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With the high auto ignition temperature of natural gas, various approaches such as high compression ratios and/or intake charge heating are required for auto ignition. Another approach utilizes the trapping of internal residual gas (as used before in gasoline controlled auto ignition engines), to lower the thermal requirements for the auto ignition process in natural gas. In the present work, the achievable engine load range is controlled by the degree of internal trapping of exhaust gas supplemented by intake charge heating. Special valve strategies were used to control the internal retention of exhaust gas. Significant differences in the degree of valve overlap were necessary when compared to gasoline operation at the same speeds and loads, resulting in lower amounts of residual gas observed. The dilution effect of residual gas trapping is hence reduced, resulting in higher NOx emissions for the stoichiometric air/fuel ratio operation as compared to gasoline.

Natural gas has a high auto-ignition temperature, requiring high compression ratios and/or intake charge heating to achieve HCCI (homogeneous charge compression ignition) engine operation. Previous work by the authors has shown that hydrogen addition improves combustion stability in various difficult combustion conditions. It is shown here that hydrogen, together with residual gas trapping, helps also in lowering the intake temperature required for HCCI. It has been argued in literature that the addition of hydrogen advances the start of combustion in the cylinder. This would translate into the lowering of the minimum intake temperature required for auto-ignition to occur during the compression stroke. The experimental results of this work show that, with hydrogen replacing part of the fuel, a decrease in intake air temperature requirement is observed for a range of engine loads, with larger reductions in temperature noted at lower loads.

Membranes are highly desirable for separating gases in life-support applications. They are small, light, efficient, selective and require little operational or physical maintenance. Facilitated transport membranes have particularly high flux and selectivity. We created enzyme-based facilitated transport membranes using isozymes and mutants as immobilized arrays alone and in conjunction with polymeric membranes. The enzyme operates efficiently at the low CO2 concentrations encountered in respiratory gases and can bring CO2 to near ambient levels. CO2 flux is greatly enhanced and selectivities for CO2 over O2 of 200:1 or greater are possible. The enzymes are robust and stable for long periods under a variety of storage and use conditions.

This paper presents the findings of theoretical and practical studies of an exhaust-gas reforming process, as applied to hydrocarbon fuels. It is shown that hydrogen-containing gaseous reformed fuels can be produced by the interaction of hot combustion products and an n-heptane feedstock in a small-scale catalytic reforming reactor. Predicted and observed reformed fuel chemical compositions were found to correlate well at the lower reactor space velocities tested, where chemical equilibrium conditions can be closely approached. Under these conditions, respective hydrogen and carbon monoxide yields of around 32 and 20 volume per cent were obtained. Under certain conditions, it was found that carbon solids were deposited on the reforming catalyst. Measures taken to avoid this problem included changes in the reforming oxidant to fuel ratio, and the addition of excess steam to the oxidant composition.

The effects of child safety seats have been well documented in the medical literature. Scattered throughout the medical literature are individual case reports of cervical injury to children restrained in child restraint systems. A review of the literature is provided identifying previous documented cases. The authors also provide new case details of children with cervical spine injury without head contact. An overview of the growth of the infant and specific details in the cervical spine that may contribute to significant cervical injury without head impact is presented.