Page 537 - Design and Operation of Heat Exchangers and their Networks

520 Appendix

for k=1 :1:j
ax = ax ∗ x/k;
if (abs(ax) > CAS_EXP_350)
ax = ax / CAS_EXP_350;
sx = sx / CAS_EXP_350;
ay = ay / CAS_EXP_350;
sy = sy / CAS_EXP_350;
ex = ex + 350;
end
sx = sx + ax;
end
sy = sy + sx;
end
while (ex > 350)
sy = sy ∗ CAS_EXP_350;
ex = ex - 350;
end
while (ex < -350)
sy = sy / CAS_EXP_350;
ex = ex + 350;
end
t_h = exp(ex) ∗ sy;
end
end

% dt_h/dx = t_c - t_h = - dt_c/dy, t_h(0,y) = 1, t_c(x,0) = 0
% t_c = exp(-x-y)∗sum < j = 1,inf >{y∗∗j/j!∗sum < k = 0,j-1 >{x∗∗k/k!}}
% x = NTU1, y = R1∗NTU1
function [t_c] = crossflow_t_c (x, y)
CAS_EXP_350 = 1.0070908870280796E152;
if (x == 0)
t_c = 1 - exp(- y);
elseif (y == 0)
t_c = 0;
else
j = 0;
sx = 1;
sy = 0;