Ultra-High Molecular Weight Polyethylene (UHMWPE) is used in biomedical applications due to its high wear-resistance, ductility, and biocompatibility. A great deal of research in recent decades has ...focused on further improving its mechanical and tribological performances in order to provide durable implants in patients. Several methods, including irradiation, surface modifications, and reinforcements have been employed to improve the tribological and mechanical performance of UHMWPE. The effect of these modifications on tribological and mechanical performance was discussed in this review.
The nitrogen (N2) expander and single mixed refrigerant (SMR) liquefaction processes are recognized as the most favorable options to produce liquefied natural gas (LNG) at small-scale and offshore ...sites. These processes have a simple and compact design that make them efficient with respect to their capital costs. Nevertheless, huge operating costs, mainly due to their lower energy efficiency, remains an ongoing issue. Utilization of design variables having non-optimal values is the primary cause for the lower energy efficiency; which, in turn, leads to exergy destruction (i.e., entropy generation), and ultimately the overall energy consumption is increased. The optimal execution of the design variables of LNG processes can be obtained through effective design optimization. However, the complex and highly non-linear interactions between design variables (refrigerant flowrates and operating pressures) and objective function (overall energy consumption) make the design optimization a difficult and challenging task. In this context, this study examines a new optimization algorithm, named “Jaya”, to reduce the operating costs of nitrogen dual expander and SMR LNG processes. The Jaya approach is an algorithm-specific parameter-less optimization methodology. It was found that by using the Jaya algorithm, the energy efficiency of the SMR process and nitrogen dual expander natural gas (NG) liquefaction process can be enhanced up to 14.3% and 11.6%, respectively, as compared to their respective base cases. Using the Jaya approach, significant improved results were observed even compared to other previously used optimization approaches for design optimization. Results of conventional exergy analysis revealed that the exergy destruction of SMR and N2 dual expander process can be reduced by 17.4% and 14%, respectively. Moreover, economic analysis identified the 13.3% and 11.6% relative operating costs savings for SMR and N2 dual expander LNG processes, respectively.
In this study, the non-edible Chinaberry Seed Oil (CBO) is converted into biodiesel using microwave assisted transesterification. The objective of this effort is to maximize the biodiesel yield by ...optimizing the operating parameters, such as catalyst concentration, methanol-oil ratio, reaction speed, and reaction time. The designed setup provides a controlled and effective approach for turning CBO into biodiesel, resulting in encouraging yields and reduced reaction times. The experimental findings reveal the optimal parameters for the highest biodiesel yield (95 %) are a catalyst concentration of 1.5 w/w, a methanol-oil ratio of 6:1 v/v, a reaction speed of 400 RPM, and a reaction period of 3 min. The interaction of the several operating parameters on biodiesel yield has been investigated using two methodologies: Response Surface Methodology (RSM) and Artificial Neural Network (ANN). RSM provides better modeling of parameter interaction, while ANN exhibits lower comparative error when predicting biodiesel yield based on the reaction parameters. The percentage improvement in prediction of biodiesel yield by ANN is found to be 12 % as compared to RSM. This study emphasizes the merits of both the approaches for biodiesel yield optimization. Furthermore, the scaling up this microwave-assisted transesterification system for industrial biodiesel production has been proposes with focus on its economic viability and environmental effects.
•The maximum biodiesel yield of 95 % was obtained.•The biodiesel yield predicted by ANN model was close to the experimental optimized yield.•The R2 value was close to one for the training and was 0.944 for validation.•RSM better described the interactions of individual parameters and ANN worked better for overall yield prediction.
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•The minimum BSFC of 0.39678 kg/kWh has been observed for B10 + DMC as compared to all other tested biodiesel blends.•BTE and EGT have been improved for biodiesel blends with the ...addition of 10% DMC.•The CO and HC emissions reduced with the addition of DMC, as well as the concentration of biodiesel increased in biodiesel blends.•Addition of fuel additive escalates the NOx emission due high cetane number and high oxygen content.•DMC improved the combustion duration of the biodiesel blends.
Present study investigates the effect of palm biodiesel blends with and without oxygenated alcohol dimethyl carbonate (DMC) on compression ignition engine. H2SO4 was used to treat the crude palm oil. Furthermore, acid treated palm oil was converted into palm biodiesel via ultrasound-assisted transesterification process at operating conditions of catalyst (KOH) concentration of 0.75 wt%, methanol to oil ratio of 60 V/V %, reaction time of 38 min, reaction temperature of 60 °C and 59% duty cycle. The antioxidant used in biodiesel blends was dimethyl carbonate. These samples were prepared by adding DMC 10% by volume into biodiesel blends at stirring speed of 2000 rpm for 30 min in order to make a homogenous blend. The key fuel properties of the six fuel samples before being engine tested were measured including kinematic viscosity, dynamic viscosity, density, flash point, acid value and calorific value. Engine performance, emission and combustion characteristics were investigated by operating engine at full load condition and varying engine speeds from 1100 rpm to 2100 rpm. Major findings were average increase of 1.70%, 1.22% and 0.95% in BP; average decrease of 1.31%, 2.93% and 1.08% in BSFC; average increase of 4.30%, 4.77% and 4.90% in BTE; average decrease of 2.63%, 2.80% and 4.54% in EGT; significant reduction of 19.04%, 25% and 26.47% in CO emissions; average reduction of 12.76%, 19.35% and 33.33% in HC emissions observed for B10 + DMC, B20 + DMC and B30 + DMC as compared to biodiesel blends without antioxidant.
The solar absorption efficiency of water as a base-fluid can be significantly improved by suspending nanoparticles of various materials in it. This experimental work presents the photo thermal ...performance of water-based nano-fluids of graphene oxide (GO), zinc oxide (ZnO), copper oxide (CuO), and their hybrids under natural solar flux for the first time. Nanofluid samples were prepared by the two-step method and the photothermal performance of these nanofluid samples was conducted under natural solar flux in a particle concentration range from 0.0004 wt % to 0.0012 wt %. The photothermal efficiency of water-based 0.0012 wt % GO nanofluid was 46.6% greater than that of the other nanofluids used. This increased photothermal performance of GO nanofluid was associated with its good stability, high absorptivity, and high thermal conductivity. Thus, pure graphene oxide (GO) based nanofluid is a potential candidate for direct absorption solar collection to be used in different solar thermal energy conversion applications.
Liquid fossil fuels are the main source of energy in transportation vehicles and aviation for many decades. This dependence on fossil fuels can be reduced by liquid biofuels blended with fossil fuels ...or utilized purely. The purpose of this research is to authenticate a method for different fuels for measurement of injection rate based on the spray momentum measurement and total fuel mass injected. So, in this research B50, B100 and simple diesel fuel hydraulic behavior was investigated. All the measurements have been taken in a chamber/cylinder filled with nitrogen gas at high pressure, which results in the gas density of 22.7kg/m3 and 34.6kg/m3, using the injection pressures 600, 800 and 1000 bar. Spray angle and spray tip penetration measurements presented that an increment in injection pressure boosted fuel spray dispersion whereas increment in ambient pressure showed a reverse effect. All fuels have almost same momentum flux for their regarding conditions. B50 and B100 have a greater momentum efficiency than simple Diesel. Momentum flux increases to a factor of almost 1.4 with every 200 bar rise in injection pressure. The fuel mass injected showed a reduction in fuel mass for B50 2–3% and for B100 5–6% as compared to diesel fuel.
In fluid sciences, flow between two cylinders has subtle industrial applications. This research has experimentally investigated the instabilities in a wide gap Taylor Couette flow with counter ...rotating cylinders of 0.1 radius ratio. Study has been done for various angular momentum ratios (λ) ranging from 0 → −3 at a constant cylinders’ rotation difference (ΔΩ) of 2500 rpm and 3000 rpm. Two specific types of vortices have been observed during the flow visualization. The first vortex originated before the middle section with larger diameter of 2.31 cm, whereas the second one formed near the outer cylinder with 0.997 diameter. Probability distribution of vortex lifetime shows that the maximum lifetime probability of vortices is between 0.44 and 0.48 s. A relatively new behavior of vortices was observed. Vortices tend to travel in pairs and near the inner, high velocity cylinder vortices were cylindrical while at the outer slow velocity cylinder they were elliptical in the shape. It is observed that in turbulence range, increasing or decreasing the Reynolds number within certain limits does not have any significant effect on the shape of the flow structures. Particle Image Velocimetry (PIV) test shown almost similar results. Vector maps were calculated using Adaptive correlation method. The maximum velocity was in the range of 0.432–0.5 m/s and it occurred near the both cylinders wall. These observations will be helpful in future studies for analyzing the mixing, transport and drag properties of the fluid. Keywords: Taylor Couette, Flow visualization, Turbulence, PIV, Vortex
Addition of a small amount of nanoparticles to the working fluids of a parabolic trough collector does not only enhance the heat transfer properties and thermal conductivity of basefluid but also ...improves the thermal efficiency of the system. The current investigation presents a comparative analysis of experimental performance of a conventional parabolic trough collector and direct absorption parabolic trough collector for capturing solar thermal energy. Two separate nanomaterials, Al
2
O
3
(with high scattering properties) and CuO (with high absorption properties), were selected for the preparation of the hybrid nanofluids. A customized experimental setup was developed to evaluate their photothermal performance. The nanofluid samples in the concentration range of 0.01–0.5 wt% were investigated under a natural solar flux. Thermal efficiency of conventional parabolic trough collector was increased by 31% using hybrid nanofluid as compared to basefluid. The thermal efficiency enhancement of direct absorption parabolic trough collector was observed as 19% higher than that of conventional parabolic trough collector due to higher heat transfer rate, solar trapping and volumetric absorption. These binary nanofluids can be potential working fluids in various applications based on solar thermal energy.
Modern manufacturing industries prefer laser drilling processes owing to the adequate controlled drilling in comparison with existing alternatives. The presented experimental study mainly accounts ...defocusing impact along with other technical parameters and optimization of Nd:YAG millisecond pulsed laser drilling; and finally their influence on the entrance and exit holes profile. The key technical parameters such as pulse frequency, pulse width and assisting gas pressure with respect to different defocused focal plane are explored experimentally for the percussion laser drilling of high grade steel 18CrNi8. Experiment results revealed that increase in defocusing distance has caused an increment in hole entrance diameter; however, with different defocusing distance, the entrance diameter increasing rate keep changing. Different trends of increasing and decreasing diameter at entrance and exit are recorded and investigated with respect to work-piece defocusing positions. The defocusing variation of laser beam has been investigated with the hole profile, changing from straight hole to tapered blind hole. Which leads to conclusive and optimized results for obtaining optimal hole profile (at entrance and exit). The optimum parametric combinations for attaining lower heat treatment effects are also discussed for superior hole quality.
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•Palm biodiesel production parameters optimized utilizing the Response Surface Methodology.•The maximum BTE recorded for B30 + Al2O3 compared to other tested blends at all the test ...conditions.•The minimum CO level observed for B30 + TiO2 as compared to other biodiesel blends at 2300 rpm.•B30 + CNT indicated a significant reduction in NOx intensity as compared to other blends.•Palm biodiesel blended with nanoparticle additives improved engine performance.
The present study aims to evaluate the emission and performance characteristics of a CI engine using biodiesel blends with three different nanoparticles. Biodiesel was prepared from palm oil using transesterification process. Biodiesel yield has been optimized using response surface methodology, which develops an interaction among the independent operating parameters reaction temperature methanol to oil ratio, and catalyst concentration, where they are changed as follows: 50–65 °C, 5:1–12:1, and 0.25–1.75, respectively. Nano fuel blends were prepared by dispersing CNT, TiO2 and Al2O3 nanoparticles into the B30 blend. The stability of these nanoparticles was improved by adding sodium dodecyl sulfate (SDS) as a surfactant, and the stability was characterized by ultraviolet–visible spectrometry. These nanoparticles were mingled with palm methyl ester at a proportion of 100 ppm using an ultrasonication water bath. The engine performance and emission characteristics were determined at varying engine speed and a full load condition. At all engine speeds, B30 with Al2O3 ternary fuel blend exhibits a promising reduction in brake specific fuel consumption (BSFC) of 5.98%. A significant improvement of 9.83%, 3.91% and 1.37% in brake thermal efficiency (BTE) has been observed for Al2O3, CNT, and TiO2 additives as compared to B10 blend, respectively. B30 with TiO2 ternary blend shows a sharp reduction of 27.89% and 30.68% in the CO and HC emissions respectively, and 10.37% decrease in NOx level with the addition of CNT as a fuel additive in the ternary fuel blend. Palm biodiesel blended with nanoparticle additives enhanced both engine performance and emission characteristics.
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