Investigation of reactivity-controlled compression ignition combustion in a two-stroke engine

Abstract

In this study, a two-stroke outboard engine was modified to accommodate two direct fuel injectors for reactivity-controlled compression ignition combustion in one cylinder, while the production direct-injection spark ignition combustion system was maintained in the other cylinder. This setup enabled direct comparisons of the performances at equivalent operating conditions. The engine’s octane requirement for homogeneous charge compression ignition combustion was studied with primary reference fuels for ranges of engine speed, load, and delivery ratio. The resulting primary reference fuel requirement was used to determine the baseline ratio of low-reactivity fuel to high-reactivity fuel. Experiments using gasoline and diesel fuel were unsuccessful as they resulted in unstable combustion and rapid accumulation of particulate matter in the emissions-sampling equipment. Reactivity-controlled compression ignition experiments with gasoline and n-heptane (higher volatility) proved to be successful. The low-reactivity fuel fraction and the high-reactivity start-of-injection timing were found to be independent combustion-control levers. At 1500 r/min, an indicated mean effective pressure of 2.5 bar and nitrogen oxides emissions of 1.25 g/kW h, reactivity-controlled compression ignition resulted in a lower coefficient of variation in the indicated mean effective pressure, lower carbon monoxide emissions and a significantly higher gross indicated efficiency than those for the direct-injection spark ignition homogeneous mode and the direct-injection spark ignition stratified mode (36.3% versus 27.0% and 25.7% respectively); at 1200 r/min, an indicated mean effective pressure of 2.0 bar and hydrocarbon + nitrogen oxide emissions of about 16.5 g/kW h, the reactivity-controlled compression ignition efficiency was still significantly better than those for the direct-injection spark ignition homogeneous mode and the direct-injection spark ignition stratified mode (32.9% versus 25.2% and 26.6% respectively). Overall, the viability of reactivity-controlled compression ignition combustion in a two-stroke engine was demonstrated; with further design optimization, it will probably be possible to use a standard diesel fuel instead of n-heptane.

Keywords

Reactivity-controlled compression ignition homogeneous charge compression ignition direct-injection spark ignition two-stroke engines dual fuel primary reference fuels low-temperature combustion

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References

Badami

Marzano

Millo

. Comparison between direct and indirect fuel injection in an S.I. two-stroke engine. SAE paper 1999-01-3311, 1999.

Wasil

Personal communication, 2015.

Westhoff

Johnson

Development of a compact intake porting design for a 2-stroke DI outboard engine. SAE paper 2012-32-0116, 2012.

Onishi

Shoda

. Active thermo-atmosphere combustion (ATAC) – a new combustion process for internal combustion engines. SAE paper 790501, 1979.

Noguchi

Tanaka

. A study on gasoline engine combustion by observation of intermediate reactive products during combustion. SAE paper 790840, 1979.

Ishibashi

Asai

Improving the exhaust emissions of two-stroke engines by applying the activated radical combustion. SAE paper 960742, 1996.

Epping

Aceves

Bechtold

. The potential of HCCI combustion for high efficiency and low emissions. SAE paper 2002-01-1923, 2002.

Stanglmaier

Roberts

CE.

Homogeneous charge compression ignition (HCCI): benefits, compromises, and future engine applications. SAE paper 1999-01-3682, 1999.

Kokjohn

Hanson

Splitter

. Experiments and modeling of dual-fuel HCCI and PCCI combustion using in-cylinder fuel blending. SAE paper 2009-01-2647, 2009.

10.

Blessinger

Stein

Ghandhi

An optical investigation of fuel composition effects in a reactivity controlled HSDI engine. SAE paper 2012-01-0691, 2012.

11.

Kokjohn

Hanson

Splitter

. Fuel reactivity controlled compression ignition (RCCI): a pathway to controlled high-efficiency clean combustion. Int J Engine Res 2011; 12: 209–226.

12.

Splitter

Wissink

DelVescovo

. RCCI engine operation towards 60% thermal efficiency. SAE paper 2013-01-0279, 2013.

13.

Splitter

Wissink

Hendricks

. Comparison of RCCI, HCCI, and CDC operation from low to full load. In: THIESEL 2012 conference on thermo- and fluid dynamic processes in direct injection engines, Valencia, Spain, 11–14 September 2012.

14.

Hanson

Spannbauer

Gross

. Highway fuel economy testing of an RCCI series hybrid vehicle. SAE paper 2015-01-0837, 2015.

15.

Lim

Walker

Kokjohn

. High speed dual-fuel RCCI combustion for high power output. SAE paper 2014-01-1320, 2014.

16.

Reitz

RD.

Directions in internal combustion engine research. Combust Flame 2013; 160: 1–8.

17.

Walker

Wissink

DelVescovo

. Natural gas for high load dual-fuel reactivity controlled compression ignition (RCCI) in heavy-duty engines. In: ASME 2014 Internal Combustion Engine Division fall technical conference, Columbus, Indiana, USA, 19–22 October 2014, paper ICEF2014-5620. New York: ASME.

18.

Hanson

Ickes

Wallner

. Use of adaptive injection strategies to increase the full load limit of RCCI operation. In: ASME 2015 Internal Combustion Engine Division fall technical conference, Houston, Texas, USA, 8–11 November 2015, paper ICEF2015-1115. New York: ASME.

19.

Dempsey

Walker

Reitz

Effect of cetane improvers on gasoline, ethanol, and methanol reactivity and the implications for RCCI combustion. SAE paper 2013-01-1678, 2013.

20.

Dempsey

Curran

Reitz

RD.

Characterization of reactivity controlled compression ignition (RCCI) using premixed gasoline and direct-injected gasoline with a cetane improver on a multi-cylinder engine. SAE paper 2015-01-0855, 2015.

21.

Walker

Dempsey

Andrie

. Use of low-pressure direct-injection for reactivity controlled compression ignition (RCCI) light-duty engine operation. SAE paper 2013-01-1605, 2013.

22.

Rocchi

Rossi

Musu

. Computational study of a two-stroke direct-injection reactivity-controlled compression ignition engine. Proc IMechE Part D: J Automobile Engineering 2014; 229(8): 980–991.

23.

Labaza

MJ.

Demonstration of reactivity controlled compression ignition (RCCI) combustion in a two-stroke cycle engine. MS Thesis, University of Wisconsin-Madison, USA, 2012.

24.

Strauss

Zeng

Montgomery

DT.

Optimization of the E-TEC™ combustion system for direct-injected two-stroke engines toward 3-star emissions. SAE paper 2003-32-0007, 2003.

25.

Foudray

Ghandhi

JB.

Scavenging measurements in a direct-injection two-stroke engine. SAE paper 2003-32-0081, 2003.

26.

Ghandhi

JB.

Pressure and heat release analysis. In: Encyclopedia of automotive engineering. Hoboken, New Jersey: John Wiley, 2014.

27.

Kokjohn

Hanson

Splitter

. Fuel reactivity controlled compression ignition (rcci) combustion in light- and heavy-duty engines. SAE paper 2011-01-0357, 2011.

28.

Kokjohn

SL.

Reactivity controlled compression ignition (RCCI) combustion. PhD Dissertation, University of Wisconsin-Madison, Madison, Wisconsin, USA, 2012.

29.

Kalghatgi

GT.

Auto-ignition quality of practical fuels and implications for fuel requirements of future SI and HCCI engines. SAE paper 2005-01-0239, 2005.

30.

Splitter

Reitz

Hanson

High efficiency, low emissions RCCI combustion by use of a fuel additive. SAE paper 2010-01-2167, 2010.

31.

Miles

SR.

Experimental investigation of reactivity controlled compression ignition (RCCI) combustion in a two-stroke cycle engine. MS Thesis, University of Wisconsin-Madison, Madison, Wisconsin, USA, 2014.

32.

Kimura

Aoki

Ogawa

. New combustion concept for ultra-clean and high-efficiency small DI diesel engines. SAE paper 1999-01-3681, 1999.

33.

US Government Publishing Office. Electronic code of federal regulations, Title 40: protection of environment, Part 1045: control of emissions from spark-ignition propulsion marine engines and vessels, http://www.ecfr.gov/cgi-bin/text-idx?SID=aafe902b8adf9ab248303f7c4e8ade8b&node=se40.33.1045_1103&rgn=div8 (2014, accessed 7 November 2014).