Rotec Design Ltd. (Brisbane, Queens-land, Australia; edlinks.chemengonline.com/ 6900-539), has filed a provisional patent application for an “Improved low heat rejection, high efficiency engine.” The engine is an improvement on the company’s Rotec EnviroDiesel Design (REDD), claimed to be the world’s first at-source diesel retrofit solution that simultaneously reduces particulate matter (PM) and NOx emissions (by up to 70%, according to the company), while also increasing fuel efficiency and engine power (by up to 90%, the company says).
Current approaches to reducing diesel emissions are to trap or convert them after the pollutants have already been produced. Such end-of-pipe solutions include expensive devices such as catalytic converters. In contrast, REDD works by minimizing the engine’s production of PM and NOx at the instant of combustion as the gases are formed.
REDD uses a reciprocating piston pump to “pulse” a diesel engine cylinder with fresh air on every piston upstroke. Rotec said of the four piston movements in a traditional four-stroke engine, only two are needed to generate power. The other two are required to expel exhaust gas from the engine cylinder and to supply fresh air to the cylinder. REDD allows clean air to be injected into the cylinder and exhaust air to be expelled in the same movement. Thus every piston downstroke generates power, doubling the number of power strokes. This allows the same amount of fuel to be spread across two power strokes rather than one to generate the same power. The resulting higher air-to-fuel ratio produces a leaner burn, thereby reducing pollutant generation, the company said.
According to CEO, Rob Rutherford, in the improved version of REDD, better insulation strategies substantially reduce the amount of heat absorbed by the incoming fresh charge because the intake charge is delivered to the cylinder in about 50% of the time compared with a 4-stroke engine. That means there is substantially less time and opportunity for heat absorption by the incoming charge, he says.