The Effect of Round Flow Path Discharger and Back Panel Open Ratio on a Performance of Open Refrigerating Showcase

2019 ◽  
Vol 27 (03) ◽  
pp. 1950025
Author(s):  
Myung Keun Gong ◽  
Gun Woo Kim ◽  
Myung Do Oh
Keyword(s):  
Cold Storage ◽  
Structural Changes ◽  
Numerical Study ◽  
Dead Zone ◽  
Ambient Air ◽  
Honeycomb Structure ◽  
Flow Path ◽  
Back Panel ◽  
Storage Area ◽  
A Performance

Numerical study is conducted to confirm the effect of round flow path control and back panel open ratio on a performance of open refrigerating showcase in this study. The rounding control is applied to flow path of air discharger in various radii and the punched panel with various open ratios is applied to back panel of showcase. These structural changes have a significant impact on its aircurtain performance because both changes can affect flow pattern of showcase. To prove it, the two-dimensional steady simulation is performed using [Formula: see text]–[Formula: see text] turbulent model. The performance of showcase is assessed using entrainment factor which is a ratio between cooled air and ambient air at the suction of refrigerating part. As a result of simulation, the curved path at air discharger reduces the entrainment factor by a maximum 9% less than typical design. The curved flow path removes the dead zone at the honeycomb structure of discharger. In addition, it is found that there is an optimal back panel open ratio at the storage space of the showcase. When the back panel open ratio is 0%, the cooled air from the discharge is attached to the cold storage area because of the Cowanda effect. However, the Cowanda effect is eliminated when back panel open ratio increases. Results address that the entrainment factor remains almost the same at back panel open ratio 3.93% or more. Lastly, the simulation of showcase with product in cold storage area is conducted to confirm the structure changes effect on performance of real use showcase according to KS Standard.

Numerical Study on Cooling Effect of Engine Room Enclosure System

2008 ◽  
Author(s):  
Yee Seok Bae ◽  
Geun Jong Yoo ◽  
Hoon Ki Choi
Keyword(s):  
Heat Exchanger ◽  
Numerical Study ◽  
Flow Analysis ◽  
Cooling Capacity ◽  
Flow Path ◽  
Cooling Effect ◽  
Engine Room ◽  
Porous Media Model ◽  
Reduction Effect ◽  
Poor Ventilation

In engine room, proper enclosure system is preferable for reducing noise level but the enclosure system in the engine room causes bad influence on cooling performance due to poor ventilation. Cooling efficiency of the enclosure system can be improved by varying fan speed and proper flow path for ventilation. In this study, numerical analysis is performed to assess cooling effect of the enclosure system using finite volume method. The RNG k-ε model is adopted for turbulence model along with heat exchanger model and porous media model for heat exchanger analysis, and moving reference frame model for rotational fan. Cold flow analysis result shows reasonable agreement with experimental data. Analysis results show direct effect of velocity and temperature distribution on cooling ability in the enclosure system. Comparing with analysis result for the engine room which has no enclosure system, the case of total enclosure system which has box hole flow path shows the reasonable cooling capacity with noise reduction effect.

Numerical study of the effect of flow path geometry on the property of a monopivot centrifugal blood pump

2017 ◽  
Vol 2017.29 (0) ◽  
pp. 1B12
Author(s):  
Daiki GOTO ◽  
Toru HYAKUTAKE ◽  
Masahiro NISHIDA ◽  
Daisuke SAKOTA ◽  
Ryo KOSAKA ◽  
...  
Keyword(s):  
Numerical Study ◽  
Flow Path ◽  
Blood Pump ◽  
Centrifugal Blood Pump ◽  
Path Geometry

S022011 Numerical Study of Impeller Flow Path Geometry of Circulatory Support Device with Monopivot Bearing

2013 ◽  
Vol 2013 (0) ◽  
pp. _S022011-1-_S022011-5
Author(s):  
Kento NAKAYAMA ◽  
Masahiro NISHIDA ◽  
Daisuke SAKOTA ◽  
Ryo KOSAKA ◽  
Takashi YAMANE ◽  
...  
Keyword(s):  
Numerical Study ◽  
Flow Path ◽  
Circulatory Support ◽  
Support Device ◽  
Path Geometry ◽  
Circulatory Support Device

scholarly journals An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

2014 ◽  
Vol 14 (11) ◽  
pp. 5639-5658 ◽  
Author(s):  
I. C. Rumsey ◽  
K. A. Cowen ◽  
J. T. Walker ◽  
T. J. Kelly ◽  
E. A. Hanft ◽  
...  
Keyword(s):  
Linear Regression ◽  
Ambient Air ◽  
Water Soluble ◽  
Performance Goal ◽  
Filter Pack ◽  
Accuracy And Precision ◽  
The Us ◽  
Us Epa ◽  
Best Fit ◽  
A Performance

Abstract. Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at an hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina, from 8 September to 8 October 2010 and focused on gaseous SO2, HNO3, and NH3 and aerosol SO42-, NO3-, and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of ≤ 25%. The accuracy of the MARGA was evaluated by calculating the MARPD for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤ 40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42−, and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for the MUs and the filter pack. Using this and results from a previous study, it is concluded that if the MUs and the filter pack were sampling the same particle size, the MUs would have good agreement in terms of precision and accuracy. The MARGA performed moderately well in measuring HNO3 and NH3, though neither met the linear regression slope goals. However, recommendations for improving the measurement of HNO3 and NH3 are discussed. It is concluded that SO42-, SO2, NO3-, HNO3, NH4+, and NH3 concentrations can be measured with acceptable accuracy and precision when the MARGA is operated in conjunction with the recommendations outlined in the manuscript.

Three-Dimensional Numerical Study on Flames

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Caimao Luo ◽  
Behdad Moghtaderi ◽  
Eric Kennedy ◽  
Bogdan Dlugogorski
Keyword(s):  
Cfd Simulation ◽  
Numerical Study ◽  
Plug Flow ◽  
Three Dimensional ◽  
Ambient Air ◽  
Combustion Products ◽  
Chemical Kinetic ◽  
Computational Domain ◽  
Counter Flow ◽  
Global Reaction

A three-dimensional (3D) model of a methane-air counter-flow, non-premixed flame with a global reaction step for methane oxidation was developed using computational fluid dynamics (CFD) simulation. A specific computational domain, and relevant thermodynamic and transport data calculated by the chemical kinetic code CHEMKIN, were incorporated into the model. The model was validated by comparing predictions with the spontaneous Raman scattered profiles of major combustion species reported in the literature. The model was employed to carefully examine the self-similarity assumptions normally invoked in simulating counter-flow non-premixed flames. It was found that while most assumptions were strictly satisfied within the jet region for the case of plug flow boundary conditions (B.C.) along the central axis, for the quadratic boundary condition case (corresponding to uniform plug-flow), assumptions were only approximately valid within the jet region. Also, the influence of shroud gas was examined by setting the surrounding gas as air and increasing the shroud gas through widening the shroud gas gap while maintaining a constant shroud gas velocity. Calculations revealed that, the resulting flames for shroud gas gaps greater than half of the jet radius, were totally insulated from mixing with the ambient air. The effect of buoyancy on the flame structures was also studied by comparing contours of the combustion products, temperature and turbulent properties.

NUMERICAL STUDY OF CONTROL OF FLOW SEPARATION OVER A RAMP WITH NANOSECOND PLASMA ACTUATOR

2016 ◽  
Vol 42 ◽  
pp. 1660151
Author(s):  
J. G. ZHENG ◽  
B. C. KHOO ◽  
Y. D. CUI ◽  
Z. J. ZHAO ◽  
J. LI
Keyword(s):  
Flow Separation ◽  
Control Mechanism ◽  
Numerical Study ◽  
Active Flow Control ◽  
Ambient Air ◽  
High Voltage Pulse ◽  
External Flow ◽  
Characterization Study ◽  
Active Flow ◽  
Residual Heat

The nanosecond plasma discharge actuator driven by high voltage pulse with typical rise and decay time of several to tens of nanoseconds is emerging as a promising active flow control means in recent years and is being studied intensively. The characterization study reveals that the discharge induced shock wave propagates through ambient air and introduces highly transient perturbation to the flow. On the other hand, the residual heat remaining in the discharge volume may trigger the instability of external flow. In this study, this type of actuator is used to suppress flow separation over a ramp model. Numerical simulation is carried out to investigate the interaction of the discharge induced disturbance with the external flow. It is found that the flow separation region over the ramp can be reduced significantly. Our work may provide some insights into the understanding of the control mechanism of nanosecond pulse actuator.

Numerical Study on High Prandtl Number Liquid Bridge

2013 ◽  
Vol 712-715 ◽  
pp. 1630-1633
Author(s):  
Ru Quan Liang ◽  
Shuo Yang ◽  
Fu Sheng Yan ◽  
Jun Hong Ji ◽  
Ji Cheng He
Keyword(s):  
Gas Phase ◽  
Liquid Bridge ◽  
Surface Deformation ◽  
Numerical Study ◽  
Mass Conservation ◽  
Ambient Air ◽  
Two Phase ◽  
High Prandtl Number ◽  
Free Surface Deformation ◽  
Ambient Gas

The overall numerical analysis of liquid bridge for high Pr number fluid and flow field of ambient air under the zero-gravity environment was carried out in the present paper. The paper used level set method of mass conservation to capture two phase interfaces. Not only the free surface deformation was considered, but also the effect of ambient gas was taken into account. Simultaneously, results of stream function in liquid bridge and ambient gas-phase were given.

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