Heat loss comparison between hydrogen, methane, gasoline and methanol in a spark-ignition internal combustion engine

Understanding the heat transfer mechanism from the combustion gases to the walls inside an internal combustion engine is key in the search for higher efficiencies, higher power outputs and lower emissions. Current heat transfer modeling concepts have been reported to be inaccurate for hydrogen engines. To investigate the heat transfer mechanisms in a hydrogen engine, we have measured the instantaneous heat loss inside a spark-ignition engine at three locations. To determine the effect of the throttle position, compression ratio, ignition timing and air-to-fuel ratio in the entire parameter space systematically, techniques of Design of Experiments are applied. The experiment has been repeated for methane, gasoline and methanol to compare hydrogen with other fuels and to build a database for the development of a fuel independent heat transfer model. The paper shows that the effect of the engine factors is similar for all the fuels. However, the heat loss to the cylinder walls of hydrogen is only at the same level of that of the other fuels for very lean mixtures. The engine efficiency drastically reduces for rich mixtures as a consequence, indicating that a lean mixture in combination with boosting and external gas recirculation should be used to obtain high power outputs with high efficiencies for port fuel injected engines. (c) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Canadian Hydrogen and Fuel Cell Association