David K. Chen

A three-dimensional model for the analysis of transient thermal and conversion characteristics of monolithic catalytic converters

A transient three-dimensional model has been developed to simulate the thermal and conversion charasteristics of nonadiabatic monolithic converters operating under flow maldistribution conditions. The model accounts for convective heat and mass transport, gas-solid heat and mass transfer, axial and radial heat conduction, chemical reactions and the attendant heat release, and heat loss to the surroundings. The model was used to analyze the transient response of an axisymmetric ceramic monolith system (catalyzed monolith, mat, and steel shell) during converter warm-up, sustained heavy load, and engine misfiring

The Development of a RTD Temperature Sensor for Exhaust Applications

A RTD (resistive temperature device) high temperature sensor was developed for exhaust gas temperature measurement. Extensive modeling and optimization was used to supplement testing in development. The sensor was developed to be capable of withstanding harsh environments (-40° to 1000°C), typical of engine applications, including poisons, while maintaining high accuracy (< 0.5% drift after 500 hrs of aging at 950°C). The following sensor characteristics are presented: resistance-temperature curve, accuracy, response time, and long-term durability. In addition, a system error analysis program was developed with representative results.

Finite Element Reliability Analysis of a Ceramic Exhaust Port Liner Subjected to Thermomechanical Interactions During Casting

This study evaluates the high transient tensile stresses generated in the port liner due to thermal shock during casting and the compressive shrinkage stresses during cooldown by finite element simulation