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Acetylene as dual fuel with diesel

Researchers from the College of Engineering at Anna University (India) are proposing the use of acetylene as a dual fuel with diesel in compression ignition engines. Dual-fuel operation with acetylene induction coupled with cooled EGR resulted in lowered NOx emissions and improved part load performance.

  Acetylene Hydrogen Diesel
Formula C2H2 H2 C8–C20
Density kg/m3 1.092 0.08 840
Auto ignition °C 305 572 257
Stoichiometric air fuel ratio 13.2 34.3 14.5
Lower calorific value (kJ/kg) 48,225 120,000 42,500
Lower heating value of stoich. mix (kJ/kg) 3396 3399 2930
Source: Lakshmanan and G. Nagarajan (2009)

Acetylene (C2H2) is the simplest alkyne, featuring a triple carbon bond between the two carbon atoms. This bond stores substantial energy that can be released as heat during combustion; combustion with oxygen achieves a flame temperature of 5,580° F (3,087° C), releasing 1,470 BTUs per cubic foot.

Lakshmanan and Nagarajan used timed manifold injection (TMI) of the gaseous fuel, controlled electronically to precisely monitor the induction of fuel to overcome the preignition problem in the intake.

In a study published in the journal Energy, they injected acetylene in the intake manifold in a single cylinder diesel engine, with a gas flow rate of 240 g/h, start of injection time of 10° aTDC and 90° CA (9.9 ms) duration, operating in dual fuel mode. In order to decrease the NOx emissions from acetylene–diesel engine, cooled EGR was employed.

In the study, they achieved 21% maximum diesel replacement, and suggest that acetylene could be commercialized as a fuel for diesel engines in the future.



Aaron Turpen

Well, I guess in India the explosive potential of acetylene is no big deal. Here in the U.S., the stuff is even harder to come by because commercial production of it is heavily restricted and controlled. There's a reason they stopped using acetylene bottles to power headlamps...


Acetylene isn't stored as compressed gas; it's held in solution in something else, IIRC. If it's significantly soluble in diesel fuel, it could be piped in through the regular fuel system. It wouldn't surprise me if it provides a major enhancement of the cetane rating, too.


Acetylene dissolves in hydrocarbons, which IIRC is how it's stored (in acetone?) for welding use.

Using dissolved acetylene in diesel fuel or other oil might be a way to both co-fuel with it and use it as a cetane enhancer without modifying the fuel system.


acetylene as an alternate fuel for si engines....

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