• Energy Research

Abstract Alcohol based fuels attract the attention of alternative fuel researchers. Many studies have been performed about combustion, performance and emission characteristics of alcohol used in internal combustion engines. Fusel oil is an alcohol based fuel obtained as a by-product during alcohol fermentation. Up to the present there has been no study regarding the combustion characteristics of fusel oil in a spark ignition engine. In this experimental study, performance, emission and combustion characteristics of fusel oil were examined in a spark ignition engine at 2500 rpm and four different engine loads. In-cylinder pressures, heat release rates, flame development and flame propagation durations, crank angles corresponding 50% of total mass fraction burnt, engine torque, brake specific fuel consumptions, CO, HC and NO x emissions were investigated. The water content and lower heating value of the fusel oil aggravated the combustion. Flame development and flame propagation durations were prolonged. As a result engine performance dropped. In addition, fusel oil usage increased CO and HC emissions up to 21% and 25% respectively. NO x emissions decreased about 31% due to worse combustion performance of fusel oil.

In this study, the biodiesel obtained from the waste olive oil by transesterification method has been mixed with a 30% of diesel fuel as volume and tested with a single cylinder direct injection diesel engine. The main purpose of this study is to obtain purer biodiesel from waste olive oil using methyl alcohol (CH3OH) and sodium hydroxide (NaOH) as catalyst in the transesterification method and research performance, combustion and emission characteristics in detail in a direct injection diesel engine. The combustion, engine performance and exhaust emission values have been also compared with diesel fuel. The test engine was operated at a constant speed of 2200 rpm and different engine loads such as 3.25 Nm, 7.5 Nm, 11.25 Nm, 18.75 Nm. According to the experimental results, the thermal efficiency of biodiesel is lower by about 1% to 5% than diesel. CO is lower about 37.5 % with biodiesel than that of diesel at 18.75 Nm. CO2 is higher 41% with biodiesel than diesel at 11.25 Nm. NOx was measured 9.5% higher than diesel fuel at 18.75 Nm. Soot emissions decreased by 37.5% compared to diesel.

Abstract In this study effects of compression ratio on HCCI combustion, performance and emissions was investigated parametrically. In addition to parametric investigation and as a novel way of the paper engine BSFC maps were obtained for RON20 andRON40 fuels and each compression ratios of 9:1, 10:1, 11:1 and 12:1. The parametric experiments were carried out at 800 rpm engine speed. In both parametric and mapping experiments were conducted at intake temperature of 353 K. In-cylinder pressure, ROHR, combustion duration, start of combustion, indicated mean effective pressure, thermal efficiency and CO, HC and NOx emissions were examined. It was determined that in-cylinder pressure and rate of heat release decreased while the mixture getting leaner. The increase of octane number of fuel led to extension of combustion duration. On the contrary, combustion duration decreased along with the increase of compression ratio. It was found that the CO and HC emission were high while NOx emissions were low at lower CR. With the increase of CR, CO and HC emissions decreased however NOx emissions increased. The maximum thermal efficiency was obtained as 38.2% at 800 rpm and 12:1 CR with RON40 fuel. The widest operational region was obtained with RON20 fuel at CR of 10:1 with a minimum BSFC value of 210 g/kWh.

In this study, the performance and exhaust emissions of homogeneous charge compression ignition engine fueled by gasoline fuel were modeled by using the response surface method. The effect of independent variables-compression ratio, engine speed inlet air temperature, lambda value, and research octane number value-on responses such as indicated mean effective pressure, indicated thermal efficiency, maximum pressure rise rate, specific fuel consumption, cyclic differences was studied together; unburned hydrocarbons, carbon monoxide, and nitrogen oxide are predicted by multi-regression. The desirability function was used to define an optimum combination of engine operating conditions. High desirability of 77% was achieved at the compression ratio of 12, intake air temperature of 333 K, lambda value of 1.8, engine speed of 935 rpm, and RON40. This homogeneous charge compression ignition engine operating condition was suggested as the optimum independent variables. At this point, 5.08 of indicated mean effective pressure, 35% of indicated thermal efficiency, 243.28 g/kWh of specific fuel consumption, 4.43 bar/CA of maximum pressure rise rate, and 3% of COVimep were achieved as responses. Additionally, the optimum values of engine emissions were found to be 355.586 ppm for unburned hydrocarbons, 3% for carbon monoxide, and 0 ppm for nitrogen oxide. This study showed that changes in performance and exhaust emissions of a homogeneous charge compression ignition engine could be successfully predicted using the response surface method. This study, which was carried out with the RSM technique, reduced the hundreds of data points needed, and all variables could be examined with only 60 data points.

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 the present study, performance of an HCCI engine powered with ethanol/toluene/n-heptane tri-fuel blend was optimized by using response surface method. The studied independent parameters were engine speed, lambda ratio, and fuel blends. The impact of these parameters on engine torque, COVimep, CA10, CA50, indicated thermal efficiency, IMEP along with emissions of NOX, CO, and HC comprehensively investigated. According to the results, the optimal HCCI engine operation condition was proposed as engine speed of 1343 rpm, lambda value of 2.29, and ethanol ratio of 22%. At this condition, the engine outputs, i.e., IMEP, COVimep, indicated thermal efficiency, CA10, and CA50, engine torque were estimated to be 4.21 bar, 4.28%, 0.37, 1.41 °CA, 4.62 °CA, and 8.2 Nm, respectively. The engine-out emissions, including HC, NOX, and CO emission, were predicted to be 243 ppm, 1.05 ppm, and 0.03%, respectively. The result indicates that using ethanol/toluene/n-heptane fuel mixture improved the HCCI combustion and NOX emission. The near-zero NOX emissions were recorded at all fuel mixture. However, enhancing ethanol ratio in the fuel blends showed an increase in CO and HC emissions. Overall, this study showed that response surface technique could be used as a promising method to model the HCCI engines.

Ignition characteristics of diesel are weak due to higher viscosity and density especially at cold start conditions. So, it is seen that the usage of dibutyl maleate having high content of oxygen as an additive to improve the bad properties of pure diesel is essential and sensible. In this research, a single cylinder DI diesel engine was operated at four different engine loads including 4.12, 9.61, 15.10 and 20.60 Nm to observe and see the influences of dibutyl maleate on performance and combustion characteristics such as heat release rate, in-cylinder pressure, ignition delay etc. and thermal efficiency. It was found that in-cylinder pressure decreased with the addition of dibutyl maleate whereas remarkable increase was observed on pressure rise rate and ringing intensity with fuel blends. ID (Ignition delay) period increased with dibutyl maleate addition into diesel due to lower cetane number while combustion duration shortened with fuel blends compared to diesel. Besides, indicated thermal efficiency decreased about 20.18% and 24.25% with D90DBM10 and D90DBM20 respectively according to neat diesel at 15.10 Nm. Specific fuel consumption increased 5.08% and 8.13% with D90DBM10 and D90DBM20 respectively compared that neat diesel. It was also seen that cyclic variations increased in case of usage dibutyl maleate addition. Test results also demonstrated that HC (Hydrocarbon) and soot reduced while CO (carbon monoxide), CO2 (carbon dioxide) and NOx (nitrogen oxides) raised with the usage of dibutyl maleate compared to neat diesel.