A promising way to increase diesel engine efficiency by more than 50 percent


Current research has found that adding gasoline to diesel truck engines can give more than 50 percent efficiency if the combustion process is done correctly.

Researchers at Competence Center Combustion Processes (KCFP) at Lund University in Sweden modified a diesel engine to achieve the right amount of ignition delay – meaning a delay between fuel injection and combustion.

During the ignition delay, the mixing that happens – a partially premixed combustion (PPC) process – produces minimal amounts of soot and nitric oxide.

This could result in a new generation of engines so clean they wouldn’t require catalytic converters, according to the researchers.

It also means greater efficiency. The Lund University engine currently has 57 percent indicated efficiency, which is almost a world record. This translates into roughly 50 percent efficiency on the output shaft of the engine.

“A reasonably efficient engine today would be in the range of 40 to 42 percent,” says Bengt Johansson, professor of combustion engines at Lund University. “We’re hoping to achieve 60 percent with this type of PPC combustion process.”

A higher efficiency could have a large impact on fuel consumption, and therefore also CO2 emissions.

The KCFP, together with Chalmers and KTH, is working to make combustion engines more efficient. KCFP is focusing on combustion processes between "conventional" HCCI (homogeneous charge compression ignition) and the classical Otto and Diesel concepts.

A video on the new engine concept can be viewed here.