scholarly journals A Simulation Study of Drying Chamber for Marine Product

2021 ◽  
Vol 13 (6) ◽  
Author(s):  
Mohd Afzanizam Mohd Rosli ◽  
◽  
Hiew Sit Jing ◽  
Nur Izzati Mohd Azhar ◽  
Maidi Saputra ◽  
...  
Keyword(s):  
Steady State ◽  
Cfd Simulation ◽  
Air Flow ◽  
Flow Distribution ◽  
Cfd Simulations ◽  
High Quality ◽  
Steady State Condition ◽  
Temperature Distributions ◽  
Marine Product ◽  
Drying Chamber

Drying chamber is a drying application for agriculture product to produce high quality and hygiene product. The purpose of this paper is to propose best configuration trays arrangement in drying chamber for better distribution of velocity and temperature. Therefore, five configurations of trays are analyzed to obtain the best performance of uniformity air flow distribution within drying chamber. CFD simulation studied the uniform air flow in the drying chamber in steady state condition. A validation is performed by comparing the data obtained from the literature review CFD simulation to ensure the methodology is correct. Then, the drying chamber with different trays arrangements are simulated using CFD simulations to obtain velocity and temperature distributions at nine plotted points on trays. From the results obtained, it concluded that design (A) and (D) are selected as the best designs for uniformity because there is less discrepancy for each point contributed the more uniformity of distribution.

Prediction of Blood Flow Distribution in Liver Radioembolization Using Convolutional Neural Networks

2020 ◽  
Author(s):  
Amirtahà Taebi ◽  
Catherine T. Vu ◽  
Emilie Roncali
Keyword(s):  
Blood Flow ◽  
Cfd Simulation ◽  
Mean Squared Error ◽  
Flow Distribution ◽  
Homogeneous Distribution ◽  
Blood Flow Distribution ◽  
Cfd Simulations ◽  
Squared Error ◽  
Network Output ◽  
Yttrium 90

Abstract We have developed a new dosimetry approach, called CFDose, for liver cancer radioembolization based on computational fluid dynamics (CFD) simulation in the hepatic arterial tree. Although CFDose overcomes some of the limitations of the current dosimetry methods such as the unrealistic assumption of homogeneous distribution of yttrium-90 in the liver, it suffers from the expensive computational cost of CFD simulations. To accelerate CFDose, we introduce a deep learning model to predict the blood flow distribution between the liver segments in a patient with hepatocellular carcinoma. The model was trained with the results of CFD simulations under different outlet boundary conditions. The model consisted of convolutional, average pooling and transposed convolution layers. A regression layer with a mean-squared-error loss function was utilized at the network output to estimate the arterial outlet blood flow. The mean-squared error and prediction accuracy were calculated to measure model performance. Results showed that the average difference between the CFD results and predicted flow data was less than 2.45% for all the samples in the test dataset. The proposed model thus estimated the blood flow distribution with high accuracy significantly faster than a CFD simulation. The network output can be used to estimate the yttrium-90 dose distribution in the liver in future studies.

scholarly journals Accuracy and Uncertainty Analysis of PSBT Benchmark Exercises Using a Subchannel Code MATRA

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Dae-Hyun Hwang ◽  
Seong-Jin Kim ◽  
Kyong-Won Seo ◽  
Hyuk Kwon
Keyword(s):  
Steady State ◽  
Turbulent Mixing ◽  
Prediction Models ◽  
Flow Distribution ◽  
Lookup Table ◽  
Distribution Data ◽  
Steady State Condition ◽  
Benchmark Data ◽  
Mixing Parameter ◽  
Exit Temperature

In the framework of the OECD/NRC PSBT benchmark, the subchannel grade void distribution data and DNB data were assessed by a subchannel code, MATRA. The prediction accuracy and uncertainty of the zone-averaged void fraction at the central region of the 5 × 5 test bundle were evaluated for the steady-state and transient benchmark data. Optimum values of the turbulent mixing parameter were evaluated for the subchannel exit temperature distribution benchmark. The influence of the mixing vanes on the subchannel flow distribution was investigated through a CFD analysis. In addition, a regionwise turbulent mixing model was examined to account for the nonhomogeneous mixing characteristics caused by the vane effect. The steady-state DNB benchmark data with uniform and nonuniform axial power shapes were evaluated by employing various DNB prediction models: EPRI bundle CHF correlation, AECL-IPPE 1995 CHF lookup table, and representative mechanistic DNB models such as a sublayer dryout model and a bubble crowding model. The DNBR prediction uncertainties for various DNB models were evaluated from a Monte-Carlo simulation for a selected steady-state condition.

scholarly journals Numerical Simulation of the Performance Characteristics of the Hybrid Closed Circuit Cooling Tower

2008 ◽  
Vol 13 (1) ◽  
pp. 89-101 ◽  
Author(s):  
M. M. A. Sarker ◽  
E. Kim ◽  
G. C. Moon ◽  
J. I. Yoon
Keyword(s):  
Pressure Drop ◽  
Experimental Measurement ◽  
Cooling Tower ◽  
Cfd Simulation ◽  
Air Flow ◽  
Flow Distribution ◽  
Cooling Capacity ◽  
Performance Characteristics ◽  
Closed Circuit ◽  
Flow Rates

The performance characteristics of the Hybrid Closed Circuit Cooling Tower (HCCCT) have been investigated applying computational fluid dynamics (CFD). Widely reported CFD techniques are applied to simulate the air-water two phase flow inside the HCCCT. The pressure drop and the cooling capacity were investigated from several perspectives. Three different transverse pitches were tested and found that a pitch of 45 mm had lower pressure drop. The CFD simulation indicated that when air is supplied from the side wall of the HCCCT, the pressure drop can be over predicted and the cooling capacity can be under predicted mainly due to the non-uniform air flow distribution across the coil bank. The cooling capacity in wet mode have been calculated with respect to wet-bulb temperature (WBT) and cooling water to air mass flow rates for different spray water volume flow rates and the results were compared to the experimental measurement and found to conform well for the air supply from the bottom end. The differences of the cooling capacity and pressure drop in between the CFD simulation and experimental measurement in hybrid mode were less than 5 % and 7 % respectively for the uniform air flow distribution.

scholarly journals Computational Fontan Analysis: Preserving accuracy while expediting workflow

2021 ◽  
Author(s):  
Xiaolong Liu ◽  
Seda Aslan ◽  
Byeol Kim ◽  
Linnea Warburton ◽  
Derrick Jackson ◽  
...  
Keyword(s):  
Particle Filtering ◽  
Cfd Simulation ◽  
Fontan Operation ◽  
Flow Distribution ◽  
Mesh Size ◽  
Computational Time ◽  
Patient Specific ◽  
Flow Loop ◽  
Cfd Simulations

Background: Post-operative outcomes of the Fontan operation have been linked to graft shape after implantation. Computational fluid dynamics (CFD) simulations are used to explore different surgical options. The objective of this study is to perform a systematic in vitro validation for investigating the accuracy and efficiency of CFD simulation to predict Fontan hemodynamics. Methods: CFD simulations were performed to measure indexed power loss (iPL) and hepatic flow distribution (HFD) in 10 patient-specific Fontan models, with varying mesh and numerical solvers. The results were compared with a novel in vitro flow loop setup with 3D printed Fontan models. A high-resolution differential pressure sensor was used to measure the pressure drop for validating iPL predictions. Microparticles with particle filtering system were used to measure HFD. The computational time was measured for a representative Fontan model with different mesh sizes and numerical solvers. Results: When compared to in vitro setup, variations in CFD mesh sizes had significant effect on HFD (p = 0.0002) but no significant impact on iPL (p = 0.069). Numerical solvers had no significant impact in both iPL (p = 0.50) and HFD (P = 0.55). A transient solver with 0.5 mm mesh size requires computational time 100 times more than a steady solver with 2.5 mm mesh size to generate similar results. Conclusions: The predictive value of CFD for Fontan planning can be validated against an in vitro flow loop. The prediction accuracy can be affected by the mesh size, model shape complexity and flow competition.

Transient Analysis of Air Flow in a Channel for Unconventional Radiator

2018 ◽  
Author(s):  
Wahidul Islam ◽  
Jobaidur Rahman Khan
Keyword(s):  
Steady State ◽  
Transient Analysis ◽  
Air Flow ◽  
Axial Flow ◽  
Flow Distribution ◽  
Transient State ◽  
Short Channel ◽  
Final Design ◽  
Uniform Flow Distribution ◽  
Transient Case

A number of cars are found to have an unconventional radiator. The radiator is placed at the back of the car instead of front, for which the radiator does not get the incoming airflow to cool the engine down and the engine gets overheated very easily. In order to deal with this problem, a channel has been mounted at the top of the vehicle to navigate incoming air flow and direct it through the radiator to cool down the engine. Three channels are tested computationally with three different lengths, which indicates the different way of studying this problem. Transient state analysis has been performed. Each length has its own characteristics. For example, a longer channel creates little circulation but more axial flow towards the radiator, while shorter channel creates smooth but less axial flow towards the radiator. All these cases in the steady state have the same domain and will have similar inlet variables like velocity, shape, size, and position. A transient state simulation, most of the circulation were shown in the left-mid plane especially in longer channels. Transient state gives more uniform flow distribution. For longer channels in transient case, the flow is symmetric and smooth, while the flow is not found symmetric for short channel. The results were all made and developed in ANSYS for the final design where the data were simulated.

Data Center Cooling Efficiency Improvement Through Localized and Optimized Cooling Resources Delivery

2012 ◽  
Author(s):  
Rongliang Zhou ◽  
Cullen Bash ◽  
Zhikui Wang ◽  
Alan McReynolds ◽  
Thomas Christian ◽  
...  
Keyword(s):  
Steady State ◽  
Data Center ◽  
Data Centers ◽  
Air Flow ◽  
Flow Distribution ◽  
Resource Provisioning ◽  
Cooling Power ◽  
Optimization Approach ◽  
Cooling Efficiency ◽  
Efficiency Improvement

Data centers are large computing facilities that can house tens of thousands of computer servers, storage and networking devices. They can consume megawatts of power and, as a result, reject megawatts of heat. For more than a decade, researchers have been investigating methods to improve the efficiency by which these facilities are cooled. One of the key challenges to maintain highly efficient cooling is to provide on demand cooling resources to each server rack, which may vary with time and rack location within the larger data center. In common practice today, chilled water or refrigerant cooled computer room air conditioning (CRAC) units are used to reject the waste heat outside the data center, and they also work together with the fans in the IT equipment to circulate air within the data center for heat transport. In a raised floor data center, the cool air exiting the multiple CRAC units enters the underfloor plenum before it is distributed through the vent tiles in the cold aisles to the IT equipment. The vent tiles usually have fixed openings and are not adapted to accommodate the flow demand that can vary from cold aisle to cold aisle or rack to rack. In this configuration, CRAC units have the extra responsibilities of cooling resources distribution as well as provisioning. The CRAC unit, however, does not have the fine control granularity to adjust air delivery to individual racks since it normally affects a larger thermal zone, which consists of a multiplicity of racks arranged into rows. To better match cool air demand on a per cold aisle or rack basis, floor-mounted adaptive vent tiles (AVT) can be used to replace CRAC units for air delivery adjustment. In this arrangement, each adaptive vent tile can be remotely commanded from fully open to fully close for finer local air flow regulation. The optimal configuration for a multitude of AVTs in a data center, however, can be far from intuitive because of the air flow complexity. To unleash the full potential of the AVTs for improved air flow distribution and hence higher cooling efficiency, we propose a two-step approach that involves both steady-state and dynamic optimization to optimize the cooling resource provisioning and distribution within raised-floor air cooled data centers with rigid or partial containment. We first perform a model-based steady-state optimization to optimize whole data center air flow distribution. Within each cold aisle, all AVTs are configured to a uniform opening setting, although AVT opening may vary from cold aisle to cold aisle. We then use decentralized dynamic controllers to optimize the settings of each CRAC unit such that the IT equipment thermal requirement is satisfied with the least cooling power. This two-step optimization approach simplifies the large scale dynamic control problem, and its effectiveness in cooling efficiency improvement is demonstrated through experiments in a research data center.

Effects of vortexes in feed header on air flow distribution of PEMFC stack: CFD simulation and optimization for better uniformity

2021 ◽  
Vol 173 ◽  
pp. 498-506
Author(s):  
Guoqing Su ◽  
Daijun Yang ◽  
Qiangfeng Xiao ◽  
Haiqin Dai ◽  
Cunman Zhang
Keyword(s):  
Cfd Simulation ◽  
Air Flow ◽  
Flow Distribution ◽  
Simulation And Optimization

Air-Flow Distribution Simulation and Experimental Analysis of a New Testing Room for Refrigerated Display Cabinet

2012 ◽  
Vol 614-615 ◽  
pp. 701-706
Author(s):  
Chao Huang ◽  
Fang Wang ◽  
Zhi Min Wu ◽  
Chao Guo
Keyword(s):  
Cfd Simulation ◽  
Design Method ◽  
Air Flow ◽  
Flow Distribution ◽  
Simulation Software ◽  
Air Distribution ◽  
Distribution Analysis ◽  
Experiment System ◽  
Quality Regulation ◽  
Testing Room

Based on European Standard EN441-2, an experiment system for measuring the thermal properties of refrigerated display cabinet is designed and constructed. Considering the practice requirements from user, the air distribution analysis is doing under various air-flow form in the testing room. This paper uses the FLUENT, which is one of the CFD simulation software, to verify the design method of air movement. Finally a series of tests required for laboratory quality regulation have been done and the data of velocity or temperature is under the new requirement.

CFD Simulation of Air Temperature inside a Bus Passenger Compartment

2015 ◽  
Vol 735 ◽  
pp. 85-90
Author(s):  
Noor Emilia Ahmad Shafie ◽  
Haslinda Mohamed Kamar ◽  
Nazri Kamsah
Keyword(s):  
Air Temperature ◽  
Cfd Simulation ◽  
Air Flow ◽  
Flow Distribution ◽  
Passenger Compartment ◽  
Air Velocity ◽  
Airflow Velocity ◽  
Respiratory Allergies ◽  
Temperature Boundary ◽  
Fluent Software

Good ventilation is important for passenger for sufficient supply of fresh air during commuting in a bus. Insufficient fresh air causes feeling of uncomfortable to passenger and affects passenger’s health. Airborne transmission disease, headache and respiratory allergies are the usual health symptoms. This paper presents the CFD study of air flow inside a bus passenger compartment. The objective is to estimate the temperature level at the diffuser, seat and floor locations of the bus passenger compartment. Two conditions of airflow velocity at the supply diffuser were examined, namely 2.7 m/s and 3.1 m/s. A CFD Fluent software was employed to develop and meshed a simplified 3D model of a quarter section of a bus passenger compartment. Air velocity and temperature boundary conditions were prescribed on the model based on the actual data obtained from field measurement. Turbulent flow analyses were carried out using standard k-ε model to visualize the air flow distribution inside the compartment. The results show that the velocity distribution is uniform when the diffuser air velocity is 3.1 m/s. When the diffuser air velocity is 3.1 m/s the air temperature of the seat area was decreased by 0.3°C. The air temperature inside the cabin can be maintained uniform at 23°C when diffuser air velocity was fixed at 3.1 m/s.

scholarly journals Computational fluid dynamics simulation of spray dryers: transient or steady state simulation?

2018 ◽  
Author(s):  
M. W. Woo ◽  
S. Afshar ◽  
H. Jubaer ◽  
B. Chen ◽  
J. Xiao ◽  
...  
Keyword(s):  
Steady State ◽  
Spray Drying ◽  
Cfd Simulation ◽  
Computation Time ◽  
Transient Simulation ◽  
Dynamics Simulation ◽  
Simulation Approach ◽  
Simulation Framework ◽  
Cfd Simulations ◽  
Steady State Simulation

Self-sustained fluctuating airflow behaviour in spray drying chambers is in essence an unsteady phenomenon requiring the transient CFD simulation framework. There is currently, however, a mixture of steady state and transient CFD simulations of spray dryers practised and reported in the literature. The choice between steady state and transient approach significantly affects the computation time of the simulation and subsequently the adoption of this approach by industry. This paper firstly examines in detail the bottleneck in computation time of the transient simulation approach. Based on past reports, this review paper then presents a discussion and provides several recommendations on the use of steady state and transient simulation approach for spray dryers. Keywords: CFD simulation, spray drying, transient, steady state, fluctuation 

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