tailieunhanh - Heat Transfer Handbook part 85

Heat Transfer Handbook part 85. 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 835 where rc Abp Aw Nss Ncc Z where with XL as the longitudinal tube pitch and Nss taken as the number of sealing strip pairs C for Res 100 for Res 100 Here Abp Lbc Ds Do is the crossflow area for the bypass where NP is the number of bypass divider lanes that are parallel to the crossflow stream B wP is the width of the bypass divider hme m and Lbc is the central baffle spacing. JS is the correction factor that accounts for variations in baffle spacing at the inlet and outlet sections as compared to the central baffle spacing Nb - 1 Lf 1 n - LQ 1 n Nb - 1 Li 1-n L 1-n where Nb is the number of balAss add LI Lbi Lbc L Lo Lbo Lbc n 3 5 for turbulent flow 3 for laminar flow Here Lbi is the baffle spacing at the inlet m Lbo is the baffle spacing at the outlet m and Lbc is the central baffle spacing m Jr is the correction factor that accounts for the temperature gradient when the shell-side fluid is in laminar flow 836 HEAT EXCHANGERS Jr for Res 100 for Res 20 For 20 Res 100 a linear interpolation should be performed between the two extreme values. In eq. Res is the shell-side Reynolds number and Nr e is the number of effective tube rows crossed thrcahh one crossflow section. Pressure Loss Data Tube Side The pressure loss inside tubes of ciscul e cmss socioon m a shel--and-tube heat exehanger is the sum of tae li ft m loss wittlin the tabes and tae tarn fosses between the passes of hee exchanger. The ftectin n tass iosife tae taecs is gtenn yy APf 4 L Pa 2 di where u is the linear veloeity of hie fluid n the n b or APf 4fG2 L Pa 2p d where G is the mass veloeity of tae fluid nn tae u . In eqs. f is the frietion fastor. The fluid will undergo an additional pressure loss due to eontraetions and expansions that oeeur during fluid turnaround between tube passes. Kern 1950 and Kern and Kraus 1972 have proposed that this loss be given by one .