Thermodynamics — Energy & Cycles

Heat conduction — the rate heat leaks

continues from lesson 5 — values defined earlier in the course stay live here

ELI5: heat flows through a wall at a rate Q/t = k·A·ΔT / L — faster through a thin, conductive, large, hot-on-one-side wall. The conductivity k is why a steel pan handle burns you but a wooden one doesn't.

k_{insul} := 0.04 W/(m*K)

= 0.04 W / (m K) fibreglass insulation

A_{wall} := 10 m^2

= 10 m^2 wall area

dT_{wall} := 20 K

= 20 K inside-to-outside difference

L_{wall} := 0.1 m

= 0.1 m wall thickness

Q_{rate} = \frac{k_{insul} \cdot A_{wall} \cdot dT_{wall}}{L_{wall}}

= 80 W heat loss rate = 80 W

✓ pass

abs(Q_{rate} - 80 W) < 1e-6 W

a steady trickle — double the insulation, halve the loss

Where next: Fluid Mechanics sets all this in motion — pressure, flow, and the pumps that drive them.