Thermal Management Concept for the Exhaust Aftertreatment of Commercial Vehicle Diesel Engines Using Variable Mixtures of Diesel Fuel and Rapeseed Oil

Abstract

The use of vegetable oil as a fuel for agricultural and forestry vehicles allows a CO2 reduction of up to 60 %. On the other hand, the availability of vegetable oil is limited, and price competitiveness depends heavily on the respective oil price. In order to reduce the dependence on the availability of specific fuels, the joint research project "MuSt5-Trak" (Multi-Fuel EU Stage 5 Tractor) aims at developing a prototype tractor capable of running on arbitrary mixtures of diesel and rapeseed oil.Depending on the fuel mixture used, the engine parameters need to be adapted to the respective operating conditions. For this purpose, it is necessary to detect the composition of the fuel mixture and the fuel quality. Regardless of the available fuel mixture, all functions for regular engine operation must be maintained. A conventional active regeneration of the diesel particulate filter (DPF) cannot be carried out because rapeseed oil has a flash point of 230°C, compared to 80°C for diesel fuel. This leads to a condensation of rapeseed oil while using post-injection at low and medium part load operating points, which causes a dilution of the engine oil.In this work, engine-internal measures for achieving DPF regeneration with rapeseed oil and mixtures of diesel fuel and rapeseed oil are investigated. In order to provide stationary operating conditions in real engine operation, a "high-idle" operating point is chosen. The fuel mixtures are examined with regard to compatibility concerning a reduction of the air-fuel ratio, late combustion phasing and multiple injections. The highest temperatures are expected from a combination of these control options. After the completion of a regeneration cycle, the fuel input into the engine oil is controlled. These investigations will serve as a basis for the subsequent development of more complex regeneration strategies for close-toreality engine operating cycles with varying load conditions.

Investigation of a Second Exhaust Valve Lift to Improve Combustion in a Methane - Diesel Dual-Fuel Engine

“…Therefore, investigations to raise the exhaust gas temperature in order to ensure sufficient conversion in the catalytic converter also need to be carried out. [32] shows examples of such measures, which could partly also be applied to a dual-fuel engine.…”

Optimization of the DPF-Regeneration Strategy for the Use of Vegetable Oil in a Multi-Fuel-Engine Concept

“…By combining throttling and double pre-injection with late main injection, the highest exhaust gas temperatures can be achieved. More detailed information on the mechanisms of the measures can be found in [25].…”

“…Under these boundary conditions, the regeneration was tested with the result that a fully loaded particle filter can be completely freed of soot within 20 minutes. The complete procedure of the regeneration test is also described in [25].…”

Innermotorische Effizienzsteigerung luftansaugender und gemischansaugender Dual-Fuel Brennverfahren

“…Entsprechende Maßnahmen wurden z.B. von Thees et al[106] bereits an einem mit Rapsöl betriebenen Dieselmotor umgesetzt. Ein rußfreier nachhaltiger Zündkraftstoff bietet hier das Potenzial, die AGR-Raten noch weiter zu steigern und so die Rohemissionen in Kombination mit einer Anhebung der Abgastemperatur weiter abzusenken.Die Verwendung von Biopropan erwies sich sowohl für den MPI-als auch den DI-Betrieb als wenig geeignet.…”