Numerical and Experimental Investigation of Combustion and Knock in a Dual Fuel Gas/Diesel Compression Ignition Engine

Abstract

Conventional compression ignition engines can easily be converted to a dual fuel mode of operation using natural gas as main fuel and diesel oil injection as pilot to initiate the combustion. At the same time, it is possible to increase the output power by increasing the diesel oil percentage. A detailed performance and combustion characteristic analysis of a heavy duty diesel engine has been studied in dual fuel mode of operation where natural gas is used as the main fuel and diesel oil as pilot. The influence of intake pressure and temperature on knock occurrence and the effects of initial swirl ratio on heat release rate, temperature-pressure and emission levels have been investigated in this study. It is shown that an increase in the initial swirl ratio lengthens the delay period for auto-ignition and extends the combustion period while it reduces NO x . There is an optimum value of the initial swirl ratio for a certain mixture intake temperature and pressure conditions that can achieve high thermal efficiency and low NO x emissions while decreases the tendency to knock. Simultaneous increase of intake pressure and initial swirl ratio could be the solution to power loss and knock in dual fuel engine.

Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine

“…With the aid of electronic controllers, HPCR system allows adjustment of injection pressure, fuel injection amount, injection timing, and injection pulse number in each combustion cycle very flexibly [1][2][3]. Then optimized injection strategies can improve diesel engine combustion for low combustion noise, high combustion efficiency, and low emissions [4,5]. It can also provide postinjection for helping after-treatment system for regeneration.…”

The Effect of Operating Parameters on Dual Fuel Engine Performance and Emissions – An Overview

“…In [21], the authors studied the effect of different boost levels on the dual fuel engine performance and as expected the increase in boost level results in an increase in the dual fuel engine power output. However, as intake pressure and temperature increase, knock tendency increases as well.…”

“…The reviewed papers [21,23] showed that the intake temperature increase leads to an increase in combustion efficiency. As the intake air temperature is increased, air mass inside the cylinder decreases which leads to a decrease in the premixed excess air ratio, which in combination with higher temperatures leads to more complete flame propagation.…”

A Review of the Utilisation of Natural Gas with High Carbon Dioxide Content as Automotive Fuel in an Indirect Injection Diesel Engine

“…Gharehghani et al [25] reported that by increasing the intake swirl ratio in dual-fuel engines, a significant reduction in NOx was achieved at high engine load with lower mass ratio of natural gas, while lower PM was recorded at lower load and higher mass ratio of natural gas. At part load, the total bsfc was considerably higher under dual-fuel mode due to the low combustion rate of gaseous fuel.…”