A plate heat exchanger needs to be connected to a primary hot water system

and the hot water flow rate through the heat exchanger modulated. The hot

water supply line is at $\frac{2\mathrm{.}5}{b}ar(g)$ and the return line at $\frac{1\mathrm{.}0}{b}ar(g).$ The information

provided by the heat exchanger supplier indicates that the design capacity on

the hot water side is $6,400\frac{L}{h}$ at $85$kPa pressure drop. Which of the modulating

control valves in the table below would you recommend? $($The pipelines are very

short so line friction losses can be ignored.$)$