• The Physics Aviary has a simple Carnot Engine simulator to show the efficiency and output energy of an ideal engine at various temperatures.

https://www.thephysicsaviary.com/Physics/Programs/Labs/CarnotEngineLab/

 

• Andrew Duffy of Boston University has a heat engine simulator that likewise lets you independently vary the operating temperatures and Carnot efficiency.

http://physics.bu.edu/~duffy/HTML5/thermo_heat_engine.html

 

• The University of Virginia has recently updated their Carnot Cycle applet to work on modern browsers. This simple animation shows the phases of isothermal and adiabatic expansion and compression with associated temperature changes (or lack thereof).

http://galileoandeinstein.phys.virginia.edu/more_stuff/Applets/carnot_cycle/carnot_cycle.html