Search results

This study aims to contrastively investigate the effects of biodiesel and diesel on the power, economy and combustion characteristics of a compression ignition aviation piston engine for unmanned aerial vehicles.

Biodiesel used as alternative fuel will not be mixed with diesel during experimental study. Pure diesel fuel is used for the comparative test. Same fuel injection strategies, including pilot and main injection, are guaranteed for two fuels in same test points.

The engine-rated power of biodiesel is lower than diesel, which results in higher specific fuel combustion (SFC) and effective thermal efficiency (ETE). Biodiesel has the faster burning rate, shorter combustion duration. The crank angle of 50% mass fraction burned (CA50) is earlier than diesel. The ignition delay angle of biodiesel and diesel in the pilot injection stage is almost the same at high engine speed. As the speed and load decrease, the ignition delay angle of biodiesel in the pilot injection stage is smaller than diesel. At 100% high load conditions, the fuel-burning fraction of biodiesel in the pilot injection is the same as diesel. The peak heat release rate (HRR) of biodiesel is slightly lower than diesel. At 20% part load conditions, the fuel-burning fraction of biodiesel in the pilot injection stage is lower than diesel. Because of the combustion participation of unburned pilot injected fuel, the peak HRR of biodiesel in the main injection is equal to or even higher than diesel.

The application feasibility of alternative fuel and its effects on aviation engine power, economy and combustion characteristics will be evaluated according to the “drop-in“ requirements and on the low-cost premise without changing the aviation engine structure and parameters.

The purpose of this paper is to perform a technical and economical analysis on the conversion of a regional turboprop platform for Airborne Early Warning and Control (AEW&C) missions by supposing installation of supplementary diesel turbo‐charged engines.

The problem has been approached by considering all issues related to conversion to AEW&C platform. Class II methods have been used for weight and drag estimations. Flight performances have been evaluated by using standard equations of flight mechanics. Costs have been evaluated by using a model developed by the authors.

As far as performances are concerned, it is possible to increase aircraft service ceiling of about 4,400 ft by installing auxiliary diesel engines in separate wing‐nacelles. The low specific fuel consumption (SFC) of diesel engines balances the reduction of mission endurance caused by the aerodynamic drag increment (i.e. additional drag of AEW radar antenna and new nacelles). The proposed solution is shown to have the best Effectiveness‐Cost performance in comparison with other AEW&C aircraft‐systems.

To convert regional turboprops to AEW&C platform by employing turbocharged diesel engines could be an interesting future perspective for aerospace companies interested in creating a new AEW&C market segment.

The proposed solution gives the possibility to reduce operating costs in the AEW&C mission field. The issue is actual due to typical high operating costs of AEW&C missions.

The study aims to determine the the optimal value of output parameters of a variable compression ratio (CR) diesel engine are investigated at different loads, CR and fuel modes of operation experimentally. The output parameters of a variable compression ratio (CR) diesel engine are investigated at different loads, CR and fuel modes of operation experimentally. The performance parameters like brake thermal efficiency (BTE) and brake specific energy consumption (BSEC), whereas CO emission, HC emission, CO₂ emission, NO_x emission, exhaust gas temperature (EGT) and opacity are the emission parameters measured during the test. Tests are conducted for 2, 6 and 10 kg of load, 16.5 and 17.5 of CR.

In this investigation, the first engine was fueled with 100% diesel and 100% Calophyllum inophyllum oil in single-fuel mode. Then Calophyllum inophyllum oil with producer gas was fed to the engine. Calophyllum inophyllum oil offers lower BTE, CO and HC emissions, opacity and higher EGT, BSEC, CO₂ emission and NO_x emissions compared to diesel fuel in both fuel modes of operation observed. The performance optimization using the Taguchi approach is carried out to determine the optimal input parameters for maximum performance and minimum emissions for the test engine. The optimized value of the input parameters is then fed into the prediction techniques, such as the artificial neural network (ANN).

From multiple response optimization, the minimum emissions of 0.58% of CO, 42% of HC, 191 ppm NO_x and maximum BTE of 21.56% for 16.5 CR, 10 kg load and dual fuel mode of operation are determined. Based on generated errors, the ANN is also ranked for precision. The proposed ANN model provides better prediction with minimum experimental data sets. The values of the R² correlation coefficient are 1, 0.95552, 0.94367 and 0.97789 for training, validation, testing and all, respectively. The said biodiesel may be used as a substitute for conventional diesel fuel.

The blend of Calophyllum inophyllum oil-producer gas is used to run the diesel engine. Performance and emission analysis has been carried out, compared, optimized and validated.

The purpose of this paper was to investigate the lubricity of palm biodiesel (PB)–diesel fuel with plastic pyrolysis oil (PPO) and waste cooking biodiesel (WCB).

Three quaternary fuels were prepared by mechanical stirring. B10 (10% PB in diesel) fuel was blended with 5%, 10% and 15% of both PPO and WCB. The results were compared to B30 (30% PB in diesel) and B10. The lubricity of fuel samples was determined using high-frequency reciprocating rig in accordance with ASTM D6079. The tribological behavior of all fuels was assessed by using scanning electron microscopy on worn steel plates to determine wear scar diameter (WSD) and surface morphology. The reported WSD is the average of the major and minor axis of the wear scar.

The addition of PPO and WCB to B10 had improved its lubricity while lowering wear and friction coefficients. Among the quaternary fuels, B40 showed the greatest reduction in coefficient of friction and WSD, with 7.63% and 44.5%, respectively, when compared to B10. When compared to B30a, the quaternary fuel mixes (B40, B30b and B20) exhibited significant reduction in WSD by 49.66%, 42.84% and 40.24%, respectively. Among the quaternary fuels, B40 exhibited the best overall lubricating performance, which was supported by surface morphology analysis. The evaluation of B40 indicated a reduced adhesive wear and tribo-oxidation, as well as a smoother metal surface, as compared to B20 and B30b.

Incorporation of PPO and WCB in PB–diesel blend as a quaternary fuel blend in diesel engines has not been reported. Only a few researchers looked into the impact of PPO and WCB on the lubricity of the fuel.

This paper aims to compare the conditions of in-service oils from diesel and gasoline engines, with focus on nitration.

Oil conditions of seven engine oil samples from five diesel-fueled vehicles and nine oil samples from eight gasoline-fueled vehicles with total mileage ranging from 13,600 to 30,000 km were determined via Fourier-transform infrared spectroscopy as well as neutralization number (NN) and total base number titration.

Chemical deterioration was characterized by significant differences in oxidation, nitration, NN increase and residual aminic antioxidant contents.

Submitted in connection with the Special Issue, “Young Tribologists – Insights into the work of the new generation”.

Uncovering differences in the oil degradation of oils from gasoline and diesel engines enables improved condition-based maintenance strategies and the prediction of oil condition dependent tribological performance.

Energy is the prime mover of economic growth and is vital to the sustenance of a modern economy. Future economic growth depends heavily on the long-term availability of energy from sources that are affordable, accessible and environmentally friendly. Regulating the sulfur content in diesel fuel is expected to reduce the lubricity of these fuels, which may result in increased wear and damage of fuel injection systems in diesel engines.

The tribological properties of the biodiesels as additive in pure petro-diesel are studied by ball-on-ring wear tester to find optimal concentration, and the mechanism of the reduction of wear and friction will be investigated by optical microscopy.

Studies have shown that low concentrations of biodiesel blends are more effective as lubricants because of their superior polarity. Using biodiesel as a fuel additive in a pure petroleum diesel fuel improves engine performance and exhaust emissions. The high biodegradability and superior lubricating property of biodiesel when used in compression ignition engines renders it an excellent fuel.

This detailed experimental investigation confirms that biodiesel can substitute mineral diesel without any modification in the engine. The use of biofuels as diesel engine fuels can play a vital role in helping the developed and developing countries to reduce the environmental impact of fossil fuels.

The purpose of this paper was to improve the frictional wear resistance properties of piston skirts caused by the low viscosity lubricant by studying the tribological performance of three novel coating materials.

Comparative tribological examinations were performed in a tribological tester using the ring-block arrangement under two viscosity lubricants, the loading force was applied as 100 N, the speed was set to 60 r/min and the testing time was 180 min.

Under low viscosity lubricant, the friction coefficient and wear of the three coatings all increase, and the friction coefficient and wear of the PTFE coating are the largest, while the MoS₂ coating has the lowest friction coefficient and wear. Under low viscosity lubricant, the friction coefficient of the MoS₂ coating is 2.1%–5.4% and 20.0%–24.3% lower than that of the SiO2 and PTFE coating, respectively. The friction coefficient and wear fluctuation rate of the MoS₂ coating is the smallest when the lubricant viscosity decreases, which indicates that the MoS₂ coating has excellent stability and adaptability under low viscosity lubricant.

To reduce the piston skirt wear caused by low viscosity lubricant in heavy-duty diesel engines, the friction and wear adaptability of three novel composite coating materials for piston skirts were compared under 0 W-20 low viscosity lubricant, which could provide a guidance for the application of wear-resistant materials for heavy-duty diesel engine piston skirt.

Engine component endurance is related to fuel properties. Decreasing the sulfur content of a fuel reduces its lubricity, thus damaging engines and fuel systems. Therefore, promoting the use of a biofuel must involve assessing the functionality and lubricity of the fuel.

The ball-on-ring (BOR) wear tester was applied to determine the optimal additive concentration and the mechanism of reduction of the wear and friction of the diesel engine fuel injection system. The lubricating efficiency of the fuels was estimated by using a photomicroscope to measure the average diameter of the wear scar produced on the test ball. An optical microscope and scanning electronic microscope were used for wear surface examinations.

The wear test revealed that the wear diameter of the steel ball lubricated with either the pure petrodiesel or 20 Wt.per cent Jatropha curcas biodiesel blends was 1.36 or 1.05 mm, respectively. The experimental results indicated that when Jatropha curcas biodiesel was added into petrodiesels to reduce friction, the wear resistance of the fuel blends increased concurrently with increasing Jatropha curcas biodiesel concentration. This was attributed to the presence of stearic acid in Jatropha curcas biodiesel blends. Stearic acid has a strong affinity for metal surfaces; therefore, a chemical coating was formed between the two motion surfaces to protect the two contacted surfaces from wear. Therefore, the proposed Jatropha curcas biodiesel can be used to effectively enhance the lubricity of a petrodiesel under the condition of boundary lubrication.

Using biofuels as the fuels for diesel engines can assist developed and developing countries in reducing the impacts of their fossil fuel consumption on the environment.