Progress and recent trends in reactivity-controlled compression ignition engines

Abstract

Low-temperature combustion is an emerging engine technology that has the ability to yield low NO x and soot emissions while maintaining high fuel efficiency. Low-temperature combustion strategies include homogeneous charge compression ignition, premixed charge compression ignition, reactivity-controlled compression ignition and partially premixed combustion. These low-temperature combustion strategies use early fuel injections to allow sufficient time for air-fuel mixing before combustion. According to the literature, some low-temperature combustion strategies are not promising for future automotive and power generation applications due to difficulties in controlling the heat release rate and the lack of a combustion phasing control mechanism. To mitigate these problems, the reactivity-controlled compression ignition combustion concept was introduced. Reactivity-controlled compression ignition is a dual-fuel partially premixed combustion concept, which uses port fuel injection of a low-reactivity fuel (e.g. gasoline, natural gas and alcohol fuels) and direct injection of a high-reactivity fuel (e.g. diesel and biodiesel) with blending inside the combustion chamber to increase the combustion duration and to provide phasing control. Combustion phasing is controlled by the relative ratios of the two fuels, and the combustion duration is controlled by spatial stratification between the two fuels. This article begins by an overview of the different low-temperature combustion strategies and demonstrates some advantages of reactivitycontrolled compression ignition, over homogeneous charge compression ignition and premixed charge compression ignition combustion strategies in regard to fuel flexibility and combustion controllability. A comprehensive review of recent research on various aspects of reactivity-controlled compression ignition and comparisons of thermal efficiency and pollutant emissions over conventional diesel combustion is also presented. This article presents the significance of reactivity-controlled compression ignition strategy as a promising solution for future automotive engines and discusses future research directions.

Effects of diesel injection strategy on natural gas/diesel reactivity controlled compression ignition combustion

“…Recently, there have been review articles in the literature on RCCI, which provide a comprehensive and thorough study regarding this newly developed combustion mode [7,8].…”

Optical Investigation of Sooting Propensity of n-Dodecane Pilot/Lean-Premixed Methane Dual-Fuel Combustion in a Rapid Compression-Expansion Machine

“…Increasing the premixed fuel equivalence ratio or the pilot fuel portion promotes complete combustion (decrease in UHC) [6] but there is an apparent tradeoff between the UHC, soot and NO x emissions [6,8,11,12]. Nevertheless, there is a general consent that by precise control of the engine operating parameters both improved engine efficiency and low emissions of NO x and soot can be achieved in the dual-fuel operation over the whole engine operating map while limiting the UHC emissions to a moderate level [4,22].…”

Investigation on partially premixed combustion fueled with gasoline and PODE blends in a multi-cylinder heavy-duty diesel engine

“…The end of main injection and the start of combustion (SOC) are expected to be separated to produce low stratified air-fuel mixture in PPC [3]. The extension of ignition delay is a key issue to achieve PPC, which is usually realized through excessive EGR rate, reduced compression ratio and fuel reactivity [4]. PPC is therefore considered as a more promising combustion concept to be utilized in practical engine than homogeneous charge compression ignition (HCCI) and control auto ignition (CAI) because of the relatively better combustion controllability [1,5].…”