The Compact Catalytical Heater (CCH): Thermal Management for HD EU-VII/EPA-27 with Low Impact on Existing EATS Architectures

Abstract

Currently the OEMs of commercial vehicles (using an internal combustion engine) are preparing for the new emission legislation EU-VII und EPA-27. The challenge is an improved NO_x-reduction at cold-start and low load conditions as well as reduced CO₂. In the meantime, also in the Off-Road sector (NRMM) the first discussions started on next steps. The existing exhaust aftertreatment systems are typically showing very high NO_x-conversion rates when operated at the appropriate temperature. OEMs are investigating a variety of possible solutions to increase the temperature level of the SCR catalysts for the critical operation points: cold start and low load. “Pure” electrical heating has quite a high CO₂-disadvantage in the case that the electrical power is coming from alternator and battery. The high power-demand for higher exhaust mass-flow is another challenge for the electrical system. Fuel dosing into the exhaust system is a state-of-the-art process for DPF regeneration and shows a high efficiency in energy release. Combining electrical heating with fuel dosing results in an efficient heating with moderate electrical power demand. “Engine-independent” heating of the exhaust system allows in turn the engine to operate in the “CO₂-bestpoint” and thus reduce the fuel consumption. The innovative compact catalytical heater as an add-on component upstream of a well proven CV-muffler allows to begin fuel dosing very early in the cold-start phase, generating high amount of energy for the fast heat-up of all components (including catalysts) within the muffler. It is also intended to operate for keeping the exhaust system warm in low load operation. The goal is to continue using already existing and well-established exhaust components (muffler) to reduce R&D efforts & tooling costs. This paper describes the development of the system including simulation as well as test results on a dynamic heavy-duty engine test bench resulting an improvement of 11%-points in the FTP cold start and in the Low Load Cycle (LLC) a NO_x conversion of 99% with active heating.