Makine Mühendisliği Bölümü Makale Koleksiyonu

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https://hdl.handle.net/20.500.12713/177

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On the Effect of Interphase Boundary Energy Anisotropy on Morphologies: A New Type of Eutectic Grain Observed in a Three-Phase Eutectic System
(Springer, 2024) Mohagheghi, S.; Şerefoğlu, M.
Eutectic microstructures are dramatically affected by the anisotropy in interphase boundary energy. Depending on this anisotropy function, different eutectic grains may grow simultaneously at the same experimental conditions. In all reported quasi-isotropic and anisotropic two-phase and three-phase eutectic grains in thin samples, lamellar morphology is observed and the microstructure is essentially two dimensional (2D), since the interphase boundaries are perpendicular to the sample walls. Using the ?(In)–In2Bi–?(Sn) system and real-time solidification experiments in thin samples, we introduce a unique and new type of anisotropic three-phase eutectic grain, entitled here as “Laminated Matrix with Rods (LMR).” In this grain, due to the anisotropy in In2Bi/?(Sn) interphase boundary, the evolving phases, and hence, the microstructures observed through the two glass plates of the thin sample are completely different, despite the strong confinement effect. During rotating directional solidification (RDS) experiments, the morphology or the aspect ratio of all phases changes periodically and drastically. Specifically, In2Bi, ?(In), and ?(Sn) phases evolve from all being lamellar perpendicular to the sample walls to the matrix, elongated/trapezoidal rods, and a lamella parallel to the sample walls, respectively. Our experimental results show that these morphological transitions are due to change in the interphase boundary orientation with respect to the growth direction. Graphical abstract: (Figure presented.) © The Author(s) 2024.
NOx emission reduction in low viscous low cetane (LVLC) fuel using additives in CI engine: an experimental study
(Springer Science and Business Media Deutschland GmbH, 2024) Sonthalia, A.; Varuvel, E.G.; Subramanian, T.; Kumar, N.
This study examines the combustion properties of pine oil (PO), which is classified as a low viscosity, low cetane (LVLC) fuel. It highlights the superior performance of pine oil in comparison to diesel fuel, but acknowledges that its low cetane index causes a delay in combustion initiation, which consequently results in elevated NOx emissions. Fuel atomization, evaporation, and air/fuel mixing are enhanced by the reduced viscosity and boiling point of PO in comparison to diesel. Nevertheless, the low cetane index of PO restricts its applicability as a diesel fuel substitute in CI engines. Due to significant heat release after an extended ignition delay, NOx emissions tend to rise with less viscous and low cetane (LVLC) fuels. A range of cetane improvers, such as diethyl ether (DEE), benzyl alcohol (Bn), diglyme (DGE), and methyl tert-butyl ether (MTBE), have demonstrated effectiveness in mitigating nitrogen oxide (NOx) emissions upon introduction into pine oil. All the cetane improvers were added 5% and 10% by volume with pine oil. A twin-cylinder tractor engine operating at a constant speed of 1500 revolutions per minute was utilized in this testing. In order to achieve a warm-up condition that would enable the smooth operation of PO, the engine was initially operated on diesel fuel. At maximum load condition, NOx emission of PO was higher by 8% in comparison to diesel. NOx emission was significantly reduced with addition of cetane improvers. Maximum reduction of 7% was observed with PO + MTBE 10% in comparison to PO which is in par with diesel. An increase in HC and CO emission was observed with all cetane improver addition with PO. Graphical abstract: (Figure presented.). © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
An innovative transient simulation of a solar energy system with a thermochemical hydrogen production cycle for zero-energy buildings
(Elsevier Ltd, 2024) Mohammadi, Z.; Ahmadi, P.; Ashjaee, M.
This research investigates the incorporation of solar power systems into buildings to meet the energy needs of near-zero-energy buildings. The study focuses on a complex buildings in Shiraz City, Iran. The primary objective of this case study is to integrate an innovative method of hydrogen production known as thermochemical hydrogen production methods to fulfill the building's energy demands. Solar energy is utilized to generate heat by parabolic trough collectors, which is the sole energy source required for the V–Cl thermochemical cycle. Consequently, hydrogen is produced and stored during the day for use at night when there is no solar radiation. To address this, a novel component has been developed for the vanadium chlorine cycle (V–Cl) within the TRNSYS software. The energy system was simulated using the TRNSYS software, a powerful transient simulation tool. Despite the numerous advantages offered by TRNSYS's energy system simulation, it lacks optimization capabilities. The use of a neural network-genetic algorithm optimization approach allows for the calculation of an optimized area for collectors and the power output of fuel cells for the building complex. The optimum configuration results in minimum installation cost, lowest CO2 emissions, and the highest power supply renewable (PSR). The results reveal that the installation of collectors with a surface area of 70 m2 and the utilization of fuel cells with a power output of 345 kW lead to a total carbon dioxide (CO2) generation of 10.31 tons per year, a PSR of 1.21, and a cost of $4.915 per hour. © 2024 Hydrogen Energy Publications LLC
A Quasi-3D theory for bending, vibration and buckling analysis of FG-CNTRC and GPLRC curved beams
(Elsevier Ltd, 2024) Pham, S.D.; Karamanli, A.; Wattanasakulpong, N.; Vo, T.P.
This paper proposes a finite element model based on Quasi-3D theory, which includes both normal and shear effects, to study the bending, vibration, and buckling responses of FG-CNTRC and GPLRC curved beams. A two-node beam element satisfying C1 continuity requirement is utilized to compute displacements, critical buckling loads, and natural frequencies for beams with various boundary conditions. To evaluate the precision of the suggested model, various numerical examples are conducted. Next, a comprehensive parameter study is carried out to study the effects of distribution patterns and fractional volume of reinforced materials, open angles, aspect ratios, and boundary conditions. Numerous numerical results can serve as benchmarks for subsequent investigations. © 2024 The Authors
Impact of hydrogen addition on diesel engine performance, emissions, combustion, and vibration characteristics using a Prosopis Juliflora methyl ester-decanol blend as pilot fuel
(Elsevier Ltd, 2024) Duraisamy, B.; Varuvel, E.G.; Palanichamy, S.; Subramanian, B.; Jerome, Stanley, M.; Madheswaran, D.K.
The research primarily focuses on investigating the impact of hydrogen induction on parameters of a compression ignition (CI) engine utilizing biodiesel blended with decanol, up to knock limit. The utilization of non-edible oil, exemplified by Prosopis Juliflora seed oil (JFO), presents inherent challenges due to its elevated viscosity, limited atomization, and suboptimal combustion attributes. However, the conversion of JFO into Prosopis Juliflora methyl ester (JFME) biodiesel substantially ameliorates its fuel characteristics, although it still exhibits relatively lower performance in comparison to conventional diesel fuel. To enhance the attributes of JFME blends, decanol is mixed with 20 % on volumetric basis (referred to as D20). Furthermore, the introduction of hydrogen into the engine's intake manifold is employed to bolster performance and curtail emissions. Different hydrogen flow rates, spanning from 2.5 to 10 litres per minute (lpm), are assessed in conjunction with the D20 biodiesel blend. The inclusion of hydrogen into D20 blends yields an enhancement in brake thermal efficiency (BTE), coupled with reductions in hydrocarbon (HC), carbon monoxide (CO), and smoke emissions. However, it should be noted that hydrogen's notable flame velocity and higher calorific value engender escalated combustion temperatures and an associated rise in Nitric oxide (NO) emission. The research also encompasses an evaluation of engine vibration during dual-fuel operation, revealing a proportional increase in engine vibration with heightened rates of hydrogen induction. In summation, the utilization of D20 in conjunction with hydrogen at a rate of 10 lpm emerges as a viable approach for operating diesel engines in a dual-fuel mode. © 2023 Hydrogen Energy Publications LLC
Influence of hydrogen injection timing and duration on the combustion and emission characteristics of a diesel engine operating on dual fuel mode using biodiesel of dairy scum oil and producer gas
(Elsevier Ltd, 2023) Lalsangi, Sadashiva; Yaliwal V.S.; Banapurmath N.R.; Soudagar, Manzoore Elahi M.; Balasubramanian, Dhinesh; Sonthalia, Ankit; Varuvel, Edwin Geo; Wae-Hayee, Makatar
The main aim of the present work is to investigate the influence of hydrogen injection timing and injection duration on the combustion and emissions of a CI engine functioning on dual fuel (DF) mode by employing diesel/dairy scum oil methyl ester (DiSOME)/Waste frying oil methyl ester (WFOME) - producer gas (PG) combination. Hydrogen flow rate was maintained constant (8 lpm) and injected in air-producer gas (PG) mixture an inlet manifold using a gas injector. In this current work, injection timing was varied from TDC to 15 deg., aTDC in steps of 5. Similarly, injection duration was adopted from 30 deg., CA to 90 deg., CA and differed in steps of 30. From the outcome of work, it is noticed that the best possible injection timing and injection duration were found to be 10 deg., aTDC and 60 deg., CA respectively. Results showed that, at optimum injection parameters, diesel-PG combination with hydrogen resulted in augmented BTE by 6.7% and 12.4%, decreased smoke by 26.04% and 36.4%, decreased HC by 16.6% and 22.4%, decreased CO by 23.5% and 29.6% and increased NOx by 12.4% and 22.1%, compared to DiSOME and WFOME supported DF operation. Investigation with DiSOME-hydrogen enriched PG combustion showed satisfactory operation. © 2022 Hydrogen Energy Publications LLC
Transient dynamics of 2D-FG porous microplates under moving loads using higher order finite element model
(Elsevier Ltd, 2023) Karamanlı, Armağan; Eltaher, Mohamed A.; Thai, Son; Vo, Thuc P.
This study presents the higher order finite element model to explore the transient vibration of two-dimensional functionally graded (2D-FG) porous microplate under harmonic moving loads, that can be helped in design of nanoplate devices such as NEMS, nanofilters, nanoresonators, and nanoswitches. A normal and shear deformable plate theory with five unknowns is exploited with the modified couple stress theory to portray the kinematic relations, constitutive stress–strain equations, and size-dependence effect. This complicated problem is investigated for the first time based on Newmark's method to obtain time history analysis of 2D-FG porous microplates having in-plane inhomogeneity. In-plane displacements and stretching component of the transverse displacement are interpolated by using Bogner-Fox-Schmit rectangular element with four degrees of freedom (DOF) for each node satisfying the C1 continuity requirement. In addition, bending and shear components of the transverse displacement are presented by a nonconforming rectangular element with six DOF for each node satisfying the C2 continuity requirement. Various boundary conditions are considered to evaluate the influences of the thickness to material length parameter, aspect ratio, gradient index in two directions, material loss due to porosity in two directions, load velocity parameter and load excitation frequency ratio. It is revealed based on the results that dynamic deflections of 2D-FG porous microplates are significantly affected by the variation of the analysis parameters mentioned above. © 2022 Elsevier Ltd
Application of Taguchi design in optimization of performance and emissions characteristics of n-butanol/diesel/biogas under dual fuel mode
(Elsevier, 2023) Goyal, Deepam; Goyal, Tarun; Mahla, Sunil Kumar; Goga, Geetesh; Dhir, Amit; Balasubramanian, Dhinesh; Hoang, Anh Tuan; Joseph Shobana Bai, Femilda Josephin; Varuvel, Edwin Geo
Combustion experts are in search of some alternative fuel from last few decades owing to diminishing petroleum products and unexpected variations in habitat, which are result of venomous emissions from the CI engines. The present investigation intended to assess the performance and emission parameters of a diesel engine by fueling it with pilot fuel (blends of diesel and n-butanol) and primary fuel (Biogas). Results revealed that BTE, HC and CO increases whilst NOx and smoke emissions were reduced by using the pilot and primary fuel together in relation with natural diesel. Experimentation was done using Taguchi L9 orthogonal array design. The engine load, flow rate of biogas and butanol in fuel blend percentage were selected as input parameters whereas brake thermal efficiency (BTE) and emission characteristics i.e., HC, CO, NOx and smoke were chosen as response variables. ANOVA was carried out for the responses by utilizing MINITAB software. The higher value of raw data and S/N ratio for BTE was noted with high engine load, low flow rate of biogas and butanol blend percent. For the emission characteristics i.e., HC, CO and smoke, lower raw data and high S/N ratio values were attained in the order of rank engine load > butanol blend percent > biogas flow rate while the similar values for NOx were attained in the rank engine load > biogas flow rate > butanol blend percent. Taguchi design was noted to be an effective tool for the optimization of various response parameters and the optimum levels of input parameters were calculated after analysis. Full engine load for BTE and HC, Biogas flow rate of 15 lpm for BTE, HC and CO, and 20 % of butanol blend for HC, CO and smoke were found to be the optimum conditions for the conducted experimentation. © 2022 Elsevier Ltd
Sustainable marina concept with green hydrogen utilization: a case study
(Elsevier, 2022) Karayel, Görkem Kubilay; Javani, Nader; Dinçer, İbrahim
The current study investigates the green hydrogen production from renewable energy for a sustainable yacht marina. The main idea is to create a sustainable harbor for utilizing renewable energy sources using electrolysers to produce hydrogen and providing power for both marina energy demand and transportation fuel needs. Generating electricity from renewable energy resources and converting into green hydrogen in marinas are the main objectives of the current study. Solar and wave energy resources are used for calculating total hydrogen production potential. Four different sizes of luxury yachts are considered in the calculations. The considered three yacht marinas are located in Malaga, Mugla, and Istanbul. The average annual green hydrogen production potential of a marina from offshore solar energy is estimated to be 1.34, 1.38, 1.47 kt, and annual green hydrogen production from wave energy is 2.66, 3.06, 3.99 kt for the considered marinas locates in Marbella, Bodrum, and Atakoy, respectively. During the summer season, 400 small-sized, 250 medium-sized, or 100 large-sized yachts are potentially considered for fueling with green hydrogen. At maximum capacity, in Atakoy marina, which is chosen for the case study, a total of 243 hydrogen-fueled mega-yachts can potentially be refueled with green hydrogen. The study results show that the marinas selected in the specified locations appear to feasible for sustainable hydrogen applications. © 2022 Elsevier Ltd
Experimental study of droplet combustion and diesel engine characteristics for azolla biodiesel
(TAYLOR & FRANCIS INC, 2022) Ganapathy, Saravanan Chidambaram; Seshadri, Thiruvenkatachari; Jayaraman, Sasikala; Raman, Vallinayagam; Malaiperumal, Vikneswaran; Varuvel, Edwin Geo; Joseph Shobana Bai, Femilda Josephin
This study pertains to studying the feasibility of the third-generation biodiesel obtained from one of the algae species known as Azolla microphylla by exploring their fundamental droplet combustion behavior and diesel engine characteristics. Firstly, the droplet evolution and burn rate are investigated for diesel, Azolla100, and Azolla50 (50% biodiesel +50% diesel) based on the experimental study of suspended droplet combustion. The diesel droplet showed steady combustion with linear regression for the decrease in droplet surface with time throughout its lifetime, while the Azolla100 and Azolla50 droplets showed a linear trend initially, and after a certain point, they resulted in a non-linear trend as a result of disruptive burning. The evaporation and burn rate was found to be higher for Azolla100 and Azolla50 than diesel during the steady burning period and thereafter it decreased with increasing Azolla concentration. The time evolution of droplet combustion images indicated that with increasing biodiesel concentration, the combustion duration was decreased due to secondary droplet ejections and microexplosion, and the residue burning duration was increased. The microexplosion increased the rate of combustion, however, droplet ejection resulted in incomplete combustion. Secondly, the engine experiments were performed for Azolla50 at different fuel injection pressures. The results showed that in-cylinder pressure and Brake thermal efficiency (BTE) for Azolla50 at 300 bar injection pressure were lower than diesel due to limitations with the physical properties of biodiesel. In order to improve the engine characteristics of Azolla50, this study increased the fuel injection pressure to 900 bar. As a result, the BTE for Azolla50 at 900 bar injection pressure is improved by 9.2% and 10.2% at low and full load conditions, respectively, compared to Azolla50 at 300 bar injection pressure. Overall, the spray-driven combustion for Azolla50 is limited by the physical properties of the biodiesel, which affects the mixture formation. On the other hand, the microexplosion and droplet ejection observed with the biodiesel during the combustion study would favor the combustion by improving the atomization and mixing process.
Experimental assessment on the performance, emission and combustion characteristics of a safflower oil fueled CI engine with hydrogen gas enrichment
(Elsevier Ltd, 2022) Praveena, V.; Joseph Shobana Bai, Femilda Josephin; Balasubramanian, Dhinesh; Devarajan, Yuvarajan; Aloui, Fethi; Varuvel, Edwin Geo
Inducting hydrogen with biodiesel in a compression ignition (CI) engine contributes to improvising the performance characteristics of the engine and minimize long-term issues. Combustion of hydrogen along with intake air impacts positively in air quality by preventing the formation of toxic emissions like hydrocarbons (HC) and carbon monoxide (CO). The benefits of hydrogen such as good diffusion rate, lesser ignition energy and fast flame propagation rate promotes a more homogenously mixed air fuel ratio. This experimental work focuses on enhancement of the performance and combustion characteristics of a direct injection compression ignition (DICI) engine by enriching the biodiesel with various levels of hydrogen gas supplement at the intake manifold. The brake thermal efficiency of the engine with safflower oil biodiesel is 31.15 % which is far inferior to that of diesel with 34 %. As an effort to improve the performance characteristics of the CI engine, hydrogen gas is inducted at 4 %, 8 % and 12 % energy share. HC, CO and smoke emission decreases by 15.09 %, 34.6 % and 18 % respectively compared to neat biodiesel at full load of 5.2 kW. An opposite trend is observed in NOx emissions which are raised from 1650 ppm to 1852 ppm. A 12.2 % increase in NOx emissions are realized due to homogenous flammable mixture that combusts closer to Top dead center (TDC). The hydrogen enrichment with safflower oil biodiesel influences the combustion characteristics in a positive vein except for the NOx emissions, which could be minimized through the use of retrofit devices like selective catalytic reducer, diesel oxidation catalyst etc.
Effect of alloying elements and ceramic coating on the surface temperature of an aluminum piston in a diesel engine
(HINDAWI LTD, 2022) Vengatesan, S.; Yadav, Paras; Varuvel, Edwin Geo
The engine piston is subjected to very high temperature during the combustion process, and it is very difficult to control the stability of the geometry at elevated temperature. The stability of the engine piston was analysed by finite element method with steady-state conditions for three different types of approach to control it, where the influence of the alloying element of aluminum piston, influence of surface coating, and its impact on the thickness variation followed by the influence of holes on the coating surface have been analysed in detail. It is observed that the coating with holes shows good agreement with requirement compared to the influence of the alloying element and coated piston. The conduction mode of heat transfer is controlled, and also, the heat transfer to the adjacent components is facilitated by holes on the coated piston.
Techno-economic review assessment of hydrogen utilization in processing the natural gas and biofuels
(Elsevier Ltd, 2022) Narayanan R., Deepak; Rajkumar, Sundararajan; N., Vinithkrishna; Thangaraja, Jeyaseelan; M., Sivagaminathan; Devarajan, Yuvarajan; Geo Varuvel, Edwin
The automobile sector dominated by conventional fossil fuels greatly impacted human lives and strengthened the economy of many countries. However, the harmful emissions from the engines have contaminated the environment and induced severe climate changes; hence the emphasis is being laid on low carbon fuels that emit lower emissions and greenhouse gases. In this regard, hydrogen (H2) is considered as a no-carbon fuel; however, safety and storage are the main concerns. Therefore, the H2 can be potentially utilized with compressed natural gas (CNG) to form hydrogen-enriched compressed natural gas (HCNG) and processed with biofuels to produce hydrogenated biofuels. HCNG emits 20% lower carbon dioxide, 30% less carbon monoxide and 25% reductions in NOx emissions compared with CNG. The hydrogenated biodiesel fuels exhibit higher cetane number and better storage stability. However, the practical challenge is to render them economically affordable with minimum carbon footprints. Thus, the current review is aimed to provide comprehensive detail on the potential of hydrogen in fuel formulation techniques and their effect on engine performance, emission characteristics and various hydrogen production methods viz. blue and green hydrogen. Further, this review highlights the techno-economic characteristics of hydrogen utilization and economic characteristics of the low carbon fuels (both liquid and gaseous fuels) for sustainable mobility.
Processing and utilization of an eco-friendly oil as heat transfer fluid derived from camelina seeds
(WILEY, 2022) Devarajan, Yuvarajan; Munuswamy, Dinesh Babu; Vellaiyan, Suresh; Jayabal, Ravikumar; Varuvel, Edwin Geo; Natrayan, L.
Bio-oil from nonedible sources is an ideal alternative for thermal oil in solar and heat applications. The significant merits of bio-oil in high-temperature applications are less volatile, higher availability, non-hazardous, environmentally friendly, and renewable resources. Heat transmission fluids (HF) are a medium that transfers heat in all solar heating applications. Generally, mineral oils derived from crude oil act as HF, harming humans and the environment during their disposal. This negative effect shall be lowered by replacing conventional fluids with bio-oil developed from vegetable or synthetic oil. Of late, fats obtained from waste and inedible sources are promising in solar applications as they eliminate associated issues. This study uses eco-friendly bio-oil as a heat transfer fluid obtained from camelina oil. Camelina oil is of inedible vegetable source and is produced by cold pressing from the Camelina sativa seeds. Heat transfer fluid is produced by subjecting raw camelina oil to a base catalyst reaction. No work till date has investigated the camelina oil as an eco-friendly heat transfer fluid. Various parameters for obtaining a higher yield of fluid with lower reagents waste are analyzed in this study. After conversion, the camelina oil was reviewed for its suitability as a heat transfer fluid. Variations in critical properties such as density, thermal conductivity, specific heat capacity, and dynamic viscosity with temperature are analyzed. Results revealed that the properties of bio-oil provided are comparable with conventional fluids. Based on the results, the maximum reaction efficiency of about 93% was achieved at 600 rpm of agitation speed, 1% wt of NaOH concentration, 5.5:1 molar proportion, and 65 degrees C of reaction temperature. The critical properties of camelina bio-oil improved with temperature and depend on the composition of fatty acids. Hence, CME acts as an improved heat transfer fluid and shall be a probable applicant to replace the synthetic fluid in heating applications.
Experimental investigation and performance prediction of gasoline engine operating parameters fueled with diisopropyl ether-gasoline blends: Response surface methodology based optimization
(Elsevier Ltd., 2022) Sathyanarayanan, Seetharaman; Suresh, Sivan; Saravanan, C. G; Vikneswaran, M.; Dhamodaran, Gopinath; Sonthalia, Ankit; Joseph Shobana Bai, Femilda Josephin; Varuvel, Edwin Geo
In this research, gasoline engine performance and emission characteristics were studied when powered by diisopropyl ether-gasoline blends. The main objective of this study is to determine the behavior of diisopropyl ether-gasoline blends at various engine speeds and compression ratios. Further, the engine parameters were optimized using the response surface methodology. Enriched oxygen, higher latent heat of vaporization, and the readily volatile nature of the fuel enhanced the brake thermal efficiency and lowered the hydrocarbons and carbon monoxide due to a better combustion rate. The developed model exhibited superior R2 values with a 0.957 desirability factor. The optimum parameters such as speed, compression ratio, and fuel-blend concentrations were found at 2250 rpm, 10:1, and D25 (75% gasoline and 25% diisopropyl ether), respectively. The responses for the optimal input parameters were brake thermal efficiency (31.53%), specific fuel consumption (0.2923 kg/kWh), carbon monoxide (0.14% by Vol.), hydrocarbons (31 ppm), and oxides of nitrogen (708 ppm). The predicted values for optimum engine parameters were validated with the experimental data, and their percentage of absolute error was found to be less than 5%. Thus, the study concludes that diisopropyl-ether gasoline blends can be used as an alternative fuel to enhance the brake thermal efficiency and reduce the pollution level, and the proposed numerical model can predict the responses with high accuracy.
Environmentally conscious manufacturing and life cycle analysis: a state-of-the-art survey
(Hindawi Limited, 2022) Paulraj, Prathap; Ilangovan, Padmanaban; Subramanian, Kannan; Nagarajan, Mohan Raj; Suthan, R.; Sakthimurugan, V.; Madhu, S.; Varuvel, Edwin Geo; Lenin, Haiter
Research on developing new methodologies on environmentally conscious manufacturing and way of reducing environmental impacts on product design was started over two decades ago. Environmentally conscious manufacturing has become a challenge to the environment and to the society itself, enforced primarily by government regulations and the customer expectation on environmental issues. In both industry and academics, there is a sizable following for environmental-related issues which are aimed at finding answers to the problems that arise in this newly emerged area. Problems are widespread including the ones related to the life cycle of products, disassembly, material recovery, and remanufacturing and pollution prevention. Only very few researchers have concentrated on ecofriendly products. This paper investigates the literature by classifying more than 200 published references into four categories, viz., design for environment checklist, environmentally conscious manufacturing, life cycle analysis, and material selection.
Combined effects of nozzle hole variation and piston bowl geometry modification on performance characteristics of a diesel engine with energy and exergy approach
(Elsevier Ltd., 2022) Praveena, V.; Leenus Jesu Martin, M.; Varuvel, Edwin Geo
This experimental work aims to address the challenges of waste management. Biomass waste is converted into useful fuel and considered as a replacement to conventional fuel in CI engines. In this context, the grape marc and grape pomace are crushed and further processed to produce grapeseed oil. The grapeseed oil is further trans esterified to produce grapeseed seed oil methyl ester. The present study aims in examining the effect of varying piston shapes and nozzle profile on energy and exergy rates of a CI engine run with grapeseed oil methyl ester (GSME) blended with cerium oxide nano particles. The CeO2 nano particles were suspended in the base fuel at a concentration of 100 ppm and stability tests were conducted. The experiments were performed on a single cylinder, water cooled diesel engine with rated power of 5.2 kW. The research work includes two additional piston shapes namely, toroidal and shallow deep and two additional nozzle profiles viz. 4 hole and 5-hole nozzle. The hemispherical shape and 3-hole nozzle were considered as the standard one. Energy and exergy analysis were done on the experimental data to understand the exergy associated with cooling water, exhaust gas and unaccounted losses. The energy and exergy rates show that increase in nozzle hole number, decreases the destructive availability of the system. The exergetic efficiency of 32.8% is higher proving that toroidal shape and 5-hole nozzle profile is comparatively better and suitable for effective engine operation. HC, CO and smoke emissions reduced considerably by 14.4%–30% by the engine modification. Brake thermal efficiency was improved from 28.2% to 31.02% for CI engine with biodiesel. The paper addresses the gap in fuel modification clubbed with engine modification using biomass waste derived fuel. Exergy and energy analysis further add value to this current experimental work.
Sustainable city concept based on green hydrogen energy
(Elsevier Ltd, 2022) Dinçer, İbrahim; Javani, Nader; Karayel, Görkem Kubilay
The current study investigates the green hydrogen production from renewable energy sources for the metropolitan city of Istanbul by using electrolysers. The main idea is to create a hydrogen map for every district in Istanbul, based on renewable energy sources and water splitting technology. The potentially available renewable sources, such as solar (including offshore), wind (including offshore), biomass, geothermal and underwater current are used for calculating the total hydrogen production potential. Istanbul's potential for producing green hydrogen is estimated to be 7.96 Mt. The study results show that Catalca, Şile, Silivri, Arnavutköy, and Beykoz come out as the districts with the highest green hydrogen potential with 1.49 Mt, 1.19 Mt, 1.12 Mt, 0.57 Mt, and 0.46 Mt, respectively. After supplying the necessary power demand for the city, the remaining power is used to produce green hydrogen which may contribute an economic value of over US $100 billion with a current price of $13/kg of hydrogen and 23.88 billion US$ with a targeted price of $3/kg of hydrogen, respectively. The available potentials for each district are also specifically studied and discussed. It is more importantly expected to reduce the greenhouse gas emissions by about 90% which will ve very important to achieve a carbon-neutral city and hence country due its dominated role. Furthermore, the results provide a clear guidance to enable policymakers and private sectors to use renewable energy potentials for their investment purposes or promote clean energy programs, tackling carbon-based energy consumption, pollution, and greenhouse effect. This, later on, can be used by policymakers and energy providers to help the city and local communities for achieving the United Nation's sustainable development goals.
Inedible oil feedstocks for biodiesel production: A review of production technologies and physicochemical properties
(Elsevier B.V., 2022) Devarajan, Yuvarajan; Munuswamy, Dinesh Babu; Subbiah, Ganesan; Vellaiyan, Suresh; Nagappan, Beemkumar; Varuvel, Edwin Geo; Thangaraja, Jeyaseelan
Biodiesel emits lesser harmful pollutant emissions than renewable and biodegradable ones compared diesel. Research confirms that edible products and crops are the major sources of biofuel production. Excessive usage of these crops leads to higher production costs, economic imbalance, and depletion of food supply. Biofuel production from inedible sources shall lower the drawbacks of edible products and crops. Inedible feedstocks are the sustainable source of biofuel production as they are mostly grown on waste/abandoned land, produce similar or higher yields than edible feedstocks, and are fairly cost-effective. Hence this present work reviews the challenges and possibilities of employing inedible oil and products as a potential feedstock for biofuel production. Salient features of inedible oil such as production technologies, cost and benefits, fatty acid and physicochemical properties and oil extraction technology are reviewed from the latest literature. The outcome of this study suggests that there is a huge prospect of utilizing inedible oil as a reliable feedstock for biofuel generation. Among various production processes, scCO2 extraction technology proved to reduce inedible oil's moisture by 70% and FFA content by 62%, with a higher conversion rate of about 97%, as methanol in supercritical conditions has lesser interaction with the FFA of inedible oil. Inedible feedstocks are effective, non-toxic and safe in biofuel production. However, there exists a challenge in restricting its development in large-scale commercialization.
Prediction compressive strength of cement-based mortar containing metakaolin using explainable Categorical Gradient Boosting model
(Elsevier Ltd, 2022) Nguyen, Ngoc-Hien; Tong, Kien T.; Lee, Seunghye; Karamanlı, Armağan; Vo, Thuc P.
Although machine learning models have been employed for the compressive strength (CS) of cement-based mortar containing metakaolin, it is difficult to understand how they work due to “black-box” nature. In order to explain the involved mechanism, Categorical Gradient Boosting (CatBoost) model with feature importance, feature interaction, partial dependence plot (PDP) and SHapley Additive exPlanations (SHAP) is proposed in this paper. A dataset consisting of 424 samples with six input variables is used to build the CatBoost model, which has optimal performance by tuning a set of seven hyper-parameters using sequential model-based optimization. Five quantitative measures (R2, MAE, RMSE, a10-, a20-index) are employed to evaluate the accuracy and the obtained results are superior to the previous study. It is from feature importance that the most significant input variable involving the CS is water-to-binder ratio, followed by age of specimen and cement grade. The strongest feature interaction is between water-to-binder ratio and metakaolin. A comprehensive parametric study is carried out via SHAP and PDP to investigate the effects of all input variables on the CS of cement-based mortar.

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