Mechanical Engineering

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Shiv Nadar University

In the present analysis, a photovoltaic (PV) integrated greenhouse system under forced mode developed for biogas heating. Different factors have been assessed for weather condition of IIT, New Delhi, India. Ambient air temperature and radiation data have been measured experimentally. Further, thermal model has been derived for the PV greenhouse and various factor like greenhouse air temperature, solar cell temperature, and outlet air temperature through duct have been evaluated with the help of MATLAB 2013a software. Thermal energy, electrical energy, overall thermal energy, overall thermal efficiency, cell efficiency and thermal efficiency have been calculated. Thermal energy, overall thermal energy electrical energy and for a clear day found to be 4.55 kWh, 0.60 and 6.14 kWh respectively. Further, overall average thermal efficiency throughout the day found to be 69%. © 2016 IEEE.

(SoE) School of Engineering

World University root node

2nd IEEE International Conference on Innovative Applications of Computational Intelligence on Power, Energy and Controls with their Impact on Humanity, CIPECH 2016

Energy analysis of photovoltaic-thermal (PVT) greenhouse under forced mode without load condition

Designing a durability test for an automatic transmission that appropriately reflects customer usage during the lifetime of the vehicle is a formidable task; while the transmission and its components must survive severe usage, overdesigning components leads to unnecessary weight, increased fuel consumption and increased emissions. Damage to transmission components is a function of many parameters including customer driving habits and vehicle and transmission characteristics such as weight, powertrain calibration, and gear ratios. Additionally, in some cases durability tests are required to verify only a subset of the total parameter space, for example, verifying only component modifications. Lastly, the ideal durability test is designed to impose the worst case loading conditions for the maximum number of internal components, be as short as practicable to reduce testing time, with minimal variability between tests in order to optimize test equipment and personnel resources. In this work, customer usage correlation data and fatigue damage models are used to analytically determine expected component level damage values. These values are then statistically evaluated to establish customer lifetime design targets. This paper describes a methodology for creating a combined duty cycle from a collection of routes by reverse deriving above design targets such that the combined duty cycle represents the customer lifetime design targets for multiple transmission components. The combined duty cycle data becomes the key input for designing or modifying a customized automatic transmission system durability key life test (KLT) for a given vehicle program. An analytical description of the method is provided, along with an example to demonstrate the concept. Copyright © 2017 SAE International.

SAE Technical Papers

A Method for Rapid Durability Test Development

Activation energy and diffusion kinetics are important in modulating the high temperature oxidation behavior of metals. Recently developed multi-principal element alloys, also called high entropy alloys (HEAs), are promising candidate material for high temperature applications. However, the activation energies and diffusion kinetics of HEAs have been limitedly explored. We investigate the diffusional activation energy for oxidation of Al0.1CoCrFeNi HEA. Compared to conventional steels and Ni-based super alloys, the HEA showed a significantly higher diffusion activation energy. This behavior is explained based on low potential energy of the lattice and interstitial sites which effectively trap the atoms, limiting their diffusion. The atomic mean jump frequency for interstitial diffusion of oxygen in the HEA is four-orders of magnitude lower than T22 and T91 steels and seven-orders of magnitude lower compared to pure iron. Al0.1CoCrFeNi HEA showed the lowest oxidation rate compared to conventionally used steels, super-alloys, and coatings. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Advanced Engineering Materials

Activation Energy and High Temperature Oxidation Behavior of Multi-Principal Element Alloy

Erosion-corrosion is a critical problem in marine components and has huge economic impact. In the current study, friction stir processing was utilized for enhancing the erosion-corrosion resistance of SS316L steel, most widely used material for marine applications. Compared to the unprocessed alloy, the friction-stir processed specimen showed nearly 3.5 times and 5 times higher erosion and erosion-corrosion resistance respectively at oblique impingement. In contrast, erosion and erosion-corrosion resistance for processed alloy was 2 times higher at normal impingement. The unusual enhancement in erosion-corrosion resistance was attributed to surface strengthening through grain-size refinement and martensite phase formation. In addition, higher corrosion resistance due to stronger passivation also contributed towards superior performance of the processed alloy. © 2017 Elsevier B.V.

Wear

Enhancing the erosion-corrosion resistance of steel through friction stir processing

Substrate-cell interactions for a bioimplant are driven by substrate's surface characteristics. In addition, the performance of an implant and resistance to degradation are primarily governed by its surface properties. A bioimplant typically degrades by wear and corrosion in the physiological environment, resulting in metallosis. Surface engineering strategies for limiting degradation of implants and enhancing their performance may reduce or eliminate the need for implant removal surgeries and the associated cost. In the current study, we tailored the surface properties of stainless steel using submerged friction stir processing (FSP), a severe plastic deformation technique. FSP resulted in significant microstructural refinement from 22 μm grain size for the as-received alloy to 0.8 μm grain size for the processed sample with increase in hardness by nearly 1.5 times. The wear and corrosion behavior of the processed alloy was evaluated in simulated body fluid. The processed sample demonstrated remarkable improvement in both wear and corrosion resistance, which is explained by surface strengthening and formation of a highly stable passive layer. The methylthiazol tetrazolium assay demonstrated that the processed sample is better in supporting cell attachment, proliferation with minimal toxicity, and hemolysis. The athrombogenic characteristic of the as-received and processed samples was evaluated by fibrinogen adsorption and platelet adhesion via the enzyme-linked immunosorbent assay and lactate dehydrogenase assay, respectively. The processed sample showed less platelet and fibrinogen adhesion compared with the as-received alloy, signifying its high thromboresistance. The current study suggests friction stir processing to be a versatile toolbox for enhancing the performance and reliability of currently used bioimplant materials. © 2017 American Chemical Society.

History

(SoHSS) School of Humanities and Social Sciences

Life Sciences

(SoNS) School of Natural Sciences

ACS Applied Materials and Interfaces

Friction Stir Processing of Stainless Steel for Ascertaining Its Superlative Performance in Bioimplant Applications

Renewable energy has a huge potential in the upcoming era due to the scarcity of fossil fuels. Taking this into account a 2D numerical simulation has been carried out to predict the performance of a five-bladed Darrieus H-type vertical axis wind turbine (VAWT). To this aim, a computational setup is built on a finite-volume method discretization of two-dimensional unsteady Reynolds-averaged Navier-Stokes equations (RANS), with k-ε turbulence modelling. The analysis is carried out adopting sliding mesh technique and validated against the experimental results. Using this approach the proposed model is solved to predict the lift and drag coefficients, the torque generated, the power coefficients at different tip speed ratios (TSR). Finally, the investigation concludes by validating the overall performance and the power output of the five-blade (NACA 0018) vertical axis wind turbine in freestream condition. The performance efficiency of the current analysis is compared with experimental three bladed (NACA 0018) wind turbine. The turbine achieves a maximum peak power coefficient (Cp) at higher wind speed and tip speed ranging from 2.5 to 3.5. This research advances on understanding the design optimization of small or medium scale VAWT with associated power rating. © 2017 Int. J. Mech. Eng. Rob. Res.

International Journal of Mechanical Engineering and Robotics Research

Parametric sensitivity analysis of vertical axis wind turbine

Amorphous metallic alloys are widely used in bulk form and as coatings for their desirable corrosion and wear behavior. Nevertheless, the effects of heat treatment and thermal cycling on these surface properties are not well understood. In this study, the corrosion and wear behavior of two Zr-based bulk metallic glasses were evaluated in as-cast and thermally relaxed states. Significant improvement in wear rate, friction coefficient, and corrosion penetration rate was seen for both alloys after thermal relaxation. A fully amorphous structure was retained with thermal relaxation below the glass transition. There was an increase in surface hardness and elastic modulus for both alloys after relaxation. The improvement in surface properties was explained based on annihilation of free volume. © 2017, The Minerals, Metals & Materials Society.

Amorphous Metallic Alloys: Pathways for Enhanced Wear and Corrosion Resistance

Friction and adhesion becomes extremely important at nano and micro length scales, modulating the durability of several nano/micro electromechanical systems (NEMS/MEMS). Bio-mimicking the surface texture of different living organisms has helped improve the tribological performance of many such systems. In this study, we examined the friction and wetting behaviour of textured surfaces derived by mimicking the surface morphology of butterfly wing. Three different derivatives of mimicked structure with similar solid/air fraction but different contact aspect ratios were fabricated on Si wafer using photolithography and deep reactive ion-etching techniques. The textured surfaces patterns were subsequently coated with polytetrafluoroethylene (PTFE), diamond-like carbon (DLC), and fluorine incorporated diamond-like carbon (F-DLC) using plasma-enhanced chemical vapor deposition (PECVD) technique. Atomic force microscope was used to investigate the friction behaviour of the coated and un-coated samples at different applied normal load. Wetting behaviour of the textured and control surfaces was measured using sessile-drop method. Results showed that both wettability and friction were significantly influenced by the shape, orientation and surface chemistry of the textured structure. The PTFE and F-DLC coatings helped reduce the friction compared to Si control surface. The developed patterned displayed dual character with wetting and friction being function of the texture shape. The increase in aspect ratio of textured geometry enhanced directional wettability and friction. The wetting was controlled by the contact-line pinning phenomenon modulated by the texture geometry. The friction behaviour of the textured geometry varied in direct correlation with the contact area. Further, the edge-effect showed prominent influence leading to an increase in friction force in lateral direction. The effect of surface chemistry and texture geometry is explained on basis of intermolecular forces and contact mechanics. The directional friction and wetting characteristics of the developed surface would be of potential use for transport applications in different systems. © 2017 Elsevier B.V.

Nanotribological behavior of bioinspired textured surfaces with directional characteristics

A general relation between adhesion and friction was elusive. This was partly due to the limitations in experimentally configuring the wide variety of geometrical and chemical cues encountered at a sliding contact. We study the combined influence of capillary and van der Waals forces on the correlation between the adhesion (pull-off force) and friction of polymer patterns. We report the existence of master curves in plot of adhesion versus friction, spanning nearly two orders of magnitude, characteristic of the effective lateral contact stiffness of the contact determined by geometry and capillary forces. Further, we showed how nanocylindrical patterns, micropatterns and PTFE-coated PMMA flat surfaces subjected to varying capillary forces displayed similar sliding characteristics despite their large differences in contact characteristics. © 2017 Elsevier Ltd

Tribology International

Effect of capillary forces on the correlation between nanoscale adhesion and friction of polymer patterned surfaces

This communication offers an investigation of photovoltaic thermal integrated greenhouse system (PVTIGS) for heating of slurry in potable biogas plant developed at IIT Delhi, India. The energy through biomass is one of the renewable and clean energy which is generated with the help of organic raw materials (such as animal dung, vegetable waste, and tree leaves) through anaerobic process. PVTIGS may utilized for different applications like making electricity, enhancing the slurry temperature (resulting in improved production of biogas), crop cultivation and cooking etc. Thermal modelling of the newly developed system (PVTIGS) with load condition has been derived. Different parameters of PVTIGS have been calculated namely, solar cell temperature, slurry temperature, greenhouse room temperature and biogas plant wall temperature with the help of thermal modelling. Further, theoretical values has been compared with experimental values. Correlation coefficient (r) and root mean square percentage deviation (e) found to be 0.93, 5.25; 0.97, 4.2; 0.98, 3.35 and 0.85, 8.07 for greenhouse room, flow air, biogas chamber and slurry temperature respectively. During sunshine hours (7 AM to 6 PM) and off sunshine hours (6 PM to 7 AM), the average temperature difference between slurry and ambient air temperature are 3.93 °C and 6.74 °C. © 2017 Elsevier Ltd