In the last issue, I mentioned about the easy and affordable energy. Energy is the lifeline of humankind, and we need to look for renewable energy sources to compensate for the fast depleting natural energy sources in vogue now. There is a lot of discussion these days about biofuels as renewable energy source. Biofuel is an excellent fuel—it burns cleaner than petroleum-based fuels and is easier on the internal combustion engine. Moreover, we can grow biofuel, which means it is totally renewable. But can biofuel completely replace crude oil? The answer, at least for now, is absolutely not—both technically and economically. Even if a fairly high-yielding biofuel crop is planted all over the world, yielding 1,000 barrels of oil per year per square kilometer, and even if this biofuel is grown on every available scrap of farmland on earth, we would only replace 20% of the energy we are currently getting from crude oil. Where will the 80% come from? But, yes, biofuels can greatly supplement crude oil supplies, and is an important part of future energy solutions, but that is as far as it goes.

A renewable alternative fuel that can be a direct replacement for diesel in Compression Ignition (CI) engines is the need of the hour, in the backdrop of the global petroleum-based fuel crisis. “Performance Evaluation of Palmester Oil Blends with Diesel in Compression Ignition Engine” by C Vijaya Bhaskar Reddy, B Jayachandraiah and K Madan Mohan Reddy is a timely study, given the search for alternative fuels to counter the ever-diminishing oil reserves. Palmester oil, a clean burning alternative fuel produced from palm oil, contains no petroleum, but it can be blended with petroleum or diesel to get a biodiesel blend. Palmester oil is simple to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics. In the present investigation, the authors prepared palmester oil by transesterification method to make it suitable for use in CI engine. The engine performance has been evaluated for six specific blends with palmester oil content varying from 10% to 50% in combination with diesel, and also with 100% palmester. The performance of the engine was evaluated with a 4-stroke single cylinder CI engine using palmester oil blends, and the performance was compared with that of 100% diesel fuel. Their results indicated that 20% palmester blend gave performance close to that of diesel and 100% palmester gave lower brake thermal efficiency.

Magnetic abrasive processes are more efficient and produce a better surface finish than the conventional super-finishing operations. The magnetic abrasives play a vital role in Magnetic Abrasive Machining (MAM), a relatively new finishing method for harder materials. Lakhvir Singh, Sehijpal Singh and P S Mishra, in their paper, “Internal Surface Finishing of Brass Tubes by Dry/Wet Magnetic Abrasives”, have compared the performance of dry and wet magnetic abrasives when used for the internal finishing of brass tubes. To make the magnetic abrasives wet, high speed diesel (20% by weight) was used as the lubricant. They have found that the improvement in surface finish and Material Removal Rate (MRR) were more in the case of wet magnetic abrasives, as compared to the dry magnetic abrasives. The maximum improvement in surface finish with dry magnetic abrasives was around 55%, while in the case of the wet magnetic abrasives, it was up to 70%. The improvement in MRR with wet magnetic abrasives was found to be around 100%. Based on the findings, the authors recommend the use of high speed diesel as the lubricant in MAM.

In the third paper, “Visualization of Air-Water Type Two-Phase Flow Patterns”, by Mahesh J Vaze and Jyotirmay Banerjee, an experimental setup has been developed to visualize the temporal and spatial organization of air-water, two-phase flow patterns, with the objective of developing a comprehensive comparison with experiments for establishing the strength and reliability of the existing CFD models. For a gas-liquid, two-phase flow, the phenomena of bubble coalescence, growth and breakup, and the mass, momentum and energy exchange between the two phases add up to the numerical complexities towards capturing these flow patterns using Computational Fluid Dynamics (CFD) models. The flow patterns captured with a high speed camera are compared with the numerically visualized flow patterns obtained using the Volume of Fluid (VOF) model for the two-phase flow. The development of stratified, wavy, plug, slug and annular flow patterns is discussed in detail, and interfacial and wall shear stresses for all these patterns are compared. The authors have established that for air-water two-phase flows, the experimentally visualized and numerically simulated images show that the VOF model captures stratified, wavy and annular flow patterns effectively. On the other hand, for slug and plug flow patterns, which involve bubble growth and disintegration, qualitative differences are observed between numerical flow patterns and experimental images.

For optimizing the cost of manufacturing parts, energy (force/power) requirement and material waste are two important factors. The techniques of moving the metal rather than removing it are two of the major options available. In getting the desired shape, localizing the deformation zone to a small volume of the workpiece results in reducing the forming forces, lower press capacity, and saving in the materials and energy for getting the final part. In the paper, “Power and Forces in the Making of Long Tubes with Different Materials”, by Sukhwinder Singh Jolly and Devinder Singh, a comparative study of the power and forces required in the making of long tubes has been carried out. The condition of volume constancy has been satisfied. The total energy and forces consumed in the deformation of various materials have been found and various process parameters have been plotted. Various conclusions with explanations have been presented.

Glass Fiber Reinforced Polymer (GFRP) composite materials are replacing traditional engineering materials owing to their better properties. The paper, “Response Surface Methodology Tool for Predicting Engineering Constants of Glass Fiber Reinforced Composite Angle Lamina”, by Syed Altaf Hussain, K Palani Kumar and V Pandurangadu, gives a finite element model incorporating the necessary boundary conditions, which was solved using the commercially available FEA (ANSYS 11.0) package. The response surface models for longitudinal Young’s modulus, transverse modulus, major Poisson’s ratio, and in-plane shear modulus have been developed using the data obtained from ANSYS results. These four important engineering constants of a GFRP angle-ply lamina have been evaluated for three fiber volume fractions. The adequacy of the developed model is verified by using coefficient of determination and Analysis of Variance (ANOVA) methods. Their study shows acceptable prediction results for the response surface models. The ANOVA F-test results show an average accuracy of 0.997 for longitudinal Young’s modulus, 0.984 for transverse modulus, 0.953 for in-plane shear modulus and 0.998 for major Poisson’ ratio.

- - R K Mittal
Consulting Editor