Carnot Cycle

The Carnot cycle, named after French engineer Nicolas Leonard Sadi Carnot, is the most efficient cycle possible. It consists of four basic reversible processes meaning that the cycle as a whole is also reversible. The four reversible processes are:

• Heat transfer from the working fluid to the low-temperature reservoir (Condenser).

• Adiabatic increase in the temperature of the working fluid (Heat Pump).

• Heat transfer from the high-temperature reservoir to the working fluid (Boiler).

• Adiabatic decrease in the temperature of the working fluid (Turbine).

An important conclusion from Carnot cycle analysis is that the maximum theoretical efficiency of heat engines is directly related to:

efficiency = D(T₂-T₁)/T₂

• where:

  • T₂ is the maximum operating temperature on absolute scale (K)

  • T₁ is the minimum operating temperature on absolute scale (K)

For a heat engine operating between 300^oC and 100^oC, with a DT of 200 degrees, this maximum efficiency would be:

efficiency = 200/(300 + 273) x 100 = 34.9%

Animation

(Courtesy Jacquie Hui Wan Ching, Department of Physics, University of Virginia )

Instructions:

Simply click START to play the movie with the default values of P1, V1, and V3.

To change values,

1. Move the cursor to the lower left bottom of the graph. Click to set the values of P1 and V1.
2. Check V3 and move the cursor to the graph and set a value for V3. V3 has to be larger than V1.
3. After setting the values, click Start and the engine moves.
4. Click restart to set different values for P1, V1, and V3.

Note: T_(hot) = 600K; T_(cold) = 300K; C_p/C_v=5/3

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