Thermodynamics
Carnot Efficiency
Maximum efficiency of heat engine between two temperatures.
Variables
ηCunitless
Carnot efficiency
Maximum efficiency
Allowed values: 0 to 1
TCK
Cold temperature
Cold reservoir temp
Allowed values: greater than 0
THK
Hot temperature
Hot reservoir temp
Allowed values: greater than 0
Derivation
From Carnot cycle: η = W/Q_H = 1 - Q_C/Q_H = 1 - T_C/T_H.
Your notes
0/5000
Check value
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- TC = 2 K (Cold temperature)
- TH = 3 K (Hot temperature)
Result: ηC = 0.33333333
Other thermodynamics formulas with the same quantities
- Coefficient of Performance (Refrigerator) (Second Law) shares Cold temperature, Hot temperature
- Coefficient of Performance (Heat Pump) (Second Law) shares Hot temperature, Cold temperature
Where this formula is listed
- Thermodynamics formulas, under Second Law, alongside Clausius Inequality.
- In the thermodynamics list it comes after Entropy Change and before Heat Engine Efficiency.
- Thermodynamics formula sheet, one of 34 formulas printed with symbol keys and SI units.
- The full formula index, grouped by category and topic.
Common questions
What is the Carnot Efficiency formula?
Carnot Efficiency is written η_C = 1 − T_C/T_H. Maximum efficiency of heat engine between two temperatures. It belongs to Thermodynamics, under Second Law.
What are the units in η_C = 1 − T_C/T_H?
In SI units, η_C is carnot efficiency (dimensionless); T_C is cold temperature, measured in K; T_H is hot temperature, measured in K.
How is the Carnot Efficiency formula derived?
From Carnot cycle: η = W/Q_H = 1 - Q_C/Q_H = 1 - T_C/T_H. The result is η_C = 1 − T_C/T_H.