Development of Comprehensive Modal Emissions Model: Operating Under Hot-Stabilized Conditions

Abstract

A comprehensive modal emission model for light-duty cars and trucks is being developed. More than 300 real-world vehicles are being recruited for in-house dynamometer testing under as-is conditions to provide the foundation for the model. The model is designed to predict second-by-second tailpipe emissions under a variety of driving conditions. The vehicles can be modeled as individual vehicles with properly functioning, deteriorated, or malfunctioning emission control conditions, or as composite vehicles representing different vehicle technology categories. The model is based on a simple parameterized physical approach and consists of six modules that predict engine power, engine speed, air/fuel ratio, fuel use, engine-out emissions, and catalyst pass fraction. When developing the model, four important vehicle operating conditions are considered: cold and warm starts; normal, stoichiometric operation; high-power enrichment; and lean-burn operation. The model concept and the expected input/output requirements of the model are discussed. The general structure of the model also is presented, focusing on emissions for vehicles operating under hot-stabilized conditions. Preliminary results of the model are given, and comparisons are made between the modeled and measurement results for 17 sample vehicles. Preliminary results show good agreement.

Akteursorientierte multimodale Straßenverkehrssimulation

“…In [Ross, 1997] [An et al, 1997]. In [Cappiello et al, 2002] und basiert auf der physikalischen Energie P , die ein Auto pro Zeiteinheit benötigt.…”

Real-World Emissions from Conventional Passenger Cars

“…For (c), our estimates are based on simplistic assumptions that could be modified when major sources of malfunction are categorized and the corresponding emissions dependence on driving simulated, a possible achievement of current research at the University of California-Riverside. 35 For (d), we have had to rely on the limited data on emissions during air conditioner use from the FTP-RP. For (e), our estimates are based on instrumented vehicle data from Spokane and Baltimore.…”

Measuring and Modeling Emissions from Extremely Low-Emitting Vehicles

“…Other key parameters relating to vehicle operation and emissions production must be deduced from actual second-by-second measured emissions data. The basic components found in the model instances include a power demand component, engine speed estimator, fuel rate model, engine-out emission component, and an after-treatment component (8). Also part of the model are specific components that mimic engine strategies that control fuel/air equivalency ratios or fuel injection timing.…”

“…As stated previously, the operating history (i.e., the last few seconds of vehicle operation) can play a significant role in an instantaneous emissions value. More detailed discussions about modal emissions modeling and CMEM can be found in (6), (7), (8), (9).…”

“…As shown in Figure 4, the generalized model consists of six distinct modules that individually predict: 1) engine power; 2) engine speed; 3) air/fuel ratio; 4) fuel use; 5) engine-out emissions; and 6) catalyst pass fraction. Details of the model structure are given in [An et al, 1997].For each sub-model, there are a number of vehicle parameters and operating variables that are considered. The vehicle parameters used are divided into two groups: 1) parameters that are obtained from the public domain (or determined generically), and 2) parameters that need to be calibrated based on the second-by-second emission measurements.…”