Boiler - Direct-Method Efficiency

Boiler thermal efficiency by direct method - steam output energy / fuel input energy.

BoilerEfficiencyDirect method

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

\eta_B = \frac{\dot m_{steam} (h_s - h_{FW})}{\dot m_{fuel} \cdot NCV}

Symbol	Meaning	Unit
$h_s, h_{FW}$	Steam, FW enthalpies	kJ/kg
$NCV$	Net calorific value	MJ/kg

Source: IAPWS-IF97 / ASME PTC 4

Boiler thermal efficiency by direct method - steam output energy / fuel input energy.