Heat Pumps & Fridges

Moving heat uphill

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Heat pumps use work to move heat from cold to hot; COP $= Q_h/W$.
• Carnot limits: heating $\frac{T_h}{T_h - T_c}$, cooling $\frac{T_c}{T_h - T_c}$.
• Small temperature lifts give high COPs.

Steps

1. Engines in reverse
2. More heat than electricity
3. How cold can it get?
4. Opening the fridge
5. A year of heating
6. Carnot’s fridge