Fuel reactivity controlled compression ignition (RCCI): a pathway to controlled high-efficiency clean combustion

TLDR

Fuel reactivity controlled compression ignition (RCCI) is a promising approach for achieving high‑efficiency, clean combustion. The study conducted heavy‑duty engine tests across a range of loads, compared RCCI to conventional diesel, and used CFD modeling to explain the observed performance trends. RCCI operated over a wide load range with near‑zero NOx and soot, acceptable pressure rise, and a peak gross indicated efficiency of 56 % at 9.3 bar and 1300 rpm, while outperforming diesel by reducing NOx by three orders of magnitude, soot by a factor of six, and increasing gross indicated efficiency by 16.4 % (7.9 % more fuel energy converted to work), largely due to lower heat‑transfer losses and improved combustion timing control.

Abstract

A fuel reactivity controlled compression ignition (RCCI) concept is demonstrated as a promising method to achieve high efficiency – clean combustion. Engine experiments were performed in a heavy-duty test engine over a range of loads. Additionally, RCCI engine experiments were compared to conventional diesel engine experiments. Detailed computational fluid dynamics modelling was then used to explain the experimentally observed trends. Specifically, it was found that RCCI combustion is capable of operating over a wide range of engine loads with near zero levels of NO x and soot, acceptable pressure rise rate and ringing intensity, and very high indicated efficiency. For example, a peak gross indicated efficiency of 56 per cent was observed at 9.3 bar indicated mean effective pressure and 1300 rev/min. The comparison between RCCI and conventional diesel showed a reduction in NO x by three orders of magnitude, a reduction in soot by a factor of six, and an increase in gross indicated efficiency of 16.4 per cent (i.e. 7.9 per cent more of the fuel energy was converted to useful work). The simulation results showed that the improvement in fuel conversion efficiency was due both to reductions in heat transfer losses and improved control over the start- and end-of-combustion.