Dq Kern Process Heat | Transfer Pdf
Where (N_B) = number of baffles, (\phi_s = (\mu/\mu_w)^0.14), and (f) is an empirical friction factor: [ f = \exp\left(0.576 - 0.19 \ln Re_s\right) \quad \text(for Re_s = 400\text–1\times10^6\text) ] Kern adopted Dittus-Boelter for turbulent flow: [ \frach_i D_ik = 0.023 Re^0.8 Pr^0.4 \quad \text(heating) \quad \textor \quad Pr^0.3 \text(cooling) ] 2.3 Overall Heat Transfer Coefficient [ \frac1U = \frac1h_o + \frac1h_do + \fracx_wk_w \fracA_oA_m + \frac1h_i \fracA_oA_i + \frac1h_di \fracA_oA_i ]
[ \frach_o D_ek = 0.36 \left( \fracD_e G_s\mu \right)^0.55 \left( \fracc_p \muk \right)^1/3 \left( \frac\mu\mu_w \right)^0.14 ] dq kern process heat transfer pdf
Selected results from Kern’s own example (Problem 6.2): Where (N_B) = number of baffles, (\phi_s = (\mu/\mu_w)^0
With (h_do, h_di) = dirt fouling factors (typical values: 0.001–0.005 hr·ft²·°F/Btu). Design problem: Cool 100,000 lb/hr of kerosene (shell side) from 400°F to 200°F using water in tubes (inlet 90°F, outlet 150°F). Exchanger: 25.25 in ID shell, 1-in OD tubes (14 BWG), 1.25-in triangular pitch, baffle spacing 5 in. Where (N_B) = number of baffles
