PASSIVE STEEL CONTAINMENT AIR COOLING SYSTEM HEAT TRANSFER CAPACITY STUDY

2019 ◽  
Vol 2019.27 (0) ◽  
pp. 1684
Author(s):  
ZHANG Yue ◽  
HE Dan ◽  
ZHAO Qiang
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Air Cooling ◽  
Air Cooling System ◽  
Heat Transfer Capacity

scholarly journals A Numerical Analysis of the Air-Cooling System of a Spark Ignition Aeronautical Engine

2020 ◽  
Vol 197 ◽  
pp. 06003
Author(s):  
Maria Faruoli ◽  
Annarita Viggiano ◽  
Paolo Caso ◽  
Vinicio Magi
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Air Cooling ◽  
Air Mass ◽  
Air Cooling System

It is well known that spark ignition internal combustion engines for aeronautical applications operate within a specific temperature range to avoid structural damages, detonations and loss of efficiency of the combustion process. An accurate assessment of the cooling system performance is a crucial aspect in order to guarantee broad operating conditions of the engine. In this framework, the use of a Conjugate Heat Transfer method is a proper choice, since it allows to estimate both the heat fluxes between the engine walls and the cooling air and the temperature distribution along the outer wall surfaces of the engine, and to perform parametric analyses by varying the engine operating conditions. In this work, the air-cooling system of a 4-cylinder spark ignition engine, designed by CMD Engine Company for aeronautical applications, is analysed in order to evaluate the amount of the air mass flow rate to guarantee the heat transfer under full load operating conditions. A preliminary validation of the model is performed by comparing the results with available experimental data. A parametric study is also performed to assess the influence of the controlling parameters on the cooling system efficiency. This study is carried out by varying the inlet air mass flow rate from 1.0 kg/s to 1.5 kg/s and the temperature of the inner wall surfaces of the engine combustion chambers from 390 K to 430 K.

Heat Transfer Characteristics of a Rotor-Stator System With Small Radial Outflow

2012 ◽  
Author(s):  
Li Lin ◽  
Jing Ren ◽  
Hongde Jiang ◽  
Peter Childs
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Small Mass ◽  
Eckert Number ◽  
Air Cooling ◽  
Air Cooling System ◽  
Radial Outflow

In some cases, the mass flow rate needed to prevent ingress through rim seals in turbine is smaller than that entrained by a free disk. In order to obtain the heat transfer features of the rotor-stator system at such a small mass flow rate, a combined computational and theoretical study has been carried out. It is found that the average Nusselt number (Nuav) on the rotor drops approximately linearly down to zero with decreasing turbulent flow parameter (λt) when λt is smaller than λt,c (λt,c < λt,fd), while Nuav almost keeps constant when λt is larger than λt,c. A correlation between Nuav and λt has been developed, which is expected to be useful in determining disk temperatures in the preliminary design of an internal air cooling system. The Eckert number, which can express the relationship between heat generated by windage and heat conducted through disk, turns out to be an important nondimensional number in describing the heat transfer features of such rotor-stator systems. Moreover, the effect of rotational speed on heat transfer when λt,c<λt<λt,fd has been studied, further identifying the significance of the Eckert number.

Computational fluid dynamics investigation and multi-objective optimization of an engine air-cooling system using genetic algorithm

2011 ◽  
Vol 225 (6) ◽  
pp. 1389-1398 ◽  
Author(s):  
B Najafi ◽  
H Najafi ◽  
M D Idalik
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Genetic Algorithm ◽  
Computational Fluid Dynamics ◽  
Convective Heat Transfer ◽  
Cooling System ◽  
Air Cooling ◽  
Multi Objective Optimization ◽  
Geometric Configurations ◽  
Air Cooling System

In this study, computational fluid dynamics (CFD) analysis is utilized in order to determine the convective heat transfer coefficient of an engine air-cooling system in different air velocity conditions. Various models with different geometric configurations are considered. Based on the CFD results, two formulas are proposed to approximate the values of convective heat transfer coefficients in zero and non-zero air velocities. Finally, two conflicting objective functions including volume of the required material for construction of the finned cylinder and heat release per unit temperature difference are considered. Multi-objective optimization using genetic algorithm is utilized, which generates a multiple set of solutions, each of which is a trade-off between two objectives. The user can select each of the optimal geometric configurations based on the project's requirements. In other words, considering the desired thermal design, designer is able to find the minimum volume of the required material for construction of the finned cylinder, which in turn leads to the least possible capital cost.

Study on flow and heat transfer of small scale gas flow for air cooling system

2015 ◽  
Vol 16 (12) ◽  
pp. 2491-2498 ◽  
Author(s):  
Hong Xiao ◽  
Yang-Yang Shi ◽  
Zhe-Zhu Xu ◽  
Dong-yang Li ◽  
Sung-Ki Lyu
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Cooling System ◽  
Small Scale ◽  
Air Cooling ◽  
Flow And Heat Transfer ◽  
Air Cooling System

Development of Inherently Safe Technologies for Large Scale BWRs: (3) Infinite-Time Air-Cooling System

2014 ◽  
Author(s):  
Akinori Tamura ◽  
Toshinori Kawamura ◽  
Naoyuki Ishida ◽  
Kazuaki Kitou
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Performance ◽  
Cooling System ◽  
Natural Circulation ◽  
Air Cooling ◽  
Transfer Performance ◽  
Infinite Time ◽  
Air Cooling System ◽  
Heat Quantity

To address long-term station black outs, which occurred at the Fukushima Nuclear Power Station, we have been developing the infinite-time air-cooling system which operates without electricity by a natural circulation loop. The air-cooling heat exchanger, which is located outside the primary containment vessel of a reactor, transfers the decay heat to the atmosphere by natural circulation resulting from the density difference of the air. Improvement in the heat-transfer performance of air-cooling is a key technology in the development of the infinite-time air-cooling system. In this paper, we developed the air-cooling enhancing technology for the infinite-time air-cooling system by using a micro-fabrication surface, turbulence-enhancing structures, and heat-transfer fins. To evaluate the performance of this air-cooling enhancing technology, we conducted a heat exchange test using an element test apparatus. A single tube of the air-cooling heat exchanger, which includes a sheath heater and thermo-couples, was used. The air flow outside the tube and the heat quantity were respectively controlled using an air-compressor and the sheath heater. The heat-transfer performance was calculated from the heat-quantity and temperature difference measured using thermo-couples. The developed air-cooling enhancing technology demonstrated superior heat-transfer performance in this test. The heat-transfer performance increased approximately 100 % with this technology compared with a bare pipe. From these experimental results, we confirmed good feasibility for implementing the infinite-time air-cooling system.

scholarly journals Air circulation in a gastrointestinal light source box and endoscope in the era of SARS-CoV-2 and airborne transmission of microorganisms

2021 ◽  
Vol 09 (03) ◽  
pp. E482-E486
Author(s):  
Stanislas Chaussade ◽  
Einas Abou Ali ◽  
Rachel Hallit ◽  
Arthur Belle ◽  
Maximilien Barret ◽  
...  
Keyword(s):  
Light Source ◽  
Cooling System ◽  
Air Cooling ◽  
Airborne Transmission ◽  
Plastic Tube ◽  
Care Workers ◽  
Air Cooling System ◽  
Forced Air ◽  
Air Circulation ◽  
Closed Environment

Abstract Background and study aims The role that air circulation through a gastrointestinal endoscopy system plays in airborne transmission of microorganisms has never been investigated. The aim of this study was to explore the potential risk of transmission and potential improvements in the system. Methods We investigated and described air circulation into gastrointestinal endoscopes from Fujifilm, Olympus, and Pentax. Results The light source box contains a lamp, either Xenon or LED. The temperature of the light is high and is regulated by a forced-air cooling system to maintain a stable temperature in the middle of the box. The air used by the forced-air cooling system is sucked from the closed environment of the patient through an aeration port, located close to the light source and evacuated out of the box by one or two ventilators. No filter exists to avoid dispersion of particles outside the processor box. The light source box also contains an insufflation air pump. The air is sucked from the light source box through one or two holes in the air pump and pushed from the air pump into the air pipe of the endoscope through a plastic tube. Because the air pump does not have a dedicated HEPA filter, transmission of microorganisms cannot be excluded. Conclusions Changes are necessary to prevent airborne transmission. Exclusive use of an external CO2 pump and wrapping the endoscope platform with a plastic film will limit scatter of microorganisms. In the era of pandemic virus with airborne transmission, improvements in gastrointestinal ventilation systems are necessary to avoid contamination of patients and health care workers.

Optimization of fog inlet air cooling system for combined cycle power plants using genetic algorithm

2015 ◽  
Vol 76 ◽  
pp. 449-461 ◽  
Author(s):  
Mehdi A. Ehyaei ◽  
Mojtaba Tahani ◽  
Pouria Ahmadi ◽  
Mohammad Esfandiari
Keyword(s):  
Genetic Algorithm ◽  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Air Cooling ◽  
Air Cooling System
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