Abstract Natural gas has been considered to be one of the most promising alternative fuels due to its lower NOx and soot emissions, less carbon footprint as well as attractive price. Furthermore, higher octane number makes it suitable for high compression ratio application compared with other gaseous fuels. For better economical and lower emissions, a turbocharged, four strokes, direct injection, high pressure common rail diesel engine has been converted into a diesel/ natural gas dual-fuel engine. For dual-fuel engine operation, natural gas as the main fuel is sequentially injected into intake manifold, and a very small amount of diesel is directly injected into cylinder as the ignition source. In this paper, a dual-fuel electronic control unit (ECU) based on the PowerPC 32-bit microprocessor was developed. It cooperates with the original diesel ECU to control the fuel injection of the diesel/natural gas dual-fuel engine. Also, a real-time diesel substitution rate control strategy for the dual-fuel engine was implemented. The validation engine results indicated that by utilizing the original diesel injection parameters (such as common rail pressure, injection fuel quantity and injection timing), both the pilot diesel and natural gas injection in the dual-fuel mode can be lexibly controlled by the dual-fuel ECU. This is accomplished without much complicated calibration work and with an average of 86% diesel substitution rate. Moreover, the PM and the NOx emissions substantially decreased in the dual-fuel mode compared to that in the pure diesel mode with a slight penalty increased THC emissions. Introduction With increasing concerns of environment pollution come increasingly more stringent emissions regulations. As a result, many methods have been proposed to simultaneously reduce particulate matter (PM) and nitrogen oxides (NOx) emissions in C.I. engines. The use of gaseous fuels in existing C.I. engine is considered to be one of the most practical ways to solve these issues [1, 2]. Natural gas has the advantages of abundant reserve, attractive price and low emissions of particulate emissions. Moreover, its high auto-ignition temperature can offer potential economical and eficiency advantages compared to other gaseous fuels [3]. In most of the diesel/natural gas dual-fuel engine, natural gas as the main fuel is inducted in the inlet manifold, and a very small amount of diesel is directly injected into the cylinder at the end of the compression stroke, which is compression ignited and acts as an ignition source [4, 5, 6]. It is known that NOx and PM emissions can be reduced drastically under the dual-fuel operation conditions, with the associated penalty in THC emissions [7, 8, 9, 10]. In addition to the economical and emissions beneits, diesel/natural gas dual-fuel engine also makes conversion of existing engine relatively simple and maintains full diesel capability in case gaseous fuel is unavailable, both of which are important to bring the technology to market [11]. Furthermore, recently, many studies [12, 13, 14] have shown that the Reactivity Controlled Compression Ignition (RCCI) combustion strategy can achieve high eficiency with low emissions in dual-fuel mode and especially, Nieman et al. [15] investigated RCCI strategy in a heavy-duty diesel engine fueling with natural gas and diesel. The results indicated that high eficiency and low emissions can be obtained using RCCI combustion strategy if a precise injection control is provided. Based on the way how natural gas is inducted into diesel engine, there are three dual-fuel engine categories. They are intake premixed, sequentially manifold injection and high- pressure direct injection (HPDI) of natural gas dual-fuel engine respectively [16]. Currently, the premixed dual-fuel engine is more popular due to lower modiication cost. However, deterioration of dynamic response and higher methane (THC) The Development of an Electronic Control Unit for a High Pressure Common Rail Diesel/Natural Gas Dual- Fuel Engine 2014-01-1168 Published 04/01/2014 Bo Yang, Xing Wei, and Ke Zeng Xi’an Jiaotong Univ. Ming-Chia Lai Wayne State Univ. CITATION: Yang, B., Wei, X., Zeng, K., and Lai, M., "The Development of an Electronic Control Unit for a High Pressure Common Rail Diesel/Natural Gas Dual-Fuel Engine," SAE Technical Paper 2014-01-1168, 2014, doi:10.4271/2014-01- 1168. Copyright © 2014 SAE International Downloaded from SAE International by Bo Yang, Tuesday, March 11, 2014 09:18:16 PM