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This session focuses on particle emissions from combustion engines, including measurement methods and fuel effects. Presenter Leonidas D. Ntziachristos, Aristotle University Thessaloniki

As emissions regulations are becoming more stringent, various efforts to improve emission performance have been carried out in different areas including the honeycomb structure of catalytic converters. This report describes the development of a simulation tool to predict emission performance and simulation results for different cell structures. The simulation model was developed based on global kinetic chemical reaction model [1]. Having tuned the reaction parameters through a light-off test and estimated oxygen storage capacity through an oxygen storage test, we ultimately tuned the model in a vehicle test (with Bags 1 and 2, FTP 75). As a result, the simulated cumulative tailpipe emissions are within ±25 percent of the test results. Parameter analyses indicate that the amount of emissions decreased as the density of cells increased and that the amount of emissions also decreased the thinner the wall thicknesses were.

Regulatory compliance measurements for vehicle emissions are generally performed in well equipped test facilities using chassis dynamometers that simulate on-road conditions. There is also a requirement for obtaining accurate information from vehicles as they operate on the road. An on-board system has been developed to measure real-time mass emission of NOx, fuel consumption, road load, and engine output. The system consists of a dedicated data recorder and a variety of sensors that measure air-to-fuel ratios, NOx concentrations, intake air flow rates, and ambient temperature, pressure and humidity. The system can be placed on the passenger seat and operate without external power. This paper describes in detail the configuration and signal processing techniques used by the on-board measurement system. The authors explain the methods and algorithms used to obtain (1) real-time mass emission of NOx, (2) real-time fuel consumption, (3) road load, and (4) engine output.

This paper proposes a high temperature manifold converter with a thin wall ceramic substrate, such as; 4mil/400cpsi and 4mil/600cpsi. Double-wall cone insulation design was proposed for close-coupled converters to protect the conventional intumescent mat from high temperature. However, the double wall cone insulation is not applicable when the converter is directly mounted to the exhaust manifold without an inlet cone. The prototype manifold converter was tested under hot vibration test with a non-intumescent ceramic fiber mat and retainer rings as a supplemental support. The converter demonstrated durability for 10 hours under 80G acceleration and 100 hours under 60G acceleration with 1,050 °C catalyst bed temperature. The skin temperature of the heat shield was kept below 400 °C.

The engine performance and emissions characteristics of a single-cylinder DI diesel engine were experimentally investigated. The combustion chamber walls of the engine were thermally insulated with ceramic materials of SSN (Sintered Silicon Nitride) and PSZ (Partially Stabilized Zirconia). Fuel economy and emissions characteristics were improved by insulating selected locations of the combustion chamber walls. The selective insulation helped to create activated diffusion combustion and resulted in more efficient use of the intake air.

Partially stabilized zirconia is an insulating ceramic which offers high strength, high thermal expansion, and wear resistance. Low thermal conductivity provides the required insulation, high strength improves reliability, and high thermal expansion provides a simple means of attachment for ceramic engine components. Pistons, cylinder liners, and cylinder heads have been insulated with PSZ and engine tested in an adiabatic diesel engine.