Method
Air sensible-heat duty divided by supplied heater efficiency.
Equations
ΔT = t2 − t1
ṁ = ρ · V̇
Q = ṁ · cp · ΔT
P = Qη
Symbols and units
| Symbol | Quantity | Unit |
|---|---|---|
| Inputs | ||
| V̇ | Airflow | m³/s |
| ρ | Air density | kg/m³ |
| cp | Air specific heat | kJ/kg·K |
| t1 | Inlet temperature | °C |
| t2 | Outlet temperature | °C |
| η | Heater efficiency | 0–1 |
| Results | ||
| ΔT | Temperature rise | K |
| ṁ | Air mass flow | kg/s |
| Q | Air heat duty | kW |
| P | Electrical input | kW |
Assumptions and limits
- Density, specific heat and efficiency are explicit inputs.
Worked example
The input values are the calculator's own verification test, run through the calculator. They show the working; they are not design values.
Inputs
| V̇ | Airflow | 1 m³/s |
| ρ | Air density | 1.2 kg/m³ |
| cp | Air specific heat | 1.005 kJ/kg·K |
| t1 | Inlet temperature | 20 °C |
| t2 | Outlet temperature | 30 °C |
| η | Heater efficiency | 1 0–1 |
Results
| ΔT | Temperature rise | 10 K |
| ṁ | Air mass flow | 1.2 kg/s |
| Q | Air heat duty | 12.06 kW |
| P | Electrical input | 12.06 kW |
A preliminary check for engineer review, not an engineering approval. The project calculation to the applicable codes, authority requirements and specification governs.