The influence of hydrogen and oxygen (HHO) gas on engine characteristics under the effect of the lean mixtures of gasoline and bioethanol

Abstract

Along with the imposed stricter ecological requirements, the new manners of reducing the emitted pollutants are extensively researched. One of the requisites is the focus on the absence or the use of an extremely low count of carbon-based fuels as an option for the internal combustion engine. The conducted research demonstrates the perspective of applying bioethanol containing hydrogen and oxygen (HHO) gas as a fuel additive to stoichiometric (λ = 1.0) and lean (λ = 1.1; 1.2; 1.3; 1.4) mixtures for gasoline employing the spark ignition engine considering changes in ignition timing in the range from 16° to 42° BTDC. Ecological (CO, CO2, HC, NOx) and energetic (torque, fuel consumption, break thermal efficiency) parameters have been measured using gasoline and bioethanol (fuels E10 and E70) enriched with HHO gas. Hydrogen and oxygen gases are produced using a HHO gas generator, which is a mobile electrolysis unit. It has been concluded that a higher concentration of ethanol in fuel and the HHO additive result in higher torque for all evaluated air/fuel ratios. The rate of the analysed heat release has showed that HHO gas increases combustion speed, shortens combustion duration and has the highest positive effect of thermal efficiency when the mixtures are lean and have a higher concentration of ethanol. The use of the HHO additive has increased NOx emissions, although CO, CH and CO2 have remained lower. The regulation of the excess air ratio and ignition timing allows for selecting the most energetically-efficient adjustment parameters and to objectively evaluate the possibilities of improving energetic and ecological indicators for engines replacing gasoline with bioethanol and additionally supplying HHO gas.