Partially Premixed Combustion (PPC)
Partially Premixed Combustion (PPC) is a type of low temperature combustion that yields record-low fuel consumption and very low exhaust emissions. The concept is based on fuel and air being sufficiently premixed before combustion to avoid high temperatures and concentrations of fuel. These will otherwise form nitric oxides and soot. The combustion is also less violent than with complete premixing, which decreases the heat losses. A challenge with high efficiencies is that the turbo obtains less exhaust heat to work with. PPC is thereby a complex combustion mode that requires well-controlled conditions to work, and much research remains before the concept can be applied in vehicles.