Thermodynamics is the thermal science dealing with energy transfer in the form of heat and work and their conversion to each other. There is always some effect of energy transfer on the physical properties of the substance. Human desires output as work and he utilizes heat as an input. Thermodynamics tells us the most economical way of utilizing heat to produce work and vice-versa. The thermal science was originated in 19th century when steam engine was introduced. The size of this engine was large and the efficiency & performance were low. For better performance and efficiency, steam turbines, I.C. engines, gas turbines were invented in last few decades.