Carnot heat engine
Let heat flow between hot and cold reservoirs and understand the theoretical limit on efficiency.
The Carnot engine gives the highest efficiency that a reversible engine operating between two constant-temperature reservoirs can achieve. Raising the hot-reservoir temperature or lowering the cold-reservoir temperature both increase the efficiency, but at finite temperatures the efficiency can never reach 100%.
Carnot efficiency vs. hot reservoir
The cold-reservoir temperature uses the current setting; the Carnot efficiency is the ideal upper limit.
Think about it
With the hot reservoir unchanged, how does the engine's maximum efficiency change if the cold-reservoir temperature is raised?
The maximum efficiency decreases. Since ηₘₐₓ = 1 − T꜀/Tₕ, the higher the cold-reservoir temperature T꜀, the smaller the fraction of heat that can be converted into work.
Model assumptionsIdeal reversible cycle · Reservoir temperatures constant, in kelvin · No friction or heat loss · Heat input per cycle set by the parameter
Data log
Set the parameters and click “Record data”. Record several rows with different parameters to plot their relationship and fit a straight line; pause and record at different times to study how a reading changes with time.