Will Q = AULMTD will suffice?the overall heat transfer coefficient will inrease the value of Q if the material has k value more than 1?
You need to know a lot of things. Q = Ao Uo LMTD is a good start. But you need to know the rough estimates of the inside and outside film coefficients on the tubes in the exchanger, ho and hi. You also need the fouling factors of each fluid. In addition, you need an area of heat transfer, number of tubes * area of each tube (Ao initially). Look up Seider-tate equation and Donohue equation, these will recalculate ho and hi for you based on #of tubes. From these you calculate a new U and, consequently, get a new A. You'll need to iterate the process until number of tubes converges to get the real value of Q added to cold fluid.
