W6.2 Energy Distribution

Key points

• District heating pipe: heat leaks through insulation + soil (series, [K/W]) → Thermal resistance
• The leak cools the flowing fluid → Advection gives the temperature drop
• Flow needed to deliver a heat demand: $\dot V = \frac{\dot Q}{\rho C_p (T_{supply} - T_{return})}$

Chain

$R_{ins} + R_{soil}$ → $\dot Q_{loss} = \Delta T / R$ → $\Delta T_{fluid} = \dot Q_{loss} / (\dot V \rho C_p)$ → $T_{out}$

Concepts

• Thermal resistance
• Advection