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

Abstract

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 (NO_x) 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.

Introduction

In the last years, the late reports on the environmental contamination and the exhaustion of the resources show the levels have been increased due of intensive use of the internal combustion engines, and for this reason it is looking for a more efficient and clean sources to produce movement and electric power. Hydrogen can be part from an integral and efficient solution for this type of problems. The fuel cells are a promising alternative in terms of power production, however these systems it is going be a reality for the next 20 years when the mass production start. The hydrogen combustion has an important advantage over the fuel cells systems, it is possible to use the infrastructure that exists to adapt the internal combustion engines to use hydrogen as a fuel, and in this manner reduce of emissions. This is the way to introduce in the market this type of conversion of engines in short term. The use of the hydrogen as a fuel in the engines has been studied by different authors [1], [2], [3] in the last decade with several degrees of success. However, these reports are not necessarily consistent among several researchers. The tendency in this type of reports is focused in results obtained for specific engines under very narrow operation conditions, and also made emphasis in the emissions and considerations of efficiency [1]. It should be taken into account what has been achieved in this field, focused in the attractive features as in the limitations associate with the disadvantages that are needed to overcome the hydrogen broadly acceptable as a fuel for engines. It is also necessary to indicate the practical steps to incorporate the different experimental condition in the existent commercial engines to operate with hydrogen gas.

White et al. [4] were made a technical revision of the internal combustion engines operate with hydrogen; their work was emphasis in the use of hydrogen/gas mixtures with light and heavy load in order to reduce the bad combustion engines. Also, they report the effect of variation in the concentration of the mixture hydrogen/air versus the emissions of NO_x.

Akansu et al. [5] also carried out a technical revision on natural gas/hydrogen mixtures. They reported the level of the pollutants emissions, such as hydrocarbons without burning and nitrogen oxides when internal combustion engines operate with natural gas and adding hydrogen. Also, they reported the efficiencies and powers of the engine.