Sensible Heat (Condensate Energy Value)

Estimates the sensible heat energy recovered by returning hot condensate to the feedwater system instead of heating cold makeup from ambient. Also used to value heat lost in blowdown.

$$Q=m\times C_p\times \Delta T$$

Variables

Symbol	Meaning	Unit
Q	Heat energy per unit time	BTU/hr
m	Mass flow rate	lb/hr
$C_p$	Specific heat of water (approximately 1.0)	BTU/lb·°F
$\Delta T$	Temperature difference (condensate or blowdown temperature minus cold makeup temperature)	°F

Worked example

Returning 5,000 lb/hr of condensate at 180°F against 55°F makeup: 5,000 × 1.0 × (180 − 55) = 625,000 BTU/hr. Over 8,760 hr/yr that is 5,475,000,000 BTU/yr (5,475 MMBTU/yr).

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Part of The Blueprint of Water