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Cold Start Scheme for Methanol Fueled Engines
Melissa G.Pike
Abstract:
Replacing gasoline fueled engines with methanol fueled engines has begun
in areas with chronic air pollution. Unfortunately, methanol’s low
air-fuel ratio, low vapor pressure and high latent heat of evaporation
result in cold starting problems. It was the objective of this study to
develop a system that would permit a methanol fueled (M100) engine to
start at –200F within 15 seconds after the initial cranking.
The cold start strategy investigated in this study uses a burner
operating with a rich methanol air diffusion flame to dissociate
methanol into hydrogen (H2) and carbon monoxide. (CO) The products of
the fuel-rich combustion are used as fuel to start the engine. Exhaust
analysis of the burner designed in this study show it contained 17.6% H2
and 14.2% CO by volume.
The results of five cold tests showed that it is possible to start a
methanol fueled engine at or below –200F. Continuous idle was sustained
in 35seconds after the initiation of cranking.
The basic problem is that at low temperature, the vapor pressure of
methanol is so low that the air vapor ratio is too high for spark
ignition to occur. Attempts to compensate for this by over-fueling can
result in spark plug wetting and subsequent plug shorting. Dissociating
the methanol into hydrogen and carbon monoxide produces fuels that are
not subject to the problems of flame quenching, plug shorting or
condensing. This strategy was considered unattractive due to long
warm-up period required for the dissociator apparatus. The strategy
ultimately used was to produce an almost instantaneous rich methanol/air
diffusion flame and dissociate excess methanol fuel with energy
produced.
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Point of Contact:
David Irick (phone: 865-974-0863,
dki@utk.edu) |
