Evaluation of electrical catalyst heater strategies under challenging cold start conditions
2022-01-0657
03/29/2022
- Content
- Electrical catalyst heater (EHC) in the three-way catalyst (TWC) of a gasoline internal combustion engine (ICE) system provides cold start exhaust pollutant emission reduction potential. The EHC can be started before switching on the ICE, thereby offering the possibility to pre-heat (PRH) the TWC, when there is no flow in the TWC. The EHC can also provide post engine start heat (PSH) when the heat is accompanied by exhaust mass flow over the TWC. A mixed heating strategy (MXH) comprises both PRH and PSH. All the three strategies are evaluated and compared in this paper under a range of challenging cold start engine operations. The evaluation is carried out using the engine-exhaust after-treatment system (EATS) simulation framework, driven by engine speed-torque requested trace, comprised of a cold-start phenomenon capturing control-oriented simulation model of the ICE and TWC with an EHC. Engine idle speed, strategic air-fuel ratio control and retarded ignition timing are the main engine control measures used to control cold start emissions. The possibility to have idle speed for minimizing cold start emissions is subject to variability due to user specific needs and behavior patterns. In this paper, idle speed duration and their placement is examined for the different EHC control strategies. Cold start emissions are also strongly impacted by variability in acceleration requested by the user. To this end, segment sequences are constructed with different speed-torque request. An analysis of the performance of the EHC strategies is performed for 2 sets of segments chosen from standard drive cycles. EHC Pre-heating strategy is found to be energy optimal with some minor exceptions in comparison to the other strategies. The domination posed by certain drive cycle segment traces causing invariant EHC usage efficiency is noticed. The evaluation framework is envisioned to develop novel EHC control strategies.
- Citation
- Velmurugan, D., McKelvey, T., and Olsson, J., "Evaluation of electrical catalyst heater strategies under challenging cold start conditions," SAE Technical Paper 2022-01-0657, 2022, .