Comparative analysis of heat recovery methods from internal combustion engines

This paper discusses different ways of recovering wasted energy from the internal combustion's engine exhaust gas. It is well known that the mechanical work produced by an internal combustion engine is only a small amount related to the fossil fuel it uses. By recovering some of the wasted energy, the internal combustion engine's efficiency can be increased especially in the cold season. The amount of the toxic compounds and greenhouse effect gases that are released in the air can also be decreased by heating up the engine very quickly, lower the engine's load and reduce fuel consumption. The energy is recovered as heat using different types of heat exchangers but can be converted to mechanical energy, electrical energy or even air conditioning power. Because we are referring at vehicle engines, special care must be taken regarding safety in normal operating conditions and also in case of a crash. Some of the methods that combine recovering and storing heat are suitable for hybrid vehicles also. The conclusion of this paper is that the internal combustion engine can take advantage of some heat recovery systems.