Page 546 - Design and Operation of Heat Exchangers and their Networks

Appendix 529

Re_tb = G_s_max ∗ d_o / mu_s; % shellside Reynolds number
Hg_lam = 140 ∗ Re_tb ∗ (((s_l / d_o) ^ 0.5 - 0.6) ^ 2 + 0.75) ...
/ (s_t_ / d_o) ^ 1.6 / (4 ∗ (s_l / d_o) ∗ (s_t / d_o) ...
/ pi - 1); % Hagen number for laminar flow
if (N_rc >= 0)
phi_t_n = 0;
else
if (s_l >= s_l_min)
phi_t_n = (1 / N_rc - 0.1) / 2 / (s_t / d_o) ^ 2;
else
phi_t_n = (1 / N_rc - 0.1) ∗ 2 ∗ ((s_d / d_o - 1) ...
/ (s_t / d_o) / (s_t / d_o - 1)) ^ 2;
end
end
Hg_tur_s_0 = phi_t_n ∗ Re_tb ^ 2 + Re_tb ^ 1.75 ∗ (1.25 + 0.6 ...
/ (s_t / d_o - 0.85) ^ 1.08 + 0.2 ∗ (s_l / s_t - 1) ^ 3 ...
-0.005 ∗ (s_t / s_l - 1) ^ 3);
Hg_tur_s = Hg_tur_s_0;
% Hagen number for turbulent flow for staggered tube bundles
if (Re_tb > 2.5E5)
Hg_tur_s = Hg_tur_s ∗ (1 + (Re_tb -2.5E5) / 3.25E5);
end
Hg = Hg_lam;
if (Re_tb > 800)
Hg = Hg + Hg_tur_s ∗ (1 - exp(1 - (Re_tb + 200) / 1000));
end
if (s_l >= s_l_min)
Nu_id = 0.404 ∗ (0.92 ∗ Hg ∗ Pr_s ...
∗ (4 ∗ s_t / pi - d_o) / s_d) ^ (1 / 3);
% Nusselt number for the staggered tube bundles
else
Nu_id = 0.404 ∗ (0.92 ∗ Hg ∗ Pr_s ...
∗ (4 ∗ s_t ∗ s_l / pi - d_o ^ 2) / (s_l ∗ s_d)) ^ (1 / 3);
% Nusselt number for the staggered tube bundles
end
alpha_id = Nu_id ∗ lambda_s / d_o;
% heat transfer coefficient for ideal crossflow

% correction factor for baffle configuration
J_c = 0.55 + 0.72 ∗ F_c;