Dual fuel configurations in compression ignition (CI) engines are here studied as a promising solu-tion to meet fuel economy and stringent emissions regulations. Looking at ethanol as one of the future key transportation biofuels, the authors investigate on the ethanol use as premixed fraction in a dual fuel engine. The present paper reports the preliminary results of a joint research activity: experiments both on a single cylinder research engine and on an optical engine have been performed, together with corresponding nu-merical simulations, resulting in a combined approach to the study of dual-fuel configuration. The two en-gines have been designed with the same combustion system architecture (Euro5 engine head). It is thus possible to exploit the potentialities of optical diagnostics and, on the other hand, to better resemble realistic engine behavior. To this aim, in both the experimental sets ethanol is vaporized in the intake manifold, while n-heptane, as diesel fuel surrogate, is directly injected in the cylinder. The results highlight the potential of dual-fuel combustion to drop down NOx and soot emissions at same engine efficiency for different speed and loads conditions, while a significant increment of HCs and CO has been obtained. Starting from this pre-liminary screening, some operating conditions have been examined on the optical engine by means of UV digital imaging: crucial chemical intermediates, like OH, HCO, CH and their spatial distribution and temporal evolution have been respectively detected. The analysis permitted to identify the in-cylinder zones with high reactivity of mixed fuels. Numerical simulations have been carried out by means of the OpenFOAM® tech-nology, in order to complete data interpretation. Thanks to the adoption of detailed reaction kinetics, the ef-fect of ethanol on n-heptane ignition has been investigated, analyzing combustion features typical of mixed injection modes.
Experimental and numerical investigations on compression ignition engines using ethanol in dual-fuel configuration
VFraioli;G di Blasio;E Mancaruso;M Migliaccio;
2012
Abstract
Dual fuel configurations in compression ignition (CI) engines are here studied as a promising solu-tion to meet fuel economy and stringent emissions regulations. Looking at ethanol as one of the future key transportation biofuels, the authors investigate on the ethanol use as premixed fraction in a dual fuel engine. The present paper reports the preliminary results of a joint research activity: experiments both on a single cylinder research engine and on an optical engine have been performed, together with corresponding nu-merical simulations, resulting in a combined approach to the study of dual-fuel configuration. The two en-gines have been designed with the same combustion system architecture (Euro5 engine head). It is thus possible to exploit the potentialities of optical diagnostics and, on the other hand, to better resemble realistic engine behavior. To this aim, in both the experimental sets ethanol is vaporized in the intake manifold, while n-heptane, as diesel fuel surrogate, is directly injected in the cylinder. The results highlight the potential of dual-fuel combustion to drop down NOx and soot emissions at same engine efficiency for different speed and loads conditions, while a significant increment of HCs and CO has been obtained. Starting from this pre-liminary screening, some operating conditions have been examined on the optical engine by means of UV digital imaging: crucial chemical intermediates, like OH, HCO, CH and their spatial distribution and temporal evolution have been respectively detected. The analysis permitted to identify the in-cylinder zones with high reactivity of mixed fuels. Numerical simulations have been carried out by means of the OpenFOAM® tech-nology, in order to complete data interpretation. Thanks to the adoption of detailed reaction kinetics, the ef-fect of ethanol on n-heptane ignition has been investigated, analyzing combustion features typical of mixed injection modes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
