Describe Carnot ideal engine lecture three

Q. What is heat engine?

Any practical machine which convert heat into mechanical work is called a heat engine.

Q.What is one cycle of operation of heat engine?

The complete changes through which the working substance undergoes from its initial state and back to its starting state constitute one cycle of operation.

Q.Write down the definition of efficiency.

The efficiency, ƞ of a heat engine is defined as the ratio of the mechanical work done by the engine in one cycle to the heat absorbed from the high temperature source.

Thus  ,   

Ƞ=                   

where Q₁ is the heat absorbed from the source at high temperature, Q₂ , is the heat rejected to a sink at low temperature and ( Q₁ – Q₂  ) is the mechanical work done by the engine in one cycle. Since ( Q₁ – Q₂  ) < Q₁ , the efficiency can never be 100%.

Q.Describe Carnot’s ideal engine.

Answer: Inventor French engineer Sadi Carnot in 1824 .

There are four important parts of Sadi Carnot’s engine.

important parts of carnot's engine 

 


 1. A cylinder having perfectly non-conducting walls, a perfectly conducting base and is provide  perfectly non conducting piston which move without friction in the cylinder. The cylinder contains one mole of perfect gas as the working substance.  

1. 2. Source. A reservoir maintained at a constant temperature T₁ from which the engine can draw heat by perfect conduction. It has infinite thermal capacity and any amount of heat can be drawn from it an constant temperature T₁.
   3.   Heat insulating stand:  A perfectly non-conducting platform acts as a stand for adiabatic process.
   
   
   
   
   4. Sink: A reservoir maintained at a constant lower temperature T₂ to which the heat engine can reject any amount of heat. The thermal capacity of sink is infinite so that its temperature remains constant at T_2, no matter how much heat is given to it.