Mechanical Engineering

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Friction and wear loss of various machining parts and pairs depend majorly on the quality of lubricants. Several types of additives are commercially used to enhance the tribological performance of a lubricant. In the present work, some novel lubricating liquids were prepared by mixing diffident additives, viz bromide, fluoride, iodide and acetate, in a commercial available SAE20W40 lubricant. Pin-on-disc investigations were performed to evaluate the effect of the prepared lubricants on wear rate and friction characteristics of mild steel and stainless steel sliding pair. Disc chamber was flooded with lubricants during testing. Fluoride was found to be the most successful additive to improve the performance of the given lubricant, whereas acetate as an additive made the base lubricant less efficient. It is believed that the strong bond stability of C–F bond during working conditions resulted in better performance of the lubricant after the addition of fluoride. © Springer Nature Singapore Pte Ltd 2020.

(SoE) School of Engineering

World University root node

Lecture Notes in Mechanical Engineering

Effect of some additives on tribological properties of SAE20W40 lubricant

Performance improvement of the PVT module is a very important topic in recent decades. Solar energy is a vital resource for mankind. Continuous elevation of the cell temperature of the PVT module results in a decrease in PV electrical efficiency. This review paper discusses the different techniques to cool the solar cell in order to reduce its cell temperature increasing its electrical efficiency and, also use the collected vital thermal energy to heat water (increase thermal efficiency) in a heat exchanger. A brief study on PVT/PCM and PVT/Nano-fluid system is done in this review paper. Furthermore, the PVT system is observed to be a very effective way to extract most of the available solar energy. Therefore, work must be carried out to increase their efficiency with the application of nano-fluids and phase change materials along with fins, or the use of binary nano-fluids/ nano- PCM to reduce the cost. This review paper highlights the application of PCM and nano-fluids for the effective cooling of the PV panel. © 2020 IEEE.

International Conference on Electrical and Electronics Engineering, ICE3 2020

Performance improvement of PVT module with applications of nano-fluids and phase change materials: A review

Vibratory finishing processes are finding extensive use in multiple industries because of their ability to be able to provide a high level of surface finish. Despite their extensive applications, it is difficult to be able to develop predictive mechanism for the process, given its sensitivity to a wide range of parameters. Simultaneously, traditional computational fluid dynamics–based attempts are limited by their mesh-based Eulerian approaches from being able to simulate problems that are more complicated. Previous computational models have had limited success in correlating the roughness parameters with the predicted values. This paper extends previous research to develop a smoothed particle hydrodynamics–based Lagrangian approach to simulate key metrics of the vibratory finishing process, which can then be used to predict the surface roughness. These models were validated against experimental results from prior research as well as a new finite volume method–based model and were found to be able to provide a better model for the material removal process than previously proposed models. Finally, this research explores the effect of the various parameters on the smoothed particle hydrodynamics formulation and validates its use for simulating granular media flows. © 2020, Springer-Verlag London Ltd., part of Springer Nature.

International Journal of Advanced Manufacturing Technology

Application of smoothed particle hydrodynamics for the simulation and analysis of vibratory finishing process

Surface with inherent self-cleaning characteristics is often deemed and desired. However, lack of durability and high cost limits the applicability of such surfaces in a real-life scenario. In present work, we report the development of durable and cost-effective nanocomposite coatings using silica particles (˜ 250 nm) derived from agricultural waste, rice-husk and different fractions of polydimethylsiloxane (PDMS). Developed coatings showed the presence of hierarchical structures with nanoscale protrusions. The surface morphology of the coatings was significantly influenced by the PDMS content with roughness factor following an inverse correlation. Static and dynamic contact angles increased with decreasing PDMS content with maximum values observed to be in excess of 160°. Simultaneously, the contact angle hysteresis (< 5° to 20°) and tilting angle (5° to 60°) were also significantly influenced by the PDMS fraction. The observed results are related with ability to retain stable Cassie state and pinning of the liquid-air interface by nano protrusions. Droplet impingement tests and critical wetting angle calculations showed transition from Cassie to metastable wetting state for coatings with higher PDMS. Durability studies performed under different modes indicated a trade-off with self-cleaning ability, highlighting an optimum composition possessing required characteristics. The selected coating subjected to weathering test showed due resilience under outdoor conditions. The present work showed that the agricultural waste can be effectively used for developing low-cost high-end product possessing exceptional functionalities. © 2019 Elsevier B.V.

Progress in Organic Coatings

Multidimensional durability of superhydrophobic self-cleaning surface derived from rice-husk ash

The groundnuts were dried inside an even span roof type free convection greenhouse dryer with a useful floor area of 1.2×0.8 m2 in the environmental conditions of Rohtak, India (28o54′-N 76o34′E). Wire mesh sieves of sizes 0.15×0.25 m2, 0.25×0.4 m2, and 0.35×0.6 m2 were used to accommodate thin layer samples of groundnuts. The groundnuts were dried till the optimum safe moisture storage level (8%-10%) was attained. Based on experimental (hourly) observations the values of constants (C and n) in the equation of Nusselt number were evaluated. The values of convective and evaporative heat transfer coefficients were calculated which were observed to decrease with the increase in the sieve size. The overall average greenhouse thermal, energy, and exergy efficiencies were evaluated as 8.83%, 22.67%, and 2.75% respectively. The overall average experimental error in terms of % uncertainty for groundnuts drying was evaluated as 37.94%. © 2019, Int. Comm. of Agricultural and Biosystems Engineering. All rights reserved.

Agricultural Engineering International: CIGR Journal

Experimental free convection thin layer groundnut greenhouse drying

Fresh water is one of the essential requirements for the human being. To ensure the availability of potable water for the society is a big challenge due to limited availability of potable water on the Earth. Solar desalination systems can be used for mitigating the scarcity of desalted water in remote areas where sunlight is available in abundance. It works on the simple principle of evaporation and condensation. These systems are almost maintenance free and zero running cost which can be fabricated by materials readily available in the local market. The various designs of passive solar stills are used to increase the efficiency and productivity of distillate. In the present work, different types of specially designed single basin solar stills have been reviewed to find out the performance based on its efficiency, productivity and economy. Various novel models have also been observed for better view of relative performance among all solar stills to establish its clear utility indications as well. The observations have been concluded with broad perspective and some recommendations have also been suggested for the future scope for developing new designs to meet the possible challenges. © 2019 International Solar Energy Society

Solar Energy

Performance analysis of specially designed single basin passive solar distillers incorporated with novel solar desalting stills: A review

In this study, we demonstrate a novel pathway to engineer the properties of metallic alloys for limiting their cavitation erosion-corrosion. A facile single-step processing technique was used to develop bimodal grain structure in stainless steel. The bimodal steel was tested in cavitation erosion and erosion-corrosion conditions. In both the cases, bimodal steel showed exceptionally high degradation resistance, nearly 7 times higher compared to as-received steel. The remarkable cavitation erosion resistance demonstrated by bimodal steel is attributed to its high yield strength along with high work-hardening rate. In addition, the bimodal steel showed significantly low corrosion rate of 0.001 mm/year in 3.5 wt \% NaCl solution compared to 0.088 mm/year for as-received stainless steel. © 2019 Elsevier Ltd

Tribology International

Exceptional cavitation erosion-corrosion behavior of dual-phase bimodal structure in austenitic stainless steel

Slurry and cavitation erosion often limits the durability of many fluid machines such as hydroturbines, pumps, and propellers. Despite good resistance against slurry erosion, thermal spray coatings generally exhibit poor resistance against cavitation erosion. The performance of thermal spray coatings under cavitation erosion is limited by the presence of defects such as pores, splat boundaries, and limited adhesion with the substrate. In the present work, we performed post-processing of the WC-10Co-4Cr and Ni coatings deposited using the detonation gun process. For post-processing, microwave technique was used owing to its capability for atomic-level heating. The microstructural characterization of the as-sprayed and post-processed coatings showed significant homogenization for the latter. Compared to the typical lamellar structure of as-sprayed, the processed samples exhibited a columnar structure with metallurgical bonding with the substrate. The mechanical properties of the coatings were significantly improved after post-processing owing to the elimination of splat boundaries and pores which significantly enhanced the cavitation and slurry erosion resistance. Post-processed coatings showed at least ten times higher resistance to cavitation erosion. The slurry erosion resistance of the coatings also improved up to three times depending upon the impingement angle. A significant difference in the erosion mechanism was also observed after post-processing. © 2019, ASM International.

Journal of Thermal Spray Technology

Microwave-Assisted Post-processing of Detonation Gun-Sprayed Coatings for Better Slurry and Cavitation Erosion Resistance

This work presents the numerical analysis of natural fiber reinforced composites (from renewable sources), to evaluate the mechanical behavior of Bio-composites and elucidated the role of micro-mechanical analytical models (Rule of Mixtures and Halpin-Tsai models). Specifically, this study is carried out to perform the Multi-scale modeling and simulation of Biocomposite that constitute of sisal fiber reinforcement and Epoxidized Soybean-Oil (ESO) based matrix. In general, it is difficult to predict the effective properties of natural fiber reinforced composites due to its heterogeneous properties. The Representative Volume Element (RVE) model is capable to estimate the effective properties of Bio-composites. Therefore, RVE model is designed and analyzed based on micro-mechanics by taking the individual properties of fiber and matrix as an input. As a result, the effective properties of Bio-composite can be obtained. Subsequently, a 3-D model of Bio-composite laminated plate behavior is analyzed based on macro-mechanics by taking the effective properties of Bio-composite obtained from micro-mechanical analysis. The obtained effective properties of Bio-composite are validated with the theoretical (Rule of Mixtures) results. The micro-mechanical analysis is carried out using the Digimat (Multi-scale modeling and simulation tool) and macro-mechanical analysis is performed using Ansys software. © 2019 IOP Publishing Ltd. All rights reserved.

Fulltext

Journal of Physics: Conference Series

Multi-scale modeling and simulation of natural fiber reinforced composites (Bio-composites)

Cracks and multiple voids resulting from manufacturing processes interact with each other and severely affect the fracture phenomenon of piezoelectric components. These geometrical discontinuities degrade the service performance and lower the reliability of the piezoelectric devices. Therefore, the present work predicts fatigue-cracking behavior of piezo-electric structures in existence of multiple geometrical discontinuities under cyclic thermal-electrical-mechanical loads using extended finite element method (XFEM). Thermal interaction integrals approach and Stroh formalism are applied for estimating stress intensity factors (SIFs). Modified hoop SIF criterion has been utilized to predict crack growth direction under quasi-static fatigue loading conditions. © 2019 Elsevier Ltd