MIT-World Peace University (MIT-WPU) is a top educational institute located in Pune, India. It is recognized within&nbsp;UGC under Government of Maharashtra Act No. XXXV 2017.&nbsp;

It is part of the MIT group of institutions (established in 1983) which covers 10+ campuses across India and has more than 50,000+ students enrolled across various disciplines at a given point of time. The institute houses 15 schools ranging from Engineering &amp; Technology, Design, Pharmacy, Commerce, Governance among others. It offers undergraduate, postgraduate and PhD programs among different disciplines.&nbsp;

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MIT World Peace University

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School of Mechanical Engineering

Engineering and Technology

Materials Today: Proceedings

A review on the factors that decrease the performance of a solar water heater

The rapid growth of the electric vehicle industry necessitates more research into electric vehicle management systems, particularly in light of the present transition from internal combustion engines toward electric drivetrains. An electric vehicle's overall design and construction would be incomplete without a battery temperature control system. With battery thermal management systems in electric vehicles, the temperature of the batteries can be maintained at a reasonable threshold while simultaneously enhancing temperature uniformity. Adopting efficient cooling systems for electric vehicles is necessity to enhance battery safety, increase life of the battery, and minimize the detrimental effects of high surface temperatures on battery cell. For this reason, researchers have come up with several designs to cool the battery pack. This study aims to analyze the present status of BTMS technologies such as natural and forced air cooling, liquid (direct and indirect) cooling, and mini channel cooling in detail and provide opportunities for the further development of BTMS. The detailed analysis and comparison is done on both the individual components and the studied BTMS solutions, looking at both their benefits and limitations and the adaptation of these systems to various Li-ion battery forms. It has been observed that a forced air cooling system offers a variety of benefits, including easy integration, minimal maintenance requirements, and minimal costs; nevertheless, the system's cooling effectiveness is lower. The direct liquid cooled BTMS system, on the other hand, offers remarkable cooling performance. © 2022

Efficient ways of thermal management of an EV battery

In a cross-flow heat exchanger, heat transfer and fluid dynamics studies were conducted to observe the performance of graphene coated pipes. The heat exchanger consists of a linear pipe made of Aluminum 6061-T6 and Mild Steel in separate studies carrying a heated fluid. The thermal interactions between the heated fluid having a laminar flow and the walls of the pipe have been studied under the influence of an external environment of water having a turbulent flow, in a direction normal to the pipe. A RANS model with a k-ε variant was used to model the behavior of different material pipes which were observed under the varying conditions of turbulence, velocity, pressure, and vorticity. When subjected to the same conditions, plots of the temperature gradient, isothermal contours, heat transfer coefficient against Reynolds number and thermal conductivity modelled against the various graphene coating thicknesses studied have shown that out of Aluminum 6061-T6 and Mild Steel, the former has shown a significant increase in thermal conductivity on the addition of a Graphene coating. Simulation results showed an increase in Aluminium 6061 T6′s conductivity by 6.8975% with a continuous decrease in the heat transfer coefficient, whereas Mild Steel showed an anomaly in the heat transfer coefficient value which peaked at 1.2 mm thickness of graphene coating with a value of 3858.862 W/m2K. © 2021

Investigations on the effect of graphene coating on thermophysical properties of aluminium and mild steel for cross flow heat exchanger

Computational Fluid Dynamics (CFD) and heat transfer simulations are conducted for a cross flow heat exchanger. The heat exchanger consists of a linear pipe carrying a heated fluid. The thermal interactions between the heated fluid having a laminar flow and the walls of the pipe have been studied under the influence of an external environment of water having a turbulent flow, in a direction normal to the pipe. A RANS model with a k-ε variant was used to model the behavior of different material pipes which were observed under the varying conditions of turbulence, velocity, pressure and vorticity. When subjected to the same conditions, plots of the temperature gradient, isothermal contours, heat transfer coefficient against Reynolds number and thermal conductivity modelled against the various graphene coating thicknesses studied have shown that out of Copper and Stainless Steel the former has shown the most significant increase in thermal conductivity on the addition of a Graphene coating. Furthermore, to check for optimum efficiency, the same study was conducted with an internal coating of a Graphene layer for the aforementioned materials. It has been observed that an outer coating was not only more economically feasible, but also showed better thermal performance compared to an inner coating of graphene for copper, however it did improve the thermal performance of Stainless Steel significantly. © 2021

Comparison of thermal performances between copper and stainless steels on application of graphene coatings

The use of composite adsorbent with nano particle additives having high surface area can lead to enhanced heat transfer, higher adsorption capacity and faster rate leading to better adsorber performance. The objectives of the present study were to investigate the effectiveness of nanofluid as a cooling fluid of a composite adsorber by carrying out nanofluid characterization and to investigate adsorption-desorption characteristics of a composite adsorbent for ammonia as an adsorbate. An experimental set up with tube-in-tube type configuration was constructed to monitor the thermal characteristics (heat transfer from and to the adsorber) and ammonia adsorption/desorption rates. The composite of calcium chloride with activated carbon and expanded graphite nanoparticles was made having different concentrations of CaCl2 ranging from 40 % to 80 % in the composite and expanded natural graphite (ENG) content ranging from 0-3 % by weight. The desorption characteristics were studied at different temperatures from 70° C to 110° C. The cooling fluid with and without graphite nanofibers (GNF) was circulated in the inner tube at different flow rates from 5 LPH to 25 LPH. From the experimentation on adsorption-desorption characteristics, it was found that the total amount of ammonia adsorbed increased from 133 g for 50:50 composition of CaCl2:AC to 156 g for CaCl2:AC composition of 50:50 with the addition of 3 % ENG nanoparticles. Also the adsorption process time reduced from 22 minutes to 18 minutes. For 50 % CaCl2 in the composite the temperature at which the maximum desorption occurred was 70°C. So, desorption could occur at lower temperature, which is advantageous as it increases the number of options for heat sources to be used. When nanofluid was used as a cooling fluid of the composite adsorber, the total amount of ammonia adsorbed increased from 79.411 g for basefluid to 90.206 g for 0.4 % graphite nanofiber nanofluid for flow rate of 25 LPH. With the use of composite adsorbent of CaCl2:AC of 50:50 composition and addition of expanded natural graphite (ENG) by 3% and when 0.4 % graphite nanofiber nanofluid was used as a cooling fluid, the maximum ammonia was adsorbed up to the bed length of 600 mm only out of the total bed length of 1 m indicating the possibility of reduction in the size of an adsorber. © 2021 Author(s).

School of Polymer Engineering

AIP Conference Proceedings

Analysis of composite adsorber with graphite nanofiber based nanofluid as coolant

Authentication is a commonly used technique in software applications to ensure whether the correct user is getting access to secured services or not. Due to the fast pace of data growth, there is an increasing need for security of online data. This is commonly achieved by the use of various CAPTCHAs. CAPTCHAs are an implementation of reverse Turing test. Turing test is used to distinguish between humans and computers. A fundamental property that the use of CAPTCHA necessitates is that the CAPTCHA must be easy and efficient for humans but difficult for computers. CAPTCHAs are used to protect the data from malicious bots and web crawlers. They are not only used in web sites but also used in banking transactions, cloud computing, distributed infrastructures and income tax services. In this paper, an analysis of the different categories of CAPTCHAs, the attacks against them and ideas and designs to develop more robust and user-friendly CAPTCHAs in the coming future are presented. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

School of Computer Engineering & Technology

Smart Innovation, Systems and Technologies

An Overview of Various Types of CAPTCHA

Adequate supply of oxygen is essential for the complete combustion of fuel in the furnace of a boiler and defective duct design may cause serious loss in the boiler efficiency due to incomplete combustion. In boiler there is a system which controls the air flow rate reaching to the furnace. FD fan helps to build the pressure and force the air to pass through the duct and wind box. In wind box, this air will be sent to the furnace for helping combustion process. The main objective of this work was to simulate the flow of air from blower to the inlet of a wind box through rectangular split duct to see whether it could provide improved flow conditions and to see whether there was equal mass flow rate of air through both the legs of a split duct. The purpose of providing a split duct was to eliminate one blower which would otherwise be required for two separate ducts arrangement. A 3D model using CFD was prepared to capture the changes in the mass flow distribution in the duct at two different outlets. Through this analysis, it was found that the mass flow rates of air through the two legs of the split duct were not equal. The damping needs to be provided for the duct having longer length in order to have equal mass flow rate of air through both the legs of the duct.

Fulltext

International Journal of Recent Technology and Engineering

Simulation of Mass Flow Rate of Air through Rectangular Split Duct

Due to the significant increase in the size of the internet and the number of users on this platform there has been a tremendous increase in load on various websites and web-based applications. This load is from the user end which causes unforeseen conditions which leads to unacceptable consequences such as crash or a data loss scenario at the webserver end. Therefore, there is a need to reduce the load on the server as well as the chances of network attacks that increase with the increased user base. The undue consequences such as data loss and server crash are caused due to two main reasons: The first one being an overload of users and the second due to an increased number of automatic programs or robots. A technique can be utilized to overcome this scenario by introducing a delay in the operation speed on the user end through the use of a CAPTCHA mechanism. Most of the classical approaches use a single method for the generation of the CAPTCHA, to overcome this proposed model uses the versatile image CAPTCHA generation mechanism. We have introduced a system that utilizes manualbased, face detection-based, colour based and random object insertion technique to generate 4 different random types of CAPTCHA. The proposed methodology implements a region of interest and convolutional neural networks to achieve the generation of the CAPTCHA effectively. © 2020 IEEE.

2020 IEEE 5th International Conference on Computing Communication and Automation, ICCCA 2020

Versatile CAPTCHA Generation Using Machine Learning and Image Processing

The heat transfer co-efficient (HTC) was measured in nanofluids made from ethylene glycol water mixture dispersed with different amounts of graphite nanoparticles (GRNP) at different flow rates (Reynolds number Re = 50 to 800) and temperatures range between 10 to 85 °C. It was observed that the HTC was highly dependent on the Re with two regimes. HTC was found to follow the power law of the type (HTC) = A (Re)χ where the exponent χ was dependent on Re range, composition and temperature. In the high Re regime, the exponent was of the order of 0.5 while at low Re regime (Re < 150) the χ value was 0.85 to 0.92. The HTC at low Re values could be correlated with the thermal conduction process and Brownian motion, while at high Re, random motion could be prevailing. The results have been compared with the reported data for carbon nanotubes (CNT) for which also the exponent was much more than 0.333 which is indicated in the standard Sieder-Tate equation. Thus, the overall variation of HTC with Re appears to be HTC= A Reχ where χ assumes values depending on the regimes of Re viz. low, intermediate and high Re with χ ≈ 0.92, 0.3 < χ <0.5 and χ ≥ 0.85 respectively.

Journal of Nanofluids (USA)

Power Law Variation of Heat Transfer Coefficient with Reynolds Number in Nanofluids Containing Graphite and Carbon Nanotubes Nanoparticles

The thermal conductivity (k), heat transfer coefficient (HTC) and viscosity of the ethylene glycol/water dispersed with graphite nanoparticles was studied under heating and cooling conditions for temperatures ranging from 0 °C to 75 °C using tubular heat exchanger system built in house. Flow rate was varied from 5 l/h to 25 l/h giving Reynolds number (Re) ranging from 50 to 750. The HTC increased with the increase of Re as well as temperature. The thermal conductivity of the nanofluid was determined at constant low Re (200) for all concentrations and temperatures used in the experiment. The concentration dependence of thermal conductivity was found to be much different than that predicted by models suggested in literature. The viscosity was measured for different concentrations of nanoparticles (0 to 0.8%) as well as temperatures 275 K to 340 K. The temperature dependence of viscosity was found to follow Arrhenius type equation η = ηoexp(E/kbT) with very little change in the activation energy from that of the base fluid. On the other hand the pre-exponential constant increased six folds with the increase in nanoparticle concentration. An empirical relation derived from Brownian motion was found between the product of viscosity and thermal conductivity (Ω = kr · ηr) with respect to concentration of the nanoparticles which was found to be true for whole range of temperature and compositions studied.