program main_ET_PTC_HTF
implicit none
Double Precision :: T_PTC
integer :: iter1, iter2
! ====== Paso 1: Calcular T_PTC con Newton-Raphson 1 variable ======
call calc_T_PTC(T_PTC, iter1)
print *, "-------------------------------------------"
print *, "Temperatura PTC calculada:", T_PTC, "K", T_PTC - 273.15d0, "°C"
print *, "Iteraciones método 1:", iter1
print *, "-------------------------------------------"
! ====== Paso 2: Usar T_PTC en Newton-Raphson 3 variables ======
call solve_HTF_system(T_PTC, iter2)
print *, "-------------------------------------------"
print *, "Iteraciones método 2:", iter2
print *, "-------------------------------------------"
contains
subroutine calc_T_PTC(T_PTC, iter)
implicit none
integer, intent(out) :: iter
Double Precision, intent(out) :: T_PTC
Double Precision :: T_PVi, T_a, T_sky, G_GHI, A_PTC, alpha_PTC, epsilon_PV, epsilon_PTC
Double Precision :: sigma, A_PV, R_conv_PTC, f_T_PTC, df_T_PTC, T_PTCe
Double Precision :: tol
integer :: max_iter
sigma = 5.670374d-8
G_GHI = 1000.0d0
A_PTC = 30.0d0
alpha_PTC = 0.03d0
epsilon_PV = 0.2d0
epsilon_PTC = 0.3d0
A_PV = 1.2d0
T_PVi = 340.5d0
T_a = 298.2d0
T_sky = 298.2d0
R_conv_PTC = 0.04336d0
T_PTC = 320.0d0
tol = 1.0d-6
max_iter = 100
do iter = 1, max_iter
f_T_PTC = G_GHI*A_PTC*alpha_PTC + epsilon_PV*sigma*A_PV*(T_PVi**4 - T_PTC**4) &
- (T_PTC - T_a)/R_conv_PTC - epsilon_PTC*sigma*A_PTC*(T_PTC**4 - T_sky**4)
df_T_PTC = -4.0d0*epsilon_PV*sigma*A_PV*T_PTC**3 - 1.0d0/R_conv_PTC &
- 4.0d0*epsilon_PTC*sigma*A_PTC*T_PTC**3
T_PTCe = T_PTC - f_T_PTC/df_T_PTC
if (abs(T_PTCe - T_PTC) < tol) then
T_PTC = T_PTCe
exit
endif
T_PTC = T_PTCe
end do
end subroutine calc_T_PTC
subroutine solve_HTF_system(T_PTC, iter)
implicit none
integer, intent(out) :: iter
Double Precision, intent(in) :: T_PTC
Double Precision :: T_abs, T_sub, T_out_HTF
Double Precision :: T_a, T_sky, T_PVi, T_in_HTF
Double Precision :: q_dot_sol_PV, P_PV
Double Precision :: G_GHI, A_abs, alpha_abs, epsilon_abs, A_PV, epsilon_PV
Double Precision :: sigma, R_conv_abs, R_cond_abs, R_cond_sub, R_cond_PV, R_conv_PV
Double Precision :: m_dot_HTF, C_p_HTF, h_HTF
Double Precision :: UA, A_hx, NTU, E
Double Precision :: f1, f2, f3
Double Precision :: J(3,3), rhs(3), dx(3)
Double Precision :: tol
integer :: max_iter
sigma = 5.67d-8
G_GHI = 1000.0d0
q_dot_sol_PV = 540.0d0
P_PV = 1722.0d0
A_abs = 0.6d0
alpha_abs = 0.9d0
epsilon_abs= 0.2d0
A_PV = 1.2d0
epsilon_PV = 0.2d0
T_a = 298.2d0
T_sky = 298.2d0
T_PVi = 355.5d0
T_in_HTF = 343.2d0
R_conv_abs = 0.0464d0
R_cond_abs = 0.00002439d0
R_cond_sub = 0.00004623d0
R_cond_PV = 0.00005d0
R_conv_PV = 0.03281d0
m_dot_HTF = 0.15d0
C_p_HTF = 4187.0d0
h_HTF = 1665.0d0
A_hx = 3.1416d0 * 0.03d0 * 10.0d0
UA = 1.0d0 / (1.0d0/h_HTF + R_cond_sub)
NTU = (UA * A_hx) / (m_dot_HTF * C_p_HTF)
E = 1.0d0 - exp(-NTU)
T_abs = 330.0d0
T_sub = 320.0d0
T_out_HTF = 345.0d0
tol = 1.0d-8
max_iter = 100
do iter = 1, max_iter
f1 = (T_PVi - T_a)/(-R_conv_PV) &
- epsilon_PV * sigma * A_PV * (T_PVi**4 - T_PTC**4) &
+ G_GHI*A_abs*alpha_abs &
- (T_abs - T_a)/R_conv_abs &
- epsilon_abs * sigma * A_abs * (T_abs**4 - T_sky**4) &
- (T_abs - T_sub)/(R_cond_abs + R_cond_sub) &
- (T_sub - T_in_HTF) * E * m_dot_HTF * C_p_HTF &
+ q_dot_sol_PV - P_PV
f2 = (T_abs - T_a)/(-R_conv_abs) &
- epsilon_abs * sigma * A_abs * (T_abs**4 - T_sky**4) &
- (T_abs - T_sub)/(R_cond_abs + R_cond_sub) &
+ G_GHI*A_abs*alpha_abs
f3 = (T_out_HTF - T_in_HTF) * m_dot_HTF * C_p_HTF &
- (T_sub - T_in_HTF) * E * m_dot_HTF * C_p_HTF
J(1,1) = -1.0d0/R_conv_abs - 4.0d0*epsilon_abs*sigma*A_abs*T_abs**3 - 1.0d0/(R_cond_abs + R_cond_sub)
J(1,2) = 1.0d0/(R_cond_abs + R_cond_sub) - E * m_dot_HTF * C_p_HTF
J(1,3) = 0.0d0
J(2,1) = -1.0d0/R_conv_abs - 4.0d0*epsilon_abs*sigma*A_abs*T_abs**3 - 1.0d0/(R_cond_abs + R_cond_sub)
J(2,2) = 1.0d0/(R_cond_abs + R_cond_sub)
J(2,3) = 0.0d0
J(3,1) = 0.0d0
J(3,2) = - E * m_dot_HTF * C_p_HTF
J(3,3) = m_dot_HTF * C_p_HTF
rhs(1) = -f1
rhs(2) = -f2
rhs(3) = -f3
call solve3x3(J, rhs, dx)
T_abs = T_abs + dx(1)
T_sub = T_sub + dx(2)
T_out_HTF = T_out_HTF + dx(3)
if (max(abs(dx(1)), max(abs(dx(2)), abs(dx(3)))) < tol) exit
end do
print *, "T_abs (K) =", T_abs, " (°C) =", T_abs - 273.15d0
print *, "T_sub (K) =", T_sub, " (°C) =", T_sub - 273.15d0
print *, "T_out_HTF (K) =", T_out_HTF, " (°C) =", T_out_HTF - 273.15d0
print *, "E =", E
end subroutine solve_HTF_system
subroutine solve3x3(A, b, x)
implicit none
Double Precision, intent(inout) :: A(3,3)
Double Precision, intent(in) :: b(3)
Double Precision, intent(out) :: x(3)
Double Precision :: M(3,3), rhs(3)
integer :: i,j,k
Double Precision :: factor
M = A
rhs = b
do k = 1, 2
if (abs(M(k,k)) < 1.0d-14) stop "Pivote casi cero"
do i = k+1, 3
factor = M(i,k) / M(k,k)
do j = k, 3
M(i,j) = M(i,j) - factor * M(k,j)
end do
rhs(i) = rhs(i) - factor * rhs(k)
end do
end do
x(3) = rhs(3) / M(3,3)
x(2) = (rhs(2) - M(2,3)*x(3)) / M(2,2)
x(1) = (rhs(1) - M(1,2)*x(2) - M(1,3)*x(3)) / M(1,1)
end subroutine solve3x3
end program main_ET_PTC_HTF
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