District Heating Temperature Capacity

Overview

Engineering reference data for District Heating Temperature Capacity in thermodynamics.

Key Formulas

First Law

$\Delta U = Q - W$

Energy is conserved — heat added minus work done.

Ideal Gas Law

$PV = nRT$

Relates pressure, volume, and temperature of an ideal gas.

Heat Transfer

$Q = mc\Delta T$

Sensible heat transfer.

Carnot Efficiency

$\eta = 1 - T_C/T_H$

Maximum efficiency between two temperatures.

Variables

Symbol	Description	Unit
$U$	Internal energy	J
$Q$	Heat	J
$W$	Work	J
$P$	Pressure	Pa
$V$	Volume	m³
$T$	Temperature	K

Data Table

Formula: Water Flow for District Heating

For a district heating system with a constant heat demand, the required water volume flow is inversely proportional to the temperature difference between the supply and return water.

$\dot{V} = \frac{\dot{Q}}{c_p \cdot \rho \cdot (T_s - T_r)}$

Where:

• $\dot{V}$ is the volume flow rate (e.g., m³/s or L/s).
• $\dot{Q}$ is the required heat transfer rate (power) (e.g., kW).
• $c_p$ is the specific heat capacity of water (≈ 4.18 kJ/kg·°C).
• $\rho$ is the density of water (≈ 1 kg/L for estimation).
• $T_s$ is the supply water temperature.
• $T_r$ is the return water temperature.

Key Property: Inverse Relationship

The core principle shown in the data is that increasing the supply temperature reduces the required water flow for a given heat load. This is because the heat content of each liter of water ($c_p \cdot \rho \cdot (T_s - T_r)$) increases with a higher temperature difference $(T_s - T_r)$. Therefore, fewer liters are needed to transport the same total amount of heat energy $\dot{Q}$.

Note: All data in the table is calculated assuming a constant return temperature of $T_r = 60°C$.

Interactive Charts

References

• Original Source