Michael J. Murphy

Flame Spread Rates Over Methanol Fuel Spills

Abstract Flame spread rates over pooled methanol and pooled gasoline were compared with flame spread rates over a porous surface saturated with these fuels. If the surface temperature was above the fuel flashpoint, the flame spread rate over a fuel-soaked porous surface was the same as for pooled fuel. Just below the flashpoint, flame spread was slower over a porous surface, since liquid flow was restricted. Far below the flashpoint, the flame spread over the porous surface more rapidly than over pooled fuel. For highly volatile fuels, such as methanol-5 percent isopentane mixture, the rate of flame spread depended on lime available for development of a flammable vapor layer over the liquid.

Measurement of Physical Environmental Parameters and Apparent Ventilation Rates Aboard Passenger Aircraft

As part of the ASHRAE RP-1262 Phase 1 study of the airliner cabin environment, measurements were made of physical environmental parameters aboard four passenger aircraft in revenue service. The objectives of these measurements were to measure physical environmental parameters and ventilation rates on board commercial airliners in revenue service and to correlate those measurements with self-reported health effects and complaints. The measurements included temperature, relative humidity, total pressure, air velocity, sound level, light level, and motion. These measurements were recorded each second throughout the flight. In addition, measurements of carbon dioxide levels in the cabin were made that, along with passenger loadings and assumed metabolic rates, allowed the calculation of an apparent air change rate. Because as another part of the study, passengers filled-out written surveys on their comfort and health experience, this study provides unique simultaneous measurement of both physical environmental parameters in an aircraft cabin and the human response. Results of these measurements are presented as temporal graphs for the duration of the flight and are compared to various benchmarks. Among the results, air change rates ranged from 10 to 16 air changes per hour, noise levels varied from 68 to 80 dBA, according to the location in the cabin. Relative humidity values declined from 30 to 35 % during the boarding process to as low as 7 to 8 % during the cruise portion of the flights. The temperature variation was greatest during the boarding process and was generally near 25°C, during the cruise portion of the flights. Over all four flights, the cabin pressure varied from 562 to 740 torr. There was a wide variation in light levels: from over 8000 lux if sunlight was present, to about 250 lux if the window shades were in use.

An improved cetane number predictor for alternative fuels

The complexity of and expense involved in determining the cetane number of diesel fuels using a standard test engine have led to the development and widespread use of the ASTM cetane index. However the cetane index was not intended for use with alternative or unusual diesel fuels; its use with such fuels can lead to large errors. Using a database of alternative diesel fuel properties, a new cetane number prediction equation has been developed for use with alternative fuels, including alcohols. Compared with the cetane index, the average error in predicted cetane number is reduced by 40% and the number of cases where the error exceeds 5 cetane numbers is reduced by 30%. The significance of the various terms in the equation is discussed.

EXTENT OF INDOOR FLAMMABLE PLUMES RESULTING FROM CNG BUS FUEL SYSTEM LEAKS

A validated three -dimensional mathematical model was used to examine the extent of flammable plumes resulting from both large and small CNG leak scenarios inside a typical transit maintenance and storage facility ventilated at a rate of five air changes per hour. The leak rates were based on an engineering and experimental analysis of actual CNG bus fuel system components. The results showed that both large and small CNG leaks produced flammable plumes, such plumes extended from a half a bus length to several bus lengths away from the leak source, and the plume from a large leak formed a layer along the ceiling before being dispersed by building ventilation.