Page 493 - Design and Operation of Heat Exchangers and their Networks

476 Appendix

mn = 66; % flow arrangement type. > 0: AB_m,n; < 0: BA_m,n
% mn =-3: example CBA
if (mn > 0 && NTUh(1) = NTUh(2))
fprintf('The available analytical equations for two-pass ');
fprintf('parallel-crossflow heat exchangers are valid \n');
fprintf('only for NTUh(1) = NTUh(2).\n');
end

aA = NTUh(1);
bA = Rh(1) ∗ NTUh(1);
aB = NTUh(2);
bB = Rh(2) ∗ NTUh(2);
phi = NTUh(2) / NTUh(1);

np = 2; % number of passes, sequence according to fluid 1
nx = 500; % number of grids in x (hot fluid flow or fluid 1) direction
ny = 500; % number of grids in y (cold fluid flow or fluid 2) direction
e = 1; % relaxation factor
eps = 1E-7; % iteration accuracy

NTUc = Rh .∗ NTUh;

nx1 = nx + 1;
ny1 = ny + 1;
t1 = zeros(np, nx1, ny1);
t2 = zeros(np, nx1, ny1);
th = zeros(nx1, ny1);
tc = zeros(nx1, ny1);
dt = zeros(nx1, ny1);
A = zeros(ny1, ny1);
T = zeros(ny1, 1);
D = zeros(ny1, 1);

if (mn > 0)
fprintf("\nAB%d\n", mn);
else
fprintf("\nBA%d\n", - mn);
end
switch mn
case -3
t1 = zeros(3, nx1, ny1);