang ◽  
Yi-Ning Zhang ◽  
Xu-Wei Wang ◽  
Yan Quan
Keyword(s):  
Fluid Dynamics ◽  
Mass Transfer ◽  
Computational Fluid Dynamics ◽  
Direct Contact ◽  
Chemical Engineering ◽  
Dynamics Simulation ◽  
Water Tank ◽  
Two Phase ◽  
Subcooled Water ◽  
Contact Condensation

The direct-contact condensation (DCC) is a significant phenomenon in a nuclear reactor and its balance facilities, together with some chemical engineering systems. DCC occurs when the vapor is ejected from the nozzle, contacts with subcooled water, and condenses at the interface directly. The DCC phenomenon accompanied with the heat transfer and mass transfer will lead to the temperature and pressure fluctuations in the tank, even some accidents under certain conditions. This paper investigates the transport phenomena concerning the DCC in the subcooled water tank using the computational fluid dynamics (CFD) commercial code, ANSYS-FLUENT, in which the DCC process is simulated with the Euler–Euler framework for two-phase flow, and the simplified Hertz–Knudsen–Schrage relation is adopted to model mass transfer. In the simulation, the flow field and temperature profile are derived. Moreover, the shape and size of the plume jet are also investigated.

Comparison of four types of membrane bioreactor systems in terms of shear stress over the membrane surface using computational fluid dynamics

2013 ◽  
Vol 68 (12) ◽  
pp. 2534-2544 ◽  
Author(s):  
N. Ratkovich ◽  
T. R. Bentzen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Membrane Fouling ◽  
Two Phase Flow ◽  
Membrane Surface ◽  
Cross Flow ◽  
Membrane Bioreactors ◽  
Phase Flow ◽  
Two Phase ◽  
Computational Fluid Dynamics Cfd

Membrane bioreactors (MBRs) have been used successfully in biological wastewater treatment to solve the perennial problem of effective solids–liquid separation. A common problem with MBR systems is clogging of the modules and fouling of the membrane, resulting in frequent cleaning and replacement, which makes the system less appealing for full-scale applications. It has been widely demonstrated that the filtration performances in MBRs can be greatly improved with a two-phase flow (sludge–air) or higher liquid cross-flow velocities. However, the optimization process of these systems is complex and requires knowledge of the membrane fouling, hydrodynamics and biokinetics. Modern tools such as computational fluid dynamics (CFD) can be used to diagnose and understand the two-phase flow in an MBR. Four cases of different MBR configurations are presented in this work, using CFD as a tool to develop and optimize these systems.

Fish-friendly design of an axial flow pump impeller based on a blade strike model

2019 ◽  
Vol 234 (2) ◽  
pp. 173-186 ◽  
Author(s):  
Qiang Pan ◽  
Weidong Shi ◽  
Desheng Zhang ◽  
BPM van Esch ◽  
Ruijie Zhao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Behavior ◽  
Integrated Design ◽  
Axial Flow ◽  
Hydraulic Performance ◽  
Fish Mortality ◽  
Computational Fluid Dynamics Analysis ◽  
Axial Flow Pump ◽  
Flow Pump

With environmental awareness growing in many countries, governments are taking measures to reduce mortality of migrating fish in pumping stations. Manufacturers seek to develop pumps that are less damaging to fish and still provide good hydraulic performance, but little is known about the implications design modifications may have on internal flow characteristics and overall hydraulic performance. In this paper, an integrated design method is proposed that combines a validated blade strike model for fish damage and a computational fluid dynamics method to assess the pump performance. A redesign of an existing, conventional, axial flow pump is presented as an example in this paper. It shows how the design of the impeller blades was modified stepwise in order to reduce fish mortality while its hydraulic performance was monitored. Computational fluid dynamics analysis of the flow near the hub of the highly skewed blades indicated that unconventional design modifications were required to ensure optimum flow behavior. In the final fish-friendly design, the risk of fish mortality has reduced considerably while the hydraulic performance of the pump is still acceptable for practical application.

Computational Fluid Dynamics Modeling of a Heat Pipe Evacuated Tube Solar Collector Integrated With Phase Change Material

2019 ◽  
Author(s):  
Vivek R. Pawar ◽  
Sarvenaz Sobhansarbandi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Storage ◽  
Phase Change ◽  
Heat Pipe ◽  
Solar Collector ◽  
Cfd Modeling ◽  
Real Field ◽  
Evacuated Tube Solar Collector ◽  
Evacuated Tube

Abstract The increase in greenhouse gas and other global warming emissions makes it necessary to utilize renewable energy sources such as solar energy with high potential for heat production by means of solar thermal collectors. Among various types of solar collectors, evacuated tube solar collector (ETC) has attracted many attentions specially for the application in solar water heater systems (SWHs). However, due to the intermittence in solar intensity during the day, the ETCs may not work at their maximum functionality. There are number of studies investigating the effect of energy storage materials to eliminate the mismatch between supply and demand during peak hours. In the recent work of the authors, application of phase change materials (PCMs) integrated directly within the ETCs is studied experimentally. In this study, the computational fluid dynamics (CFD) modeling of heat pipe evacuated tube solar collector (HPETC) is performed. In order to cross-validate the obtained results to the recent experimental analysis, the boundary conditions are set as the real field-testing data. In the first part of the study, the 3D model of commercially available HPETC is simulated, while in the second part the HPETC integrated with the PCM is developed to analyze the improved thermal distribution. The selected type of PCM is Tritriacontane paraffin (C33H68), with a melting point of 72 °C and latent heat capacity of 256 kJ/kg. The simulation results show a acceptable agreement between the CFD modeling and the experimental data. The results from this study can be the benchmark for efficiency improvement of the ETCs in thermal energy storage systems.

Circular Cylinder Exposed to Cross Flow Fluid Forces – Parameters of Influence – Limits of Numerical Models

2003 ◽  
Author(s):  
Christoph Reichel ◽  
Klaus Strohmeier
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Models ◽  
Lift Coefficient ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Rigid Cylinder ◽  
Fluid Forces ◽  
Wide Range ◽  
Dynamics Simulations

In many technical fields, e.g. heat exchangers, circular cylinders are involved in Fluid Structure Interaction (FSI) problems. Therefore correct frequency and magnitude of fluid forces, respectively Strouhal number, drag and lift coefficient are needed. If fluid forces are evaluated with Computational Fluid Dynamics (CFD), mostly flow around a rigid cylinder is used to verify model and numerical methods. Unfortunately experimental as well as numerical results show great variation, making verification and testing of models difficult. Reynolds number is regarded as main influencing parameter for a rigid cylinder in cross flow. Most of experimental deviations can be related to other parameters, which differ from experiment to experiment. In this paper such parameters are specified and it is shown, that a closer look is needed, if one really wants to verify a model. Besides experimental results, which can be found in literature, some parameters are investigated by numerical simulation. Like experiments CFD (Computational Fluid Dynamics) simulations show a huge bandwidth of results, even when the same turbulence model is used. Flow around cylinders separates over a wide range of Reynolds numbers. It will be demonstrated that, using CFD, large deviations in fluid forces can often be related to miscalculation of the point of separation.

INVESTIGATION OF FLOW BEHAVIOR AND GAS TRANSFER PERFORMANCE OF AN OXYGENATOR WITH COMPUTATIONAL FLUID DYNAMICS(CFD)

ASAIO Journal ◽  
2002 ◽  
Vol 48 (2) ◽  
pp. 153
Author(s):  
N. Katagiri ◽  
A. Funakubo ◽  
Y. Taenaka ◽  
E. Tatsumi ◽  
T. Nishinaka ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Behavior ◽  
Gas Transfer ◽  
Transfer Performance ◽  
Computational Fluid Dynamics Cfd
Sign in / Sign up

Export Citation Format

Share Document