FLUID TEMPERATURE DISTRIBUTION IN CROSS-F LOW TUBE BUNDLES

A new analytical method is presented for the determination of temperat ure distribution and effectiveness of heat transfer in different cross -flow arrangements. As an improvement over the known analytical soluti ons simplified energy balance equations are used. This simplification consists only in their notation but not in representation of the exact energy balance. The demanded accuracy of the thermal analysis is achi eved by proper selection of a mean value of fluid temperature outside the tube. For each tube i in the bundle a mean value theta(i) of the d imensionless fluid temperature outside the tube is introduced accordin g to theta(i) = omega theta(i+1/2) + (1 - omega) theta(i-1/2) where th eta(i-1/2) and theta(i+1/2) are the local temperatures in front and be hind the i-th tube, respectively. With symbol omega a weight coefficie nt is denoted omega = e(-NTUperpendicular-to/n))-n/NTU(perpendicular-t o) The number of tube rows in the bundle is n and the number of transf er units of the outside stream is NTU(perpendicular-to). Through the i ntroduction of the weight coefficient omega, the mathematical operatio ns related to calculation of the temperature field are radically simpl ified. This enabled the development of the procedure, valid for three codirected cross-flow arrangements (Fig. 1) and any number n of the ro ws.