Vernon P. Roan

Comparison between oscillometric and invasive blood pressure monitoring during cardiac surgery

We compared values of invasive blood pressure measured intra-arterially with those measured noninvasively with an automated oscillometric monitor. Twenty-eight patients undergoing cardiac surgical procedures under general anesthesia were studied and 552 determinations were made. The two methods of measuring blood pressure correlated within the expected bounds of experimental accuracy and physiological variation. However, the correlation between invasive and noninvasive methods varied, apparently arbitrarily, with time. These disparities could not be explained by a linear combination of physiological variables recorded. Systolic determinations correlated the best and diastolic the least between the invasive and noninvasive methods. In general, the correlation was better for adults than for children, except with diastolic blood pressure.

Enhancing hydrogen production for fuel cell vehicles by superposition of acoustic fields on the reformer: a preliminary study

Because of recent interest in energy efficiency and environmental issues, fuel cell vehicles are seen by many to be the way of the future. As near term fuel cell vehicles will likely use the existing liquid fuel infrastructure, the efficient reformation of hydrocarbon fuels is one technological hurdle that must addressed. An investigation has been made into the possibility of enhancing reformation processes through superposition of an acoustic field on the catalyst bed of a methanol steam reformer. As part of this study, background is given outlining the difficulties and liabilities of steam-reformation for transportation applications. Proven acoustic enhancement of various processes is reviewed and theory of acoustic enhancement of the steam-reforming process is developed. The facility studied includes a steam-reforming reactor that has been modified to accept an acoustic field. Relevant parameters of the acoustic field are quantified and discussed. The effect of the acoustic field has been investigated with relation to the reactor output parameters. Although the facility used has not been optimized for utilizing acoustic waves, significant acoustic enhancement of the steam-reformation process is demonstrated by the study and such enhancement has shown a positive effect on the reformation process. Potential benefits insulting from acoustic enhancement of steam reforming as shown by this study are: an increased reactor capacity for a given size and mass, smoothing of the temperature profile and better control of the temperatures in the catalyst bed. It is expected that for different fuels and/or reforming methods, similar results would be obtained for comparable process constraints.

An Analysis of Shutdown for an Operational Fuel Cell Transit Bus

Author(s): Heckwolf, Michael J.; Erickson, Paul A.; Simmons, Timothy C.; Roan, Vernon P., Jr. | Abstract: International Truck a Bus Meeting a Exhibition, Chicago, IL, Session: Hybrids a Fuel Cells The shutdown process of an operational phosphoric acid fuel cell transit bus has been investigated. The bus employs a hybrid arrangement of a 50 kW Phosphoric Acid Fuel Cell (PAFC) engine in parallel with Nickel-Cadmium batteries on a 30-foot heavy-duty transit bus chassis manufactured by Bus Manufacturing Inc. The bus uses methanol as the primary fuel, which is processed through a steam-reformer to produce hydrogen used in the fuel cell. Rapid cooling of PAFC power plants will induce component damage. Shutdown of the fuel cell bus is defined as the time that is required for the controlled reduction from operating temperatures within the fuel cell stack and reformer to minimize component degradation. While in general fuel cell vehicles produce low emissions and are very efficient while operating, shutdown of the fuel cell bus represents a significant time requirement, power and fuel consumption, and considerable pollutant emissions with no usable output power. A description of the shutdown procedure for the bus, fuel and power usage, average time required, and analysis of emissions data are presented.

Discussion and Analysis of Flue Gas Utilization in a Phosphoric Acid Fuel Cell Engine During Idle Operation

Fuel cell technology has in recent years won the favor of all major car manufacturers as a likely future replacement of the internal combustion engine. This has been driven by the potential for high efficiency and low emissions. Still, fuel cell engines must overcome major hurdles before being introduced into the market. One such hurdle is systems integration; in particular, with fuel cell engines that do not use hydrogen as their primary fuel. In these engines, fuels, such as methanol, are employed instead of hydrogen because of their high-energy density and ease of storage. However, these benefits are counterbalanced by the need to reform these fuels on-board the fuel cell vehicle, thus substantially increasing the complexity of the fuel cell engine. Through the course of operating a 30 ft methanol-fueled phosphoric acid fuel cell bus, repeated overheating of the steam-reformer catalyst bed at low engine power outputs was noted. For the purpose of better understanding these overheating events, relevant data was obtained from the bus. Bus operation at low-power outputs was found to have low hydrogen consumption (∼40% to ∼60% of the stacks incoming hydrogen) due to low electrical demands and reformate flow rate constraints. In the bus, the anode flue gas is burned in the reformer burner, which provides the heat required for the endothermic methanol steam reforming reaction (see Fig. 1 later). At low engine power, the flue gas is the reformer burners only fuel, but the energy carried by the flue gas is much greater than the energy required for the reforming reaction and consequently causes reformer overheating at low power. This case serves as an example of how appropriate fuel cell system integration is crucial in order to harness fuel cell benefits. To study such system integration problems, a steady-state model of the fuel cell bus engine was developed. Using this model the bus reformer overheating problem was understood and several possible improvements for utilization of the flue gas were conceited.

A Preliminary Assessment of the Possible Acceptance of Fuel Cell Bus Technology by Current Fleet Vehicle Operators

Author(s): Simmons, Timothy; Erickson, Paul; Betts, Daniel; Roan, Vernon, Jr. | Abstract: Presented at the International Truck a Bus Meeting a Exhibition, November 2002, Detroit, MI, USA,Session: User Experience with Alternative Fuel / Propulsion Transit BusesFuel cell engines are expected to deliver greater efficiency and lower emissions than conventional transit bus powertrains in the near future. Although experimental vehicles have demonstrated the emission and efficiency benefits of fuel cell power, the next step toward implementation is widespread fleet demonstrations to prove the technology in the field. In order to aid in the start of new demonstrations and speed fuel cell technology towards the fleet vehicle marketplace, an honest assessment of the needs, risks, and advantages of using fuel cell power must be obtained from a consumer perspective. It has been assumed that the increased fuel efficiency that is inherent to fuel cell systems will lower operating costs as compared with conventional diesel powertrains. A comparison of two fuel cell buses and a diesel bus was completed in order to quantify the operational cost benefits and identify potential cost deterrents to fuel cell bus implementation. A limited survey of Florida mass transit operators was also conducted to gauge the desire for some of the intangible benefits of fuel cell buses. Some of these issues included reduced emissions, decreased noise, lack of oil and minimized vibration. This information can be used to help analyze the status of fuel cell power for transit applications and begin to form economic and technological goals for future design of fuel cell transit buses.

An Analysis of Start-up for an Operational Fuel Cell Transit Bus

Author(s): Erickson, Paul A.; Betts, Daniel A.; Simmons, Timothy C.; Roan, Vernon P., Jr. | Abstract: Presented at the International Truck a Bus Meeting a Exposition, Portland, OR Session: Fuel Cells The start-up process of an operational phosphoric acid fuel cell transit bus has been investigated. The bus employs a hybrid arrangement of a 50 kW Phosphoric Acid Fuel Cell (PAFC) engine in parallel with Nickel-Cadmium batteries on a 30-foot heavy-duty transit bus chassis manufactured by Bus Manufacturing Inc. The bus uses methanol as the primary fuel, which is processed through a steam-reformer to produce hydrogen used in the fuel cell. Start-up of the fuel cell bus is defined as the time that is required to heat up the fuel cell and subcomponents to operating temperatures and to establish operating flow conditions. While in general fuel cell vehicles produce low emissions and are very efficient while operating, start-up of the fuel cell bus represents a significant time requirement, power and fuel consumption, and considerable pollutant emissions with no usable output power. A description of the start-up procedure for the bus, fuel and power usage, average time required, and analysis of emissions data are presented.