I have hijacked stirling engine discussion. Now I decide to create this new topic.
In a nutshell, Chen engine is any engine that use direct air injection into cylinders to purge out waste gas and oxidize CO and HC. Until now, all solutions addressing scavenging exhaust gas is incomplete, thus Otto engines can not optimize gas consumption through out the entire operating range. The operating range suffered the most(however ignored by most) is the low load region, meaning cylinder vacuum is high. This Chen engine concept uses injected air to purge out all waste gases and allows higher efficiency during idle and city driving. The reason for this inefficiency is the CO2 and H2O act as heat absorber in the combustion process, thus deplete the energy this could have been used to expand the gas volume, pushes cylinder down.
The physics is that H2O and CO2 have large vibration modes and rotation modes, The chemical energy go into these modes become useless as kinetic energy.
Modern car manufactures only concentrate on improving highway gas efficiency. But most of the cars are operating in city environment. Chen engine will improve the city MPG by a large amount. The improvement on Sports car will be most significant as they operate at highest vacuum in city driving, thus most inefficient at low load.
The second important benefit of Chen Engine is that it does not emit CO and HC pollutants. The injected air burns up CO and HC at high temperature. In this sense, it behaves like a diesel, only NOx is emitted. As we all know that gasoline cars emit CO and HC in first five minutes of driving until catalytic converter is warmed up to 300C. If all your trips are short, you are a big polluter using gas engine.
As this is a F1 forum, Chen engine will have flat torque from idle to maximum rpm. Thus, it is very similar to diesel but does not have the drop off of diesel. Chen engine has maximum low rpm torque.
There are many design considerations of this engine. I'll present them in coming days.
Regards,
Chengine