Статті в журналах з теми "Pore per inch"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Pore per inch.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Pore per inch".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Hakam, Mohamed, Wael Hashima, Ibrahim Elhawary, and Adel Elgeiheini. "Introducing a Newly Developed Fabric for Air Filtration." Autex Research Journal 20, no. 2 (May 13, 2020): 148–54. http://dx.doi.org/10.2478/aut-2019-0024.
Повний текст джерелаАнотація:
AbstractWoven and nonwoven fabrics present filtration efficiency higher than other air filtration media. Fabrics are selected according to air flow conditions and particle characteristics. The majority of air filtration media are nonwoven fabrics because of their cost, but they need high filtration area for high efficiency. Modified construction of woven fabric introduces high performance in air filtration and decreases filter size, which tends to have better competition abilities. The designed fabrics have considerable thickness and suitable pore characteristics by applying roving instead of weft yarns. Four factors (roving count and their turns per inch, picks per inch and fabric designs) were varied in order to study the effect of these factors on their performance in filtration. Optimum operating conditions for a determined range of air permeability and pore size were obtained.
2
Hur, Bo Young, Bu Keoun Park, Sang Youl Kim, and Hoon Bae. "Compressive Properties of Open Cell Aluminum Foams." Materials Science Forum 486-487 (June 2005): 472–75. http://dx.doi.org/10.4028/www.scientific.net/msf.486-487.472.
Повний текст джерелаАнотація:
The uniaxial compressive test results of several aluminum foams are compared with aluminum alloy and ppi (pore per inch) of open cell foam. The compressive stress-strain curve of aluminum alloy foams exhibits universal three deformation regions: an initial linear elastic response, and then extended plateau region with a nearly constant flow stress, a final densification as collapsed cells are compacted together. The lower the foam densities are, the longer the plateau region is, but lower densities also imply lower yield stress.
3
Azamar, Manuel F., Ignacio A. Figueroa, Gonzalo González, and Ismeli Alfonso. "Assessment of the flow behavior and structural performance of open-cell aluminum foams at critical flow conditions of pressure and temperature." Journal of Materials Research 37, no. 1 (October 12, 2021): 225–35. http://dx.doi.org/10.1557/s43578-021-00382-4.
Повний текст джерелаАнотація:
Abstract Open-cell Al foams were produced by the replication casting technique in three different pore sizes. All produced foams were physically characterized, determining their relative density, porosity, and pores per inch, as well as their mean pore surface area and diameter. Permeability tests were carried out by means of the injection of a highly pressurized gasoline additive at room temperature and 200 °C, at pressures of up to 25,000 psi. The structural capacity of the studied specimens to conduct fluids at these critical experimental conditions was assessed by means of compression tests in order to determine their mechanical properties after the permeability tests, e.g., energy absorption capacity, Young’s modulus, and plateau stress. It was found that the produced open-cell Al foams were able of conducting the gasoline additive at critical flow conditions of pressure and temperature, without suffering important physical nor structural damage. Graphic abstract
4
Hsu, Y. H., I. G. Turner, and A. W. Miles. "Fabrication of Porous Calcium Phosphate Bioceramics as Synthetic Cortical Bone Graft." Key Engineering Materials 284-286 (April 2005): 305–8. http://dx.doi.org/10.4028/www.scientific.net/kem.284-286.305.
Повний текст джерелаАнотація:
The aim of this study was to fabricate porous Hydroxyapatite/Tricalcium phosphate (HA/TCP) bioceramics with an adequate degree of interconnected porosity combined with optimal mechanical properties. Porous HA/TCP bioceramics with interconnected porosity and the controlled pore sizes necessary to simulate natural bone tissue morphology were fabricated by a novel technique of vacuum impregnation of reticulated polymeric foams with ceramic slip. By varying the characteristics of the slips and using foams of different pores per inch (ppi), samples of porous HA/TCP, blocks and granules, with a wide range of pore sizes were successfully manufactured. Functionally gradient materials (FGM) with porosity gradients were also made and no weakness was found at the interface. The pore size of the HA/TCP bioceramics was in the range of 197 – 254 µm (for 20 ppi foam), 143 – 182 µm (for 30 ppi foam) and 105 – 127 µm (for 45 ppi foam). The compressive strengths and the apparent densities of the HA/TCP samples were in the range of 30 –170 MPa and 2.34 – 2.76 g/cm3 respectively. These results indicate that it is possible to manufacture open pore HA/TCP bioceramics with compressive strengths comparable to human bone which could be of clinical interest.
5
Fadhala, Karrar, Ekhlas Fayyadh, and Ali Mohammed. "Experimental investigation on the thermal-hydraulic performance of channel with gradient metal foam baffles." FME Transactions 51, no. 1 (2023): 14–22. http://dx.doi.org/10.5937/fme2301014f.
Повний текст джерелаАнотація:
Metal foam is a novel material recently utilized in baffles as an alternative to solid baffles for reducing flow resistance. However, the metal foam baffles are accompanied by low heat transfer efficiency. To overcome this issue, a new design of copper foam baffles has been suggested in this research, called baffles having a gradient pore density of the copper foam. The pore density either increases or decreases towards the wall. So, the experimental tests were carried out in a square channel and heated uniformly at the bottom wall of the test section. Its walls are mounted copper foam baffles at a fixed porosity of 95%. Baffles were alternately fixed upon the walls' bottom and top in staggered mode. The results were determined for various kinds of copper foam (10 and 20) pores per inch (PPI), and the gradient pore density was either with the order decreasing (DPPI) 10/20 PPI or increasing (IPPI) 20/10 PPI with a window cut ratio of 25% and a constant heat flux of 4.4 kW/m2 . The Reynolds number was changed from 3.8x104 to 5.4x104 . The data for conventional copper solid baffles were used to compare the influence of foam metal type. The obtained results revealed an enhancement in thermohydraulic performance for baffles with a gradient pore density of the order decreasing DPPI (10/20 PPI) higher than all the models of copper foam baffles.
6
Sutygina, Alina, Ulf Betke, and Michael Scheffler. "Manufacturing of Open-Cell Aluminium Foams: Comparing the Sponge Replication Technique and Its Combination with the Freezing Method." Materials 15, no. 6 (March 15, 2022): 2147. http://dx.doi.org/10.3390/ma15062147.
Повний текст джерелаАнотація:
The manufacturing of aluminium foams with a total porosity of 87% using the sponge replication method and a combination of the sponge replication and freezing technique is presented. Foams with different cell counts were prepared from polyurethane (PU) templates with a pore count per inch (ppi) of 10, 20 and 30; consolidation of the foams was performed in an argon atmosphere at 650 °C. The additional freezing steps resulted in lamellar pores in the foam struts. The formation of lamellar pores increased the specific surface area by a factor of 1.9 compared to foams prepared by the sponge replication method without freezing steps. The formation of additional lamellar pores improved the mechanical properties but reduced the thermal conductivity of the foams. Varying the pore cell sizes of the PU template showed that—compared to foams with dense struts—the highest increase (~7 times) in the specific surface area was observed in foams made from 10 ppi PU templates. The effect of the cell size on the mechanical and thermal properties of aluminium foams was also investigated.
7
Er, Yusuf, and Emine Unsaldi. "The Production of Nickel-Chromium-Molybdenum Alloy with Open Pore Structure as an Implant and the Investigation of Its Biocompatibility In Vivo." Advances in Materials Science and Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/568479.
Повний текст джерелаАнотація:
A dental crown material, Nickel-Chrome-Molybdenum alloy, is manufactured using precision casting method from a polyurethane foam model in a regular and open-pore form, as a hard tissue implant for orthopedic applications. The samples produced have 10, 20, and 30 (±3) pores per inch of pore densities and 0.0008, 0.0017, and 0.0027 g/mm3densities, respectively. Samples were implanted in six dogs and observed for a period of two, four, and six months for the histopathological examinations. The dogs were examined radiologically in 15-day intervals and clinically in certain intervals. The implants were taken out with surrounding tissue at the end of these periods. Implants and surrounding tissues were examined histopathologically in terms of biocompatibility. As a result, it is seen that new bone tissue was formed, in pores of the porous implant at the head of the tibia in dogs implanted. Any pathology, inflammation, and reaction in old and new tissues were not observed. It was concluded that a dental alloy (Ni-Cr-Mo alloy) could also be used as a biocompatible hard tissue implant material for orthopedics.
8
Donmus, Sinem, Moghtada Mobedi, and Fujio Kuwahara. "Double-Layer Metal Foams for Further Heat Transfer Enhancement in a Channel: An Analytical Study." Energies 14, no. 3 (January 28, 2021): 672. http://dx.doi.org/10.3390/en14030672.
Повний текст джерелаАнотація:
A local thermal non-equilibrium analysis of heat and fluid flow in a channel fully filled with aluminum foam is performed for three cases: (a) pore density of 5 PPI (pore per inch), (b) pore density of 40 PPI, and (c) two different layers of 5 and 40 PPI. The dimensionless forms of fully developed heat and fluid flow equations for the fluid phase and heat conduction equation for the solid phase are solved analytically. The effects of interfacial heat transfer coefficient and thermal dispersion conductivity are considered. Analytical expressions for temperature profile of solid and fluid phases, and also the channel Nusselt number (NuH) are obtained. The obtained results are discussed in terms of the channel-based Reynolds number (ReH) changing from 10 to 2000, and thickness ratio between the channel height and sublayers. The Nusselt number of the channel with 40 PPI is always greater than that of the 5 PPI channel. It is also greater than the channel with two-layer aluminum foams until a specific Reynolds number then the Nusselt number of the channel with two-layer aluminum foams becomes greater than the uniform channels due to the higher velocity in the outer region and considerable increase in thermal dispersion.
9
Hrubesh, Lawrence W., and Richard W. Pekala. "Thermal properties of organic and inorganic aerogels." Journal of Materials Research 9, no. 3 (March 1994): 731–38. http://dx.doi.org/10.1557/jmr.1994.0731.
Повний текст джерелаАнотація:
Aerogels are open-cell foams that have already been shown to be among the best thermal insulating solid materials known. This paper examines the three major contributions to thermal transport through porous materials, solid, gaseous, and radiative, to identify how to reduce the thermal conductivity of air-filled aerogels. We found that significant improvements in the thermal insulation property of aerogels are possible by (i) employing materials with a low intrinsic solid conductivity, (ii) reducing the average pore size within aerogels, and (iii) affecting an increase of the infrared extinction in aerogels. Theoretically, polystyrene is the best of the organic materials and zirconia is the best inorganic material to use for the lowest achievable conductivity. Significant reduction of the thermal conductivity for all aerogel varieties is predicted with only a modest decrease of the average pore size. This might be achieved by modifying the sol-gel chemistry leading to aerogels. For example, a thermal resistance value of R = 20 per inch would be possible for an air-filled resorcinol-formaldehyde aerogel at a density of 156 kg/m3, if the average pore size was less than 35 nm. An equation is included which facilitates the calculation of the optimum density for the minimum total thermal conductivity, for all varieties of aerogels.
10
Li, De Bo, Qi Sheng Xu, Yue Liang Shen, Zhi Yong Wen, and Ya Ming Liu. "Experimental and Numerical Study of Premixed Combustion within Porous Media." Advanced Materials Research 557-559 (July 2012): 1572–83. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.1572.
Повний текст джерелаАнотація:
A transient numerical model and experimental study of combustion and heat transfer for methane and oxygen within a two-section porous burner are presented in this paper. It is found that the maximum flame velocity is influenced by the combined effects of extinction coefficient and convection heat transfer coefficient, and that the minimum flame velocities of ceramics with various pore densities have slight differences at different equivalence ratios, while maximum flame velocities have large differences. In addition, the flame velocity depends not only on the interfacial convection heat transfer, but also on the radiation heat transfer of the ceramic foams, which is in accordance with our numerical simulation. Meanwhile, the numerical research in the present paper indicates that radiation extinction coefficient or pores per inch is not the only reason to characterize the heat regeneration effect of ceramic foams.
11
Bhattacharya, A., and R. L. Mahajan. "Finned Metal Foam Heat Sinks for Electronics Cooling in Forced Convection." Journal of Electronic Packaging 124, no. 3 (July 26, 2002): 155–63. http://dx.doi.org/10.1115/1.1464877.
Повний текст джерелаАнотація:
In this paper, we present recent experimental results on forced convective heat transfer in novel finned metal foam heat sinks. Experiments were conducted on aluminum foams of 90 percent porosity and pore size corresponding to 5 PPI (200 PPM) and 20 PPI (800 PPM) with one, two, four and six fins, where PPI (PPM) stands for pores per inch (pores per meter) and is a measure of the pore density of the porous medium. All of these heat sinks were fabricated in-house. The forced convection results show that heat transfer is significantly enhanced when fins are incorporated in metal foam. The heat transfer coefficient increases with increase in the number of fins until adding more fins retards heat transfer due to interference of thermal boundary layers. For the 20 PPI samples, this maximum was reached for four fins. For the 5 PPI heat sinks, the trends were found to be similar to those for the 20 PPI heat sinks. However, due to larger pore sizes, the pressure drop encountered is much lower at a particular air velocity. As a result, for a given pressure drop, the heat transfer coefficient is higher compared to the 20 PPI heat sink. For example, at a Δp of 105 Pa, the heat transfer coefficients were found to be 1169W/m2-K and 995W/m2-K for the 5 PPI and 20 PPI 4-finned heat sinks, respectively. The finned metal foam heat sinks outperform the longitudinal finned and normal metal foam heat sinks by a factor between 1.5 and 2, respectively. Finally, an analytical expression is formulated based on flow through an open channel and incorporating the effects of thermal dispersion and interfacial heat transfer between the solid and fluid phases of the porous medium. The agreement of the proposed relation with the experimental results is promising.
12
Hayashi, Thamy C., Isabel Malico, and J. F. C. Pereira. "Analysis of the Flow at the Interface of a Porous Media." Defect and Diffusion Forum 283-286 (March 2009): 616–21. http://dx.doi.org/10.4028/www.scientific.net/ddf.283-286.616.
Повний текст джерелаАнотація:
The influence of inserting ceramic foam in a pipe with a 1:4 sudden expansion was numerical investigated. The foam, with a thickness to diameter ratio of 0.60, was positioned at different distances from the sudden pipe expansion wall. Three different porosities were analyzed (10, 20 and 60 pores per inch) for pore Reynolds numbers in the range of 20-400, corresponding to pipe Reynolds numbers of 2400 to 22000 in the pipe section upstream the sudden expansion. Predictions of the sudden pipe expansion cavity assuming laminar flow within the foam yield the penetration of the separated flow region into the foam. Considering turbulent flow in the porous foam and the model of Pedras and Lemos [14] prevents this penetration. The numerical and physical models used could not reproduce completely the foam influence on the separated turbulent flow region between the sudden pipe expansion and the foam inlet.
13
Mabrouk, Riheb, Hassane Naji, Hacen Dhahri, and Zohir Younsi. "Insight into Foam Pore Effect on Phase Change Process in a Plane Channel under Forced Convection Using the Thermal Lattice Boltzmann Method." Energies 13, no. 15 (August 2, 2020): 3979. http://dx.doi.org/10.3390/en13153979.
Повний текст джерелаАнотація:
In this work, the two-dimensional laminar flow and the heat transfer in an open-ended rectangular porous channel (metal foam) including a phase change material (PCM; paraffin) under forced convection were numerically investigated. To gain further insight into the foam pore effect on charging/discharging processes, the Darcy–Brinkmann–Forchheimer (DBF) unsteady flow model and that with two temperature equations based on the local thermal non-equilibrium (LTNE) were solved at the representative elementary volume (REV) scale. The enthalpy-based thermal lattice Boltzmann method (TLBM) with triple distribution function (TDF) was employed at the REV scale to perform simulations for different porosities (0.7≤ε≤0.9) and pore per inch (PPI) density (10≤PPI≤60) at Reynolds numbers (Re) of 200 and 400. It turned out that increasing Re with high porosity and PPI (0.9 and 60) speeds up the melting process, while, at low PPI and porosity (10 and 0.7), the complete melting time increases. In addition, during the charging process, increasing the PPI with a small porosity (0.7) weakens the forced convection in the first two-thirds of the channel. However, the increase in PPI with large porosity and high Re number limits the forced convection while improving the heat transfer. To sum up, the study findings clearly evidence the foam pore effect on the phase change process under unsteady forced convection in a PCM-saturated porous channel under local thermal non-equilibrium (LTNE).
14
Prasanth, Achuthamenon Sylajakumari, Vijayan Krishnaraj, Jayakrishnan Nampoothiri, Ramalingam Sindhumathi, Mohamed Raeez Akthar Sadik, Juan Pablo Escobedo, and Krishna Shankar. "Uniaxial Compressive Behavior of AA5083/SiC Co-Continuous Ceramic Composite Fabricated by Gas Pressure Infiltration for Armour Applications." Journal of Composites Science 6, no. 2 (January 20, 2022): 36. http://dx.doi.org/10.3390/jcs6020036.
Повний текст джерелаАнотація:
A novel approach of a gas pressure infiltration technique is presented for the synthesis of Co-Continuous Ceramic Composite (C4). SiC foams of varying pore sizes were infiltrated with aluminium AA5083. Optical examination revealed that the SiC foams contained open cells with a network of triangular voids. The number of pores-per-inch (PPI) in the foams was found to depend on the strut thickness and pore diameter. The compressive strengths of two foam configurations, 10 and 20 PPI, were estimated to lie between 1–2 MPa. After infiltration, the compressive yield strength of the resulting C4 was observed to increase to 126 MPa and 120 MPa, respectively, for the 10 and 20 PPI C4. Additionally, the infiltration of ceramic foam with the AA5083 alloy resulted in an increase in strength of 58–100 times when compared with plain ceramic foam. The failure modes of the composites in compression were analyzed by crack propagation and determining the type of failure. The study revealed that shear failure and vertical splitting were the predominant mechanisms of compression failure, and that the fabricated C4 is advantageous in mechanical properties compared to the plain ceramic foam. This study, therefore, suggests the use of C4 composites in armour applications.
15
Sadam Hussain, A. Shakoor, and T. Yasmin. "Analysis and characterization of 20 ppi open cell aluminum foam under mechanical loading." Journal of Mechanical Engineering and Sciences 16, no. 3 (September 28, 2022): 9110–21. http://dx.doi.org/10.15282/jmes.16.3.2022.12.0721.
Повний текст джерелаАнотація:
In this research the analysis and characterization of open cell aluminium foam with 20 pores per inch (ppi) of Alporas rout under mechanical loading is presented in order to provide a basic understanding with respect to pore size per unit length for the right selection in various engineering applications. For this purpose, three point bending test, tensile test, compression test, vickers hardness test and charpy impact test were performed to seek out the respective properties of each test. All samples and test procedure were performed as per ASTM standards. The scanning electron microscopy (SEM) will performed of the fractured surfaces of the specimens to investigate the failure mode. The SEM photograph shows that; some internal defects were found such as the tinny cracks some irregular shape holes in the cell wall which have been created during foaming process. The shredded cell wall is looked over which was ductile in nature and have occurred during flexural, tensile and charpy impact test. In compression; all pores are collapsed in plateau region, and some crumples and brittle tiny cracks are detected in densifications stage. Dislocation band also detected on the walls and struts of the effected sample of tensile and charpy impact test.
16
Hsu, Y. H., I. G. Turner, and A. W. Miles. "Techniques for Manufacturing FGM Bioceramics." Key Engineering Materials 361-363 (November 2007): 123–26. http://dx.doi.org/10.4028/www.scientific.net/kem.361-363.123.
Повний текст джерелаАнотація:
Several novel methods for the production of calcium phosphate based functional gradient materials have been explored. The processes involved the use of polyurethane foams with a different number of pores per inch which were joined together in a variety of ways to form unique templates prior to vacuum impregnation with a ceramic slip. Before processing, rectangular blocks of foam were joined by stitching or trapezoidal blocks were compressed into rectangular shapes to produce a gradient of porosity along the length of the template. Four-point bend testing of the sintered samples which combined two porous structures showed them to have comparable mechanical properties to homogeneous ceramics based on foam templates with uniform pore sizes, with no evidence of weakness at the interface. The method was further developed to make a cylindrical sample with two diverse porous structures which more closely mimic the natural bone morphology. The two very different areas, which represented cortical and cancellous bone, had good structural integrity at the interface.
17
Kuleshov, F. S., S. V. Golovastov, and G. Yu Bivol. "Influence of a Porous Polyurethane Partition on Hydraulic Characteristics of the Flow and on Flame Front Propagation in an Open Channel." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 3 (102) (June 2022): 110–23. http://dx.doi.org/10.18698/1812-3368-2022-3-110-123.
Повний текст джерелаАнотація:
The purpose of the research was to experimentally study the influence of a porous polyurethane partition on the flow parameters and on the flame front propagation in front of the partition upon initiation at the open end of the channel. The flame front velocities were determined in a hydrogen-air mixture at atmospheric pressure in a channel open on both sides with an inner diameter of 20 mm. The ratio between hydrogen and air was varied, so that the molar excess of hydrogen varied from 0.3 (ultra-poor mixture) to 1.0 (stoichiometric composition). The pore size varied within 0.3--2.5 mm, which corresponded to the number of pores per inch in the range of 10--80. The coefficients of hydraulic resistance of a polyurethane partition with an open pore type, depending on the size of the pores and the thickness of the partition, were calculated from the pressure loss when the air flow passes through the porous element. The flame front velocity was determined using the shadow method and high-speed survey. Findings of the research show that the optimal value of the thickness of the porous partition, after which the polyurethane partition begins to show filtration properties, in most cases is approximately equal to twice the pore size and the drag coefficient depends linearly on the total thickness of the partition. In this case, the deficit of the flow velocity with increasing thickness increases according to a power law. A qualitative correspondence between the flame front velocity in front of the porous partition and the flow velocity deficit is shown
18
G, Trilok, N. Gnanasekaran, and Moghtada Mobedi. "Various Trade-Off Scenarios in Thermo-Hydrodynamic Performance of Metal Foams Due to Variations in Their Thickness and Structural Conditions." Energies 14, no. 24 (December 10, 2021): 8343. http://dx.doi.org/10.3390/en14248343.
Повний текст джерелаАнотація:
The long standing issue of increased heat transfer, always accompanied by increased pressure drop using metal foams, is addressed in the present work. Heat transfer and pressure drop, both of various magnitudes, can be observed in respect to various flow and heat transfer influencing aspects of considered metal foams. In this regard, for the first time, orderly varying pore density (characterized by visible pores per inch, i.e., PPI) and porosity (characterized by ratio of void volume to total volume) along with varied thickness are considered to comprehensively analyze variation in the trade-off scenario between flow resistance minimization and heat transfer augmentation behavior of metal foams with the help of numerical simulations and TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) which is a multi-criteria decision-making tool to address the considered multi-objective problem. A numerical domain of vertical channel is modelled with zone of metal foam porous media at the channel center by invoking LTNE and Darcy–Forchheimer models. Metal foams of four thickness ratios are considered (1, 0.75, 0.5 and 0.25), along with varied pore density (5, 10, 15, 20 and 25 PPI), each at various porosity conditions of 0.8, 0.85, 0.9 and 0.95 porosity. Numerically obtained pressure and temperature field data are critically analyzed for various trade-off scenarios exhibited under the abovementioned variable conditions. A type of metal foam based on its morphological (pore density and porosity) and configurational (thickness) aspects, which can participate in a desired trade-off scenario between flow resistance and heat transfer, is illustrated.
19
Kong, Wenjie, Hao Dong, Jie Wu, Yidi Zhao, and Zhou Jin. "Experimental Study on the Effect of Porous Media on the Aerodynamic Performance of Airfoils." Aerospace 10, no. 1 (December 27, 2022): 25. http://dx.doi.org/10.3390/aerospace10010025.
Повний текст джерелаАнотація:
Porous media has potential applications in fluid machinery and in aerospace science and engineering due to its excellent drag-reduction properties. We carried out experimental time-resolved particle image velocimetry (TR-PIV) research, laying porous media with different pore densities on the suction side of an airfoil in the low-turbulence recirculation wind tunnel of Nanjing University of Aeronautics and Astronautics to study the effects and mechanisms of porous media on airfoil aerodynamic performance. We also used a smooth airfoil model in the experiment for comparison. Comparing the aerodynamic forces, pressure distributions, and the airfoil’s suction side flow field, we found that the porous media with different pore densities had different effects on the airfoil’s aerodynamic performance. Although the porous media with 20PPI (pores per inch) increased the pressure drag and reduced the airfoil lift, it considerably reduced the friction drag, thus significantly improving the airfoil’s aerodynamic force. The flow visualization results indicated that, although the porous media with 20PPI reduced the circulation of flow velocity around the suction side of airfoil, it also destroyed the vortex structure, broke the low-frequency large-scale vortex into a high-frequency granular vortex, inhibited the amplitude of vortex fluctuation, reduced the shear stress on the airfoil surface, weakened the vortex energy of different modes, and accelerated the vortex’s spatio-temporal evolution.
20
Arreola-Ramos, Carlos E., Omar Álvarez-Brito, Juan Daniel Macías, Aldo Javier Guadarrama-Mendoza, Manuel A. Ramírez-Cabrera, Armando Rojas-Morin, Patricio J. Valadés-Pelayo, Heidi Isabel Villafán-Vidales, and Camilo A. Arancibia-Bulnes. "Experimental Evaluation and Modeling of Air Heating in a Ceramic Foam Volumetric Absorber by Effective Parameters." Energies 14, no. 9 (April 27, 2021): 2506. http://dx.doi.org/10.3390/en14092506.
Повний текст джерелаАнотація:
Reticulate porous ceramic reactors use foam-type absorbers in their operation which must fulfill two essential functions: favoring the volumetric effect and increasing the mass and heat transfer by acting as a support for the reactive materials. Heating these absorbers with highly inhomogeneous concentrate irradiation induces high thermal gradients that affect their thermal performance. Owing to the critical function of these component in the reactor, it is necessary to define a selection criterion for the foam-type absorbers. In this work, we performed an experimental and numerical thermal analysis of three partially stabilized zirconia (PSZ) foam-type absorbers with pore density of 10, 20, and 30 PPI (pores per inch) used as a volumetric absorber. A numerical model and an analytical approximation were developed to reproduce experimental results, and calculate the thermal conductivity, as well as volumetric heat transfer coefficient. The results show that an increase in pore density leads to an increase in the temperature difference between the irradiated face and the rear face of the absorber, this occurs because when pore density increases the concentrated energy no longer penetrates in the deepest space of the absorber and energy is absorbed in areas close to the surface; therefore, temperature gradients are created within the porous medium. The opposite effect occurs when the airflow rate increases; the temperature gradient between the irradiated face and the rear face is reduced. This behavior is more noticeable at low pore densities, but at high pore densities, the effect is less relevant because the internal structure of porous absorbers with high pore density is more complex, which offers obstructions or physical barriers to airflow and thermal barriers to heat transfer. When the steady state is reached, the temperature difference between the two faces of the absorber remains constant if the concentrate irradiation changes slightly, even changing the airflow rate. The results obtained in this work allow us to establish a selection criterion for porous absorbers that operate within solar reactors; this criterion is based on knowledge of the physical properties of the porous absorber, the environment, the working conditions, and the results expected.
21
Azamar, Manuel F., Ignacio A. Figueroa, Gonzalo Gonzalez, and Ismeli Alfonso. "Drop of Pressure Behavior of Open-Cell Aluminum Foams at High Pressure Flow." Journal of Applied Research and Technology 19, no. 6 (December 31, 2021): 603–21. http://dx.doi.org/10.22201/icat.24486736e.2021.19.6.1274.
Повний текст джерелаАнотація:
Open-cell aluminum foams were produced by the replication technique in three different pore sizes, ranging from 0.71 to 4.75 mm. The manufactured specimens were physically characterized, determining their porosity, relative density, pores per inch and interconnection windows density. A new experimental design is proposed in order to assess the drop of pressure behavior resulting from the injection of gasoline additive at increasing high pressure intervals, ranging from 200 to 25,000 psi, reproducing the tests at room temperature and 200 °C. The regime governing the flow through the investigated samples was determined as a function of flowrate and the foams physical properties. The structural capacity of open-cell Al foams to conduct highly pressurized flow was evaluated by means of compression tests. It was found that at room temperature, the drop of pressure behavior is strongly associated to physical parameters, whilst at 200 °C, dimensional and geometrical properties are negligible. In addition, in this investigation, it is presumed that the studied foams have the structural capacity to conduct fluids at critical conditions of pressure and temperature.
22
Wen, Mingcai, Yiqiang Tang, Cong Yuan, Enhua Cui, Keju Ji, and Zhendong Dai. "Effect of interconnected metal skeletons on the tribological properties of polyurethane elastomers." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, no. 10 (April 20, 2020): 1635–41. http://dx.doi.org/10.1177/1350650120920503.
Повний текст джерелаАнотація:
Electrostatic cumulative discharges from the surfaces of polyurethane elastomers are often the primary cause of accidents and disasters, such as equipment failures, fires, and explosions, in industries. In this study, in order to improve the electrostatic protection performance of PU as well as to enhance the wear resistance of the PU matrix, copper foam was embedded in polyurethane to form a copper foam-based polyurethane composite with a three-dimensional connected metal skeleton. The mechanical properties, wear resistance, and antistatic capability of the composite were experimentally investigated. The results indicated that the connected metal skeleton structure forms a good conductive network and reduces the static electricity on the polyurethane composite surface to less than 1/10 of that on polyurethane. Moreover, owing to the mechanical support offered by metal skeletons with pore densities greater than 50 pores per inch, the wear resistance of the polyurethane composite is also enhanced, and consequently, its degree of wear is reduced to ∼1/5 of that of polyurethane under the same conditions.
23
Schmidt, Jens, Matthias Scheiffele, Alexander Mach, and Franz von Issendorff. "Fabrication and Testing of Corrugated 3D SiSiC Ceramics for Porous Burner Applications." Advances in Science and Technology 45 (October 2006): 2316–22. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2316.
Повний текст джерелаАнотація:
Non-oxide SiC ceramics can withstand high temperatures ~1400 °C in severe combustion environments. Therefore such ceramics are interesting candidates for advanced combustion technologies, e.g. sophisticated porous burners. For the fabrication of porous SiSiC ceramics the DLR developed a new technology based on carbon sheets and lamellae. These basic materials can be combined to lightweight 3D C/C stacks. Through the variation of the amplitude and number of lamellae per inch, the open porosity and orientation of the pore channels could be tailored in a wide range. By using the pyrolysis followed by the liquid silicon-melt infiltration process the carbon stack could be directly converted into SiC in one shot. The residual open porosity can easily be filled with pure silicon to obtain 3D SiSiC structures with adequate mechanical strength and sufficient damage tolerance. Best results from durability tests were obtained with structures which are composed of oriented pore channels. Suitable structures should have angles (α) of about α = ± 60° or less. The results from burner rig tests at LSTM with improved components have been very promising, since a lifetime up to 500 hours and 2000 start-ups could be obtained with α = ± 50° as well as with α = ± 60° sample. So far, no significant oxidation or degradation could be observed after 1939 h/10800 start-ups with α = ± 45° sample. These proof tests are ongoing and show that these novel cardboard like structures have a high potential for industrial applications.
24
Eleroğlu, Hasan. "Beç Tavuklarında (Numida meleagris) Sayısal Görüntü Analizi ve Matematiksel Formüller Kullanılarak Yumurta Kalite Özelliklerinin Belirlenmesi." Turkish Journal of Agriculture - Food Science and Technology 9, no. 11 (December 2, 2021): 2056–64. http://dx.doi.org/10.24925/turjaf.v9i11.2056-2064.4839.
Повний текст джерелаАнотація:
A total of 200 Guinea fowl (Numidae meleagris) eggs were obtained from guinea fowl flock at the age of 42 weeks of age, which are breeding at an altitude of 1240 m in the Wild Animals Breeding Station affiliated to Ministry of Forest and Water Affairs in Yozgat/Turkey. Eggs were taken at a resolution of 72 pixels per inch and 5184 × 3456 pixels in size, with the individual egg weights. Average Projection area (16,07 cm2), Perimeter (15,82 cm), Circularity (0,81), Height (5,17 cm), Width (4,04 cm), Mean grey value (82,82), Semi axis (2,02 cm), First long half height (2,96 cm), Second short half height (2,20 cm) values were determined by numerical image analysis. Mean Elongation (1,28), Shape Index (78,27) were calculated over the obtained data. Surface area (55,43 cm2), Height (5,16 cm), Width (3,77 cm), Elongation (1,37), Shape Index (73,01), Volume (40,14 cm3), Surface / Volume ratio (1,38), Shell weight (3,17 g), Shell thickness (0,28 mm), pore numbers (6666,25; 5132,39; 5011,12), pore density (120,32; 92,56; 90,31), Yellow ratio (14,85), Yellow Weight (5,95 g), Albumen Weight (30,75), Albumen ratio (77,21) parameters have been calculated using individual egg weights. Eggs were divided into 3 groups as 90 in terms of gray value, eggs 79 in terms of shape index, and 43 in terms of weight. The effects on the properties were investigated. As a result, it is thought that the data obtained can be used in scientific studies.
25
Dyga, Roman, and Małgorzata Płaczek. "Influence of Hydrodynamic Conditions on the Type and Area of Occurrence of Gas–Liquid Flow Patterns in the Flow through Open–Cell Foams." Materials 13, no. 15 (July 22, 2020): 3254. http://dx.doi.org/10.3390/ma13153254.
Повний текст джерелаАнотація:
This paper reports the results of a study concerned with air−water and air−oil two–phase flow pattern analysis in the channels with open–cell metal foams. The research was conducted in a horizontal channel with an internal diameter of 0.02 m and length of 2.61 m. The analysis applied three foams with pore density equal to 20, 30 and 40 PPI (pore per inch) with porosity, typical for industrial applications, changing in the range of 92%–94%. Plug flow, slug flow, stratified flow and annular flow were observed over the ranges of gas and liquid superficial velocities of 0.031–8.840 m/s and 0.006–0.119 m/s, respectively. Churn flow, which has not yet been observed in the flow through the open–cell foams, was also recorded. The type of flow patterns is primarily affected by the hydrodynamic characteristics of the flow, including fluid properties, but not by the geometric parameters of foams. Flow patterns in the channels packed with metal foams occur in different conditions from the ones recorded for empty channels so gas−liquid flow maps developed for empty channels cannot be used to predict analyzed flows. A new gas−liquid flow pattern map for a channel packed with metal foams with the porosity of 0.92–0.94 was developed. The map is valid for liquids with a density equal to or lower than the density of water and a viscosity several times greater than that of water.
26
Waramit, Pathiwat, Apinunt Namkhat, and Umphisak Teeboonma. "The Influence of Stainless Steel Mesh Porous Burner on Drying Kinetics of Nile Tilapia." Key Engineering Materials 805 (June 2019): 116–21. http://dx.doi.org/10.4028/www.scientific.net/kem.805.116.
Повний текст джерелаАнотація:
This paper studied the influence of porous burner effect on drying kinetics of Nile tilapia drying using stainless steel mesh porous burner as heat source. Drying kinetics was analyzed by determination of drying rate (DR), drying specific energy consumption (SEC) and dryer thermal efficiency (). In this study, the stainless steel mesh was used as porous media with porosity of 10, 20 and 50 pore per inch (PPI), drying air velocity of 0.5, 1.0 and 1.5 m/s, and drying temperature of 50, 60 and 70 °C, respectively. The results were found that the application of porous burner as heat source can improve the drying kinetics. It was found, at the porosity of 50 PPI, the drying temperature of 70 °C and the air velocity of 1.5 m/s, the moisture ratio of the drying was decreased rapidly, the highest drying rate was found to be 150 g (water evap.)/hr., the lowest drying energy consumption was found to be146.75 MJ/kg, and the thermal efficiency of the dryer was found to increase by 17.79% and the CO and NOx concentration in case of applying porous burner as heat source is lower than without porous burner.
27
Salas, Ken I., and Anthony M. Waas. "Convective Heat Transfer in Open Cell Metal Foams." Journal of Heat Transfer 129, no. 9 (December 8, 2006): 1217–29. http://dx.doi.org/10.1115/1.2739598.
Повний текст джерелаАнотація:
Convective heat transfer in aluminum metal foam sandwich panels is investigated with potential applications to actively cooled thermal protection systems in hypersonic and re-entry vehicles. The size effects of the metal foam core are experimentally investigated and the effects of foam thickness on convective transfer are established. Four metal foam specimens are utilized with a relative density of 0.08 and pore density of 20 pores per inch (ppi) in a range of thickness from 6.4mmto25.4mm, in increments of approximately 6mm. An exact-shape-function finite element model is developed that envisions the foam as randomly oriented cylinders in cross flow with an axially varying coolant temperature field. A fully developed velocity profile is obtained through a semi-empirical, volume-averaged form of the momentum equation for flow through porous media, and used in the numerical analysis. The experimental results show that larger foam thicknesses produce increased heat transfer levels, but that this effect diminishes for thicker foams. The finite element simulations capture the thickness dependence of the heat transfer process and good agreement between experimental and numerical results is obtained for larger foam thicknesses.
28
Kim, Youngwoo, Chanhee Moon, Omid Nematollahi, Hyun Dong Kim, and Kyung Chun Kim. "Time-Resolved PIV Measurements and Turbulence Characteristics of Flow Inside an Open-Cell Metal Foam." Materials 14, no. 13 (June 25, 2021): 3566. http://dx.doi.org/10.3390/ma14133566.
Повний текст джерелаАнотація:
Open-cell metal foams are porous medium for thermo-fluidic systems. However, their complex geometry makes it difficult to perform time-resolved (TR) measurements inside them. In this study, a TR particle image velocimetry (PIV) method is introduced for use inside open-cell metal foam structures. Stereolithography 3D printing methods and conventional post-processing methods cannot be applied to metal foam structures; therefore, PolyJet 3D printing and post-processing methods were employed to fabricate a transparent metal foam replica. The key to obtaining acceptable transparency in this method is the complete removal of the support material from the printing surfaces. The flow characteristics inside a 10-pore-per-inch (PPI) metal foam were analyzed in which porosity is 0.92 while laminar flow condition is applied to inlet. The flow inside the foam replica is randomly divided and combined by the interconnected pore network. Robust crosswise motion occurs inside foam with approximately 23% bulk speed. Strong influence on transverse motion by metal foam is evident. In addition, span-wise vorticity evolution is similar to the integral time length scale of the stream-wise center plane. The span-wise vorticity fluctuation through the foam arrangement is presented. It is believed that this turbulent characteristic is caused by the interaction of jets that have different flow directions inside the metal foam structure. The finite-time Lyapunov exponent method is employed to visualize the vortex ridges. Fluctuating attracting and repelling material lines are expected to enhance the heat and mass transfer. The results presented in this study could be useful for understanding the flow characteristics inside metal foams.
29
Mabrouk, Riheb, Hassane Naji, and Hacen Dhahri. "Numerical Investigation of Metal Foam Pore Density Effect on Sensible and Latent Heats Storage through an Enthalpy-Based REV-Scale Lattice Boltzmann Method." Processes 9, no. 7 (July 5, 2021): 1165. http://dx.doi.org/10.3390/pr9071165.
Повний текст джерелаАнотація:
In this work, an unsteady forced convection heat transfer in an open-ended channel incorporating a porous medium filled either with a phase change material (PCM; case 1) or with water (case 2) has been studied using a thermal lattice Boltzmann method (TLBM) at the representative elementary volume (REV) scale. The set of governing equations includes the dimensionless generalized Navier–Stokes equations and the two energy model transport equations based on local thermal non-equilibrium (LTNE). The enthalpy-based method is employed to cope with the phase change process. The pores per inch density (10≤PPI≤60) effects of the metal foam on the storage of sensible and latent heat were studied during charging/discharging processes at two Reynolds numbers (Re) of 200 and 400. The significant outcomes are discussed for the dynamic and thermal fields, the entropy generation rate (Ns), the LTNE intensity, and the energy and exergy efficiencies under the influence of Re. It can be stated that increasing the PPI improves the energy and exergy efficiencies of the latent heat model, reduces energy losses, and improves the stored energy quality. Likewise, at a moderate Re (=200), a low PPI (=10) would be suitable to reduce the system irreversibility during the charging period, while a high value (PPI = 60) might be advised for the discharging process. As becomes clear from the obtained findings, PPI and porosity are relevant factors. In conclusion, this paper further provides a first analysis of entropy generation during forced convection to improve the energy efficiency of various renewable energy systems.
30
Akbarnejad, Shahin, Anders Tilliander, Dong-Yuan Sheng, and Pär Göran Jönsson. "Effect of Batch Dissimilarity on Permeability of Stacked Ceramic Foam Filters and Incompressible Fluid Flow: Experimental and Numerical Investigation." Metals 12, no. 6 (June 10, 2022): 1001. http://dx.doi.org/10.3390/met12061001.
Повний текст джерелаАнотація:
Ceramic foam filters (CFFs) are used to remove inclusions and/or solid particles from molten metal. In general, the molten metal poured on the top of a CFF should reach a certain height to form the pressure (metal head) required to prime the filter. For estimating the required metal head and obtaining the permeability coefficients of the CFFs, permeability experiments are essential. Recently, electromagnetic priming and filtration of molten aluminum with low and high grades of CFF, i.e., 30, 50 and 80 pore per inch (PPI) CFFs, have been introduced. Since then, there has been interest in exploring the possibility of obtaining further inclusion entrapment and aluminum refinement by using electromagnetic force to prime and filter with stacked CFFs. The successful execution of such trials requires a profound understanding concerning the permeability parameters of the stacked filters. Such data were deemed not to exist prior to this study. As a result, this study presents experimental findings of permeability measurements for stacks of three 30, three 50 and three 80 PPI commercial alumina CFFs from different industrial batches and compares the findings to numerically modelled data as well as previous research works. Both experimental and numerical findings showed a good agreement with previous results. The deviation between the experimentally and numerically obtained data lies in the range of 0.4 to 6.3%.
31
Du, Hai, Qinlin Zhang, Qixuan Li, Wenjie Kong, and Lejie Yang. "Drag reduction in cylindrical wake flow using porous material." Physics of Fluids 34, no. 4 (April 2022): 045102. http://dx.doi.org/10.1063/5.0085990.
Повний текст джерелаАнотація:
Due to its unique pore structure, porous materials have the potential to be used in the fields of acoustic noise reduction and flow drag reduction control. In order to study their effects and mechanism of drag reduction on the flow around a circular cylinder, experiments are conducted in a low-speed wind tunnel with low turbulence intensity. The drag forces acting on a circular cylinder model are measured using wind tunnel balance when porous materials with different permeability are applied within different intersection angles on the trailing-edge and leading edge, and the flow fields are visualized with a particle image velocimetry system with high time resolution. The method of dynamic mode decomposition (DMD) is also used for reduced-order analysis of the vorticity field in the wake of the cylinder. The measured drag forces and wake flow fields are then compared with those of a smooth cylinder, and the results show that porous materials laid on the trailing-edge can reduce drag, when a porous material with 20 pores per inch is laid within 270° on the leeward side, the best effect of the drag reduction ratio of 10.21% is reached. The results of flow visualization indicate that after the porous material is applied, the vortex region in the wake of the cylinder is expanded; both the frequency of vortex shedding and the magnitude of vorticity fluctuation decrease; the Reynolds-shear-stress decreases significantly, and both indicate that vorticity is dissipated earlier. The results of DMD analysis show that porous materials can effectively relax the energy of vortices in different modes.
32
Mabrouk, Riheb, Hassane Naji, Hacen Dhahri, and Zouhir Younsi. "On Numerical Modeling of Thermal Performance Enhancementof a Heat Thermal Energy Storage System Using a Phase Change Material and a Porous Foam." Computation 10, no. 1 (January 10, 2022): 3. http://dx.doi.org/10.3390/computation10010003.
Повний текст джерелаАнотація:
In this investigation, a comprehensive numerical analysis of the flow involved in an open-ended straight channel fully filled with a porous metal foam saturated and a phase change material (paraffin) has been performed using a single relaxation time lattice Boltzmann method (SRT-LBM) at the representative elementary volume (REV) scale. The enthalpy-based approach with three density functions has been employed to cope with the governing equations under the local thermal non-equilibrium (LTNE) condition. The in-house code has been validated through a comparison with a previous case in literature. The pore per inch density (10≤PPI≤60) and porosity (0.7≤ε≤0.9) effects of the metal structure were analyzed during melting/solidifying phenomena at two Reynolds numbers (Re = 200 and 400). The relevant findings are discussed for the LTNE intensity and the entropy generation rate (Ns). Through the simulations, the LTNE hypothesis turned out to be secure and valid. In addition, it is maximum for small PPI value (=10) whatever the parameters deemed. On the other hand, high porosity (=0.9) is advised to reduce the system’s irreversibility. However, at a moderate Re (=200), a small PPI (=10) would be appropriate to mitigate the system irreversibility during the charging case, while a large value (PPI = 60) might be advised for the discharging case. In this context, it can be stated that during the melting period, low porosity (=0.7) with low PPI (=10) improves thermal performance, reduces the system irreversibility and speeds up the melting rate, while for high porosity (=0.9), a moderate PPI (=30) should be used during the melting process to achieve an optimal system.
33
Pinto, Carlos Eduardo, Jurandir Almeida Dias, Eduardo Amaral Moura Sá, Audrey Tieko Tsunoda, and Rodrigo Nascimento Pinheiro. "Tratamento Cirúrgico do Câncer de Esôfago." Revista Brasileira de Cancerologia 53, no. 4 (December 31, 2007): 425–30. http://dx.doi.org/10.32635/2176-9745.rbc.2007v53n4.1776.
Повний текст джерелаАнотація:
Este estudo tem como objetivo analisar os resultados do tratamento cirúrgico do câncer de esôfago na Seção de Cirurgia Abdominopélvica do Instituto Nacional de Câncer (INCA). Foram analisados, retrospectivamente, os prontuários de 93 pacientes portadores de câncer de esôfago, submetidos à esofagectomia no INCA entre janeiro de 1997 e dezembro de 2005 (período no qual organizou-se o Grupo de Esôfago). Os principais parâmetros avaliados no estudo foram: tempo de internação hospitalar, percentual de morbidade operatória e percentual de mortalidade operatória. Em relação aos resultados, a mediana de idade foi de 57 anos (25 anos - 85 anos), sendo 71 pacientes do sexo masculino e 22 pacientes do sexo feminino. A mediana do tempo de internação foi de 20 dias. O percentual de complicação operatória foi de 61% e a mortalidade operatória foi de 7%. Após a avaliação dos resultados e revisão da literatura, pode-se concluir que a esofagectomia por câncer de esôfago, apesar de apresentar elevada morbidade operatória, permanece como o tratamento-padrão para pacientes com doença ressecável e sem contra-indicação clínica; e que a redução da mortalidade operatória com a esofagectomia, atualmente observada, decorre de uma melhor seleção de pacientes para os quais é indicada a cirurgia, além de maior nível de especialização da equipe cirúrgica e atenção voltada para os cuidados per e pós-operatórios.
34
Yao, Shiyin, Donald R. Helinski, and Aresa Toukdarian. "Localization of the Naturally Occurring Plasmid ColE1 at the Cell Pole." Journal of Bacteriology 189, no. 5 (December 8, 2006): 1946–53. http://dx.doi.org/10.1128/jb.01451-06.
Повний текст джерелаАнотація:
ABSTRACT The naturally occurring plasmid ColE1 was found to localize as a cluster in one or both of the cell poles of Escherichia coli. In addition to the polar localization of ColE1 in most cells, movement of the plasmid to the midcell position was observed in time-lapse studies. ColE1 could be displaced from its polar location by the p15A replicon, pBAD33, but not by plasmid RK2. The displacement of ColE1 by pBAD33 resulted in an almost random positioning of ColE1 foci in the cell and also in a loss of segregational stability, as evidenced by the large number of cells carrying pBAD33 with no visible ColE1 focus and as confirmed by ColE1 stability studies. The addition of the active partitioning systems of the F plasmid (sopABC) or RK2 (OB1 incC korB) resulted in movement of the ColE1 replicon from the cell pole to within the nucleoid region. This repositioning did not result in destabilization but did result in an increase in the number of plasmid foci, most likely due to partial declustering. These results are consistent with the importance of par regions to the localization of plasmids to specific regions of the cell and demonstrate both localization and dynamic movement for a naturally occurring plasmid that does not encode a replication initiation protein or a partitioning system that is required for plasmid stability.
35
Machado, André Wilson, and Bernardo Quiroga Souki. "Simplificando a obtenção e a utilização de imagens digitais: scanners e câmeras digitais." Revista Dental Press de Ortodontia e Ortopedia Facial 9, no. 4 (August 2004): 133–56. http://dx.doi.org/10.1590/s1415-54192004000400012.
Повний текст джерелаАнотація:
Um dos grandes benefícios que a evolução tecnológica proporcionou à Ortodontia foi a utilização das imagens digitais. O uso dessa nova tecnologia em Odontologia, e especificamente em Ortodontia, aliada à introdução da Fotografia Digital, permite aos profissionais desta área utilizar recursos, antes inimagináveis, facilitando a elaboração do diagnóstico ortodôntico, auxiliando a comunicação entre profissionais, bem como com os pacientes, além de ilustrar comunicações científicas, em conferências, cursos e publicações, sendo uma excelente ferramenta para o ensino e pesquisa. Com o objetivo de lançar mão dessa nova tecnologia, o ortodontista pode obter imagens digitais por meio da digitalização da documentação ortodôntica convencional composta basicamente de fotografias analógicas (em papel ou em slide), modelos de estudo e radiografias ou pela obtenção de imagens digitais com câmeras fotográficas digitais. Desta forma, o objetivo desse trabalho é esclarecer alguns conceitos básicos relacionados às imagens digitais e tentar responder às perguntas mais freqüentes em relação ao tema: Como digitalizar as minhas documentações ortodônticas com um scanner? Como obter imagens digitais com uma câmera fotográfica digital? Que tipo de resolução em DPI (dots per inch, ou pontos por polegada) ou em Megapixel (MP), tamanho e formato de arquivo devo utilizar para as minhas necessidades ortodônticas de rotina? A obtenção de imagens com finalidade apenas de visualização no monitor do computador é diferenciada daquela para outros fins, como impressão de relatórios, banners ou apresentações com recurso de multimídia? E por fim, qual resolução deve ser utilizada para obter imagens digitais que serão encaminhadas para publicações científicas?
36
Kober, Leya Roshani, Pranay Shrestha, Chaeyoung Tina Ham, and Aimy Bazylak. "Investigating the Influence of Humidity on Liquid Water Transport Mechanisms in Fuel Cell Gas Diffusion Layers Using Operando X-Ray Computed Tomography." ECS Meeting Abstracts MA2022-02, no. 39 (October 9, 2022): 1411. http://dx.doi.org/10.1149/ma2022-02391411mtgabs.
Повний текст джерелаАнотація:
The intermittent nature of many renewable energy sources, such as solar and wind, presents the need to acquire on-demand renewable energy either through energy storage or energy production methods. The polymer electrolyte membrane (PEM) fuel cell is quickly becoming an attractive solution as it can produce high power densities under a rapid change in load while producing zero local carbon emissions [1] and is ideal for large-scale applications, such as automotive [2]. However, barriers to their widespread implementation are attributed to the high costs associated with mass transport losses at high current density operation due to inefficiencies in liquid water management in the gas diffusion layer (GDL) [3][4]. Understanding the relationship between liquid water distributions in the cathode GDL and transport properties of PEM fuel cells under varying operating conditions can lead to improved GDL configurations for improved performance. Previously, studies have been conducted to characterize the effect of operating temperature on liquid water pathways in GDLs by using 3D imaging techniques on operando PEM fuel cells [5]. High-speed, high-resolution 3D imaging techniques, such as computed tomography (CT), enable the visualization of dynamic pore-scale effects and are advantageous in elucidating transport mechanisms in the GDL. In this work, the effect of operating relative humidity on the formation of liquid water pathways in the GDL will be explored by imaging an operando PEM fuel cell with synchrotron X-ray CT. To date, a custom PEM fuel cell has been developed in-house which features a novel design with two rotary unions on either side of the cell. The rotary unions enable continuous rotation of the cell during imaging, and thus are central to achieving high temporal resolution for visualizing the development of preferential water pathways. High spatial resolution (pixel resolution of 1.44 microns per pixel [6]) is also obtained with the synchrotron beam, which allows for the visualization of liquid water in individual pores at the microscale in the GDL. Visualizing water in the micropores of the GDL can help us further understand water transport mechanisms within the complex structure of the GDL to ultimately develop methods to expel excess water efficiently. In the next steps of this research, we will use the results from electrochemical testing and the reconstructed images of the fuel cell to draw important conclusions about the relationship between liquid water distributions in the GDL and fuel cell performance. As well, the effect that operating relative humidity has on this relationship will be determined. The aim of this work is to inform optimal design for GDL materials for improved PEM fuel cell performance, which will ultimately accelerate their utilization on a global scale as a reliable and sustainable energy source. [1] P. Shrestha, CH. Lee, K. F. Fahy, M. Balakrishnan, N. Ge, and A. Bazylak, “Formation of Liquid Water Pathways in PEM Fuel Cells: A 3-D Pore-Scale Perspective,” Journal of The Electrochemical Society, vol. 167, no. 5, p. 054516, Jan. 2020, doi: 10.1149/1945-7111/ab7a0b. [2] S. Park, J. W. Lee, and B. N. Popov, “A review of gas diffusion layer in PEM fuel cells: Materials and designs,” International Journal of Hydrogen Energy, vol. 37, no. 7, pp. 5850– 5865, Apr. 2012, doi: 10.1016/J.IJHYDENE.2011.12.148. [3] Y. Nagai et al., “Improving water management in fuel cells through microporous layer modifications: Fast operando tomographic imaging of liquid water,” Journal of Power Sources, vol. 435, p. 226809, Sep. 2019, doi: 10.1016/J.JPOWSOUR.2019.226809. [4] U. U. Ince et al., “3D classification of polymer electrolyte membrane fuel cell materials from in situ X-ray tomographic datasets,” International Journal of Hydrogen Energy, vol. 45, no. 21, pp. 12161–12169, Apr. 2020, doi: 10.1016/J.IJHYDENE.2020.02.136. [5] Hong Xu, Shinya Nagashima, Hai P. Nguyen, Keisuke Kishita, Federica Marone, Felix N. Büchi, Jens Eller, Temperature dependent water transport mechanism in gas diffusion layers revealed by subsecond operando X-ray tomographic microscopy, Journal of Power Sources, Volume 490, 2021, 229492, ISSN 0378-7753, https://doi.org/10.1016/j.jpowsour.2021.229492. [6] Canadian Light Source, “Detectors,” BMIT. [Online]. Available: https://bmit.lightsource.ca/tech-info/detectors/. [Accessed: 05-Apr-2022].
37
Dukhan, Nihad. "Analysis of Brinkman-Extended Darcy Flow in Porous Media and Experimental Verification Using Metal Foam." Journal of Fluids Engineering 134, no. 7 (June 29, 2012). http://dx.doi.org/10.1115/1.4005678.
Повний текст джерелаАнотація:
Momentum transport in porous media exists in numerous engineering and process applications, e.g., ground water pollution, storage of nuclear waste, heat exchangers, and chemical reactors. In many of such applications, the porous medium is confined by solid boundaries. These impermeable boundaries give rise to shear stress and boundary layers. The Brinkman-extended Darcy equation describes the momentum transport due to Newtonian fluid flow in confined porous media. This equation is solved analytically in a cylindrical system, employing an existing fully-developed boundary-layer concept particular to porous media flows. The volume-averaged velocity increases as the distance from the boundary increases reaching a maximum at the center. The mean and maximum velocities are obtained and their behavior is investigated in terms of pertinent flow parameters. The friction factor is defined based on the mean velocity and is found to be inversely proportional to the Reynolds number, the Darcy number, and the mean velocity. The analytical results are verified by experiments using two types of metal foam. In the Darcy regime, reasonably good agreement is found between the analytical and the experimental friction factors for the 20-pore-per-inch foam, while a poor agreement is found for the 10-pore-per-inch foam.
38
Singh, Prashant, Karthik Nithyanandam, Mingyang Zhang, and Roop L. Mahajan. "The Effect of Metal Foam Thickness on Jet Array Impingement Heat Transfer in High-Porosity Aluminum Foams." Journal of Heat Transfer 142, no. 5 (March 17, 2020). http://dx.doi.org/10.1115/1.4045640.
Повний текст джерелаАнотація:
Abstract High-porosity metal foam (MF) is a popular option for high-performance heat exchangers as it offers significantly higher heat transfer participation area per unit volume compared to other convection enhancement cooling methods. Further, metal foams provide highly tortuous flow paths resulting in thermal dispersion assisted by enhanced mixing. This paper presents experimental and numerical studies and the detailed underlying physics of jet array impingement onto high-porosity (ε∼0.95) thin aluminum foams. The jet and foam configurations were designed for the maximum utilization of the foam area for heat transfer and reduced penalty on the pumping power requirement. Three different pore density foams were tested with three different array-jet impingement configurations. The minimum possible thickness for each pore density was tested, viz., 5 pores-per-inch (PPI): 19 mm, 10 PPI: 12.7 mm, and 20 PPI: 6.35 mm. The baseline case for these foam-based jet impingement configurations was the corresponding configuration of orthogonal jet impingement onto a smooth heated surface, where the distance between the jet-issuing plane and the heated surface was maintained at the foam thickness level. In general, thinner foams facilitated greater jet penetration and increased foam volume usage, resulting in higher heat transfer rates for a given pore density, especially when combined with jet configurations with larger open areas. Finally, we evaluated the thermal hydraulic performance for different foam configurations and the optimum value of a given PPI was found to be at an intermediate rather than the lowest foam thickness.
39
"Boiling Heat Transfer in Copper Foam Bilayers in Positive and Inverse Gradients of Pore Density." Journal of Applied Fluid Mechanics 16, no. 5 (February 5, 2023). http://dx.doi.org/10.47176/jafm.16.05.1624.
Повний текст джерелаАнотація:
Gradient metal foam is an advanced heat transfer material that decreases resistance to bubble escape and enhances the transfer of boiling heat. In this study, boiling heat transfer and bubble behavior were studied in an experimental set-up with copper foam bilayers configurated either in positive or inverse gradients, utilizing deionized water as working fluid. Positive gradient refers to arranging metal foam layers with high pore density at the bottom, above the heat source, and low pore density on the top. Results show that the heat transfer is higher for gradient metal foam surfaces, of 6.14×105 W/m2, versus a uniform metal foam surface, of 3.94×105 W/m2. For the positive gradient configuration, boiling heat transfer performance first increased with the pore density, then decreased when the pore density was higher than 60 pores per inch (PPI). By contrast, for the inverse gradient, the heat transfer performance was nearly constant with increasing pore density. At the low pore density, the inverse gradient performed better than the positive gradient during the whole boiling process. At high pore density, the positive gradient structure performed better in heat transfer at the early boiling stage. Three main types of bubble escape were observed: For the positive gradient bilayer, the bubbles moved up or down without lateral interference. In contrast, for inverse gradient, the bubbles mostly escape from the sides, which is easy to induce bubble merging. The inverse gradient surface generates larger bubbles, while the positive gradient surface produces a higher frequency of bubble detachment. Accordingly, two liquid replenishment models are proposed: for the positive gradient, external liquid replenishes from the side into the copper foam, while for inverse gradient, the liquid is mainly replenished from the top.
40
Broughton, Justin, and Yogendra K. Joshi. "Comparison of Single-Phase Convection in Additive Manufactured Versus Traditional Metal Foams." Journal of Heat Transfer 142, no. 8 (June 8, 2020). http://dx.doi.org/10.1115/1.4046972.
Повний текст джерелаАнотація:
Abstract Metal foams have been often used for thermal management due to their favorable characteristics including high specific surface area (SSA), high thermal conductivity, and low relative density. However, they are accompanied by shortcomings including the significant contact resistances due to attachment method, as well as the need for characterization of foam parameters such as pore diameter and SSA. Additive manufactured (AM) metal foams would eliminate the substrate/foam thermal resistance, decrease the need for pre-usage characterization, and allow for tailoring structures, while also taking advantage of the characteristics of traditionally manufactured foams. A commercial, aluminum foam (nominally 5 pores per inch (PPI), 86.5% porosity) was analyzed using X-ray microcomputed tomography, and a custom-designed metal foam based on the cell diameter and porosity of the commercial sample was subsequently manufactured. Reduced domain computational fluid dynamics/heat transfer (CFD-HT) models were compared against experimental data. Postvalidation, the flow behavior, effect of varying attachment thermal conductivities, and thermal performance were numerically investigated, demonstrating the usefulness of validated pore-scale models, as well as the potential for improved performance using AM metal foams over traditionally manufactured foams.
41
Changrani, Rajnish, and Gregory B. Raupp. "Performance Evaluation of a Titania-coated Reticulated Foam Photocatalytic Oxidation Reactor." Journal of Advanced Oxidation Technologies 3, no. 3 (January 1, 1998). http://dx.doi.org/10.1515/jaots-1998-0312.
Повний текст джерелаАнотація:
AbstractWe have constructed and evaluated the performance of a gas-solid annular photocatalytic oxidation reactor that incorporates an alumina reticulated foam monolith element as a titania catalyst support. The reticulate occupies the annular region formed by the lamp and the outer reactor tube. Three alumina reticulates possessing different mean pore sizes and pore densities, designated as 10, 20 and 30 pores-per-inch (PPI) were employed. The reticulates were wash-coated with Degussa P25 titania. Light transmittance measurements through the reticulates showed that 30 PPI reticulate, the least optically dense element, captures the most light. Photocatalytic oxidation of dilute isopropanol (IPA) in air was chosen as the probe reaction to assess the performance of each reticulate- catalyst coating configuration. Process parameters varied were inlet IPA concentration, incident UV intensity, and mean gas residence time. For similar catalyst loadings, the 30 PPI reticulate outperformed both the 20 and 10 PPI reticulates, while the 20 PPI reticulate modestly outperformed the 10 PPI reticulate. With increasing titania coating yielding thicker titania films, general performance increases until a critical thickness is achieved. Light intensity measurements and simple forward UV intensity profile calculations reveal that reticulate performance is largely governed by the UV intensity profile. For a given reticulate, results suggest that the optimum thickness of the TiO
42
Jazi, H. R. Salimi, J. Mostaghimi, S. Chandra, L. Pershin, and T. Coyle. "Spray-Formed, Metal-Foam Heat Exchangers for High Temperature Applications." Journal of Thermal Science and Engineering Applications 1, no. 3 (September 1, 2009). http://dx.doi.org/10.1115/1.4001049.
Повний текст джерелаАнотація:
Open pore metal foams make efficient heat exchanger because of their high thermal conductivity and low permeability. This study describes a novel method of using wire-arc spraying to deposit Inconel 625 skins on the surface of sheets of 10 and 20 pores per linear inch nickel foam. The skins adhere strongly to the foam struts, giving high heat-transfer rates. Tests were done to determine the hydraulic and thermal characteristics of the heat exchangers and correlations developed to calculate Fanning friction factor and Nusselt number as a function of Reynolds number for airflow through the foam. Measured heat-transfer coefficients for the foam heat exchangers are greater than those of straight flow channels at the same flow rate. A ceramic thermal barrier coating was deposited on one face of the heat exchanger using plasma spraying. The coating and heat exchanger survived prolonged exposure to the flame of a methane-air burner.
43
Venkateshwar, Kumar, Soroush Ebadi, Hari Simha, and Shohel Mahmud. "Influence of Pore Density and Porosity on the Melting Process of Bio-Based Nano-Phase Change Materials Inside Open-Cell Metal Foam." Journal of Thermal Science and Engineering Applications 11, no. 4 (May 23, 2019). http://dx.doi.org/10.1115/1.4043662.
Повний текст джерелаАнотація:
In this paper, experimental investigations were carried out to observe the melting process of a bio-based nano-phase change materials (PCM) inside open-cell metal foams. Copper oxide nanoparticles with five different weight fractions (i.e., 0.00%, 0.08%, 0.10%, 0.12%, and 0.30%) were dispersed into bio-based PCM (i.e., coconut oil) to synthesize nano-PCMs. Open-cell aluminum foams of different porosities (i.e., 0.96, 0.92, and 0.88) and pore densities (i.e., 5, 10, and 20 pores per inch (PPI)) were considered. An experimental setup was constructed to monitor the progression of the melting process and to measure transient temperatures variations at different selected locations. Average thermal energy storage rate (TESR) was calculated, alongside the melting time was recorded. The effects of various nanoparticles concentration, metal foam pore densities, porosities, and isothermal surface temperature on the melting time, TESR, thermal energy distribution, and the melting behavior were studied. It was observed that the melting time significantly reduced by using metal foam and increasing the isothermal surface temperature. It was concluded that the effect of adding nanoparticles on the TESR depends on the characteristics of metal foam, as well as, the weight fractions of nanoparticles. The change in TESR varied from −1% to 8.6% upon addition of 0.10 wt % nanoparticles compared to pure PCM, whereas the increase in the nanoparticles concentration from 0.10% to 0.30% changed TESR by −10.6% to 4.5%. The results provide an insight into the interdependencies of parameters such as pore density and porosity of metal foam and nanoparticles concentration on the melting process of nano-PCM in metal foam.
44
Farsad, E., S. P. Abbasi, and M. S. Zabihi. "Fluid Flow and Heat Transfer in a Novel Microchannel Heat Sink Partially Filled With Metal Foam Medium." Journal of Thermal Science and Engineering Applications 6, no. 2 (January 24, 2014). http://dx.doi.org/10.1115/1.4025823.
Повний текст джерелаАнотація:
Performance of microchannel heatsink (MCHS) partially filled with foam is investigated numerically. The open cell copper foams have the porosity and pore density in the ranges of 60–90% and 60–100 PPI (pore per inch), respectively. The three-dimensional steady, laminar flow, and heat transfer governing equations are solved using finite volume method. The performance of microchannel heatsink is evaluated in terms of overall thermal resistance, pressure drop, and heat transfer coefficient and temperature distribution. It is found that the results of the surface temperature profile are in good agreement with numerical data. The results show the microchannel heatsink with insert foam appears to be good candidates as the next generation of cooling devices for high power electronic devices. The thermal resistance for all cases decreases with the decrease in porosity. The uniformity of temperature in this heatsink is enhanced compared the heatsink with no foam. The thermal resistance versus the pumping power is depicted, it is found that 80% is the optimal porosity for the foam at 60 PPI with a minimum thermal resistance 0.346 K/W. The results demonstrate the microchannel heatsink partially filled with foam is capable for removing heat generation 100 watt over an area of 9 × 10−6 m2 with the temperature of heat flux surface up to 59 °C.
45
Gaikwad, P. S., B. K. Yadav, S. Anandakumar, M. Loganathan, and S. Shanmugasundaram. "Effect of PP Nanocomposite Multi-layered Film on Physicochemical Properties of Ready-To-Cook (RTC) Idli Batter and Prepared Idli Cake." International Research Journal of Pure and Applied Chemistry, February 22, 2020, 46–63. http://dx.doi.org/10.9734/irjpac/2020/v21i130149.
Повний текст джерелаАнотація:
Aim: The current study focuses on the effect of PP nanocomposite multi-layered film on physicochemical properties of stored idli batter and prepared idli cakes.
Place and Duration of Study: Department of Food Packaging and System Development at Indian Institute of Food Processing Technology, Thanjavur, Tamil Nadu, India, between Aug 2018 and Dec 2019.
Methodology: The developed PP nanocomposite multi-layered film composed with depositing silicon dioxide (SiO2) on polypropylene (PP) film (0.010 mm) and attached with ethylene-vinyl alcohol (EVOH 32%) film (0.066 mm). The Physico-chemical properties of developed multi-layered and commercial PP film stored idli batter with different blend ratios of rice to black gram (3:1 and 4:1) were evaluated in terms of pH, percent titrable acidity (% TA), colour value (∆E), viscosity (cP) and volume measurement (ml). Idli cake prepared with batter stored in multi-layered film and evaluated in terms of colour, texture and percent pore characteristics. The percent pore presents in per square inches of prepared idli cake with different blend ratios and fermentation time were analysed using the grayscale image in MATLAB.
Results and Discussion: The pH value of stored batter ranges from 6.7 to 4.5 or lower, to reach pH below 4.5 or lower commercially stored batter took 24 h and batter stored in the multi-layered film took 36 h at ambient temperature. The multi-layered stored batter showed better results of physicochemical properties in terms of fermentation time. Idli cake prepared with 3:1 blend ratio showed good results in terms of textural properties with compared to 4:1 blend ratio. Idli cake prepared with 3:1 blend ratio showed more pore percentage (21.88-36.80%) as compared to 4:1 blend ratio (18-32.98%) in per square inch. Due to higher barrier properties of the multi-layered film, the bacterial count increases at a slow rate and help to extend the shelf life of packaged batter more than 30 h at ambient temperature.
46
Rajamuthu, Varun Prasanna, Sanskar Panse, and Srinath V. Ekkad. "Heat Transfer Enhancement Through Array Jet Impingement on Strategically Placed High Porosity High Pore-Density Thin Copper Foams." Journal of Electronic Packaging, November 19, 2020. http://dx.doi.org/10.1115/1.4049173.
Повний текст джерелаАнотація:
Abstract High porosity, high pore-density (pores per inch: PPI) metal foams are a popular choice in high heat flux cooling applications as they offer large heat transfer area over a given volume, however, accompanied by a concomitant increase in pumping power requirements. Present experimental study aims towards developing a novel metal-foam based cooling configuration featuring thin copper foams (3 mm) subjected to orthogonal air jet array impingement. The foam configurations allowed strategic and selective placement of high pore-density (90 PPI) and high porosity (~ 96%) copper foam on the heated surface with respect to the jet array in the form of foam stripes aiming to enhance heat transfer and reduce pressure drop penalty. The thermal-hydraulic performance was evaluated over range of Reynolds numbers, jet-to-jet (x/dj ,y/dj) and jet-to-target (z/dj) spacings and compared with a baseline smooth surface. The effect of pore-density was further analyzed by studying 40 PPI copper foam and compared with corresponding 90 PPI foam arrangement. The thermal-hydraulic performance was found to be governed by combinational interaction of three major factors: heat transfer area, ease of jet penetration and foam volume usage. Strategic placement of metal foam stripes allowed better utilization of the foam heat transfer area and available foam volume by aiding penetration of coolant fluid through available foam thickness. Thus, performing better than the case where entire heat transfer area was covered with foam. For a fixed pumping power of 10 W, the optimal metal foam-jet configuration showed ~50% higher heat transfer with negligible increase in pumping power requirements.
47
Richardson, James T., and Martyn V. Twigg. "Ceramic Foam Catalyst Supports Preparation and Properties." MRS Proceedings 368 (1994). http://dx.doi.org/10.1557/proc-368-315.
Повний текст джерелаАнотація:
Successful catalyst supports must fulfill different requirements simultaneously [1]. By serving as a base for catalytic components, they provide good activity and selectivity, but certain physical properties are equally important. For example, small catalyst particles are desirable in order to avoid external heat and mass transfer limitations and to provide high effectiveness for the active component dispersed throughout the particle. However, small particles pack with low bed porosities and unacceptable pressure drop results. Open-pore ceramic foams show promising properties that could overcome these difficulties. They have good high temperature resistance, low bulk density and tortuous flow patterns, together with open porosity as high as 85% formed from megapores 0.04 to 1.5 mm in diameter [2]. Characteristic parameters include cell size, window size and surface area, all correlated with the number of pores per inch [PPI]. Ceramic foams were first used as molten metal filters [3,4] and catalytic combustion devices [5–7]. Catalytic applications are beginning to appear and these have been reviewed by Twigg and Richardson [8].
48
Tsolas, Nicholas, and Sanjeev Chandra. "Forced Convection Heat Transfer in Spray Formed Copper and Nickel Foam Heat Exchanger Tubes." Journal of Heat Transfer 134, no. 6 (May 8, 2012). http://dx.doi.org/10.1115/1.4006015.
Повний текст джерелаАнотація:
A thermal spray coating process was used to deposit dense 2 mm thick metal skins on the surfaces of square cross-section channels (300 mm × 20 mm × 20 mm) of nickel and copper foams with 10 and 40 PPI (pores per inch) pore densities. A heater was wrapped around the channels to apply surface heat-fluxes varying from 427 to 6846 W/m2. Compressed air was blown through the channels at flow rates of 5–80 l/min. Foam and fluid temperature distributions along the length of the channel and the pressure drop across it were measured. The foam was modeled as a porous medium and properties such as permeability K and inertial coefficient CF were determined from the experimental data. Local and average convective heat transfer coefficients were calculated from air and foam temperature measurements. Nusselt numbers were calculated and correlated in terms of the Reynolds, Prandtl, and Darcy numbers. Heat transfer to air flowing through a 10 PPI foam channel was shown to have increased nearly seven times compared to that of hollow tube with the same dimensions.
49
Feng, S. S., J. J. Kuang, T. J. Lu, and K. Ichimiya. "Heat Transfer and Pressure Drop Characteristics of Finned Metal Foam Heat Sinks Under Uniform Impinging Flow." Journal of Electronic Packaging 137, no. 2 (June 1, 2015). http://dx.doi.org/10.1115/1.4029722.
Повний текст джерелаАнотація:
A numerical investigation was carried out to characterize the thermal performance of finned metal foam heat sinks subject to an impinging air flow. The main objective of the study was to quantify the effects of all relevant configurational parameters (channel length, channel width, fin thickness, and fin height) of the heat sink upon the thermal performance. Open-cell aluminum foam having fixed porosity of 0.9118 and fixed pore density of five pores per inch (PPI) was used in the study. A previously validated model based on the porous medium approach was employed for the numerical simulation. Various simulation cases for different combinations of channel parameters were carried out to obtain the Nusselt number correlation. Based on the inviscid impinging flow, a pressure drop correlation was derived for impinging flow in finned metal foam heat sinks. By using these correlations, the thermal performance of finned metal foam heat sinks was compared with the conventional plate-fin heat sinks. It was demonstrated that the finned metal foam heat sinks outperformed the plate-fin heat sinks on the basis of given weight or given pumping power.
50
Mazumder, Abul Fazal, Harsha Amunugama, and Upul Attanayake. "Impact of Concrete Mix Ingredients and Surface Treatments on Epoxy Overlay Performance." Transportation Research Record: Journal of the Transportation Research Board, June 1, 2021, 036119812110148. http://dx.doi.org/10.1177/03611981211014887.
Повний текст джерелаАнотація:
Epoxy overlays are applied on bridge decks after curing concrete in patches and repairs for 28 days. A tensile bond pull-off strength of at least 250 pounds per square inch (psi) is expected from a properly applied overlay. Even though the overlay performance at room temperature is mostly satisfactory, the performance at elevated temperatures is not convincing. The degradation of mechanical and adhesion properties of epoxy, shear stress at the concrete/overlay interface caused by thermal incompatibility, and the interface moisture vapor pressure are the commonly cited parameters for poor bond strength at elevated temperatures. A combined effect of these parameters results in the most unfavorable failure mode (which is bond failure at the concrete/overlay interface) at a strength lower than the specified limit of 250 psi. The moisture migration through concrete depends on many factors including moisture content along the depth of concrete, pore microstructure, exposure condition, and drying period. This study investigated the impact of concrete mix ingredients and surface treatments on the thin epoxy overlay bond strength. The results show that the use of concrete mixes with slag and penetrating sealant pretreatment improves the bond strength.