MTU has produced the first example of a heat exchanger demonstrator for the Clean (component validator for environmentally friendly aero engines) turbofan programme. The exchanger will be tested early next year in a high-altitude test chamber in Stuttgart, Germany.

The exchanger takes cool air from the high-pressure compressor and pipes it through the hot turbine exhaust before re-injecting it into the compressor. The method makes better use of the heat energy generated in the engine cycle, says Klaus Steffens, president and chief executive of MTU Aero Engines.

"Theoretically we could get up to 20% fuel savings, based on a recuperator thermal efficiency of 58%," says Steffens.

He says the exchanger has almost no effect on thrust levels due to the carefully designed shape of the 7,000m (23,000ft) of piping in the exchanger. "Each pipe is shaped like an aerofoil to maximise surface area and reduce flow losses," says Steffens.

MTU is using a combination of compressor flow heating and intercooling to energise the compressor flow without increasing the work required to compress the air.

The Clean advanced technology engine programme, headed by Snecma and MTU, is intended to validate components for use in low ecological impact engines. The overall goal is to cut emissions of CO2 by 20% and oxides of nitrogen by 80%. Steffens says that the technology could be incorporated in an advanced turbofan by 2015.

Source: Flight International