Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.
Hydrogen enhanced combustion (HEC) is promoted as an end-user add-on that has the capability of reducing both engine tailpipe emissions and fuel consumption. An experimental investigation was carried out to measure the effects of HEC in typical engines through laboratory dynamometer testing. Three engines – (1) a carburetted petrol engine, (2) a fuel injected petrol engine and (3) a diesel engine – were tested to investigate the effects of adding hydrogen to the air intake of the engines and measure the effects on performance and emissions (HC, CO and CO2). The engines were tested at different engine speeds and loads to simulate a wide range of operating conditions. The hydrogen was produced from the electrolysis of a solution of distilled water and sodium hydroxide using two different electrolyser designs. The electrolyser constructions were suitable for automotive applications, that is, small in size and consuming current within the capability of a typical car alternator. Both the hydrogen and oxygen that were produced by electrolysis were added to the engine‘s intake during the tests. Results showed that the addition of HHO is most effective in stabilizing and enhancing the combustion of lean air-fuel mixtures inside the petrol injected engine, allowing for lower HC, CO and CO2 emissions. Thus hydrogen enhanced combustion could play a role in stabilizing lean burn petrol engines.
