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Hazardous components, such as NOx, CO and HC, in the spark ignition engine exhaust gases may cause serious consequences for human health. The hazardous components in the engine exhaust gases and thermal losses resulting from the engine work can be reduced to a great extent. Energy is released from the system in the form of heat, which use in preparation of the air-fuel mixture has a significant effect on the combustion process. The aim of the article is to, firstly, give an overview of the design and development processes of a heat exchange reactor on a four stroke spark ignition engine, and, secondly, to analyse the effect of a heat exchanger on the engine output parameters. In this research, a heat exchanger is fitted on a four stroke internal combustion engine-generator. The prototype of the heat exchanger is designed and tested. The influence of the heat exchanger on the engine work parameters is outlined and the problems are described and discussed. The results of prototyping indicate that a heat exchange reactor on a four stroke engine reduces harmful emissions of the test engine. More precisely, CO emissions decrease, when preheated air-fuel mixture is formed and directed into the spark ignition engine. The existing calculation models of the heat exchanger give inaccurate results of heat exchanger parameters. Based on the abovementioned, effective engine work with a heat exchanger needs further development.

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This research resulted from military interest in finding methods to provide distributed electricity generation in order to support comprehensive state defence measures. The aim of the study was to investigate the effect of a heated air-fuel mixture on the combustion process of a spark ignition (SI) engine, and to highlight the maximum temperatures to be applied to air-fuel mixtures with different fuel fractions in order to avoid any detonation of the fuel mixture in the engine. Tests were carried out with a petrol engine generator (GENSET) so that an investigation could be conducted into the effect of the air-fuel mixture on the engine’s combustion. It turned out that heating the air-fuel mixture permits the use of heavier fraction fuels than engine petrol in SI engines does, including diesel fuel and biodiesel fuel, and also that the use of heavy fraction fuels in SI engines is effective mainly under low and middle loads.

An internal combustion engine consumes a maximum of a quarter of the energy that is fed into it in the form of fuel. Most of the useful energy leaves the engine in the form of heat energy, specifically as exhaust gases. In addition, exhaust gases contain a number of harmful components, which can be significantly reduced by improving the efficiency of the combustion process. The aim of this article is, firstly, to provide an overview of the design and development of a heat exchanger, one which uses exhaust gas energy to heat the air-fuel mixture and which is installed into the fuel supply system; and secondly, to analyse the impact of the pre-heated air-fuel mixture on the test engine's output parameters. The improved fuel supply system allows for the more efficient mixing and heating of the air-fuel mixture. Heating the air-fuel mixture allows light and heavy fuels to be used in a spark ignition engine. Additional mixing and heating of the air-fuel mixture ensures a faster and more complete combustion process in the engine cylinder. The present study compares the efficacy and economical parameters of a small displacement, four-stroke, spark ignition engine, which is equipped with an advanced fuel system. Experiments were carried out using standard petrol, ethanol, and diesel fuels. Data gained from this experiment have been compared and presented. The results show that further mixing and heating of the fuel mixture makes it possible to use different fuels in a spark ignition engine, while also significantly reducing fuel consumption levels and the volume of harmful components in exhaust gases (such as CO, HC, CO2 and soot).