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Nondestructive Evaluation of Stiffness and Stresses of Ceramic Candle Filters at Elevated Temperature under Vibrational Environment

Description: In recent years a significant amount of effort has been devoted to develop damage-tolerant hot gas filter elements, which can withstand chemical, high pressure and extreme thermal cyclic loading in the coal-based environment (Alvin 1999, Spain and Starrett 1999). Ceramic candle filters have proven to be an effective filter for the ash laden gas streams, protecting the gas turbine components from exposure to particulate matter (Lippert et al. 1994). Ceramic candle filters need to sustain extreme thermal environment and vibration-induced stresses over a great period of time. Destructive tests have been used to describe physical, mechanical and thermal properties of the filters and to relate these properties and behaviors to in-service performance, and ultimately to predict the useful life of the filter materials (Pontius and Starrett 1994, Alvin et al. 1994). Nondestructive evaluation (NDE) techniques have been developed to determine the deterioration or the presence of damage and to estimate the remaining stiffness of ceramic candle filters (Chen and Kiriakidis 2001). This paper presents a study of parameters involved in the prediction of remaining life of ceramic candle filters under service conditions. About one hundred ceramic candle filters from previous studies (Chen and Kiriakidis 2000) and forty-six filters received during this project have been nondestructively evaluated. They are divided in Pall Vitropore, Schumacher and Coors filters. Forty-six of these filters were used having various in-service exposure times at the PSDF and the rest were unused filters. Dynamic characterization tests were employed to investigate the material properties of ceramic candle filters. The vibration frequency changes due to exposure hours, dust cake accumulation, candle's axisymmetry, boundary conditions and elevated temperatures are studied. Investigations on fatigue stresses of the filters due to vibration of the plenum and back pulse shaking are also studied. Finite element models (FEM) are built to calculate the filter's ...
Date: September 19, 2002
Creator: Chen, R.H.L. & Kiriakidia, A.
Partner: UNT Libraries Government Documents Department

Diesel and CNG Transit Bus Emissions Characterization By Two Chassis Dynamometer Laboratories: Results and Issues

Description: Emissions of six 32 passenger transit buses were characterized using one of the West Virginia University (WVU) Transportable Heavy Duty Emissions Testing Laboratories, and the fixed base chassis dynamometer at the Colorado Institute for Fuels and High Altitude Engine Research (CIFHAER). Three of the buses were powered with 1997 ISB 5.9 liter Cummins diesel engines, and three were powered with the 1997 5.9 liter Cummins natural gas (NG) counterpart. The NG engines were LEV certified. Objectives were to contrast the emissions performance of the diesel and NG units, and to compare results from the two laboratories. Both laboratories found that oxides of nitrogen and particulate matter (PM) emissions were substantially lower for the natural gas buses than for the diesel buses. It was observed that by varying the rapidity of pedal movement during accelerations in the Central Business District cycle (CBD), CO and PM emissions from the diesel buses could be varied by a factor of three or more. The driving styles may be characterized as aggressive and non-aggressive, but both styles followed the CBD speed command acceptably. PM emissions were far higher for the aggressive driving style. For the NG fueled vehicles driving style had a similar, although smaller, effect on NO{sub x}. It is evident that driver habits may cause substantial deviation in emissions for the CBD cycle. When the CO emissions are used as a surrogate for driver aggression, a regression analysis shows that NO{sub x} and PM emissions from the two laboratories agree closely for equivalent driving style. Implications of driver habit for emissions inventories and regulations are briefly considered.
Date: May 3, 1999
Creator: Nigel N. Clark, Mridul Gautam; Rapp, Byron L.; Lyons, Donald W.; Graboski, Michael S.; McCormick, Robert L.; Alleman, Teresa L. et al.
Partner: UNT Libraries Government Documents Department

Application of the New City-Suburban Heavy Vehicle Route (CSHVR) to Truck Emissions Characterization

Description: Speed-time and video data were tractor-trailers performing local deliveries in logged for Akron, OH. and Richmond, VA. in order to develop an emissions test schedule that represented real truck use. The data bank developed using these logging techniques was used to create a Yard cycle, a Freeway cycle and a City-Suburban cycle by the concatenation of microtrips. The City-Suburban driving cycle was converted to a driving route, in which the truck under test would perform at maximum acceleration during certain portions of the test schedule. This new route was used to characterize the emissions of a 1982 Ford tractor with a Cummins 14 liter, 350 hp engine and a 1998 International tractor with a Cummins 14 liter, 435 hp engine. Emissions levels were found to be repeatable with one driver and the drier-to-driver variation of NO{sub x} was under 4%, although the driver-to driver variations of CO and PM were higher. Emissions levels of NO{sub x} for the Ford tractor at a test weight of 46,400 lb. u sing the CSHVR were comparable with values obtained using the WVU 5 mile route and the EPA Urban Dynamometer Driving Schedule for Heavy Duty Vehicles (''Test D''). The PM missions were slightly higher for the CSHVR than the 5 mile route and Test D. The effect of test weight on emissions, in units of mass/distance, was assessed using the International tractor with the CSHVR at 26,000, 36,000 and 46,400 lb. test weights. Variation of all regulated exhaust emissions was small between test weights, although the CO{sub 2} level reflected the additional energy used at higher weights. The small variation in regulated emissions may be attributed to the fact that in all three cases, the route called for full power operation of the vehicle, and that PM puff associated with gear shifting would ...
Date: May 3, 1999
Creator: Clark, Nigel N.; Daley, James J.; Nine, Ralph D. & Atkinson, Christopher M.
Partner: UNT Libraries Government Documents Department