An Experimental Study of Operating Range, Combustion and Emission Characteristics in an RCCI Engine Fueled with Iso-Propanol/n-Heptane

Recently, studies have been carried out using environmentally sustainable technologies with more efficient energy conversion to fulfill emission requirements. One of these technologies, reactivity controlled compression ignition (RCCI), is a low-temperature combustion mode and has a dual fuel strategy. The controllability of combustion, high thermal efficiency and low nitrogen oxide (NOx) and soot emissions are some of the most prominent advantages of this combustion mode. In this study, the effects of the premixed ratio (PR) and intake air temperature (IAT) on the operating range, combustion characteristics and emissions were investigated experimentally. In the experiments, iso-propanol and n-heptane were used as fuels. The experiments were carried out for two different case studies. In the first case, the experiments were performed at a 50 °C intake air temperature and three different premix ratios (PR25, PR50, PR75). The minimum brake-specific fuel consumption (BSFC) was 268 g/kWh and the widest operating range was obtained with PR25. In addition, the lowest emission values in NOx, hydrocarbon (HC) and carbon monoxide (CO) emission formation were recorded with the use of PR25 fuel. In the other case, experiments were conducted at three different intake air temperatures (30 °C, 50 °C, 70 °C) with PR50. The minimum BSFC was measured as 268 g/kWh and the widest operating range was observed at a 70 °C intake air temperature. At the same time, the lowest NOx emission values were obtained at a 30 °C intake air temperature. The maximum HC emission was determined as 586 ppm at a 30 °C intake air temperature. In addition, the minimum CO emission was measured as 0.142% by volume at a 70 °C intake air temperature.