The feedwater exit temperature is calculated by adding the heat gained (recovered heat) divided by the feedwater heat capacity rate to the inlet temperature. This represents the preheated feedwater temperature leaving the heat exchanger.

\begin{equation}\label{eq:water-heating-flue-feedwater-exit-temp} T_{fw,out} = T_{fw,in} + \frac{Q_{rec}}{\dot{C}_{fw}}\end{equation}

Symbols

\(T_{fw,out}\)	Feedwater exit temperature \([\unit{ \kelvin}]\)
\(T_{fw,in}\)	Feedwater inlet temperature \([\unit{ \kelvin}]\)
\(Q_{rec}\)	Recovered heat \([\unit{ \kilo\joule\per\hour}]\)
\(\dot{C}_{fw}\)	Feedwater heat capacity rate \([\unit{ \kilo\joule\per\hour\kelvin}]\)