A Compact Pollution-Free
External Combustion Engine
with High Part-Load Efficiency
An external combustion engine using steam is described
which has good efficiency at full power and even better efficiency at
the low power settings common for passenger vehicles. The engine is compact
with low weight per unit power. All of its components fit in the engine
compartment of a front-wheel drive vehicle despite the space occupied
by the transaxle. It readily fits in a rear-drive vehicle.
Calculated net efficiencies, after accounting for all
losses, range, depending on engine size, from 28-32% at full power
increasing to 33-36% at normal operating part-load power settings. The
part-load efficiencies are 50-100% higher than gasoline engines and about the same
as diesel engines.
Pollution-free combustion is due to a two-stage burner,
100% excess air, and combustion temperature below 1500°C. These assure
complete combustion of the fuel and no nitrous oxides or carbon monoxide.
The engine can cleanly burn a wide variety of fuels and fuel mixes, which
should encourage the development of a diverse fuel industry. An attractive
fuel blend would be methanol and ethanol with some gasoline.
Extensive software has been written that calculates full
power and part-load energy balances, structural analysis and heat transfer,
and performance in specified vehicles including using SAE driving cycles.
Engines have been sized from 22 kW to 2400 kW. Due to this analysis, a
prototype, when built, should perform as expected.