Reactivity controlled compression ignition (RCCI) engines use a minimum of two fuels with dissimilar reactivities. The current experimental study examined the effects of compression ratio (CR)

hydrogen flow rate

and load on performance

knocking tendency

emissions

and different phases of co-combustion in a hydrogen–diesel RCCI engine employing conventional diesel in-cylinder injection and hydrogen induction into the manifold

which reduces the system cost. A constant-speed stationary engine was selected for this study because it has rarely been studied. Compared with the existing literature

wider ranges of hydrogen flow rates (up to 30 slpm) and CRs (15–20) were investigated in this study. The results indicate that the maximum brake thermal efficiency was obtained at low hydrogen flow rates (3–5 slpm). Under part-load conditions

the maximum heat release rate and cylinder pressure decreased with an increase in the hydrogen flow rate. At high loads and high CRs

a second peak was observed in the heat release curve

the magnitude of which increased with the hydrogen flow rate owing to H2 + air-premixed combustion. The knocking tendency increased with an increase in the hydrogen flow rate and a decrease in the CR. These findings can potentially help in identifying the best operating conditions for stationary constant-speed compression ignition engines adapted for H2–diesel RCCI operations

as these engines find wide application in rural economies for powering electric generators

water pumps

and agricultural equipment.