Innovative energy conversion aims to boost engine efficiency

A team from Waseda University has discovered a compressive combustion principle that can yield engines with the ultimate level of efficiency. According to him, the energy conversion principle could boost the efficiency of engines, such as in automobiles, power generation and aircraft, twofold.

Ken Naitoh of Waseda University's Faculty of Science and Engineering (Department of Applied Mechanics and Aerospace Engineering, School of Fundamental Science and Engineering) and his associates have discovered a revolutionary energy conversion principle (new compressive combustion principle) able to yield stand-alone engines with double or higher the thermal efficiency potential of conventional engines, independent of their size. If engines using this principle can be put to use in practical applications, it is believed that they could become innovations with the ability to solve today's immediate environmental energy problems.

Prototype engine for automobiles

This compressive combustion principle was formulated by Naitoh through the development of a new thermofluid dynamics theory, as well as thought experiments, supercomputer simulations and high-speed airflow experiments drawing on that theory. The fundamental principle is that while thermal efficiency can be raised by reaching a high compression ratio, achieved through pulsed collisions of multiple high-speed jets of an air-fuel gas mixture at microscopic regions in the central area of a combustion chamber, expanded uses and ranges of application were attained with the further addition of three new measures. This method is also considered to be lower in cost than batteries, as well as having possibilities for noise reduction and the potential to eliminate the need for cooling mechanisms.

If the effectiveness of this principle can be confirmed through combustion tests, it will not only open up the doors to new lightweight, high-performance aerospace vehicles, but would also lead to prospects of next-generation, high-performance engines for automobiles. The maximum thermal efficiency of present-day gasoline engines for automobiles is on the order of 30 percent, believed to fall to a level as low as 15 percent in states from idling to low-speed city driving. Therefore, if automobiles could be equipped with "low-cost, ultimate-efficiency engines," reaching a stand-alone thermal efficiency of 60 percent or higher over a wide range of driving conditions, it is believed that a substantial fuel consumption superior to that of current hybrid system automobiles could be a reality. Furthermore, if such automobiles, equipped with these high-efficiency engines, could be used to generate power at individual households, it would open up possibilities for improving the total energy efficiency of our entire society.