PI: Ron Matthews, University of Texas.
TxDOT has approximately 2000 high-emitting Diesel-powered dump trucks. One option for reducing emissions and achieving fuel cost savings is to replace their existing engines with engines fueled with either CNG alone or dual-fueled with CNG and a pilot injection of Diesel fuel. This would be a very expensive option, however. A much lower cost option would be to convert existing engines to dual-fuel operation on CNG with Diesel fuel pilot ignition. Several different dual-fuel conversion technologies are available, however. These include fumigation of CNG using a gas mixer that continuously or nearly continuously mixes the CNG with air in the intake manifold upstream of the turbocharger compressor. Then there is the controlled periodic metered injection of the fuel into the intake manifold, again, upstream of the compressor, with a CNG fuel injector; this provides more accurate metering of the fuel, reducing methane/unburned hydrocarbon emissions. A third, but more costly option is the injection of both the CNG and diesel pilot directly into the engine combustion chamber with a special fuel injector designed to inject both natural gas and the Diesel pilot. This method prevents fuel from entering combustion chamber crevices where is can escape the combustion process. This method reduces methane/hydrocarbon emissions further and reduces the tendency for knock, which can damage engines; in addition, it allows higher EGR levels to further reduce NOx emissions.In a two-year project, the UT Engines and Automotive Research Group proposes to study the potential benefits of converting a portion of TxDOT’s existing dump trucks to CNG/Diesel dual fuel operation and make recommendations to TxDOT which will include appropriate technologies, technical feasibility, and costs. The TxDOT Dump Truck Retrofit Evaluation Study will consist of: 1) Assess TxDOT dump truck fleet, 2) Assess retrofit options, 3) Conduct pilot testing with UT lab Diesel engine, 4) Select and prioritize dump trucks for retrofit evaluation, and 5) Data analysis, retrofit performance, reporting.