1. Resistance in Thermal Systems 4.4

2. Thermal Resistance a measure of an object’s ability to oppose heat transfer. Rthermal = -ΔT/Q (Thermal resistance = temperature drop divided by heat flow rate)—Compare to fluid and electrical— Rfluid = -ΔP/V

3. Rthermal = Δx/kA (Thermal resistance = change in thickness of slab divided by constant · Area) ***the ratio of the prime mover to a flow rate

4. Units—°C /cal/s or °C·s/cal—°F/Btu/s or °F·s/Btu Temperature drop across a slab is proportional to the heat flow rate.

5. Thermal Resistance in Series Heat flows through each resistance, one at a time, just like current flows through each resistance in a series circuit. R total = R 1 + R 2