• Energy Research
• 2021-2025close

In this numerical study, the effects of the premixed ratio, intake manifold pressure and intake air temperature on a four-cylinder, four-stroke, direct injection, low-compression-ratio gasoline engine, operated in reactivity-controlled compression ignition (RCCI) combustion mode at a constant engine speed of 1000 rpm, were investigated using Converge CFD software. The results of numerical analyses showed that the maximum in-cylinder pressure and heat release rate (HRR) increased and the combustion phase advanced depending on the rise in both intake manifold pressure and intake air temperature. The CA50 shifted by 18.5 °CA with an increment in the intake air temperature from 60 °C to 100 °C. It was observed that the combustion duration dropped from 44 °CA to 38 °CA upon boosting the intake manifold pressure from 103 kPa to 140 kPa. Moreover, a delay in the combustion phase occurred at a constant intake air temperature with an increasing premixed ratio. The maximum value of in-cylinder pressure was recorded as 36.15 bar (at 11 °CA aTDC) with the use of PRF20. Additionally, as the content of iso-octane in the fuel mixture was increased, combustion delay occurred, and the maximum value of in-cylinder temperature obtained was 11 °CA aTDC using PRF20 fuel at the earliest point. While HC and CO emissions reached the highest values at a 60 °C intake air temperature, NOx and soot emission values were detected at quite low levels at this temperature. The values of all these emissions increased with rising intake manifold pressure and reached their highest values at 140 kPa. In addition, while the highest HC and CO emission values were observed with the use of PRF60 fuel, the results revealed that the control of the combustion phase in the RCCI strategy is notably affected by the premixed ratio, intake manifold pressure and intake air temperature.

Additives are added to conventional fuels to ensure complete combustion of fuels, increase engine performance and reduce harmful emissions from vehicles. Hydrogen and oxygen-containing fuel additives added to fossil-based internal combustion engine fuels improve the properties of the fuels and reduce vehicle-related emissions. Evaluation of mixed fuels created by adding different types of alcohol and nano-sized additives to motor fuels as an alternative fuel in motor vehicles is among the most researched scientific studies recently. In this study, alcohol-gasoline fuels (E5, M5), NaBH4-alcohol-gasoline fuels (ES5, MS5), and pure gasoline were tested in a gasoline engine. Fuels used in engine tests; E5 fuel (5% by volume ethanol 95% gasoline blend), M5 fuel (5% by volume methanol 95% gasoline blend), ES5 fuel (5% by volume NaBH4-ethanol solution 95% gasoline blend), MS5 fuel (5% by volume NaBH4-methanol solution 95% gasoline mixture) and pure gasoline. In the experiments, brake thermal efficiency, engine torque, specific fuel consumption, and exhaust gas temperature were measured and compared with pure gasoline. Compared to gasoline, the exhaust gas temperatures of all blended fuels decreased. On the other hand, there was an increase in engine torque values, except for ES5 fuel. At the same time, there was an increase in both specific fuel consumption and brake thermal efficiency. When the CO and HC emission values of the blended fuels are compared with the gasoline fuel values, the highest reduction in CO emissions occurred in ES5 blended fuel with 65.53%, while the highest decrease in HC emission was realized in E5 fuel with 19.09%. On the other hand, when NOx and CO2 emissions of E5, M5, ES5, MS5 mixed fuels are compared with gasoline, NOx emissions are 12.63%, 28.37%, 19.65%, respectively; decreased by 36.03% but CO2 emissions increased by 8.51%, 30.46%, 34.48%, 25.95% respectively. © 2022 Elsevier Ltd

Abstract In this study, biodiesel was produced from Crambe Abyssinica plant with KOH and NaOH catalysts and mixed with standard diesel fuel in different proportions. The effects of the test fuels obtained by adding organic manganese at the rate of 5 µmol/L. Experiments of all fuel types were carried out on a test setup containing a single-cylinder diesel engine under 2200 rpm engine speed, 3.75, 7.5, 11.25 and 15 Nm engine load conditions. The pressure data obtained as a result of the tests were analyzed in the MATLAB / Simulink simulation program environment, and the heat release rate, combustion stages, thermal efficiency, indicated mean effective pressure (imep), ignition delay (ID), maximum pressure rise rate (MPRR), ringing intensity (RI), cyclic of variations (COVimep) and brake specific fuel consumption (BSFC) values were calculated. Higher thermal efficiency was obtained as 21.58% with CANB25K fuel usage compared to CAKB25K fuel (20.82%). BSFC increased 0.96%, 8.24% and 10.36% with CAKB25K, CAKB50K and CAKB75K according to diesel at 11.25 Nm load respectively. Likewise, 1.51% 4.83% and 7.33% increase was seen with CANB25K, CANB50K and CANB75K according to diesel at 11.25 Nm load respectively.