Inverted Reactivity Controlled Compression Ignition (iRCCI) with Methanol Fuel & Reactivity Enhancers
2022-01-0555
03/29/2022
- Content
- Reactivity Controlled Compression Ignition (RCCI) is a low temperature combustion regime that has demonstrated ultra-low NOx and soot while achieving high thermal efficiency. RCCI uses a low reactivity premixed charge which is ignited via direct injection of a high reactive fuel. The aim is to create a nearly homogeneous charge but maintain control over the combustion timing via the ratio between the premixed and direct injected fuel. RCCI combustion with gasoline as the premixed fuel and diesel as the high reactivity fuel has shown good combustion timing controllability. However, RCCI with alcohol fuels, in which a pure alcohol is the low reactivity premixed fuel and the alcohol doped with a reactivity enhancer is the direct injected high reactivity fuel, has shown a lack of control over the combustion timing, which is undesirable. This study attempts to regain control over the timing of combustion by using the high reactivity fuel (alcohol/reactivity enhancer) as the premixed charge while direct injecting the low reactivity fuel (pure alcohol). Thus, this strategy is referred to as inverted RCCI (iRCCI). The charge cooling effect of the direct injected alcohol results in a reactivity stratification in-cylinder and regains control over combustion phasing through the ratio of the premixed charge and direct injected fuel. Methanol was used as the base fuel and blended with a commercial reactivity improver, di-tert-butyl peroxide (DTBP). These blends of fuel were tested under lean premixed combustion conditions with neat methanol as the direct injected fuel and methanol/DTBP blends as the premixed charge. Computational simulations were run to demonstrate the feasibility of iRCCI and demonstrate that this fueling layout has a high level of combustion timing controllability. Selected operating conditions were then tested in a heavy-duty engine. Experimental results were compared to RCCI and conventional diesel combustion. The modeling and the experiments show that inverted RCCI can regain control over combustion phasing while retaining the emissions and efficiency benefits of RCCI.
- Citation
- Chowdhury, M., and Dempsey, A., "Inverted Reactivity Controlled Compression Ignition (iRCCI) with Methanol Fuel & Reactivity Enhancers," SAE Technical Paper 2022-01-0555, 2022, .