Mechanical Engineering Analysis and Techniques for a Diesel Engine Mechanical Systems

Conceptually, diesel engines achieve their performance and efficient fuel consumption by adiabatically high-pressure compression of air (typically of the ratios between 14:1 and 25:1) in the cylinders before injecting small amounts of fuel into the compressed air. For example, the high temperatures generated during the compression of air enhance the evaporation of the pulverized fuel which then mixes with the existing hot air to auto burn ignite and burn thereby releasing energy in form of heat.

On the other hand, the energy released from the burning fuel then raises the pressure on the surface of the pistons, making it return to the bottom dead center(PMI) thereby resulting in a power cycle as shown in figure 2 below:

Diesel engines have a wide range of applications some of which include driving industrial mechanical systems, locomotives, marine vessels, construction equipment, generators and automobiles among others. Generally, diesel engines are widely considered to be much more efficient and are in most cases preferred to their gasoline counterparts due to a number of their potential advantages some of which include:

High engine temperatures are one of the major concerns in many diesel car engines. This particularly attributed to the fact that diesel engines typically have a considerably higher temperature of combustion as well as greater expansion ratios. Although this ensures that the engines have greater fuel combustion efficacy, high engine temperatures also result in a number of challenges related to engine cooling systems. For example, without an efficient cooling system and temperature control mechanism, the temperatures in diesel engines may rise to dangerous levels resulting in increased tear and wear of the engine parts. In addition, the extremely high local peak temperatures may also contribute to the formation of nitric oxide (through the binding of NO and NO2), which is one of the major harmful pollutants.