A counterflow double$-$pipe heat exchanger is designed to cool lubricating oil for a large industrial gas turbine engine. The flow rate of cooling water through the inner tube is $0\mathrm{.}2k\frac{g}{s},$ and the water enters the tubes at $20C,$ while the flow rate of oil through the outlet annulus is $0\mathrm{.}4k\frac{g}{s}.$ The oil and water enter the heat exchanger at temperatures of $60C$ and $30C,$ respectively. The heat transfer coefficients in the annulus and in the inner tube have been estimated as $8$ and $2445\frac{W}{m^2}*K,$ respectively. The outer diameter of the inner tube is $25$ mm $,$ and the inner diameter of the outer tube is $45$ mm $.$ The total length of the double$-$pipe heat exchanger $($total length per hairpin$)$ is $15$ m $,$ and total heat exchanger area is $325m^2.$ In the analysis, the tube wall resistance and the curvature of the wall are neglected. What is the total value of the fouling resistance used in this design?