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Turboexpansion is a concept which is aimed at reducing the fuel consumption of pressure-charged combustion engines by providing over-cooled air to the engine prior to its induction in the combustion chamber. The performance of the engine is dependent on intake charge density which is preferred to be high at reduced charge air temperature. This becomes achievable through a cooling system known as a turbo expander which expands a high-pressure gas to produce work that is usually employed to drive a compressor. Though, initially used for the purpose of refrigeration in industries, for the past few decades various researches have proved its efficiency in internal combustion engines. In gasoline engines, it is usually employed to extend the knock limit and reduce carbon emissions. Also, an extension to the knock limit allows several improvements in parameters such as increased specific output, an increase in compression ratio and a reduction in the fuel consumption of the engine.

The interest of using alternative fuels in diesel engines has been accelerated exponentially due to a foreseen scarcity in world petroleum reserves, increase in the prices of the conventional fossil fuels and restrictions on exhaust emissions such as greenhouse gases from internal combustion (IC) engines initiated by environmental concerns. The constant trade-off between efficiency and emissions should be in proper balance with the conventional fuels in a fuel design process for future combustors. Unlike gasoline and diesel, alcohols act as oxygenated fuels. Adding alcohols to petroleum products allows the fuel to combust properly due to the presence of oxygen, which enhances premixed combustion phase, improves the diffusive combustion phase which increases the combustion efficiency and reduces air pollution. The higher activation energy of alcohols leads to better resistance to engine knocking that allows higher compression ratios and greater engine thermal efficiencies.