Thermal balance in internal combustion engine with gasoline 2021-36-0025

The automotive internal combustion engine is a thermal machine that, from the combustion of the fuel inside the combustion chamber, releases thermal energy for the engine operation and consequently the displacement of the vehicle. A considerable part of this thermal energy is lost and the way to detect this loss is through experimental testing and applying the thermal balance to the engine. This work aimed to perform a thermal balance of the Otto cycle engine involving the energy released due to the gasoline combustion process, power delivered from the engine shaft, energy rate rejected for the cooling system, energy rate rejected for the exhaust system and energy rate rejected to the environment in the form of heat and incomplete combustion. The experiment consisted of making a thermal balance of the engine running with gasoline from experimental data measured on the engine operating on a bench dynamometer varying load and rotation conditions. The results showed that, concerning the energy rate released in the gasoline combustion process, approximately 27% was converted to thermal efficiency (shaft power), 16% was dissipated to the cooling system, 29% was rejected to the exhaust system and approximately 32% was energy lost to the environment, incomplete combustion and lubrication system. This research is important because it correlates useful energy in an Otto cycle engine with the actual losses. This allows, based on the detected energy losses, an opportunity for a more detailed study to optimize and improve engine performance.