نتایج جستجو برای: volume fraction
تعداد نتایج: 447302 فیلتر نتایج به سال:
In this article CuO/water nanofluid was synthesized by using polyvinylpyrolidone (PVP) as the dispersant. Thenanofluid stability period and the heat transfer enhancement were determinedby measuring the thermal conductivities. To study the nano-fluid stability, zeta (ζ) potential, and absorbency were measured under different pH values and PVP surfactant concentrations; also thermal conductivity...
Although the volume fraction is a constant for a statistically homogeneous random medium, on a spatially local level it fluctuates. We study the full distribution of volume fraction within an observation window of finite size for models of random media. A formula due to Lu and Torquato for the standard deviation or ‘‘coarseness’’ associated with the local volume fraction j is extended for the n...
Currently available non-invasive clinical methods for diagnosing osteoporosis are mainly associated with ionizing radiation. Ultrasonic assessment of bone disease is a more recent technology. A theoretical explanation for the relationship between ultrasonic parameters and bone structure is necessary. Thus, two types of bone samples of perspex (HAP) and perspex-glass beads were produced. Ea...
In the present work the effect of Cu-Water nanofluid, as heat transfer fluid, on the performance of a parabolic solar collector was studied numerically. The temperature field, thermal efficiency, mean-outlet temperatures have been evaluated and compared for the conventional parabolic collectors and nanofluid based collectors. Further, the effect of various parameters such as fluid velocity, vol...
In the present work, the mathematical model of a homogeneous, isotropic thermoelastic double porous micro-beam, based on the Euler-Bernoulli theory is developed in the context of Lord-Shulman [1] theory of thermoelasticity. Laplace transform technique has been used to obtain the expressions for lateral deflection, axial stress, axial displacement, volume fraction field and temperature distribut...
In the present research, the laminar forced convective heat transfer and fluid flow characteristics for Al2O3-water nanofluid flowing in different bend (i.e., 180o and 90o) pipes have been investigated numerically in a three-dimensional computational domain using the finite volume technique. The effects of different pertinent parameters, such as the Reynolds number of the duct, volume fraction ...
In this paper, convection heat transfer of Al2O3-water nanofluid turbulent flow through internally ribbed tubes with different rib shapes (rectangular, trapezoidal and semi-circular) is numerically investigated. For each rib shape, the optimum geometric ratio and volume fraction were calculated using entropy generation minimization technique. The governing equations in...
Liquid paraffin as a coolant fluid can be applied in electronic devices as a result to its suitable capabilities such as electrical insulating, high heat capacity, chemical and thermal stability, and high boiling point. However, the poor thermal conductivity of paraffin has been confined its thermal cooling application. Addition of high conductor nanoparticles to paraffin can fix this drawback...
In this study, at first Al-Al2O3 composite powders having different volume fractions of Al2O3 (0, 10, 20, 30 and 40 vol.%) were produced by low energy mechanical alloying, which were used as foam materials. Then, composite foams with 50, 60, and 70 percent of porosity were produced by space-holder technique. Spherical carbamide particles (1-1.4 mm) were used to achieve spherical porosities. In ...
The effects of lower bainite volume fraction on tensile and impact properties of D6AC ultrahigh strength steel were studied in the current work. To obtain mixed microstructures containing martensite and different volume fractions of the lower bainite, specimens were austenitized at 910° C, then quenched in a salt bath of 330°C for different holding times, finally quenched in oil. In order to ob...
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