Title:Investigating the Work of Internal Combustion Heat Machines - Bamyan University

Title:Investigating the Work of Internal Combustion Heat Machines

 

Abstract

According to second law of thermodynamics, heat flows form a body at higher temperature to a body at low temperature. Therefore, we can say that heat energy is converted into mechanical energy and vice versa. The instrument which converts the heat energy into other form of energies are called heat engines. In general, there are two types of heat engines, like external combustion engine and internal combustion engine. In external combustion engine, the combustion of fuel takes place outside of the cylinder of engine. e. g. steam engine. In internal combustion engine, the combustion of fuel takes place inside the cylinder of engine. For such engines, the working substance is air, but actually air is mixed with a small quantity of combustible gas or vapor. Internal combustion engine also are two types like Otto engine and diesel engine. All internal combustion heat engine act in four strokes and six operations, in every strokes and operation fallow from laws of thermodynamics. 

In Otto engine, air is working substance and petrol vapor acts as the fuel. The mixture of air and petrol vapor enter to cylinder and burns by high voltage spark of current. The produced heat energy is absorbed and given during isochoric process. There are small compression ratio, danger explosion and small efficiency.

 In diesel engine, air is the working substance and oil acts as the fuel. The oil injected separately with a pump and adiabatic compression causes ignition. The produced heat energy is absorbed and rejected during isobaric process. This type of engine is heavy and bulky. There are large compression ratio, high efficiency and lack of danger explosion.