tailieunhanh - Heat Transfer Handbook part 84

Heat Transfer Handbook part 84. The Heat Transfer Handbook provides succinct hard data, formulas, and specifications for the critical aspects of heat transfer, offering a reliable, hands-on resource for solving day-to-day issues across a variety of applications. | SHELL-AND-TUBE HEAT EXCHANGER 825 Figure shows a single-pass tube side and a baffled single-pass shell side. A toroidal expansion joint in the center of dee shell accommodates the differential thermal expansion between the tubes and the shell. Figure employs U-tubes within the baffled single-pass shell. In this case account must be taken of the fact that approximately halfofthe tube-side surface is in counterflow and the other halfofthe tube-side surface is in co-current flow with the shell-side fluid. The unit shown in Fig. has a flow pattern that is similar to the unit shown in Fig. . However the construction is more complex to facilitate inspection ofthe inside ofthe tubes the cleaning of the mechanically and the reptacement of eft l vffve tubes While the configuration of Fig. does not provide for differential thermal expansion between the tubes and the shell the floating head allows for thermal expansion between the tubes and the shell and for large temperature differences between the fluids. In Fig. leakage from one fluid stream into the other through the packed joints ofthe floating head goes directly to the exterior ofthe shell where it can be detected readily and without contamination of the other stream. Figure indicates a further variation of the oU exchanger showu in Fig. . Physical Data Tube Side For a tube bundle containing nt tubes of length L with outside and inside diameters of do and di respectively the flow area will be nntd2 Af 4np where np is the number of j . Ttte surfcue areo for toe nt tubes is So ndoLnt The equivalent diameter to be used in establishing the heat transfer coefficient is de di and the length of the tube to be used w pressure toss computations ss LT Lt L 2 m where c is the thickness of the tube sheet Because the tube side is concerned only with the number of tubes and tube passes and not with the tube layout eqs. through .