Search results

(1 - 1 of 1)

Title

EFFECTS OF FUEL PROPERTIES ON THE COMBUSTION PROCESS OF AN ADVANCED DIESEL ENGINE

Creator

Ramos Silva, Cedric Zacarias

Date

2015, 2015-12

Description

Internal combustion engines are encountered in our everyday lives in passenger cars and heavy-duty vehicles such as trucks and buses. While...
Show moreInternal combustion engines are encountered in our everyday lives in passenger cars and heavy-duty vehicles such as trucks and buses. While conventional compression ignition engines burn diesel fuel with an oxidizer (generally air) in a combustion chamber, much recent research has focused on improving the efficiency of combustion and reducing vehicle pollutant output through the usage of fuels with properties which differ from those of diesel fuel. In particular, this study focuses on a dual fuel engine in which two fuels (usually gasoline or diesel fuel mixed with an alternate fuel) are separately injected and combusted. Results from an Argonne National Laboratory test cell utilizing a 13 Liter (L) heavy duty dual fuel engine running in a combustion mode known as Reactivity Controlled Compression Ignition (RCCI) were leveraged in this work. In a RCCI engine, two fuels of different reactivities (low reactivity and high reactivity) are used in order to control in-cylinder fuel reactivity and allow for the optimization of combustion phasing and duration. In addition, RCCI combustion has been shown to produce low amounts of nitrogen oxides (NOx) as well as particulate matter (PM) emissions which may eliminate the need for expensive after-treatment systems. The combustion shaping capabilities and low emissions of RCCI dual fuel engines enable reductions in heat transfer losses and as such the increase of fuel efficiency. In order to understand the dynamics of such engines, a detailed simulation model of a RCCI dual fuel engine was constructed and developed using the Gamma Technologies (GT) simulation suite in particular GT-POWER and GT-SUITE. Modeling of the complex gas exchange process as well as the combustion process of the 13L RCCI dual fuel engine were both undertaken. This model was then leveraged to examine the effect of fuel properties on the combustion process using GT simulation suite. Experimental data from the 13L engine at Argonne was used to validate the models of the gas exchange and combustion processes. For the gas exchange process as well as the combustion process, the results from the simulation model fairly accurately match the experimental data from the Argonne engine. To achieve RCCI, the engine is equipped with a complex air handling system which includes two turbochargers as well as exhaust gas recirculation (EGR). To ensure that the gas exchange process was accurately captured, the experimental intake pressure, EGR fraction (EGR mass flow rate divided by the sum of EGR mass flow rate and air mass flow), fresh airflow rate, maximum in-cylinder pressure, IMEP and exhaust pressure were compared with the simulation results given by GT-POWER and GT-POST. By modeling the engine components in GT-POWER and adding additional control algorithms, the previously mentioned parameters predictions were within 10% of the engine data. The combustion process was modeled using a Direct-Injection Jet (DI-Jet) combustion model. The DI-Jet model is a predictive combustion model which predicts the burn rate, combustion rate and NOx emissions. This model was calibrated by comparing the experimental and simulation heat release curves. Particular attention is given to accurately capturing the start of combustion and ignition delay period because they affect the combustion process the most.
M.S. in Mechanical and Aerospace Engineering, December 2015
Show less