The Diesel engine is the most efficient prime mover on earth due to the high operating cylinder pressures. The very high cylinder pressure that helps thermodynamic efficiency unfortunately generates a lot of piston friction. Much of the piston friction in the diesel engine is via metallic contact (boundary friction, generates wear) and another portion is viscous friction (caused by lubricant resistance to motion, but does not generate wear). The friction coefficient of boundary friction is 10 to 100 times higher than that of viscous friction. The boundary friction is generated close to the top piston reversal area, because there is not sufficient motion to build the transition to viscous lubrication, and its magnitude is enhanced by the high operating cylinder pressure.
The Rotating Liner Engine is a unique concept where the cylinder liner rotates in order to ensure that the viscous lubrication regime is present throughout the operation of the engine. The technical challenge involves the construction of a sealing mechanism that contains the high cylinder pressure combustion gas without leakage and without metallic contact. The group of researchers and students at the University of Texas have accomplished this difficult task on a single cylinder test rig. Through extended testing, the reliability of the seal has been confirmed. The overall engine has been tested extensively in one of the UT dynamometers, and the improved performance of the engine has been confirmed.
Wide application of the concept can lead to the reduction of diesel fuel consumption in diesel engines by approximately 10 %. There are millions of engines in use all over the world, and due to their very high thermal efficiency, they will continue to be used for decades to come. Therefore, the potential benefit of greenhouse gas emissions reduction is huge.
In order to move the project to the next stage, a complete engine needs to be constructed based on the current design. A complete 4-cylinder Cummins 3.9 liter engine needs to be constructed in order to further advance the design. A complete engine will allow long term testing which will attract investor funding and government grants, as well as stimulate the interest of the very conservative diesel industry.
The concept fundamentals can be seen in the following video:
A tear down of the single cylinder prototype can be seen here:
The prototype seen above is designed such that all cylinders can be equipped with rotating liners, and the driving mechanism can be installed in an extension outside the block. The funds requested are towards fabricating this new prototype.
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