A Study on the Application of Turbo Expansion in Light Duty Gasoline and Diesel Engines: A Review

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. Without its application in gasoline engines, the engine must operate at lower compression ratio in order to prevent knock. When applied to the diesel engines, it has been found to be effective in lowering the nitrous oxide levels which is central to the formation of ground-level ozone which is associated with hazardous health effects. In addition to that, it also reduces the peak combustion temperature as in the case of the gasoline engine. This paper aims to review advantageous and disadvantageous effects as well as results of the application of turbo expansion in light-duty gasoline and diesel engines.