FAQ on Thermodynamic Cycles

What is a thermodynamic cycle?

A thermodynamic cycle is a series of processes that involve heat and work transfer, returning a system to its initial state. These cycles are used to model the operation of heat engines, refrigerators, and heat pumps.

What is the Carnot cycle?

The Carnot cycle is an idealized thermodynamic cycle that provides the maximum possible efficiency for a heat engine. It consists of two isothermal processes and two adiabatic processes.

What are the steps of the Carnot cycle?

The Carnot cycle consists of four steps:

• Isothermal Expansion: The system absorbs heat while expanding at a constant temperature.
• Adiabatic Expansion: The system expands without exchanging heat, causing its temperature to drop.
• Isothermal Compression: The system releases heat while being compressed at a constant temperature.
• Adiabatic Compression: The system is compressed without exchanging heat, causing its temperature to rise.

What is the Rankine cycle?

The Rankine cycle is a thermodynamic cycle used as a model for steam turbine power plants. It converts heat into mechanical work and consists of four main processes: isentropic compression, isobaric heat addition, isentropic expansion, and isobaric heat rejection.

How does the Rankine cycle differ from the Carnot cycle?

The Rankine cycle uses a phase change (boiling and condensing) of the working fluid, typically water, to improve efficiency. The Carnot cycle, on the other hand, is an idealized cycle that does not involve phase changes and operates between two isothermal and two adiabatic processes.

What is the efficiency of the Carnot cycle?

The efficiency of the Carnot cycle is determined by the temperatures of the heat source (T_hot) and the heat sink (T_cold), and is given by the formula:

Efficiency = 1 - (Tcold/Thot)

where temperatures are in absolute scale (Kelvin).

What is meant by isentropic process?

An isentropic process is a thermodynamic process that occurs at constant entropy. It is an idealized process in which the system is both adiabatic (no heat transfer) and reversible.

What is an isobaric process?

An isobaric process is a thermodynamic process that occurs at a constant pressure. In the Rankine cycle, heat addition and heat rejection processes are typically isobaric.

What is an adiabatic process?

An adiabatic process is a thermodynamic process in which there is no heat transfer into or out of the system. In the Carnot cycle, both expansion and compression are adiabatic.

How does the Rankine cycle improve efficiency?

The Rankine cycle improves efficiency by using a condenser to condense the exhaust steam from the turbine back into liquid water, which can then be pumped to a higher pressure and recycled through the boiler. This reduces the amount of work required by the pump compared to compressing steam.