Question

Discuss the four steps of a carnot cycle

Answer 1

 Carnot Cycle consists of four steps, two isothermal processes and two adiabatic (isentropic) processes. The cycle gives us an abstract view of an engine that converts heat into work and enables us to calculate the maximum efficiency with which a heat engine can carry out such a conversion. The engine consists of an expandable volume (such as a cylinder fitted with a piston) filled with an ideal gas. We can put the engine into or out of contact with two heat reservoirs, a hot reservoir (kept at absolute temperature Th) and a cold reservoir (kept at absolute temperature Tc).

    At the first step the engine touches the hot reservoir and the gas in it expands. As the gas does work upon the engine it draws heat from the reservoir to keep the its temperature unchanged, the heat compensating the gas for the energy lost in doing work on the engine. We call this step isothermal because it occurs while the temperature of the gas remains unchanged.

    At the second step the engine breaks contact with the hot reservoir while the gas continues to expand and do work upon it. In this step the temperature of the gas goes down as the expansion of the gas continues to convert heat into work. We call this step adiabatic because no heat flows into or out of the engine during its occurrence. We also call it isentropic because the entropy of the system does not change.

    At the third step the engine touches the cold reservoir and the engine does work upon it to compress it. As the engine does work on the gas heat flows into the cold reservoir to remove the energy that the work puts into the gas. Again we have an isothermal process.

    At the fourth and final step the engine breaks contact with the cold reservoir while it continues to compress the gas to its original volume. Now adiabatic compression heats the gas back to its original temperature and the engine stands