A review on the technical adaptations for internal combustion engines to operate with gas/hydrogen mixtures

The use of the hydrogen as fuel in the internal combustion engine represents an alternative use to replace the hydrocarbons fuels, which produce during the combustion reaction a pollutes gases. The hydrogen is the most abundant material in the universe and during its combustion with air only produces nitrous oxides (NOx) gas, which can collect and avoid their emission to the atmosphere. In this paper we can present the most significant advances and developments made on the technical adaptations in the internal combustion engines which operate with mixtures of gas/hydrogen, doing more emphasis in the fuel injection and cooling systems. To understand such technical adaptations, it is necessary to know the chemical and physical characteristics of the hydrogen, and the processes relate with the chemical reaction between air and hydrogen, from a point of view of the thermo-chemistry and the chemical kinetics, as well as the ratios of the mixtures in the combustion process. Also, it mentions the advantages and disadvantages of the integration of hydrogen as a fuel, such as the pre-ignition, spontaneous ignition, knocking and backfire, also the advances in the research to avoid these phenomena during the combustion. Finally, it describes the best conditions of the ratio-mixtures in the internal combustion engines when they are fed with hydrogen. Also, it describes the perspectives and the futures fields on the future investigation.