---

ExxonMobil has provided further insight into the five-year design and construction project that led to the development of a one-tenth-scale working model of a single-cylinder, two-stroke marine diesel engine which the company is now using to support the development of the next generation of marine lubricants.

Built by an international consortium of engineers that was led by Mahle Powertrain and included Danish family-run engineering business Hans Jensen Lubricators, the scaled-down engine is now installed at Oak Ridge National Laboratory in Tennessee and is said to reproduce the temperatures and pressures found in a full-sized ship's engine using the same marine fuel and lubes.

Explaining the challenges of constructing the unique engine, Paul Truckel, Team Leader, Design & Development - Mahle Powertrain, said: "Most of the industry around here is geared up around automotive or, in some cases heavy duty diesel, but nothing quite this size. Conversely, a lot of the marine engine component suppliers are used to delivering components that are on a much larger scale, this being a one-tenth scale. So we were kind of stuck in this middle ground of too big for the automotive suppliers, too small for the marine diesel suppliers."

Among the technical requirements was a fully functioning smaller-sized oil flow control system. Vince Carey, consultant at ExxonMobil Paulsboro NJ, explained that it was important to have an accurate flow of cylinder oil to the liner, and a consistent flow to ensure that the experiments were well-controlled over time.

Research programme

Two months after the first successful engine firing, the research programme was officially launched at Oak Ridge on October 24, 2016.

The marine engine test facility has started a 10-year programme of experimental analysis which is designed to help ExxonMobil position itself the cutting edge of marine fuels and lubrication research in the face of new regulations and shorter R&D cycles resulting from the rapid pace of technology change.

Testing new fuels and lubrication oils on full-sized working engines is expensive and requires the regular removal of huge pistons to physically measure microscopic metal erosion and liner wear. The new test engine has been built to reduce the need for this, allowing researchers to trial different fuel and lubrication formulas under scientifically controlled conditions with faster results.

"We're trying to do step-out research. We're trying to be innovative, develop the next-generation of products that the business needs to sell. So this [test engine] will give us the tool that we need to develop those products for the future," said John Fogarty, Technical Program Leader - Marine, Gas Engine & Aviation Lubricants.