Effect of nitrogen flow ratio on structure and properties of zirconium nitride films on Si(100) prepared by ion beam sputtering

In this study, zirconium nitride thin films were deposited on Si substrates by ion beam sputtering (IBS). Influence of N₂/(N₂+Ar) on the structural and physical properties of the films has been investigated with respect to the atomic ratio between nitrogen and zirconium. It was found that the thickness of layers decreased by increasing the F(N₂). Moreover, crystalline plane peaks such as (111), (200) and (220) with (111) preferred orientation were observed due to strain energy which associate with (111) orientation in ZrN. Also, the fluctuation in nitrogen flow ratio results in colour and electrical resistivity of films.     

Digital mass flow rate meter using square-root analogue to digital converter

This paper deals with the design and construction of a digital signal processing meter to provide a digital output proportional to the moss flow rate of a gas. It employs a triple-slope technique and a non-linear square-root type of analogue to digital converter (ADC). The triple-slope square-root ADC is based on a dual-slope integrating converter. Linear and digital ICs have been used throughout the design of this digital meter.     

PROCESS INTENSIFICATION OF MEMBRANE SYSTEM FOR CRUDE PALM OIL PRETREATMENT

In the study conventional refining, microfiltration and ultrafiltration processes have been used experimentally to pretreat crude palm oil (CPO) samples with the aim of moving from the usual huge refinery plant to a more process integrated membrane module at ultrascale size that will even perform better than the former. Reduction of phosphorus for the membrane‐permeate of 43.4% was higher than that of bleached oil of 34.4%. When ceramic membranes with pore diameters of 0.45 µm and 0.2 µm were used in microfiltration, it was found that membrane with pore size of 0.45 µm was able to reject 14% of phosphorus, while ceramic membrane with pore size of 0.2 µm showed better phosphorus rejection of 56.8%. Upon applying ceramic membrane with pore sizes of 20 nm and 50 nm, 78.1% and 60% of phosphorus were rejected, respectively. Attributed to the superior performance of the membrane with 20 nm pore size over other membranes and conventional refining method on phosphorus content, a simulation study thus made, showed that the average slurry volume after about 22‐min runs for membrane with pore sizes of 0.45 µm, 0.2 µm, 50 nm and 20 nm, and the average slurry volumes are 0.05, 0.09, 0.13 and 0.18 m ³ , respectively. The percentage decrease between membrane pore size of 0.45 µm and 0.2 µm; 0.45 µm and 50 nm; and 0.45 µm and 20 nm are 73, 49 and 24%, respectively. The ultrafiltration achieved order of process miniaturization of about 10 ² ?10 ³ , which is in accordance with literature. This is a considerable size reduction in the process size, which reflects the magnitude of slurry volume that can be produced within a given time and meets every standard for process intensification through simulated process miniaturization.     

Turbulent Magneto-Convection in a Differentially Heated Enclosure

Numerically investigation was carried out for turbulent magnetohydrodynamics natural convection in a square enclosure.The vertical walls are maintained isothermal at different temperatures and the horizontal walls are adiabatic.Non linear goveming equations for the fluid flow and heat transfer are solved by finite volume method.The computations are carded out for Rayleigh number 107,Hartmann numbers from 0 to 800 and Prandtl number 0.01(sodium).It is observed that as the Hartmarm number increases the stratification of the temperature field in the interior reduces,and the thermal boundary layers at the two side walls begin to diminish and the isotherms become almost parallel to the vertical walls which indicates that natural convection heat transfer has been changed to conduction mode.     

Visualization and Modeling of Flow Boiling of R-134A in Minichannels with Transverse Ribs

This research was undertaken to investigate the flow boiling of R-134a in minichannels with transverse ribs. The test channel consisted of two parallel plates; the lower plate was heated, and the upper plate was adiabatic. A number of transverse ribs were deployed along the lower plate. The hydraulic diameter of the channel was 1.93 mm. In these experiments, the main test parameters were mass flux, saturation temperature, heat flux, and average vapor quality. With these parameters, the convective and boiling numbers ranged from 0.04 to 0.90 and 7.49 × 10^{? 4} to 8.98 × 10^{? 4} , respectively. Of a total of 60 data points recorded, 78% of the data fell in the convective boiling region, while the remaining 22% were in the nucleate boiling region. A two-equation model was fit to a total of 60 experimental data, resulting in a correlation that predicted 58 data points to within ± 10%.     

Efficient three‐phase reconstruction of heterogeneous material from 2D cross‐sections via phase‐recovery algorithm

Digital reconstruction of a complex heterogeneous media from the limited statistical information, mostly provided by different imaging techniques, is the key to the successful computational analysis of this important class of materials. In this study, a novel approach is presented for three‐dimensional (3D) reconstruction of a three‐phase microstructure from its statistical information provided by two‐dimensional (2D) cross‐sections. In this three‐step method, first two‐point correlation functions (TPCFs) are extracted from the cross‐section(s) using a spectral method suitable for the three‐phase media. In the next step, 3D TPCFs are approximated for all vectors in a representative volume element (RVE). Finally, the 3D microstructure is realized from the full‐set TPCFs obtained in the previous step, using a modified phase‐recovery algorithm. The method is generally applicable to any complex three‐phase media, here illustrated for an SOFC anode microstructure. The capabilities and shortcomings of the method are then investigated by performing a qualitative comparison between example cross‐sections obtained computationally and their experimental equivalents. Finally, it is shown that the method almost conserves key microstructural properties of the media including tortuosity, percolation and three‐phase boundary length (TPBL).     

PROCESSING OF CRUDE PALM OIL WITH CERAMIC MICROFILTRATION MEMBRANE

Membrane separation technology offers a potential application in the processing of crude palm oil. Ceramic membranes with different pore diameters (0.45 and 0.2 micron) were used to conduct the study on micromembrane process. Quality parameters of membrane-processed oils examined included free fatty acid (FFA), carotene, fatty acid composition (FAC), phosphorus and iron contents. The effect of operating parameters such as transmembrane pressure, feed flow and time on permeate flux were evaluated. It was found that 'Ceraflo'ceramic membrane with a pore size of 0.45 micron was only able to reject 14% of phosphorus from the crude oil. Ceramic membrane with pore size of 0.2 micron showed a better phosphorus rejection of 56.8%. The permeate was found to contain 7.13 ppm of phosphorus. The 0.2 micron membrane was also able to remove more than 80% of the iron from crude palm oil. Pore sizes for both membranes were not small enough to remove other components such as FFA, and carotene. Both membranes showed a similar trend in which the permeate flux increased with transmembrane pressure and feed flow until a certain limit where the flux declined with increasing pressure and feed flow. The limits in transmembrane pressures for membrane with pore sizes of 0.45 and 0.2 micron were 1.65 and 1.25 bar, respectively. Whereas the limits in feed flow for 0.45 micron and 0.2 micron membranes were 9.2 and 9.8 L/min