Carnot Cycle: Interactive Simulations
The first simulation will run on your browser. The second simulation was prepared using Mathematica. Download the free Wolfram player, and then download the simulation CDF file (link given below or click on figure to download). Try to predict the behavior when a parameter changes before using a slider to change that parameter. Screencast below explain how to use the simulations.
Simulation: Carnot Cycle on Ideal Gas
Try to answer these questions before determining the answer with the simulation. We suggest that you write down the reasons for your answers.
- How does the pressure versus volume plot change when the cold reservoir temperature increases? When the hot reservoir temperature increases?
- How does the efficiency change when the cold reservoir temperature increases?
This Demonstration shows Carnot cycles operating both as a heat engine and as a heat pump, with finite temperature differences between the hot and cold reservoirs and the high and low temperatures parts of the Carnot cycle, respectively. The entropy changes for the reservoirs, ΔSh and ΔSc, are calculated, as is the overall entropy change ΔStotal. When the temperature differences between the reservoir and the engine/pump are nonzero, the total entropy change is positive. The entropy change of the engine/pump, which is at steady state, is zero. All energies and entropy changes are expressed per unit time, since these are continuous processes, but the time scale is arbitrary. The cycle efficiency η is calculated for the heat engine, and the coefficient of performance (COP) is calculated for the heat pump. As the temperature difference between the reservoirs and the engine/pump increases, the efficiency or the coefficient of performance decreases. For the Carnot heat engine, the value of QH is held constant as the temperature differences change. For the heat pump, the value of QC is held constant as the temperature differences change. For the heat engine, the reservoir temperatures are held constant at 275 K and 500 K. For the heat pump, the reservoir temperatures are held constant at 275 K and 325 K.
Try to answer these questions before determining the answer with the simulation. We suggest that you write down the reasons for your answers.
- Does the efficiency of a Carnot heat pump increase or decrease as the temperature difference between the hot reservoir and hot temperature of the cycle increases?
- Does the coefficient of performance of a Carnot heat pump increase or decrease when the low temperature of the cycle increases and all other values are held constant?