Cold Start Thermal Management with Electrically Heated Catalyst: A Way to Lower Fuel Consumption

Abstract

Recent engine development has been mainly driven by increased specific volumetric power and especially by fuel consumption minimization. On the other hand the stringent emission limits require a very fast cold start that can be reached only using tailored catalyst heating strategy.This kind of thermal management is widely used by engine manufactures although it leads to increased fuel consumption. This fuel penalty is usually higher for high power output engines that have a very low load during emission certification cycle leading to very low exhaust gas temperature and, consequently, the need of additional energy to increase the exhaust gas temperature is high.An alternative way to reach a fast light off minimizing fuel consumption increase is the use of an Electrical Heated Catalyst (EHC) that uses mechanical energy from the engine to generate the electrical energy to heat up the catalyst. Following this thermal management strategy the energy input can be tailored according to the component need and the energy loss in the system can be minimized. Moreover, the efficiency of such systems can be further optimized using for example brake energy recuperation or advanced thermal management.The present work describes the different engine management strategies tested by Ferrari to find the best compromise between fuel consumption and emission reduction.

Diesel particulate filter regeneration mechanism of modern automobile engines and methods of reducing PM emissions: a review

“…The traditional active regeneration is powered by an external device, and the captured particulate matter is oxidized by increasing the exhaust temperature. The specific heating technologies include fuel injection combustion (Fu et al 2018 ), electric heating (Presti et al 2013 ) and microwave (E et al 2019b ).…”

Energy-efficient heating strategies of diesel oxidation catalyst for low emissions vehicles

“…This application can also preheat the catalyst (while the vehicle is running on a battery with off engine) for quick catalyst light-off after the engine is turned on [20]. Trends in vehicles hybridisation and electrification make the application of EHC a promising alternative method to other engine-based catalyst heating strategies for future vehicles [21]. The main advantages of an EHC compared to engine-based heating strategies are: i) direct application of thermal energy at the catalyst site [22], ii) the higher degree of control over the heating intensity and period [23], iii) reduced loading of precious metals for catalysts [24] and iv) potential in reducing vehicles' carbon dioxide (CO2) emissions, as the engine can be recalibrated to more efficient conditions [21].…”

“…Trends in vehicles hybridisation and electrification make the application of EHC a promising alternative method to other engine-based catalyst heating strategies for future vehicles [21]. The main advantages of an EHC compared to engine-based heating strategies are: i) direct application of thermal energy at the catalyst site [22], ii) the higher degree of control over the heating intensity and period [23], iii) reduced loading of precious metals for catalysts [24] and iv) potential in reducing vehicles' carbon dioxide (CO2) emissions, as the engine can be recalibrated to more efficient conditions [21]. Knorr et al [25] found the potential HC, CO, NOx and CO2 exhaust emission reduction and lower fuel consumption for HEV equipped with EHC coupled with advanced aftertreatment system compared with conventional engine-based catalytic convertor heating strategies.…”

Autoignition characteristics of diesel spray under different injection pressures and cold start strategy for compression ignition engines

“…Despite its more enormous significant advantages, the diesel engine remains by far inferior to the spark-ignition engines during the starting process, especially for the cold start conditions. 18–20 Under these adverse conditions, the engine oil viscosity increases significantly, which causes low cranking speeds and high friction losses. At the same time, the increase in the cylinder clearance will also lead to quite high blow-by levels.…”