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Abstract In this study, the combustion, performance, and emission results of the HCCI engine under different fuel and engine parameters conditions were examined experimentally and statistically. Engine speed, excess air ratio, and fuel types with different fusel oil concentrations were used as variable parameters. The engine speed was determined as 1000 and 1200 rpm, excess air ratio 1.7 and 2.1, and fusel oil ratio in fuel was determined as 15% and 30%. When the HCCI engine was operated with these input parameters, the effective torque indicated thermal efficiency, maximum pressure increase rate, COVimep, HC, CO, and NOx values were examined. Experiments were carried out in line with the determined experimental series, and the data obtained were analyzed. Optimization has been made to determine the optimum input parameters by inputting the targeted response parameters from the HCCI engine. After the optimization study, it was concluded that the optimum response parameters, engine speed was 1262.44 rpm, excess air ratio was 1.91631, and was obtained by using F30 fuel. Under optimum input parameters, the effective torque is 5.751 Nm, ITE 34.089%, MPRR 7.257%, COVimep 4.009%, CA50 7 ° CA, HC 454.185 ppm, CO 0.0727%, and NOx 0.000169486 ppm.

Abstract This study was designed to analyses the performance and exhaust emissions of a direct-injection diesel engine fueled with multi-walled carbon nanotubes (MWCNTs) included in biodiesel-blended diesel fuel using response surface method (RSM). The influence of input parameters —engine load and MWCNTs concentration — on the response parameters (i.e., BSFC, BTE, CO, NOX, and UHC) were investigated and predicted. MWCNTs were added into B20 fuel (20% biodisesel+80% diesel) in various concentrations (25, 50, 75, and 100 ppm). The tests performed under varying engine load conditions (5, 10, 15, and 20 Nm) at a constant engine speed of 1800 rpm. Multi-regression models for BTE, BSFC, and CO, UHC, and NOX emissions were derived using RSM and were found to be statistically significant. Exhaust UHC and CO concentrations for the studied fuel blend decreases with the addition of MWCNTs into B20 fuel, while NOx emissions drastically increased. The optimal engine working conditions were found to be an engine load of 10 Nm and MWCNTs concentration of 98 ppm. Based on the optimized values, the most optimal results for BTE and BSFC along with CO, UHC, and NOX emissions were found to be 28.57 (%), 269.84 (g/kWh), 0.03 (%Vol.), 44.16 (ppm), and 458.81 (ppm).

Abstract In this study, a single cylinder, four-stroke, naturally aspirated with compression ratio of 18:1 direct injection diesel engine was run with opium poppy oil biodiesel-diesel fuel blends. The effects of diesel and biodiesel-diesel fuel blends were investigated experimentally on combustion, performance and emissions. Experiments were conducted with standard diesel fuel and opium poppy oil biodiesel-diesel fuel blends (OP10 and OP20) at maximum brake torque speed of 2200 rpm and five different engine load including 25%, 50%, 75% and 100%. This study focuses on the detailed performance and combustion analysis with opium poppy biodiesel under different engine load and speeds. Test results showed that in-cylinder presssure and heat release rate increased with the increase of engine load when biodiesel fuel blends were used. ID period increased with the usage of biodiesel. Thermal efficiency decreased by about 5.73% and 13.05% with OP10 and OP20 compared to diesel respectively owing to lower calorific value of opium poppy oil biodiesel at 75% engine load. NOx increased 2.9% and 5.98% with OP10 and OP20 according to diesel at full load. On the contrary, CO decreased 14% and 17.42% with OP10 and OP20 compared to diesel at full load.

Abstract Turkey's economy is mainly dependent on agriculture and the country provides almost all petroleum demand through imports, the evaluation of vegetable alternative engine fuels is of great importance. In this study, usability of methyl ester of rapeseed oil and hazelnut produced abundant in Turkey was examined. Experiments were carried out in a four-cylinder, four-stroke, 46 kW, direct injection diesel engine. A comparison of diesel fuel, the rapeseed oil methyl ester and the hazelnut oil methyl ester blends was made from the engine performance and emissions point of view. Engine performance and emission tests were carried out with 4 different fuel that 100% diesel (SD), 50% rapeseed oil methyl ester and 50% diesel (B1), 50% hazelnut oil methyl ester and %50 diesel (B2), 25% rapeseed oil methyl ester, 25% rapeseed oil methyl ester and 50% diesel (B3). Highest engine performance and lowest specific fuel consumption were obtained with SD fuel. But the use of biodiesel led to reduction in CO and smoke emissions accompanying with the imperceptible torque loss. As the rapeseed methyl ester rate increased in the blend, smoke and CO emissions decreased, NOx and CO2 emissions increased. With the use of B1 fuel, NOx emissions increased up to 7.2%.

This study presents a beta type Stirling engine mechanism and its performance analysis. The displacer motion of the engine is performed by a lever mechanism. The performance of the engine was investigated via comparing with a rhombic-drive engine possessing an equal sided rhombic. Comparison was made for kinematic behaviors, power and thermal efficiency. For comparison; the piston swept volume, the inner heat transfer area, the hot and cold end temperatures, the inner heat transfer coefficient, charge pressure and dead volumes were kept equal for both engines. As working fluid the helium was used. Thermodynamic treatments of engines were performed via the nodal analysis. The power of the lever driven engine was found to be greater than the power of the rhombic drive engine. Under the equal charge pressure, the thermal efficiency of the lever driven engine was found to be lower than the efficiency of the rhombic drive engine however, under the equal working fluid mass the thermal efficiency of the lever driven engine was found to be greater than that of the rhombic drive engine. The external volume and mass of the lever driven engine is lower than the rhombic drive engine.

In this study, the effects of water injection quantity and injection timing were investigated on engine performance and exhaust emissions in a six-stroke engine. For this purpose, a single cylinder, four-stroke gasoline engine was converted to six-stroke engine modifying a new cam mechanism and adapting the water injection system. The experiments were conducted at stoichometric air/fuel ratio (k = 1) between 2250 and 3500 rpm engine speed at full load with liquid petroleum gas. Water injection was performed at three different stages as before top dead center, top dead center and after top dead center at constant injection duration and four different injection pressure 25, 50, 75 and 100 bar. The test results showed that exhaust gas temperature and specific fuel consumption decreased by about 7% and 9% respectively. In contrast, fuel consumption and power output increased 2% and 10% respectively with water injection. Thermal efficiency increased by about 8.72% with water injection. CO and HC emissions decreased 21.97% and 18.23% until 3000 rpm respectively. NO emissions decreased with water injection as the temperature decreased at the end of cycle. As a result, it was seen that engine performance improved when suitable injection timing and injected water quantity were selected due to effect of exhaust heat recovery with water injection.

Abstract In this study, it was aimed that the effects of naphtha on homogeneous charged compression ignition (HCCI) combustion, performance, exhaust emissions and operating range were researched experimentally in an HCCI engine. The test engine was able to operate with HCCI mode between 800 and 2000 rpm and λ = 1.61–λ = 2.93 lambda values range at constant inlet air temperature of 60 °C. Pure n-heptane and naphtha, N25, N50 and N75 fuel blends were used as test fuels. Experiments showed that knocking tendency reduced with the increase of lambda. Similarly, more stable combustion was obtained with the addition of naphtha into n-heptane due to higher octane number. Test results showed that HCCI combustion was delayed when naphtha fraction increased in the test fuels. MPRR was obtained as 15.6 bar/°CA and 11.9 bar/°CA with n-heptane and naphtha respectively at λ = 2 and 1000 rpm. ITE increased from 29% to 37% with naphtha according to n-heptane at λ = 2 and 1000 rpm. On the contrary, HC and CO increased from 331 ppm to 411 ppm and 0.051% to 0.075% with naphtha compared to n-heptane at λ = 2 and 1000 rpm, respectively. It was also seen that Naphtha showed wider HCCI operating range according to n-heptane especially knocking zone.

AbstractStirling engines take attention due to their high thermal efficiency potential. Many experimental and numerical studies have been performed up to date. Numerical performance analyses of Stirling engines implemented with CFD simulations are classified as 4th order analyses. In the present study, the effect of compression ratio on engine performance of a beta type Stirling engine with rhombic mechanism was investigated by 2D CFD simulation. CFD simulations of the Stirling engine were performed by ANSYS Fluent software. The engine examined by CFD analysis was modeled using the dimensions of an engine manufactured and tested in a previous study, and validation of the CFD simulation was conducted regarding in‐cylinder pressure at 4 bar charge pressure. The crank radius and length of the regenerator zone of the engine were optimized by considering the compression ratio of the engine and engine performance was investigated. Maximum engine performance was obtained at a compression ratio of 2.24 which was ensured by 31.5 mm crank radius and 609.9 mm a length of the regenerator zone. By optimizing the dimensions the engine performance was improved by 99% compared to the base engine configuration. The cyclic work, power, torque, and thermal efficiency were calculated as 62.47 J, 728.93 W, 9.94 Nm, and 37.7% respectively.