Effect of water depth on internal heat and mass transfer for active solar distillation

In this communication, an attempt has been made to find out the convective heat transfer coefficient for active solar distillation system. It is a well-known fact that the distillate output (the yield) decreases significantly with the increase of water depth in the basin of the solar still. It is also known that more yield is obtained in case of active solar distillation system as compared to passive solar still due to higher temperature difference between the water and inner glass cover temperatures in the active mode. For the present study, experiments have been conducted for 24 hours during winter months for different water depths in the basin (0.05, 0.1 and 0.15 m) for passive as well as active solar distillation system. The objective of the present paper is to study the effect of different water depths in the basin on the heat and mass transfer coefficients. It is inferred that the convective heat transfer coefficient between water and inner condensing cover depends significantly on the water depth in the basin. It is also observed that more yield is obtained during the off shine hours as compared to daytime for higher water depths in solar still (0.10 m and 0.15 m) due to storage effect.     

Mechanism of C2+ oxygenate synthesis on Rh catalysts

This paper examines the reaction pathways and the nature of active sites for CO hydrogenation in general and C₂₊ oxygenate synthesis over Rh catalysts in particular.     

Solid Suspension in Jet Mixers

Experiments have been carried out with jet mixers to study the solid suspension characteristics. The jet velocities required for solid suspension in 0.5 and 1 m ID tanks were measured experimentally. The nozzle diameter was varied from 0.0156 to 0.05 m. The nozzle clearance from the tank bottom was varied from 0.1 to 0.9 m. Tap water and sand of average sizes 100, 300, and 500 µm were used. The solid loading was varied from 1 to 5% (wt.). The effect of nozzle angle was also studied. A semi‐empirical model has been developed to predict the jet velocity needed to achieve a certain degree of suspension.     

Effect of immobile water content on contaminant transport in unsaturated zone

The effect of immobile water content on contaminant advection and dispersion in unsaturated porous media has been studied using a formulation which assumes that even in the immobile liquid zone, there occurs minor liquid flow. An approach is proposed for computing this liquid velocity. One dimensional numerical simulation is carried out to study the effect of immobile water content on the time of appearance of contaminant at the bottom of an unsaturated column. The numerical model developed is verified using analytical solutions for simple advective-dispersive cases. From the simulations, it was observed that increase in the immobile water content leads to quicker appearance of contaminant.     

Investigation on the Phase Diagram of LiCl-KCl-NdCl<Subscript>3</Subscript> Pseudo-Ternary System

The ternary phase diagram of LiCl-KCl-NdCl₃ system has been investigated by differential thermal analysis (DTA), followed by characterization of the coexisting phases in the solid state by x-ray diffraction, in order to understand the interactions in the NdCl₃-LiCl-KCl ternary system. The results of these experiments showed that LiCl and K₂NdCl₅ form a non binary join section. This divides the LiCl-KCl-NdCl₃ system into two quasi-ternary sections, namely (1) LiCl-KCl-K₂NdCl₅ and (2) LiCl-K₂NdCl₅-NdCl₃ systems. Both are simple eutectic ternary phase diagrams. The ternary eutectic temperatures and eutectic compositions are determined to be 316?±?3 °C and 53.9 mol.% LiCl-38.7 mol.% KCl-7.4 mol.% K₂NdCl₅ in the LiCl-KCl-K₂NdCl₅ quasi-ternary section, while the other eutectic temperature and composition are determined to be 376?±?9 °C and 46.2 mol.% LiCl-32.5 mol.% K₂NdCl₅-21.3 mol.% NdCl₃ in the LiCl-K₂NdCl₅-NdCl₃ quasi-ternary section. A quasi-ternary peritectic reaction is observed at 37.7 mol.% LiCl-36.2 mol.% KCl-26.1 mol.% K₂NdCl₅ at 445?±?1°C. The primary and secondary crystallization temperatures for the samples are deduced from the heating runs of DTA traces, and the phases responsible for the various thermal events are ascertained. Isothermal sections at chosen temperatures and polythermal liquidus projection with isothermal contours are drawn over the ternary phase field.     

Enhanced nanofluidization by alternating electric fields

We show experimental results on a proposed technique to enhance the fluidization of nanoparticle beds. This technique consists of the application of an alternating electric field to the nanofluidized bed. Three different field configurations have been tested: co‐flow field, cross‐flow field, and variable field configurations. Nanoparticle agglomerates are naturally charged by contact and tribo charging mechanisms and therefore are agitated by the action of the externally applied field, which enhance fluidization. According to our observations, the best results are obtained for the variable field configuration. In this configuration, the electric field strength is higher at the bottom of the bed, whereas it is almost negligible at the free surface. Thus, the larger agglomerates, which tend to sink at the bottom of the bed due to stratification, and usually impede uniform fluidization, are strongly agitated. It is thought that the strong agitation of the bigger agglomerates that usually sink to the bottom of the bed contributes to further homogenize the distribution of the gas flow within the bed by destabilizing the development of gas channels close to the gas distributor. On the other hand, the smaller agglomerates at the vicinity of the free surface are just weakly excited. Consequently, fluidization is greatly enhanced, whereas at the same time excessive elutriation is avoided. It is demonstrated that this technique is even suitable to achieve highly expanded fluidization of unsieved nanopowder samples even though the fluidization state returns to be heterogeneous upon the electric field being turned off. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

The First Example of Saccharin‐Lithium Bromide Catalysis: Direct Synthesis of N‐Tosylimines from Alcohols

The first procedure to access N‐tosylimines directly from alcohols under mild and neutral conditions is reported. The protocol involves saccharin‐lithium bromide‐catalyzed oxidation of alcohols to aldehydes/ketones with chloramine‐T followed by their condensation with the in situ generated oxidation by‐product p‐toluenesulfonamide in the same reaction vessel to afford N‐tosylimines in 40–90% overall yields. The present work opens up a new and efficient synthetic route to N‐tosyimines directly from alcohols in a one‐pot procedure.     

Synthesis of Amido‐N‐imidazolium Salts and their Applications as Ligands in Suzuki–Miyaura Reactions: Coupling of Hetero‐ aromatic Halides and the Synthesis of Milrinone and Irbesartan

A new catalytic system based on palladium‐amido‐N‐heterocyclic carbenes for Suzuki–Miyaura coupling reactions of heteroaryl bromides is described. A variety of sterically bulky, amido‐N‐imidazolium salts were synthesized in high yields from the corresponding anilines. This catalytic system effectively promoted Suzuki–Miyaura couplings of heteroaryl bromides and chlorides with a range of boronic acids to give the corresponding aryl compounds in high yield. The yield was increased with increasing steric bulkiness of the substituted group. Especially, 1‐(2,6‐diisopropylphenyl)‐3‐N‐(2,4,6‐tri‐tert‐butylphenylacetamido)imidazolium bromide ( 4bc ) exhibited 850,000 TON in the coupling reaction of 2‐bromopyridine and phenylboronic acid. In addition, pharmaceutical compounds such as milrinone and irbesartan were synthesized via Suzuki–Miyaura coupling using sterically bulky, amido‐N‐imidazolium salt ( 4bc ) as a ligand.     

A Novel FRFT Beamformer for Rayleigh Faded Channels

A method of optimal beamforming for flat Rayleigh faded channels using the Fractional Fourier Transform (FRFT) is considered in this paper. It has been demonstrated through simulations that optimal beamforming with FRFT allows smaller mean-square errors in restoring signals degraded with linear time-or frequency variant distortions and Additive White Gaussian Noise. This is made possible by the additional flexibility that comes with free parameter ‘a’ of the fractional Fourier transform as oppose to the classical Fourier transform (FT). The method is especially useful in moving source problems, where Doppler Effect produces frequency shift when the source is moving, as in mobile and wireless communication where user produces the frequency shift while moving. In this paper it is shown through simulations that beamforming in fractional domain reduces BER as compared to time or frequency domain.     

Experimental and Morphological Investigations Into Electrical Discharge Surface Grinding (EDSG) of 6061Al/Al2O3p 10% Composite by Composite Tool Electrode

In this study, a special experimental setup of EDSG using EDM and surface grinding machine has been developed in the laboratory to investigate the effect of seven input parameters namely tool polarity, peak current, pulse on-time, pulse off-time, rotational speed, abrasive particle size, and abrasive particle concentration on material removal rate (MRR) as performance measure of the process. The novelty of the present research work is that successful efforts have been made to machine the 6061Al/Al₂O_3p 10% metal matrix composites (MMC) by composite tool itself. The copper-based composite tool electrodes were fabricated by powder metallurgy route with different sizes of abrasives of silicon carbide, while 6061Al/Al₂O_3p 10% MMC were fabricated through stir-casting process. The research outcome will identify the important parameters and their effect on MRR of 6061Al/Al₂O_3p 10% composite in EDSG. The experimental results reveal that tool polarity, peak current, and rotational speed are the most influential parameters that affect MRR in EDSG process. The micro-structural and morphological analysis of machined surfaces has also been carried out to analyze the surface topography. It has been concluded that the abrasive particles substantially improves the MRR after removing the resolidified layer from the machined surface.