# Heat transfer and pressure drop across tube bundles (ht.conv_tube_bank)¶

ht.conv_tube_bank.dP_Kern(m, rho, mu, DShell, LSpacing, pitch, Do, NBaffles, mu_w=None)[source]

Calculates pressure drop for crossflow across a tube bank according to the equivalent-diameter method developed by Kern [R647650], presented in [R648650].

\begin{align}\begin{aligned}\Delta P = \frac{f (m/S_s)^2 D_s(N_B+1)}{2\rho D_e(\mu/\mu_w)^{0.14}}\\S_S = \frac{D_S (P_T-D_o) L_B}{P_T}\\D_e = \frac{4(P_T^2 - \pi D_o^2/4)}{\pi D_o}\end{aligned}\end{align}
Parameters: m : float Mass flow rate, [kg/s] rho : float Fluid density, [kg/m^3] mu : float Fluid viscosity, [Pa*s] DShell : float Diameter of exchanger shell, [m] LSpacing : float Baffle spacing, [m] pitch : float Tube pitch, [m] Do : float Tube outer diameter, [m] NBaffles : float Baffle count, [] mu_w : float Fluid viscosity at wall temperature, [Pa*s] dP : float Pressure drop across bundle, [Pa]

Notes

Adjustment for viscosity left out of this function. Example is from [R648650]. Roughly 10% difference due to reading of graph. Graph scanned from [R647650], and interpolation is used to read it.

References

 [R647650] (1, 2, 3) Kern, Donald Quentin. Process Heat Transfer. McGraw-Hill, 1950.
 [R648650] (1, 2, 3) Peters, Max, Klaus Timmerhaus, and Ronald West. Plant Design and Economics for Chemical Engineers. 5E. New York: McGraw-Hill, 2002.

Examples

>>> dP_Kern(m=11., rho=995., mu=0.000803, mu_w=0.000657, DShell=0.584,
... LSpacing=0.1524, pitch=0.0254, Do=.019, NBaffles=22)
18980.58768759033

ht.conv_tube_bank.dP_Zukauskas(Re, n, ST, SL, D, rho, Vmax)[source]

Calculates pressure drop for crossflow across a tube bank of tube number n at a specified Re. Method presented in [R649652]. Also presented in [R650652].

$\Delta P = N_L \chi \left(\frac{\rho V_{max}^2}{2}\right)f$
Parameters: Re : float Reynolds number, [-] n : float Number of tube rows, [-] ST : float Transverse pitch, used only by some conditions, [m] SL : float Longitudal pitch, used only by some conditions, [m] D : float Tube outer diameter, [m] rho : float Fluid density, [kg/m^3] Vmax : float Maximum velocity, [m/s] dP : float Pressure drop, [Pa]

Notes

Does not account for effects in a heat exchanger. Example 2 is from [R650652]. Matches to 0.3%; figures are very approximate. Interpolation used with 4 graphs to obtain friction factor and a correction factor.

References

 [R649652] (1, 2) Zukauskas, A. Heat transfer from tubes in crossflow. In T.F. Irvine, Jr. and J. P. Hartnett, editors, Advances in Heat Transfer, volume 8, pages 93-160. Academic Press, Inc., New York, 1972.
 [R650652] (1, 2, 3) Bergman, Theodore L., Adrienne S. Lavine, Frank P. Incropera, and David P. DeWitt. Introduction to Heat Transfer. 6E. Hoboken, NJ: Wiley, 2011.

Examples

>>> dP_Zukauskas(Re=13943., n=7, ST=0.0313, SL=0.0343, D=0.0164, rho=1.217, Vmax=12.6)
235.22916169118335
>>> dP_Zukauskas(Re=13943., n=7, ST=0.0313, SL=0.0313, D=0.0164, rho=1.217, Vmax=12.6)
217.0750033117563