Effects of speed extension on PCCI combustion and emissions in a heavy-duty diesel engine at medium load. (1st April 2022)

• Record Type: Journal Article
• Authors: Lu, Yingying; Fan, Chao; Liu, Yize; Pei, Yiqiang
• Is Part Of: Fuel. Volume 313(2022)
• Publication Date: 2022-04-01
• Subjects: ATDC after top dead center -- AMR Adaptive Mesh Refinement -- BTDC before top dead center -- CA crank angle -- CLR the combustion energy loss ratio -- CO carbon monoxide -- CO2 carbon dioxide -- EGR exhaust gas recirculation -- ELR the exhaust energy loss ratio -- EVs electric vehicles -- LHV the low heat value of the fuel -- mf the cycle fuel mass -- NOx nitrogen oxides -- NOx-C simulation calculated NOx emissions in g/kWh -- NOx-E experimental measured NOx emissions in g/kWh -- HCCI homogeneous charge compression ignition -- HTLR the heat-transfer energy loss ratio -- ICEs internal combustion engines -- IMEP indicated mean effective pressure -- ITEg the gross indicated thermal efficiency -- [O2] intake oxygen volume -- Pb boost pressure -- PCCI premixed charge compression ignition -- Qactual the actual heat which the fuel is released (in J) -- Qcomb the combustion energy loss (in J) -- Qexh the exhaust energy loss (in J) -- Qfuel the total cycle fuel energy (in J) -- QHT the heat-transfer energy loss (in J) -- Qin the energy inflow of the system (in J) -- Qout the energy outflow of the system (in J) -- RCCI reactivity controlled compression ignition -- ROHR rate of heat release -- Soot-C simulation calculated soot emission in g/kWh -- Soot-E experimental measured soot emission in g/kWh -- Tavg in-cylinder average temperature -- TDC top dead center -- Tin intake temperature -- Tmax in-cylinder maximum temperature -- UHC unburned hydrocarbon -- Wg the gross indicated work per cycle (in J) -- φ the local equivalence ratio -- Φoxy fuel-to-oxygen equivalence ratio -- ηc the combustion efficiency; Heavy-duty diesel engine -- Premixed charge compression ignition combustion -- Medium load -- Engine speed extension -- Thermal efficiency -- Emissions; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2021.123048
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Intake boost helps form lean mixture, increases the indicated thermal efficiency. Increasing speed retards ignition time and decreases over-rich mixture mass fraction. Increasing speed decreases NOx, soot, CO and UHC emissions simultaneously. Increasing speed increases the indicated thermal efficiency. Retarding injection timing decreases soot, CO and UHC emissions. Abstract: Effects of boost pressure, engine speed and multi-pulse injection timing on premixed charge compression ignition (PCCI) combustion and emissions in a heavy-duty diesel engine at medium load were studied experimentally and numerically. Results show that, intake boost makes the high temperature ignition timing advance, but the mass fraction of lean mixture increases dramatically and the mass fractions of rich and over-rich mixtures decrease significantly, indicating that intake boost helps the formation of lean and homogeneous mixture; the indicated thermal efficiency increases and the combustion loss decreases. When the engine speed is increased with other variables constant, the high temperature ignition timing is retarded, the mass fraction of over-rich mixture decreases; the NOx, soot, CO and UHC emissions are all decreased; the indicated thermal efficiency increases, the combustion loss decreases, but the exhaust loss increases. The delay of multi-pulse fuel injection timing with other variables constant shortens the mixing time, increases the mass fraction of over-rich mixture, and increases the initial soot generation. However, due to the combined effect of mixing space and combustion temperature, the final soot, CO and UHC emissions are all decreased, and the NOx emissions have little change; the indicated thermal efficiency increases, the combustion loss decreases, but the exhaust loss increases.