The internal combustion engine suffers from fairly low efficiency due to
theoretical thermodynamic limitations of ideal cycles as well as additional
energy losses due to deviations from ideal cycles and friction between moving
parts. Typically, only ~30% of the chemical energy of fuel is converted into
useful work; ~40% is removed as heat by cooling water, and another 30% is lost
with exhaust gases.
There are many different types of engines, operating on various
thermodynamic cycles, and an even greater number of modifications
within each type. These different types exist because each offers certain
advantages over others. For example, at the same compression ratio, Diesel
cycle engines are slightly less efficient than Otto cycle engines, however the
Diesel engine is capable of operating at higher compression ratios at which it
becomes more efficient than the Otto engine.
The development of the patent pending High Efficiency Hybrid Cycle engine aims to combine the benefits of several thermodynamic cycles.
