Annual compressor-air heat recovery calculator

Recovery only counts while rejected heat and useful heating demand coincide.

Units

Q_{\text{rec}} = \dot{V} \times \rho \times c_{p} \times \Delta T \times 60 \times h \times \mathrm{LF}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

Q_{\text{rec}} = 3600 \times 0.075 \times 0.24 \times 38 \times 60 \times 1700 \times 0.78 = 195{,}908{,}544

Symbol	Meaning	Unit
$Q_{\text{rec}}$	annual recovered air heat	Btu/yr
$\dot{V}$	cooling-air flow	ft³/min
$\rho$	cooling-air density	lb/ft³
$c_{p}$	air specific heat	Btu/(lb·°F)
$\Delta T$	cooling-air temperature rise	°F
$h$	hours with useful heating demand	h/yr
$\mathrm{LF}$	applicable load fraction	fraction

Symbol	Meaning	Unit
$Q_{\text{rec}}$	annual recovered air heat	kWh/year
$\dot{V}$	cooling-air flow	L/s
$\rho$	cooling-air density	kg/m³
$c_{p}$	air specific heat	kJ/(kg·K)
$\Delta T$	cooling-air temperature rise	K
$h$	hours with useful heating demand	h/yr
$\mathrm{LF}$	applicable load fraction	fraction

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.