The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform
Raafat N Ibrahim - One of the best experts on this subject based on the ideXlab platform.
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Using S–N curves to analyse cracking due to repeated thermal shock
Journal of Materials Processing Technology, 2004Co-Authors: Brian B Kerezsi, John W H Price, Raafat N IbrahimAbstract:Abstract Thermal shock loading of operating pressure equipment is a common occurrence, particularly in thermal power stations. The tensile stresses that are produced at the surface of a Heated Component exposed to a rapid thermal down shock can be very high, particularly in the presence of stress concentrations such as an abrupt change in geometry. Repeated application of the thermal shocks may eventually lead to crack initiation and crack growth. In some cases these cracks lead to Component failure while in other cases the cracks arrest at a harmless depth. The ability to use current codes and standards to describe this type of crack growth is particularly desirable. Unfortunately, thermal shock is a very complex transient situation with highly non-linear stress distributions and environmental effects that are not well described by some codes. This paper describes attempts to use the stress versus cycles curve ( S – N curves) described in the ASME Boiler and Pressure Vessel code to predict crack initiation in a flat plate carbon steel specimen exposed to repeated thermal shock from temperatures below the creep range. The issue considered in this paper is how to estimate stresses in this complex situation for notched specimens. Modifications to the code are suggested where necessary to achieve the desired accuracy.
Nicolas Galanis - One of the best experts on this subject based on the ideXlab platform.
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heat transfer enhancement using al2o3 water nanofluid for an electronic liquid cooling system
Applied Thermal Engineering, 2007Co-Authors: Cong Tam Nguyen, Gilles Roy, Christian Gauthier, Nicolas GalanisAbstract:Abstract We have experimentally investigated the behaviour and heat transfer enhancement of a particular nanofluid, Al 2 O 3 nanoparticle–water mixture, flowing inside a closed system that is destined for cooling of microprocessors or other electronic Components. Experimental data, obtained for turbulent flow regime, have clearly shown that the inclusion of nanoparticles into distilled water has produced a considerable enhancement of the cooling block convective heat transfer coefficient. For a particular nanofluid with 6.8% particle volume concentration, heat transfer coefficient has been found to increase as much as 40% compared to that of the base fluid. It has also been found that an increase of particle concentration has produced a clear decrease of the Heated Component temperature. Experimental data have clearly shown that nanofluid with 36 nm particle diameter provides higher heat transfer coefficients than the ones of nanofluid with 47 nm particle size.
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Heat transfer enhancement using Al2O3–water nanofluid for an electronic liquid cooling system
Applied Thermal Engineering, 2006Co-Authors: Cong Tam Nguyen, Gilles Roy, Christian Gauthier, Nicolas GalanisAbstract:Abstract We have experimentally investigated the behaviour and heat transfer enhancement of a particular nanofluid, Al 2 O 3 nanoparticle–water mixture, flowing inside a closed system that is destined for cooling of microprocessors or other electronic Components. Experimental data, obtained for turbulent flow regime, have clearly shown that the inclusion of nanoparticles into distilled water has produced a considerable enhancement of the cooling block convective heat transfer coefficient. For a particular nanofluid with 6.8% particle volume concentration, heat transfer coefficient has been found to increase as much as 40% compared to that of the base fluid. It has also been found that an increase of particle concentration has produced a clear decrease of the Heated Component temperature. Experimental data have clearly shown that nanofluid with 36 nm particle diameter provides higher heat transfer coefficients than the ones of nanofluid with 47 nm particle size.
Brian B Kerezsi - One of the best experts on this subject based on the ideXlab platform.
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Using S–N curves to analyse cracking due to repeated thermal shock
Journal of Materials Processing Technology, 2004Co-Authors: Brian B Kerezsi, John W H Price, Raafat N IbrahimAbstract:Abstract Thermal shock loading of operating pressure equipment is a common occurrence, particularly in thermal power stations. The tensile stresses that are produced at the surface of a Heated Component exposed to a rapid thermal down shock can be very high, particularly in the presence of stress concentrations such as an abrupt change in geometry. Repeated application of the thermal shocks may eventually lead to crack initiation and crack growth. In some cases these cracks lead to Component failure while in other cases the cracks arrest at a harmless depth. The ability to use current codes and standards to describe this type of crack growth is particularly desirable. Unfortunately, thermal shock is a very complex transient situation with highly non-linear stress distributions and environmental effects that are not well described by some codes. This paper describes attempts to use the stress versus cycles curve ( S – N curves) described in the ASME Boiler and Pressure Vessel code to predict crack initiation in a flat plate carbon steel specimen exposed to repeated thermal shock from temperatures below the creep range. The issue considered in this paper is how to estimate stresses in this complex situation for notched specimens. Modifications to the code are suggested where necessary to achieve the desired accuracy.
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Using the ASME and BSI codes to predict crack growth due to repeated thermal shock
International Journal of Pressure Vessels and Piping, 2002Co-Authors: Brian B Kerezsi, John W H PriceAbstract:Abstract This paper examines the use of the ASME and British Standard codes to estimate the growth of cracks driven mainly by thermal shocks. Thermal shock loading of operating pressure equipment is a common occurrence, particularly in thermal power stations. The tensile stresses that are produced at the surface of a Heated Component exposed to a rapid thermal down shock can be high, particularly in the presence of stress concentrations. Repeated application of the thermal shocks may lead to crack initiation and crack growth. The ability to use current codes and standards to describe this type of crack growth is desirable. Unfortunately, thermal shock is a complex transient situation with highly non-linear stress distributions and environmental effects that are not well described by some codes. This paper describes attempts to use the techniques described in the ASME Boiler and Pressure Vessel code Section XI and British Standard BS7910 to predict crack growth rates derived from Monash University experiments. Areas of large conservatism in the methods currently used in industry are identified and possible alternative, less conservative approaches are suggested. If the methods are fully applied, the possibility of crack growth slowing can be captured and the replacement or repair of equipment with thermal shock cracking might be avoided.
Alexander M Korsunsky - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the spray field development on a vertical surface during water spray-quenching using a flat spray nozzle
Applied Thermal Engineering, 2009Co-Authors: W J J Vorster, S.a. Schwindt, Jon Schupp, Alexander M KorsunskyAbstract:Abstract The aims of this study were (i) to conduct experimental spatially and time-resolved measurements of flow development on large Heated surfaces during transient spray cooling operations and (ii) to investigate and discuss the influence of spray cooling mechanisms such as bubble formation and the flow field development of the cooling fluid and how this affects heat transfer. Quartz plates were Heated to above 500 °C and then sprayed with pressurised water subcooled to 80 K. High speed images of the quench process were collected at a rate of 3000 Hz making it possible to track the movement of the quench front as the plate cools below the Leidenfrost temperature of the fluid at that location. Observations showed that the relative importance of droplet-surface interactions decreases once the Leidenfrost temperature is reached on the plate: It was found that once the water contacts the surface, a water pool develops rapidly which grows larger as the pool floods the Heated surface. Comparisons between the spatial flow development and heat transfer on the plate are made in order to describe these interactions more accurately. This information not only provides crucial input into process simulations, but is also useful to develop theoretical models of fluid–solid interaction describing the wetting of a Heated Component due to water spraying.
John W H Price - One of the best experts on this subject based on the ideXlab platform.
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Using S–N curves to analyse cracking due to repeated thermal shock
Journal of Materials Processing Technology, 2004Co-Authors: Brian B Kerezsi, John W H Price, Raafat N IbrahimAbstract:Abstract Thermal shock loading of operating pressure equipment is a common occurrence, particularly in thermal power stations. The tensile stresses that are produced at the surface of a Heated Component exposed to a rapid thermal down shock can be very high, particularly in the presence of stress concentrations such as an abrupt change in geometry. Repeated application of the thermal shocks may eventually lead to crack initiation and crack growth. In some cases these cracks lead to Component failure while in other cases the cracks arrest at a harmless depth. The ability to use current codes and standards to describe this type of crack growth is particularly desirable. Unfortunately, thermal shock is a very complex transient situation with highly non-linear stress distributions and environmental effects that are not well described by some codes. This paper describes attempts to use the stress versus cycles curve ( S – N curves) described in the ASME Boiler and Pressure Vessel code to predict crack initiation in a flat plate carbon steel specimen exposed to repeated thermal shock from temperatures below the creep range. The issue considered in this paper is how to estimate stresses in this complex situation for notched specimens. Modifications to the code are suggested where necessary to achieve the desired accuracy.
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Using the ASME and BSI codes to predict crack growth due to repeated thermal shock
International Journal of Pressure Vessels and Piping, 2002Co-Authors: Brian B Kerezsi, John W H PriceAbstract:Abstract This paper examines the use of the ASME and British Standard codes to estimate the growth of cracks driven mainly by thermal shocks. Thermal shock loading of operating pressure equipment is a common occurrence, particularly in thermal power stations. The tensile stresses that are produced at the surface of a Heated Component exposed to a rapid thermal down shock can be high, particularly in the presence of stress concentrations. Repeated application of the thermal shocks may lead to crack initiation and crack growth. The ability to use current codes and standards to describe this type of crack growth is desirable. Unfortunately, thermal shock is a complex transient situation with highly non-linear stress distributions and environmental effects that are not well described by some codes. This paper describes attempts to use the techniques described in the ASME Boiler and Pressure Vessel code Section XI and British Standard BS7910 to predict crack growth rates derived from Monash University experiments. Areas of large conservatism in the methods currently used in industry are identified and possible alternative, less conservative approaches are suggested. If the methods are fully applied, the possibility of crack growth slowing can be captured and the replacement or repair of equipment with thermal shock cracking might be avoided.