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W Q Tao - One of the best experts on this subject based on the ideXlab platform.
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a numerical study of film condensation on a Metallic Foam sintered plate with considering convection and super cooling effects
International Communications in Heat and Mass Transfer, 2016Co-Authors: Z G Qu, A Li, W Q TaoAbstract:Abstract A numerical solution was presented for film condensation on a vertical plate sintered with Metallic Foam. In the Metallic Foam region, the Brinkman-Darcy model was employed to establish the fluid flow equation, and the thermal equilibrium model was used to describe local heat transfer. Through introduction of dimensionless distance, namely, the ratio of the coordinate normal to the plate and the local film thickness, the computational domain was regularized in a rectangular zone. The effects of convection and explicit heat of super-cooled liquid on the condensation film were considered. The temperature and velocity profile, film thickness, and the local and average Nu number were obtained. The effects of Ja and Da number on the velocity profile and heat transfer performance were investigated. The numerical model was verified through comparison of the predicted results with those in the literature, which neglected convection and explicit heat of super-cooling effects. Convection and explicit heat of super-cooling can play a positive role in reducing the velocity level in the film. The two effects played a positive role in heat transfer improvement when the dimensionless location along the gravity direction (X) was > 0.15, which was associated with reduced film thickness. The two effects also had a mild influence on the linear distribution of dimensionless temperature. The heat transfer performance deteriorated with an increase in Ja number or Da number.
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experimental study of pool boiling heat transfer on horizontal Metallic Foam surface with crossing and single directional v shaped groove in saturated water
International Journal of Multiphase Flow, 2012Co-Authors: Z G Qu, Chuangyao Zhao, Z G Xu, W Q TaoAbstract:Abstract Pool boiling heat transfer on horizontal Metallic Foam surface with crossing and single-directional V-shaped groove was experimentally investigated at atmospheric pressure using deionized saturated water as the working liquid. Boiling patterns were captured using a high speed camera. The porosity of studied copper Foam was fixed as 0.95. Thirty test samples categorized into three groups were studied. The influences of crossing V-shaped groove array configuration, single-directional groove width, and number on the heat transfer performance were examined respectively for the three groups in turn. The boiling process was governed by combinational interaction of three major factors of bubble escaping resistance, heat transfer surface area, and capillary force. The exhibited heat transfer performance of the Metallic Foam depended on whichever of the above factors dominated the boiling progress. Almost all V-shaped grooves could enhance the pool boiling heat transfer compared with Foam surface without grooves. The optimal groove array configuration corresponding to highest heat transfer coefficient was connected to its groove volume ratio which was the very transition point for the behavior of the dominant factor. The optimal volume ratio for crossing groove array was 7.76% at pore density of 100 PPI and 5.84% at pore density of 130 PPI. The effect of groove number was heavily dependent on Foam thickness. The optimal groove width of 2 mm was found for the three groove number values (1, 2, and 3). The boiling characteristics were illustrated with boiling patterns obtained from the high speed camera. The present study could aid enhanced boiling surface design of sintered porous surface.
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pool boiling heat transfer on open celled Metallic Foam sintered surface under saturation condition
International Journal of Heat and Mass Transfer, 2011Co-Authors: Z G Xu, Chuangyao Zhao, Z G Qu, W Q TaoAbstract:The current study investigated the saturated pool boiling heat transfer of deionized water with added surfactant on a horizontal Metallic Foam surface with V-shape grooves under atmospheric pressure. The influences of the groove configurations, sodium dodecyl sulfate (SDS) concentration, Foam thickness, and thermal conductivity of Foam material on heat transfer performance and bubble growth patterns were studied. SDS with concentrations of 100, 400, and 800 ppm was used as the surfactant. The Foam porosity was fixed at 0.95. V-shape grooves with various widths and groove number were manufactured in the Foam samples, with three pore densities of 20, 100, and 130 PPI. Results showed that the effects of the groove configuration, SDS concentration, and thickness on boiling heat transfer are heavily dependent on Foam pore density. The counter-flow between the released bubbles and sucked liquid plays a significant role in heat transfer performance. The existence of sufficient grooves delays the critical heat flux (CHF), whereas SDS can achieve CHF earlier.
Lorna J. Gibson - One of the best experts on this subject based on the ideXlab platform.
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Creep of sandwich beams with Metallic Foam cores
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003Co-Authors: Olivera Kesler, L.k. Crews, Lorna J. GibsonAbstract:The steady state creep deflection rates of sandwich beams with Metallic Foam cores were measured and compared with analytical and numerical predictions of the creep behavior. The deflection rate depends on the geometry of the sandwich beam, the creep behavior of the Foam core and the loading conditions (stress state, temperature). Although there was a considerable scatter in the creep data (both of the Foams and of the sandwich beams made using them), the data for the sandwich beams were fairly well described by the analysis.
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Size effects in Metallic Foam core sandwich beams
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2002Co-Authors: Olivera Kesler, Lorna J. GibsonAbstract:Abstract Foams exhibit size effects: if the specimen dimensions are of the same order as the cell size, the moduli and strength depend on specimen size. Metallic Foams have particularly large cells (typically 2–20 mm), potentially giving rise to size effects when they are used in sandwich beams. Previous studies have shown that the shear strength of Metallic Foams bonded to rigid plates increases by over 50% if the specimen thickness is equal to the cell size. In this study, sandwich beams with aluminum alloy faces and aluminum alloy Foam cores were tested in three-point bending to characterize the effect of the beam depth on the limit load. Beams of constant ratio of core thickness to span length but different absolute values of core thickness were tested, and the measured limit loads were compared to analytical values. The analysis gives a good description of the measured limit load when the shear size effect is accounted for.
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Failure of sandwich beams with Metallic Foam cores
International Journal of Solids and Structures, 2001Co-Authors: T M Mccormack, Ronald E Miller, Olivera Kesler, Lorna J. GibsonAbstract:Abstract Sandwich beams with Metallic Foam cores can fail by several modes: face yielding, face wrinkling, core yielding and indentation. We estimate the initial failure load, corresponding to the first deviation from linearity in the load–deflection curve as well as the peak load for each mode. Failure mode maps are constructed which illustrate the dominant failure mode for practical beam designs. The results of the analysis are compared with experiments on sandwich beams with aluminum Foam cores in three-point bending. The peak loads and the failure modes are described well by the analysis.
Taegyu Kim - One of the best experts on this subject based on the ideXlab platform.
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preparation and evaluation of a Metallic Foam catalyst for steam co2 reforming of methane in gtl fpso process
Fuel Processing Technology, 2014Co-Authors: Daeil Park, Dong Ju Moon, Taegyu KimAbstract:Abstract A Metallic Foam catalyst was used to improve the heat transfer of a reactor for the steam-CO 2 reforming (SCR) of methane in the GTL-FPSO (gas to liquid-floating production storage and offloading) process. The Metallic Foam catalyst was prepared and examined by scanning electron microscopy, fall-off test and SCR reaction. The radial heat transfer was characterized in terms of the Nusselt number and was compared with the pellet catalyst to confirm the improvement in the heat transfer of the Metallic Foam catalyst. As a result of the fall-off test, the adhesion strength was highest at an Al 2 O 3 /AIP molar ratio of 5. The Nusselt number of the Metallic Foam catalyst was higher than that of the conventional pellet catalyst. Therefore, the reformer had a uniform temperature distribution along the catalyst-bed when the Metallic Foam catalyst was used.
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steam co2 reforming of methane on ni γ al2o3 deposited Metallic Foam catalyst for gtl fpso process
Fuel Processing Technology, 2013Co-Authors: Daeil Park, Dong Ju Moon, Taegyu KimAbstract:Abstract The steam-CO 2 reforming (SCR) of methane on a Ni/γ-Al 2 O 3 -deposited Metallic Foam catalyst was assessed for the GTL-FPSO (gas to liquids-floating production, storage and offloading) process. The Metallic Foam catalyst was prepared by the wash-coating of a γ-Al 2 O 3 layer and the subsequent impregnation of a Ni catalyst. The prepared Ni/γ-Al 2 O 3 /Ni Foam catalyst was characterized by scanning electron microscopy and X-ray diffraction. The SCR reaction on the Ni/γ-Al 2 O 3 /Ni Foam catalyst was evaluated at different temperatures and space velocities. A uniform and robust catalyst layer was formed on the surface of the Ni Foam. The Metallic Foam catalyst showed a higher CH 4 conversion than a pellet catalyst. The durability of the Metallic Foam catalyst was evaluated at a space velocity of 130,000 h − 1 for 50 h. The CH 4 conversion decreased by 10% compared to that after the reaction was initiated.
Lin Jing - One of the best experts on this subject based on the ideXlab platform.
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blast resistance and energy absorption of sandwich panels with layered gradient Metallic Foam cores
Journal of Sandwich Structures and Materials, 2019Co-Authors: Lin Jing, Longmao ZhaoAbstract:The dynamic response, blast resistance and energy absorption capability of clamped square sandwich panels comparing two aluminum alloy face-sheets and a layered gradient Metallic Foam core, subject...
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perforation resistance of sandwich panels with layered gradient Metallic Foam cores
Composite Structures, 2017Co-Authors: Fei Yang, Lin Jing, Longmao ZhaoAbstract:Abstract The perforation resistance capability of clamped square sandwich panels with layered gradient Metallic Foam cores subjected to the hemispherical-nosed projectile impact was investigated numerically. The previous penetration tests on monolithic Foam core sandwich panels were used to validate the present simulation approach, and then the deformation process, critical velocity and energy absorption of monolithic Al plate, ungraded and layered-gradient sandwich targets were studied, respectively. Influences of the strain rate and asymmetric face-sheets on the perforation resistance of the layered-gradient sandwich target were also discussed. The simulation results indicate that layered-gradient sandwich targets have the worst perforation resistance and energy absorption capability, and then the ungraded sandwich panel, and the monolithic plate is the best. For layered-gradient sandwich panels, the perforation resistance is hard to improve obviously by changing the arrangements of core-layers. Besides, the strain rate effect of materials and asymmetric face-sheets contribute to enhance the perforation resistance of layered-gradient sandwich targets only for the low-velocity penetration condition. These findings are beneficial for guiding the design and assessment of layered-gradient sandwich structures in engineering applications.
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an approximate theoretical analysis for clamped cylindrical sandwich shells with Metallic Foam cores subjected to impulsive loading
Composites Part B-engineering, 2014Co-Authors: Zhihua Wang, Lin Jing, Longmao ZhaoAbstract:Abstract A simplified theoretical analysis is developed to predict the dynamic response of clamped cylindrical sandwich shells with aluminum Foam cores under air blast loading. In this analytical solution, the whole response of the sandwich shell is split into three sequential stages, similar with the existing three-stage theoretical framework of sandwich structures. In the first stage the blast impulse is assumed to only transfer to the velocity of the front face-sheet. The Metallic Foam core is considered approximately to be a progressive compressive mode in the second stage, while the back face-sheet is still stationary. In the final stage, the classical monolithic shell theory based on an energy dissipation rate balance approach is employed; and the “upper” and “lower” bounds of the maximum back face-sheet central point deflections and response time are obtained by incorporating a comprehensive circumscribing and inscribing yield loci. A reasonable agreement between the theoretical predictions and experimental results is found for the maximum back face-sheet central point deflection of sandwich shells. The proposed theoretical consideration is significant to guide the engineering applications of cellular metal sandwich structures subjected to air blast loading.
Z G Qu - One of the best experts on this subject based on the ideXlab platform.
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a numerical study of film condensation on a Metallic Foam sintered plate with considering convection and super cooling effects
International Communications in Heat and Mass Transfer, 2016Co-Authors: Z G Qu, A Li, W Q TaoAbstract:Abstract A numerical solution was presented for film condensation on a vertical plate sintered with Metallic Foam. In the Metallic Foam region, the Brinkman-Darcy model was employed to establish the fluid flow equation, and the thermal equilibrium model was used to describe local heat transfer. Through introduction of dimensionless distance, namely, the ratio of the coordinate normal to the plate and the local film thickness, the computational domain was regularized in a rectangular zone. The effects of convection and explicit heat of super-cooled liquid on the condensation film were considered. The temperature and velocity profile, film thickness, and the local and average Nu number were obtained. The effects of Ja and Da number on the velocity profile and heat transfer performance were investigated. The numerical model was verified through comparison of the predicted results with those in the literature, which neglected convection and explicit heat of super-cooling effects. Convection and explicit heat of super-cooling can play a positive role in reducing the velocity level in the film. The two effects played a positive role in heat transfer improvement when the dimensionless location along the gravity direction (X) was > 0.15, which was associated with reduced film thickness. The two effects also had a mild influence on the linear distribution of dimensionless temperature. The heat transfer performance deteriorated with an increase in Ja number or Da number.
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experimental study of air natural convection on Metallic Foam sintered plate
International Journal of Heat and Fluid Flow, 2012Co-Authors: Z G Qu, Tiansong Wang, Wenquan Tao, T J LuAbstract:Abstract The natural convection on Metallic Foam-sintered plate at different inclination angles was experimentally studied. Seven copper Foam samples with different pore densities (10–40 pore per inch), porosities (0.90–0.95), and aspect ratios (the ratio of Foam thickness to sample length, 0.1–0.5) were measured at inclination angles of 0° (vertical orientation), 15°, 30°, 45°, 60°, 75°, 90° (horizontal orientation). The heat conduction and natural convection inside the Foam both contributed to the total heat transfer. Although, the form and viscous drag, which are influenced by permeability and viscous friction in the thermal boundary layer respectively, tend to suppress the natural convection, the heat transfer was finally enhanced by the Foam sintered surface due to large surface area extension. Optimum inclination range 60–75° corresponding to maximum average Nu number was found in the heat flux range of 600–1800 W/m 2 . The sintered Foam surface with lower porosity and pore density was recommended for heat transfer enhancement. Particularly, the sample with porosity 0.9, pore density of 10 PPI, aspect ratio of 0.5 offered the highest average Nu number among the studied samples. An empirical correlation for modified Nusselt number at isoflux boundary condition considering the Foam morphology parameter and inclination angle was proposed within deviation ±15% between the correlation and the experimental data.
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experimental study of pool boiling heat transfer on horizontal Metallic Foam surface with crossing and single directional v shaped groove in saturated water
International Journal of Multiphase Flow, 2012Co-Authors: Z G Qu, Chuangyao Zhao, Z G Xu, W Q TaoAbstract:Abstract Pool boiling heat transfer on horizontal Metallic Foam surface with crossing and single-directional V-shaped groove was experimentally investigated at atmospheric pressure using deionized saturated water as the working liquid. Boiling patterns were captured using a high speed camera. The porosity of studied copper Foam was fixed as 0.95. Thirty test samples categorized into three groups were studied. The influences of crossing V-shaped groove array configuration, single-directional groove width, and number on the heat transfer performance were examined respectively for the three groups in turn. The boiling process was governed by combinational interaction of three major factors of bubble escaping resistance, heat transfer surface area, and capillary force. The exhibited heat transfer performance of the Metallic Foam depended on whichever of the above factors dominated the boiling progress. Almost all V-shaped grooves could enhance the pool boiling heat transfer compared with Foam surface without grooves. The optimal groove array configuration corresponding to highest heat transfer coefficient was connected to its groove volume ratio which was the very transition point for the behavior of the dominant factor. The optimal volume ratio for crossing groove array was 7.76% at pore density of 100 PPI and 5.84% at pore density of 130 PPI. The effect of groove number was heavily dependent on Foam thickness. The optimal groove width of 2 mm was found for the three groove number values (1, 2, and 3). The boiling characteristics were illustrated with boiling patterns obtained from the high speed camera. The present study could aid enhanced boiling surface design of sintered porous surface.
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pool boiling heat transfer on open celled Metallic Foam sintered surface under saturation condition
International Journal of Heat and Mass Transfer, 2011Co-Authors: Z G Xu, Chuangyao Zhao, Z G Qu, W Q TaoAbstract:The current study investigated the saturated pool boiling heat transfer of deionized water with added surfactant on a horizontal Metallic Foam surface with V-shape grooves under atmospheric pressure. The influences of the groove configurations, sodium dodecyl sulfate (SDS) concentration, Foam thickness, and thermal conductivity of Foam material on heat transfer performance and bubble growth patterns were studied. SDS with concentrations of 100, 400, and 800 ppm was used as the surfactant. The Foam porosity was fixed at 0.95. V-shape grooves with various widths and groove number were manufactured in the Foam samples, with three pore densities of 20, 100, and 130 PPI. Results showed that the effects of the groove configuration, SDS concentration, and thickness on boiling heat transfer are heavily dependent on Foam pore density. The counter-flow between the released bubbles and sucked liquid plays a significant role in heat transfer performance. The existence of sufficient grooves delays the critical heat flux (CHF), whereas SDS can achieve CHF earlier.