EXPERIMENTAL INVESTIGATION OF THE EFFECTS OF HYDROGEN ENHANCED COMBUSTION IN SI AND CI ENGINES ON PERFORMANCE AND EMISSIONS

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 effect s of HEC in typical engines through laboratory dynamometer test ing. Three engines ‐ (1) a carburetted petrol engine, (2) a fu el injected petrol engine and (3) a diesel engine ‐ were tested to investigate the effects of adding hydrogen to the a ir intake of the engines and measure the effects on performance and emissions (HC, CO and CO 2). The engines were tested at different engine speeds and loads to simulate a wid e range of operating conditions. The hydrogen was produced from the electrolysis of a solution of distilled water and s odium hydroxide using two different electrolyser designs. The electrolyser constructions were suitable for automo tive applications, that is, small in size and consuming current within the capability of a typical car alternator. Both th e hydrogen and oxygen that were produced by electrolysis were adde d to the engine‘s intake during the tests. Results showed th at the addition of HHO is most effective in stabilizing an d 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.