The three ways heat moves
Conduction, convection and radiation, and which one engineers actually use.
You'll learn
- Explain the three ways heat moves at engineering level
- Read the numbers that define the behaviour
- Apply the idea to a real vehicle
Overview
Every thermal system in an EV is built from just three physical mechanisms. Understanding which one dominates in each component tells you why the design looks the way it does.
In depth
| Mechanism | How it works | Where it dominates in an EV |
|---|---|---|
| Conduction | Heat moves through direct contact between solids | Cell to cold plate, die to substrate |
| Convection | A moving fluid carries heat away from a surface | Coolant loops, cabin air, refrigerant |
| Radiation | Heat leaves as electromagnetic waves, no medium needed | Minor — mostly cabin heat gain through glass |
Formula
Q = U × A × ΔT
Heat flow equals an overall heat transfer coefficient times area times temperature difference. Every cooling surface in the car is designed around this one relationship.
Example: A cold plate with U = 800 W/m²K, 0.6 m² area and 10 K difference moves 4.8 kW.
Key takeaways
Remember this
- Conduction, convection and radiation are the only mechanisms available.
- Q = U·A·ΔT governs every heat exchanger in the car.
- Area and contact quality are usually cheaper wins than raw flow rate.
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