Refine Your Search

Search Results

Viewing 1 to 5 of 5
Technical Paper

Effect of Phased Air/Fuel Ratio Perturbation and Catalyst O2 Storage Capability on Catalyst Conversion Efficiency

Recent internal research performed at SwRI examined an emissions control mechanism that we have labeled, ‘phased A/F perturbation.’ The suggested mechanism of phased perturbation involves independently controlling the fuel delivered to each bank of a dual bank engine, which allows the two banks to have an adjustable, relative A/F perturbation phase-shift from one another. Exhaust from the two banks can be combined to achieve a near-stoichiometric mixture prior to entering a single underbody catalyst. Since both rich and lean exhaust species would be present simultaneously, a highly reactive mixture would continuously enter the catalyst. In that work, it was found that A/F phasing produced as significant an effect on conversion efficiency as perturbation amplitude and frequency, i.e. A/F phasing was identified as a third dimension for optimization of exhaust gas composition as it enters the catalyst.
Technical Paper

Container Deformation Procedure for Ceramic Monolith Catalytic Converters

A typical automotive catalytic converter is constructed with a ceramic substrate and a steel shell. Due to a mismatch in coefficients of thermal expansion, the steel shell will expand away from the ceramic substrate at high temperatures. The gap between the substrate and shell is usually filled with a fiber composite material referred to as “mat.” Mat materials are compressed during assembly and must maintain an adequate pressure around the substrate under extreme temperature conditions. The container deformation measurement procedure is used to determine catalytic converter shell expansion during and after a period of hot catalytic converter operation. This procedure is useful in determining the potential physical durability of a catalytic converter system, and involves measuring converter shell expansion as a function of inlet temperature. A post-test dimensional measurement is used to determine permanent container deformation.
Technical Paper

Mobile Fuel Filtration/Additive Unit

Due to the serious need of the U.S. Army for a simple and rapid mobile fuel filtration system, a Filtration/Additive Unit (FAU) has been designed and fabricated. The primary use of the FAU is to aid in the cleanup of fuel in Army ground vehicles and equipment fuel cells and storage tanks. The FAU provides a simple and rapid means to remove gross quantities of particulate and water. The unit consists of a trailer-mounted filtration and additive system capable of dispensing three separate additives into the fuel. The FAU was designed to rapidly clean and additive-treat diesel or aviation-type fuels in volumes between 400 and 4500 liters. However, the FAU is capable of processing larger quantities, such as in storage tanks. The designed pump rate is 225 liters per minute (minimum) using diesel fuel at its maximum viscosity (4.1 cSt at 40°C).
Technical Paper

Fuel Issues for Liquefied Natural Gas Vehicles

Natural gas vehicle (NGV) fuel energy storage density is a key issue, particularly in many heavy-duty applications where compressed natural gas may have unattractively low energy density. For these uses, benefits can be derived by using liquefied natural gas (LNG). From a market perspective, LNG can play a role for transportation because it is available in various areas of the United States and throughout the world. This paper provides a general overview of LNG use for vehicles and specifically an analysis of factors governing the behavior of this cryogenic fluid in a confined vessel. This is intended to provide an understanding of the cause/effect relation between LNG fuel composition, tank heat influx, and rate of fuel usage or storage time.
Technical Paper

Cold-Start Hydrocarbon Collection for Advanced Exhaust Emission Control

This paper describes the findings of a laboratory effort to demonstrate improved automotive exhaust emission control with a cold-start hydrocarbon collection system. The emission control strategy developed in this study incorporated a zeolite molecular sieve in the exhaust system to collect cold-start hydrocarbons for subsequent release to an active catalytic converter. A prototype emission control system was designed and tested on a gasoline-fueled vehicle. Continuous raw exhaust emission measurements upstream and downstream of the zeolite molecular sieve revealed collection, storage, and release of cold-start hydrocarbons. Federal Test Procedure (FTP) emission results show a 35 percent reduction in hydrocarbons emitted during the cold-transient segment (Bag 1) due to adsorption by the zeolite.