Ricardo/Valeo See Ultraefficient Diesel Hybrid

Diesel Fuel News, Oct 15, 2001 by Jack Peckham

Valeo (France) and Ricardo (U.K.) announced they're teaming up on a mild-hybrid "I-MoGen" diesel-electric system that could boost fuel economy 30% (to 4 liters fuel/100 kilometers) on a "C-class" car and cut emissions to half of Euro IV levels, employing new 42-volt electrical technology.

The system, expected to be commercialized around 2005, will employ an exhaust close-coupled oxidation catalyst with "some deNOx capability," along with a electrically-heated, silicon-carbide diesel particulate matter (PM) filter with an upstream 6kW/42V radiative heater for regeneration assist, Ricardo told us.

The system will also include a filter pressure differential sensor and a post-PM filter clean-up catalyst.

According to Ricardo, the system aims to maximize exhaust gas recirculation (EGR) for NOx control. Heavy EGR would boost PM emissions, but the filter will oxidize all the PM -- and the electric heater will overcome PM filter plugging that would be expected with low-exhaust-temperature duty cycles typical of hybrid-electrics.

When the PM filter approaches plugging, EGR will be switched off to boost oxygen, inlet air throttled to reduce exhaust mass flow rate and hike exhaust temperature, and the electric heater switched on, Ricardo officials explain.

A combination of convective and radiative heating will boost PM filter face temps above 600[degrees]C, causing soot oxidation.