Heat Engine Based on Carnot Cycle

The Carnot cycle is a theoretical thermodynamic cycle that is used to describe the most efficient heat engine possible. It consists of four reversible processes: isothermal expansion, adiabatic expansion, isothermal compression, and adiabatic compression. The cycle is often represented on a pressure-volume diagram, where the area enclosed by the cycle represents the net work done by the engine.

Heat Addition in Carnot Cycle

In the Carnot cycle, heat is added to the working substance at a constant temperature. This is because the isothermal expansion process is where heat is added to the system, and this process must be carried out at a constant temperature in order to maintain the efficiency of the cycle.

The reason for this is that during an isothermal process, the temperature of the working substance remains constant. This means that the heat added to the system is converted entirely into work, without any loss due to a change in temperature.

Constant Temperature

Therefore, in order to maintain the efficiency of the cycle, it is necessary to add heat to the system at a constant temperature. This is achieved by using a heat source that is at a constant temperature, such as a reservoir of hot water or steam.

Conclusion

Thus, in a heat engine based on the Carnot cycle, heat is added to the working substance at a constant temperature. This is necessary to maintain the efficiency of the cycle, as it ensures that the heat added to the system is converted entirely into work, without any loss due to a change in temperature.