Cold emission optimization of a diesel- and alternative fuel-driven CI engine

Abstract

This paper deals with the emission optimization of a compression ignition (CI) engine during cold ambient operation. Hence, in the present study, the effect of different injector nozzle geometries and pilot injection strategies, but also the influence of intake swirl, rail pressure, exhaust gas recirculation (EGR) as well as EGR cooling on the emission behavior during cold run are investigated. Therefore, test bed experiments under steady-state cold conditions are conducted on a state-of-the-art CI single cylinder research engine (SCRE) with approximately 0.5 l swept volume representing the typical passenger car (PC) cylinder size. The cold charge air temperature of down to −8 $$^{\circ }\hbox { C}$$ ∘ C and a low engine coolant and lube oil temperature represent a cold run close to reality. For emulating the higher friction of a typical 4-cylinder PC engine during cold run, the indicated mean effective pressure (IMEP) is increased according to a specifically developed equation and the turbocharger main equation is solved permanently to adjust the gas exchange loss. To take account of a potential future tightening of emission legislation, in addition to limited exhaust gas emissions, non-limited emissions such as carbonyls are measured as well. Since alternative fuels are able to make a significant contribution to the defossilisation of transportation, an oxygen-containing fuel, consisting of 100 % renewable blend components (HVO, ethers and alcohols) and fulfilling the EN 590 legislation is investigated under the same cold conditions in addition to the research on conventional diesel fuel.

Current experimental developments in 48 V-based CI-driven SUVs in response to expected future EU7 legislation

“…CO poses almost no threat, and especially in diesel engine combustion. The newly considered species formaldehyde (HCHO) was mainly formed during cold start phases [34], and a crucial share was subsequently oxidized by the DOC, allowing the low limit value of 5 mg/km to be met. NH 3 is deliberately not shown, since the TP level is negligible (< 0.1 mg/km) due to the appropriately calibrated urea double-dosing and the use of an ASC.…”