The sensible heat recovery is calculated by multiplying the specific heat of the flue gas by the temperature difference (inlet minus outlet) and the mass flow rate. The result is divided by 1,000,000 to convert from Btu/hr to MMBtu/hr. This represents the heat recovered by cooling the flue gas without phase change.

\begin{equation}\label{eq:air-water-cooling-flue-sensible-heat-recovery} Q_{sensible} = \frac{C_{p,flue} \cdot (T_{in} - T_{out}) \cdot \dot{m}_{flue}}{10^{6}}\end{equation}

Symbols

\(Q_{sensible}\)	Sensible heat recovery \([\unit{ \mega\btu\per\hour}]\)
\(C_{p,flue}\)	Specific heat of flue gas \([\unit{ \btu\per\pound\degreeFahrenheit}]\)
\(T_{in}\)	Flue gas inlet temperature \([\unit{ \degreeFahrenheit}]\)
\(T_{out}\)	Flue gas outlet temperature \([\unit{ \degreeFahrenheit}]\)
\(\dot{m}_{flue}\)	Flue gas mass flow rate \([\unit{ \pound\per\hour}]\)