Onboard Water Research Articles

Optimization of a water–gas shift reactor over a Pt/ceria/alumina monolith

The water–gas shift (WGS) reaction is an important step in the purification of hydrogen for fuel cells. It lowers the carbon monoxide content and produces extra hydrogen. The constraints of automotive applications render the commercial WGS catalysts unsuitable. Pt/ceria catalysts are cited as promising catalysts for onboard applications as they are highly active and non-pyrophoric. This paper reports on a power law rate expression for a Pt/CeO 2/Al 2O 3 catalyst. This rate equation is used to compare different reactor configurations for an onboard water–gas shift reactor. A one-dimensional heterogeneous model that accounts for the interfacial and intraparticle gradients has been used to optimize a dual stage adiabatic monolith reactor.

Passive Fire Protection Success

TESTS recently conducted by the Fire Research Station on behalf of the CAA to assess the effectiveness of onboard water sprinklers involved the construction of a test rig based on the fuselage of a Boeing 707 passenger aircraft. Major fire conditions were created outside and the flames were also drawn into the fuselage in a series of tests.

A Rankine Bottoming Cycle System for Heavy-Duty Applications

Fuel costs represent a major portion of the total operating expense of a heavy-duty engine in continuous service. Many new technologies are being developed to lower engine fuel consumption, but a 10–15 percent reduction in fuel costs is now achievable using Rankine Bottoming Cycle (RBC) technology. System economics require integration of state-of-the-art technology in the turbine, heat exchangers, and automatic controls. This paper describes the design and initial test results of a project to demonstrate a diesel engine-RBC power plant. The system was constructed for a Caterpillar 3500 series 16-cylinder (3516) engine with a combined output of 1415 kW. Initial test results have demonstrated a 10.4 percent fuel savings at a thermal efficiency of 44.5 percent. The RBC module is a steam-based, stand-alone unit featuring unattended operation through the use of on-board water treatment, a once-through boiler, automatic control system, and a unique design three-stage-dual pressure steam turbine. The modular concept allows the system to be adapted to other engines and alternative heat sources.

Propulsion for the space station

Propulsion for the Space Station requires a unique, challenging combination of features. The propulsion requirements demand responsive capabilities for orbit control and countering on-board or externally induced forces, and precision control for station-keeping with minimum disturbances. The propulsion design must provide high performance to minimize propellant requirements, have extremely high reliability, provide an extended long-life capability, control emissions and outgasses that could impact in-space operations, and provide maximum safety. Comprehensive evaluations have been performed of numerous design options; these included monopropellants, earth-storable bipropellants, subcritically and supercritically stored cryogenic propellants, use of residual and/or waste fluids, pump-fed and pressure-fed systems, systems with and without gas accumulators, various pressurization methods, and several types of thrusters. The NASA Space Station program office has defined a baseline propulsion system based on hydrogen/oxygen thrusters, using an on-board water electrolysis system to provide the propellants. This system is combined with a low thrust (100 millipound) resistojet propulsion module that can operate using excess or waste fluids. With this combined on-board propulsion system the need to transport propellants to orbit is basically eliminated, as is the need to collect, store, and return waste fluids to earth. Prototype thrusters for the on-board propulsion have been fabricated and tested, with excellent performance and durability demonstrated. Features that enhance long life, maintainability, servicing, and health monitoring have been studied and are being incorporated. A versatile propulsion test bed has been designed and an extensive demonstration program initiated.