Hydrogen fuel cell (H 2 FC) buses operating in every day public transport services around Europe are assessed for their sustainability against environmental, economic and social criteria. As part of this assessment the buses are evaluated against diesel buses both in terms of sustainability and in terms of meeting real world requirements with respect to operational performance. The study concludes that H 2 FC buses meet operability and performance criteria and are sustainable environmentally when 'green' hydrogen is used. The economic sustainability of the buses, in terms of affordability, achieves parity with their fossil fuel equivalent by 2030 when the indirect costs to human health and climate change are included. Societal acceptance by those who worked with and used the buses supports the positive findings of earlier studies, although satisfactory operability and performance are shown to be essential to positive attitudes. Influential policy makers expressed positive sentiments only if 'green' hydrogen is used and the affordability issues can be addressed. No "show-stopper" is identified that would prevent future generations from using H 2 FC buses in public transport on a broad scale due to damage to the environment or to other factors that impinge on quality of life.
Basic heat release data have been obtained by analysis of cylinder pressure diagrams from a variety of engines, two-stroke and four-stroke, small (3·4-in bore) to medium size (12-in bore) over ranges of power, speed, and air supply conditions. The paper gives an account of early attempts to obtain a simple formula for heat release suitable for performance calculations by computer, using the simple and widely used single-zone model for conditions in the cylinder. The conclusion is reached that although it is possible to obtain useful calculations in this way, more sophisticated models are necessary for better understanding of conditions in the engine.
While the design of diesel engines is necessarily based upon some estimate of the pressure and temperature conditions expected in the cylinder and in the air and exhaust manifolds, such estimates have usually been very approximate. The suitability of the design has to be proved, or improved, during a considerable programme of rigorous development.As engines become more highly rated the value of more accurate early estimates of engine performance, as a guide to the designer, becomes more obvious. The paper describes a method of calculating t h i s information by digital computer based on a fundamental approach to the processes involved. It is demonstrated that the cylinder pressures and temperatures, exhaust gas temperatures, fuel consumption, air flow, heat losses, piston and wall temperatures and engine output so calculated, correlate very well with experimental results.Using this technique, Merent combinations of engine variables can be 'tested' by computation to reduce the range of engine tests necessary to develop the optimum design, and allow the designer and the development engineer to concentrate their practical experience and technical 'know-how' on the formidable problems of mechanical development and combustion improvement.
The authors have outlined the simple theory of the exhaust gas driven turbocharger in association with the diesel engine. After a short statement of early empirically based assessments of the effect of altitude on supercharged engine output the theory is used to derive a method of calculation of engine performance, using a digital computer. A semi-empirical graphical method is then developed which may be used to assess the effect of turbocharger match, altitude, ambient temperature and fuel consumption on a known engine. Experimental evidence of the validity of the method is given.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.