Calculate the length of the pipe bundle in a countercurrent bundle exchanger in which $0\mathrm{.}004m^3.s^{-1}$ of methanol is cooled from $65C$ to $25C($the volume is measured at $25C).$ The cooling water enters at $19C$ and flows through the intertube space at $0\mathrm{.}6m.s^{-1}.$ The bundle consists of $25$ steel tubes with an outer diameter of $20mm$ and an inner diameter of $16mm,$ enclosed in a casing consisting of a tube with an inner diameter of $200mm.$

Result:

The required length of the bundle is $12,4m.$ The exchanger would need to be divided into two or three sections connected in series.