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Formulas & Density at different temperatures
Power formula
P = ρ × V × cₚ × ΔT
Flow rate formula
V = P / (ρ × cₚ × ΔT)
Where
- P = power [kW]
- ρ = density [kg/m³]
- V = volume flow rate [m³/s]
- cₚ = specific heat capacity [kJ/(kg·K)]
- ΔT = temperature difference [K]
Constants
- Water: cₚ = 4,19 kJ/(kg·K)
- Air: cₚ = 1,005 kJ/(kg·K)
Water - ρ(T)
| T [°C] | ρ [kg/m³] |
|---|---|
| 10 | 999,7 |
| 20 | 998,2 |
| 40 | 992,2 |
| 60 | 983,2 |
| 80 | 971,8 |
Air - ρ(T)
| T [°C] | ρ [kg/m³] |
|---|---|
| -20 | 1,395 |
| 0 | 1,293 |
| 20 | 1,204 |
| 30 | 1,165 |
| 40 | 1,127 |
Tip: Enter temperatures (supply/return for water, inlet/heated air for air), from which ΔT and average temperature are calculated. Density is determined automatically based on the average temperature.