The thermodynamic cycles is one of the method to obtain useful work from thermodynamics.  Simple engines and mass lifters are some of the examples which use the thermodynamic cycles.  We can explain this thermodynamic cycles using simple lab equipment.

    Suppose you have car making plant and you want to lift handles from ground level conveyor to higher level conveyor.  to raise handles, you need work.  This work can be done by mass lifter.  We can express this mass lifter using simple thermodynamic machine: "The Incredible Mass Lifter".  This Incredible Mass Lifter consists of Erlenmeyer flask, low fraction syringe, hot water bath, and ice water bath.  The handle is expressed by a 50g weight.  First, the erlenmeyer flask with syringe in the ice water bath is placed next to the ground level conveyer.  The weight is placed onto the syringe.  Then, the ice water bath is replaced with hot water bath to raise the syringe.  When the syringe is leveled with the higher level conveyer, the weight is removed from the syringe and placed onto the higher level conveyer.  To lift next coming handle, the syringe must be lowered to the ground level conveyer.  To lower the syringe, the hot water bath is replaced with ice water bath again.  When the syringe is lowered, this cycle is started again.  This process can be summarized as below.

   A-B) A mass was placed on the piston.  Temperature was kept constant, but the volume decreased due to
              increased pressure.
    B-C) The temperature was increased with warm water.  The volume was increased but the pressure was kept constant.
    C-D) The mass was removed.  The temperature was kept constant, but the volume increased due to decreased
             pressure.
    D-A) The temperature was decreased with ice water bath.  The pressure was kept constant, but the volume was
             decreased to the starting level.

    The graph of the volume and the pressure is shown below.

    The work done by the "Incredible Mass Lifter" can be expressed by the meaning of the pressure and the volume as below.

    Therefore, we can measure the mechanical work of this mass lifter by measuring the area surrounded by the four points (ABCD) in the graph of pressure and volume.

     We can also calculate the thermodynamic quantity of work done by the "Incredible Mass Lifter" by measuring the mass of the syringe, the height the syringe is moved.  The equation for calculating the work is shown below.

    The thermodynamic quantity of work was 0.042632Nm.  The mechanical work was 0.028152Nm.  The percentage difference between two values was 34.0%.   There was large difference between the two numbers, because after point D, the piston did not go back to the original point of A.  This could be due to the loss of air from syringe.