Summarizing Applications of Thermodynamics

Summary

• An artifact of the second law of thermodynamics is the ability to heat an interior space using a heat pump. Heat pumps compress cold ambient air and, in so doing, heat it to room temperature without violation of conservation principles.
• To calculate the heat pump’s coefficient of performance, use the equation \({\text{COP}}_{\text{hp}}=\cfrac{{Q}_{\text{h}}}{W}\).
• A refrigerator is a heat pump; it takes warm ambient air and expands it to chill it.

Glossary

heat pump

a machine that generates heat transfer from cold to hot

coefficient of performance

for a heat pump, it is the ratio of heat transfer at the output (the hot reservoir) to the work supplied; for a refrigerator or air conditioner, it is the ratio of heat transfer from the cold reservoir to the work supplied