Turbo Compounding

Turbo compounding refers to the
use of a turbine for heat recovery
from the exhaust system of an engine.
Bowman has pioneered electric
turbo compounding for power gen.

Turbo Compounding

Turbo Compounding

Turbo compounding refers to the use of a turbine to recover energy from the exhaust system of a reciprocating engine and reintroduce that energy back into the engine.  There are currently two forms; mechanical turbo compounding, which was introduced in the aerospace sector during the 1940s, and electrical turbo compounding, pioneered by Bowman for use in the power generation and heavy vehicle sectors.

In mechanical turbo compounding, the energy recovered from the exhaust gases (waste heat recovery) is converted into kinetic energy and fed back into the engine via a high ratio transmission.  In electrical turbo compounding the energy is converted to electrical power and then electrically transmitted to the engine by a power electronics module.

The success of both types of turbo compounding depends on the successful redesign of the engine’s turbo charger, which must be made more efficient (by 5-10%) in order to prevent an excess of back pressure in the exhaust system when the turbo generator is fitted.  The important advantage offered by electrical turbo compounding over mechanical turbo compounding, is that the former allows precise control of turbo generator performance via the Bowman power electronics module.  This means that heat recovery can be optimised over a much wider range of engine loadings, leading to greater overall efficiency.

The above can be demonstrated by the impact of the two turbo compounding techniques on BSFC in class 8 trucks.  Mechanical turbo compounding produces an average improvement of circa 3%, but can actually have a negative effect depending upon engine load.  The improvements offered by Bowman electrical turbo compounding are closer to 7%, with no possibility of a negative impact at any point.

Please contact us to discuss your engine specifications and requirements.