A triple tubes parallel flow shell and tube heat exchanger is used to cool the oil in the pump.The oil leaves the pump with $200\backslash$deg c to enter the heat exchanger at the same temperature. In the other side, the cooled water enters the heat exchanger at $20\backslash$deg c and increased by $30\backslash$deg c at the exit side. The mass flowrate of the oil equals the mass flowrate of the water. The inner radius of the tube side is $15$ mm and the thickness is $2$ mm while the length on the single tube is $55$ cm$.$If the overall heat transfer coefficient from oil to water is $537$ W$/$m$?$K$,($CPoil$=1\mathrm{.}75$ KJ$/$Kg$.\backslash$deg C$,$ Pwater $=4195$ J$/$kg$.$k$).$ Note,juse the LMTD technique to solve the problem

$1.$ The heat transfer rate?

$2.$ Minimum flow rate of water in L$/$min$?$

$3.$ The reduction in the length if we used counter flow heat exchanger with the same tube radius and thickness. And keep the same heat transfer rate between two fluids.