Page 544 - Design and Operation of Heat Exchangers and their Networks

Appendix 527

else
s_t_ = s_d;
end
N_t = round(0.156 ∗ (d_otl / d_o) ^ 2.291, 0); % number of tubes
N_t_p = ceil(N_t / N_p); % number of tubes per pass
N_b = floor(L / l_bc) - 1; % number of baffles
N_rc = floor((d_s - 2 ∗ l_c) / s_l); % number of effective tube rows
theta_ds = 2 ∗ acos(1 - 2 ∗ l_c / d_s);
% central angle of baffle cut, rad
theta_ctl = 2 ∗ acos((d_s - 2 ∗ l_c) / d_ctl);
% upper central of baffle cut, rad
F_w = (theta_ctl - sin(theta_ctl)) / (2 ∗ pi);
% fraction of the number of tubes in one window section
F_c =1-2 ∗ F_w;
% fraction of the total number of tubes in the crossflow section
l_bi = (L - (N_b - 1) ∗ l_bc) / 2; % inlet baffle spacing, m
l_bo = l_bi; % outlet baffle spacing, m

delta_st = d_s - d_otl; % shell-to-tube-bundle clearance, m
delta_sb = 0.0031 + 0.004 ∗ d_s; % shell-to-baffle clearance, m
if (max(l_bi, l_bc) > 0.914 && d_o <= 0.0318)
delta_bt = 0.0004; % baffle-hole-to-tube clearance, m
else
delta_bt = 0.0008;
end
delta_tp_ = delta_tp / 2;
% effective width of pass divider lane. 0 for standard calculation;
% d_o for estimation; delta_tp / 2 for rating
A_sc = l_bc ∗ (delta_st + sqrt(2) ∗ d_ctl ∗ (1 - d_o / s));
% shellside crossflow area of main stream, m2
A_sb = (pi - theta_ds / 2) ∗ d_s ∗ delta_sb / 2;
% shell-to-baffle leakage area, m2
A_bt = pi / 4 ∗ ((d_o + delta_bt) ^ 2 - d_o ^ 2) ∗ N_t ∗ (1 - F_w);
% baffle-hole-to-tube leakage area, m2
A_bp = l_bc ∗ (delta_st + N_tp ∗ delta_tp_);
% shell-to-tube-bundle bypass area, m2
r_s = A_sb / (A_sb + A_bt); % tube-to-baffle leakage area ratio
r_lm = (A_sb + A_bt) / A_sc; % baffle-to-shell leakage area ratio
r_b = A_bp / A_sc; % bypass area ratio