Refer below heat exchanger inlet and outlet temperature for hot and cold liquid:

a$)$ What is the $U,$ overall heat transfer coefficient for the above heat exchanger after one year operation?

b$)$ From the above calculated U $($after one year operation$),$ what can you understand from this when compare with initial condition?

C$)$ Why the $Q($heat duty$)$ and $U$ different between initial conditon and after one year operation

if cold and hot liquid flowrate maintain the same for both condition?