Boiler thermal efficiency by direct method - steam output energy / fuel input energy.
Formula
$$ \eta_B = \frac{\dot m_{steam} (h_s - h_{FW})}{\dot m_{fuel} \cdot NCV} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $h_s, h_{FW}$ | Steam, FW enthalpies | kJ/kg | IAPWS-IF97 |
| $NCV$ | Net calorific value | MJ/kg | ISO 8217 |
Sources
- IAPWS-IF97 / ASME PTC 4.