A refrigerator's coefficient of performance compares useful evaporator cooling with compressor work input.
Difficulty
Intermediate
Read time
4 min
Prerequisites
Consistent SI units, algebra, and the physical assumptions listed below
Source
Teng-Jui Lin — Equation SheetsAdapted from Teng-Jui Lin, Equation Sheets — Mechanical Engineering, under CC BY 4.0.
Adapted notation and added original explanations, variables, assumptions, applications, and a worked example. Renumbered the states to the standard compressor 1→2 convention used in FormuLab's concept lesson.
A refrigerator's coefficient of performance compares useful evaporator cooling with compressor work input. A COP greater than one is normal because work moves heat rather than creating all of the cooling energy directly.
| Symbol | Meaning | Units |
|---|---|---|
| Refrigeration coefficient of performance | ||
| Specific enthalpy at evaporator exit / compressor inlet | ||
| Specific enthalpy at compressor exit / condenser inlet | ||
| Specific enthalpy at valve exit / evaporator inlet |
Evaluate a four-state vapor-compression cycle.
Distinguish cooling COP from heat-engine efficiency.
For illustrative refrigerant enthalpies h₁ = 400, h₂ = 440, and h₄ = 250 kJ/kg, find the refrigeration COP.
Adapted from Teng-Jui Lin, Equation Sheets — Mechanical Engineering, under CC BY 4.0.
Adapted notation and added original explanations, variables, assumptions, applications, and a worked example. Renumbered the states to the standard compressor 1→2 convention used in FormuLab's concept lesson.
Assumptions
FormuLab is a study reference. Verify formulas, units, assumptions, and course-specific conventions before relying on them.
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