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In the present study, a two-step process involving microwave-enhanced alkali pretreatment (MEAP) of rice husk followed by the copyrolysis of pretreated rice husk with LDPE was adopted to produce biochars in conventional electrically heated pyrolyzer (CPR) and microwave pyrolyzer (MWPR). Proximate and ultimate analysis revealed that biochar produced in MWPR exhibited higher fixed carbon (73.36%), lower volatile matter (8.45%), lower ash yield (17.41%), higher-carbon content (73.57%) and lower H/C and O/C ratios (0.19 and 0.12, respectively), as compared to biochar produced in CPR. BET analysis indicated that the surface area and total pore volume were significantly higher for biochar produced under microwave irradiation (1280.31 m2 g−1 and 0.41 cc g−1), as compared to biochar produced in CPR (470.25 m2 g−1 and 0.12 cc g−1). The XRD analysis showed that the biochar produced in MWPR exhibited two peaks at 26° (JCPDS No. 41-1487) and 43° (JCPDS Card No. 75-1621), thus closely resembling the reduced graphene oxide. Furthermore, uniform and cleaner pores were observed for MWPR chars in contrast with heterogeneous surface and blocked pores for CPR chars. [ABSTRACT FROM AUTHOR]

Designing heat exchangers (HEXs) for a wide range of applications, involves a complex interplay of factors like cost, maintenance, material selection, pressure drop, fluid flow configuration, and heat transfer. Due to this complexity, empirical relationships are used performance evaluation, focusing on heat transfer rate (q), overall heat transfer coefficient U , and effectiveness ε . Testing is crucial to measure the outlet temperatures for specific inlet conditions and fluid flow characteristics. This paper introduces a simple and reliable iterative procedure for estimating cold ( T co ) and hot ( T ho ) fluid outlet temperatures in a Chevron plate heat exchanger (CPHE). This procedure relies on two basic equations of heat transfer rate (q), and logarithmic mean temperature difference (LMTD), Δ T lm , incorporating specified inlet parameters. The proposed approach was validated by comparing its predictions to measured data. The method is general and adaptable to other HEX types. by properly defining the temperature differences in the LMTD and evaluating the HEX performance using relevant empirical relationships for the output responses with estimates of T co and T ho to the inlet parameters. The estimated and measured cold fluid outlet temperature ( T co ) exhibited a relative error of 1.8 to 2.6%. Similarly, the hot fluid outlet temperature ( T ho ) showed a relative error of 2.4 to 3.5%. This work provides valuable insights for designers, enabling them to assess HEX performance before conducting costly and time-consuming testing. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) and carbon nitride nanotube (CNNTs) were synthesized by the pyrolysis-assisted chemical vapor deposition (PA-CVD)—pyrolysis method. The crystal structure, surface morphology, and photoluminescence properties of these materials were influenced by the deposition temperature and the choice of metal substrate. This study provides a detailed discussion of the structural growth of CNNTs and graphitic carbon nitride. As the temperature increases to 800 °C, the quantity of amorphous nature in the carbon structures increases along with an increase in the defect states. The d-spacing of interlayers of g-C3N4 and carbon nitride nanotubes (CNNTs) obtained from X-ray diffraction are 3.2 Ȧ and 3.3 Ȧ, respectively. The calculated crystallite size is about 87 nm for g-C3N4, and the lattice strain is 3.14. FESEM analysis shows a clear difference in the nanotube structures, CNNTs prepared at 600 °C have linear structures with a minimum of 60 nm diameters, whereas CNNTs prepared at 800 °C show spiral, knot, and irregular structures with a minimum of 40 nm diameter. In addition, the nano-level features and interplanar spacings are confirmed by HRTEM and SAED investigations. The maximum photoluminescence intensity observed at 574 nm and 579.5 nm for g-C3N4 on Cu substrate at 800 °C lies in the yellow light region. Additionally, smaller peaks were noted at higher wavelengths in the visible light spectrum. The estimated optical bandgap from the prepared samples from photoluminescence studies lies around 2.14 eV. [ABSTRACT FROM AUTHOR]

Pulsating heat pipes (PHPs) offer a promising solution for thermal management in diverse industries owing to their simplicity, cost-effectiveness, and impressive cooling capabilities. The angle of inclination of the heat pipe with reference to the horizontal plane significantly influences PHP performance. Unsatisfactory outcomes were observed at 90° and 180° inclination angles. A comprehensive investigation explored the impact of tilt angle and fill ratio on PHP performance indicators, specifically heat transfer rate (HTR), overall heat transfer coefficient (OHTC), and thermal resistance (TR). Tilt angles ranged from 30° to 60°, while fill ratios varied from 40 to 80%. To optimize PHP working parameters that maximize HTR, minimize TR, and enhance OHTC, a modified Taguchi approach was integrated with a robust multi-objective optimization technique. Empirical models for HTR, TR, and OHTC were developed and validated against experimental data. The recommended PHP working parameters are a 60% fill ratio and a 30° tilt angle. For the optimal parameters, HTR estimates ranged from 33.96 to 34.29 W, with the experimental value of 34.124 W falling within this range. TR estimates ranged from 0.0207 to 0.1097 °C W−1, encompassing the experimental value of 0.078 °C W−1. OHTC estimates varied between 835.8 and 958.42 W m−2 K−1, including the experimental value of 835.79 W m−2 K−1. The developed empirical relationships provide valuable insights into PHP performance for any fill ratio and tilt angle within the applicable range. PHPs find diverse applications in refrigeration, aerospace, waste heat recovery, and the utilization of low-grade energy. [ABSTRACT FROM AUTHOR]

The investigation revolves around conducting experiments to examine the heat transport properties of an STHX while utilizing various combinations of ethylene glycol (EG) and deionized water (DW) coolants, namely EG50:DW50, EG60:DW40, EG40:DW60, and EG40:DW60:NP10 (0.1%). The experiments were conducted with two different baffle angles (10° and 20°) and a fixed flow rate of 18 LPM. From the experimental outcomes, it was found that the 20° baffle angle provided better effectiveness for all coolant combinations compared to the 10° baffle angle with the same input temperature. Among these, the combination of EG40:DW60 with graphene nanoparticles (0.1%) showed the maximum effectiveness, reaching up to 58.68%, at the 20° baffle angle. To anticipate the heat exchanger's effectiveness, three machine learning algorithms—Random Forest Regressor, Linear Regression, and XG Boost—were taken into account. The experimental data were separated into training and test datasets, and the machine learning model's performance was evaluated. The results indicated that, overall, the XG Boost algorithm outperformed the other two algorithms across all parameters. The XG Boost algorithm achieved a mean average error of 0.0205 and a Root Mean Squared Error of 0.0222, demonstrating its superior accuracy in predicting the heat exchanger's effectiveness. [ABSTRACT FROM AUTHOR]

Various nanofluids (NFs) have been prepared using nanoparticles (NPs) for dual fuel engine application in this present work. In the initial segment of the work, the NF's are prepared using aluminum oxide nanoparticles (Al2O3). Further, nanoparticles were blended with diary scum oil methyl ester (DiSOME) in the mass fraction of 10–30 ppm in steps of 10, with the assistance of a mechanically operated conventional homogenizer and an ultrasonicator. In the next segment of the work, Al2O3 NP's effect on the characteristics of ignition and engine outgas levels of a single cylinder four strokes direct injection diesel engine functioning on dual fuel mode using DiSOME and producer gas (PG) has been investigated. Engine testing showed that experiments with Al2O3 based NF and PG operation resulted in 11.5% amplified brake thermal efficiency, 23.2% reduction in smoke, 18.2–21.4% reduction in hydrocarbon (HC) and carbon monoxide (CO) emissions, while more significant nitric oxide (NOx) levels by 32.6% were achieved than the same fuel combination excluded NP's at 80% load. [ABSTRACT FROM AUTHOR]

During the last few years, green composites are gaining prominence as alternative materials for aerospace, automotive and construction sectors. Green composites are renewable in nature, economical and biodegradable. The present work mainly focuses on the development of novel green composites to meet the ever-increasing demands of industry for structural applications. Green composites were developed using different fillers obtained from outermost peels of onion, potato and carrot, respectively. The percentage of fillers was varied from 10 to 30% in steps of 10% in the epoxy holding matrix. Accordingly, for each composition, six composite specimens were fabricated and were analyzed for mechanical properties and microstructure studies of the samples were also carried out using SEM. Onion-embedded epoxy samples showed maximum tensile strength (20.8 MPa) and hardness (50.75 HRB) when compared to other fillers. Further, the study revealed that mechanical properties were found to be maximum for 10% volume fraction of all fillers used in the polymer holding matrix. SEM images showed uniform distribution of the fillers in the holding matrix. Finally, the experimental results were compared with FEA and analytical calculation was found in good agreement. [ABSTRACT FROM AUTHOR]

In the present study, graphene nanobiodiesel was prepared by dispersing of graphene in Simarouba methyl ester (SME) blend with diesel. Dispersion was characterized with ultraviolet-visible (UV-Vis) spectrometry. The performance and emission characteristics of graphene nanobiodiesel were carried out on a single-cylinder, water-cooled, direct injection, four-stroke computerized diesel engine. The characteristics are measured for 3 different dosing levels of graphene nanoparticle. It resulted in improved brake thermal efficiency by 9.14%, reduction in unburnt hydrocarbon (HC) by 15.38%, carbon monoxide (CO) by 42.855 and oxides of nitrogen (NOx) emission by 12.71% with SME2040. Also the addition of graphene nanoparticles has resulted in a significant reduction in the combustion duration and a marginal increase in peak cylinder pressure at all operational loads. [ABSTRACT FROM AUTHOR]

The fossil fuels are not considered as sustainable energy sources due to their continuous depletion. To overcome this issue, alternative fuels are required to be used in diesel engine applications. Present paper investigates the performance of tire pyrolysis oil (TPO)-fueled diesel engine with minor modification in the engine operating parameters such as injection timing (IT), injector opening pressure (IOP) and nozzle geometry. Initially, experimentations are carried out to optimize the IT for which the best brake thermal efficiency (BTE) is revealed. In the next phase of the work, the effect of IOP and nozzle geometry on the performance was studied. For the diesel engine operation with TPO as fuel, it has been reported that IT of 27∘ BTDC, IOP of 240 bar and injector of 5 holes yield better performance in terms of BTE with reduced emissions. [ABSTRACT FROM AUTHOR]

This study deals with an experimental investigation to assess the characteristics of a modified common rail direct injection (CRDI) engine utilizing diesel, Mahua biodiesel, and their blends with synthesized zinc oxide (ZnO) nano additives. The physicochemical properties of diesel, diesel + 30 ppm ZnO nanoparticles (D10030), 20% Mahua biodiesel (MOME20), and Mahua biodiesel (20%) + 30 ppm ZnO nanoparticles (MOME2030) were measured in accordance to the American Society for Testing and Materials standards. The effects of modification of fuel injectors (FI) holes (7-hole FI) and toroidal reentrant combustion chamber (TRCC) piston bowl design on the performance of CRDI using different fuel blends were assessed. For injection timings (IT) and injection opening pressure (IOP) average increase in brake thermal efficiency for fuel blend D10030 and MOME2030 was 9.65% and 16.4%, and 8.83% and 5.06%, respectively. Also, for IT and IOP, the average reductions in brake specific fuel consumption, smoke, carbon monoxide, hydrocarbon and nitrogen oxide emissions for D10030 and MOME2030 were 10.9% and 7.7%, 18.2% and 8.6%, 12.6% and 11.5%, 8.74% and 13.1%, and 5.75% and 7.79%, respectively and 15.5% and 5.06%, 20.33% and 6.20%, 11.12% and 24.8%, 18.32% and 6.29%, and 1.79% and 6.89%, respectively for 7-hole fuel injector and TRCC. The cylinder pressure and heat release rate for D10030 and MOME2030 were enhanced by 6.8% and 17.1%, and 7.35% and 12.28%. The 7-hole fuel injector with the nano fuel blends at an injection timing and pressure of 10° btdc and 900 bar demonstrated the overall improvement of the engine characteristics due to the better air quality for fuel mixing. Similarly, the TRCC cylinder bowl geometry illustrated advanced ignition due to an improved swirl and turbulence. Also, the engine test results demonstrated that 30 ppm of ZnO nanoparticles in Mahua biodiesel (MOME2030) and diesel (D10030) with diethyl ether resulted overall enhancement of CRDI engine characteristics. [ABSTRACT FROM AUTHOR]