Thermodynamic Principles of I.C. Engines

Thermodynamics is a very important subject of science. It can be defined as the study of the relationship between heat, mechanical work and forms of energy along with energy transfer. Thus, when we study heat, temperature and the process involved in converting heat into mechanical work as well as vice-versa comes under thermodynamics. 

Internal Combustion Engines (ICE)

The form of heat engines that can be commonly found in various vehicles such as boats, aeroplanes, ships etc. is known as internal combustion engines. In an internal combustion engine, the fuel is ignited to do work inside the engine. This same fuel along with the air mixture is later emitted in the form of exhaust. 

Laws of thermodynamics

After understanding the basics of thermodynamics, it is important to shed light on the laws of thermodynamics so as to understand how thermodynamics impact internal combustion engines. 

Here are the various laws of thermodynamics briefly explained:

–       Zeroth Law of Thermodynamics states that if 2 bodies are placed separately within thermal equilibrium along with a 3rd body then it can be said that the initial 2 bodies are also considered to be in thermal equilibrium concerning each other. For example, if X is in equilibrium with Y and Z is in equilibrium with Y then it can be said both X and Z are also in equilibrium. 

–     First law of Thermodynamics states that one cannot generate or destroy energy rather simply convert it from one form to some other. Mathematically, 

ΔQ=ΔU+W

Where, 

ΔQ = Heat given or lost

ΔU = Change in internal energy

W = Work done

• The second law of thermodynamics states that in an isolated system, thermodynamics asserts that entropy can always be found to be increasing.
• Lastly, according to the third law of thermodynamics, it can be said that as the temperature reaches absolute zero, the entropy of the system reaches a constant value. 

Thus, these are the few laws of thermodynamics that help in bringing more clarity to the subject. 

The Ideal Gas Law

According to the ideal gas law, Pv = nRT, where, 

P = Pressure

v = Volume 

n = No. of moles of gas

T = Temperature

R = Ideal gas constant

This law plays a crucial role in heat engines. As per the law and workings of heat engines, when the temperature of gas has increased leads to an increase in pressure which leads to expansion of gas. An ICE has a chamber with fuel added to it which ignites so as to increase gas’s temperature. 

Conclusion

As we have come to the conclusion, the concepts of thermodynamics have been well understood. In brief, thermodynamics can be referred to as the branch of physics and chemistry which helps in gaining an understanding of heat, energy and the transfer of energy that takes place from one form to another. There are various concepts such as that of an open system, closed system and isolated system which help in understanding thermodynamics in depth. Further, the laws of thermodynamics also shed light upon the functioning of various systems in the Universe. We also learnt about internal combustion engines (ICE) which use the ideal gas law for proper functioning.