Thermodynamic Cycles

This simulation is designed for the study of cyclical thermodynamic processes.

Choose a cyclic process on the (P,V) graph. Compare different cycles from the perspective of their usage in heat engines.

A heat engine is a device that converts heat into work. The working substance in any heat engine is brought into contact with a hot body (a heater) in order to get a certain amount of heat Q1 from it. Then, it is brought into contact with a cool body (a refrigerator) in order to give heat away (the quantity of heat given away is Q2 < Q1.) This process is repeated continuously, which explains its name as the cyclic or circular process.)

According to the laws of thermodynamics, the amount of heat that is acquired from the heaters cannot be completely converted into work (the second law of thermodynamics).

According to the law of conservation of energy, or the first law of thermodynamics, the amount of work W produced by a heat engine is
W = Q1 - Q2
The relationship
 e = W = 1 - Q2 < 1 Q1 Q1

is known as the efficiency factor of a heat engine.

The simplest circular process, wherein the substance that performs work (an ideal gas) is periodically brought into contact with one heater (T1) and one refrigerator (T2) is known as the Carnot cycle, and it consists of two isotherms and two adiabats.

The efficiency factor of such idealized heat engine is at its maximum, and is equal to
 emax = (T1 - T2) T1

It is necessary to have an infinite set of heaters and refrigerators with different temperatures in order to carry out other circular processes in a quasi-static fashion. (Q1 is the total amount of heat absorbed from all heaters, and Q2 is the total amount of heat given away to all refrigerators.) The efficiency factor for any circular process is always less than that of the Carnot cycle, which incorporates the maximal temperature of the heater and the minimal temperature of the refrigerator.

You can select cycles of various shapes, and to determine the efficiency η for each cycle on the (p, V) plane. The quantity of heat added to the system (Q), the amount of work produced (W) and the change ΔU in the internal energy are displayed on the energy diagram.

Note that after completing a cycle, the total work done is numerically equal to the cycle's area, and the change in the experimental substance's internal energy is equal to zero.

The working substance in this simulation constitutes 1 mole of a mono-atomic ideal gas.