How can i calculate convecting heat transfer coefficient for 1 shell p ,4 tube p heat exchanger ?

the type of heat exchanger is shell&tube , 4 tube p and 1shell p , cross flow as steam condenser the vapour p through shell and cold water through tubes ,the number of tubes is 1090 tube and length is 3 meters and cross section area is 18 mellimeter and thickness is 1.5 mm,if cold water entrance is about 27 c and return is 40 c and vapour resulting from ammonium sulphate solution at 74 c and va over it (pressure of vapour is 273 mbar ) and vapour under suction by steam ejector the exit temperature of condensed water is unknown to me because it must be as the temperature of vapour but it may be decrease with 2 or more degrees , but condensate tank record temperature of water is about 64 c but it is under atmospheric pressure