Jg. Hawley et al., THE EFFECTS OF NON-AIR MIXTURES ON THE OPERATION OF A DIESEL-ENGINE BY EXPERIMENT AND BY SIMULATION, Proceedings of the Institution of Mechanical Engineers. Part A, Journal of power and energy, 212(1), 1998, pp. 55-68
This paper presents the findings of a detailed investigation to determ
ine the performance effects of a diesel engine when the inert nitrogen
(N-2) in air is replaced by carbon dioxide (CO2). The requirement for
a diesel engine to operate in such a manner is access to free air bei
ng prohibited, as is the case with a submarine power generation unit.
Numerous projects have investigated non-air-breathing diesel engine sy
stems. The more recent ones have concentrated on strategies whereby th
e recirculated non-air mixture maintains the thermodynamic properties
of free air such that engine performance is not compromised. This has
led to the addition of argon and other inert gases. However, systems u
tilizing purely fuel, oxygen and carbon dioxide mixtures have not been
investigated since the 1960s, and owing to the confidentiality of def
ence-related work little public data have been made available. A Perki
ns T4.236 truck engine has been configured to operate on a mixture of
70 mol % CO2 and 30 mol % O-2 when preheated to a temperature of 150 d
egrees C. Performance results show that under such inlet conditions th
e rated brake power of the engine las defined by fuelling rate) degrad
es by 20-23 per cent with a subsequent increase in brake specific fuel
consumption of 23-28 per cent. In-cylinder observations in relation t
o ignition delay and exhaust oxygen concentrations lead to the hypothe
sis that the carbon dioxide is seriously affecting both pre-and post-i
gnition processes by slowing down reaction rates. Investigations were
also carried out to assess the capability of an existing diesel engine
model, based on the filling and emptying technique, suitably modified
such that it could be used to simulate non-air performance. The modif
ications to the model to allow parametric comparisons to be undertaken
of non-air brake performance indicators were found to be within 5 per
cent of experimental values.