Page 545 - Design and Operation of Heat Exchangers and their Networks

528 Appendix

r_ss = N_ss / N_rc;
% ratio for correction of the effects of bundle and pass partition
% bypasses
N_tw = F_w ∗ N_t; % number of tubes in one window section
N_rw = floor(0.8 ∗ (l_c - (d_s - d_ctl) / 2) / s_l);
% number of effective tube rows in the windows section
A_sw = d_s ^ 2/8 ∗ (theta_ds - sin(theta_ds)) ...
- N_tw ∗ pi / 4 ∗ d_o ^ 2;
% shellside flow area in the window section, m2
% dh_w = 4 ∗ A_sw / (N_tw ∗ pi ∗ d_o + d_s ∗theta_ds / 2);
% shellside hydraulic diameter in window section

t_t_out = t_t_in;
t_s_out = t_s_out_max;
for iter = 1 : 100

% calculation of tubeside heat transfer coefficient
t_t_m = (t_t_in + t_t_out) / 2;
% seawater mean temperature (tubeside), °C
% t_t_w = t_t_m; % wall temperature at tube (seawater) side, °C
[rho_t, cp_t, lambda_t, mu_t] = ...
seawater_properties(t_t_m, S_seawater);
Pr_t = mu_t ∗ cp_t / lambda_t;
Re_t = 4 ∗ m_t / (N_t_p ∗ pi ∗ d_i ∗ mu_t);
% tubeside Reynolds number
Nu_t = 0.023 ∗ Re_t ^ 0.8 ∗ Pr_t ^ 0.4; % tubeside Nusselt number
alpha_t = Nu_t ∗ lambda_t / d_i;
% tubeside heat transfer coefficient, W/m2K

% calculation of shellside heat transfer coefficient
t_s_m = (t_s_in + t_s_out) / 2;
% oil mean temperature (tubeside), °C
% t_s_w = t_s_m; % wall temperature at shell (oil) side, °C
[rho_s, cp_s, lambda_s, mu_s] = oil_properties(t_s_m);
Pr_s = mu_s ∗ cp_s / lambda_s;
if (s_l >= s_l_min)
G_s_max = m_s / (d_s ∗ l_bc) ∗ s_t / (s_t - d_o);
else
G_s_max = m_s / (d_s ∗ l_bc) ∗ s_t / 2 / (s_d - d_o);
end