def heat_exchanger_sizing2(Thi, Tho, Tci, Tco, Q, dint, N_tubes, U):
R = (Thi - Tho) / (Tco - Tci)
P = (Tco - Tci) / (Thi - Tci)
Xp = 0.9
W = (R + 1 + (((R**2) + 1)**0.5) -
(2 * R * Xp)) / (R + 1 + (((R**2) + 1)**0.5) - (2 * Xp))
num_shell = (math.log((1 - (R * P)) / (1 - P))) / (math.log(W))
num_shell2 = math.ceil(num_shell)
N = num_shell2
Ft = ht.F_LMTD_Fakheri(Tci=Tci, Tco=Tco, Thi=Thi, Tho=Tho, shells=N)
LMTempDiff = ht.LMTD(Thi=Thi, Tho=Tho, Tci=Tci, Tco=Tco)
UA = Q / (Ft * LMTempDiff)
A = UA / U
tubes_length = A / (N_tubes * 3.14 * dint)
return {
'UA': UA,
'U': U,
'A': A,
'Ft': Ft,
'LMTD': LMTempDiff,
'Shell number': N,
'Number of tubes': N_tubes,
'tubes_length': tubes_length
}
def _design(self):
# This functions also finds the cost
A_range, C_func, U, _ = self._evap_data
components = self.components
evaporators = components['evaporators']
Design = self._Design
Cost = self._Cost
CE = bst.CE
evap0 = evaporators[0]
hu = evap0._heat_utilities[0]
duty = evap0._H_out - evap0._H_in
hu(duty, evap0.ins[0].T, evap0.outs[0].T)
Q = abs(duty)
Tci = evap0.ins[0].T
Tco = evap0.outs[0].T
Th = evap0._heat_utilities[0]._fresh.T
LMTD = ht.LMTD(Th, Th, Tci, Tco)
ft = 1
A = HXutility._calc_area(LMTD, U, Q, ft)
self._evap_costs = evap_costs = [C_func(A, CE)]
# Find condenser requirements
condenser = components['condenser']
condenser._design()
condenser._cost()
Cost['Condenser'] = condenser._Cost['Heat exchanger']
# Find area and cost of evaporators
As = [A]
for evap in evaporators[1:]:
Q = evap._Q
Tc = evap.outs[0].T
Th = evap.outs[2].T
LMTD = Th - Tc
A = HXutility._calc_area(LMTD, U, Q, ft)
As.append(A)
if not A_range[0] < A < A_range[1]:
warn('area requirement ({A}) is out of range, {A_range}')
evap_costs.append(C_func(A, CE))
self._As = As
Design['Area'] = A = sum(As)
Design['Volume'] = vol = self._N_evap * self.tau * self.ins[0].volnet
Cost['Evaporators'] = sum(evap_costs)
# Calculate power
power, cost = vacuum_system(
massflow=0,
volflow=0,
P_suction=evap.outs[0].P,
vol=vol,
vacuum_system_preference='Liquid-ring pump')
Cost['Vacuum liquid-ring pump'] = cost
self._power_utility(power)
def heat_exchanger_sizing(Thi, Tho, Tci, Tco, Q, dext, dint, hsf, htf, REs,
Prs, ks, REt, Prt, kt, k, tubes_length):
R = (Thi - Tho) / (Tco - Tci)
P = (Tco - Tci) / (Thi - Tci)
Xp = 0.9
W = (R + 1 + (((R**2) + 1)**0.5) -
(2 * R * Xp)) / (R + 1 + (((R**2) + 1)**0.5) - (2 * Xp))
num_shell = (math.log((1 - (R * P)) / (1 - P))) / (math.log(W))
num_shell2 = math.ceil(num_shell)
N = num_shell2
Ft = ht.F_LMTD_Fakheri(Tci, Tco, Thi, Tho, shells=N)
LMTempDiff = ht.LMTD(Thi=Thi, Tho=Tho, Tci=Tci, Tco=Tco)
UA = Q / (Ft * LMTempDiff)
shell_Nu = ht.conv_external.Nu_cylinder_Sanitjai_Goldstein(Re=REs, Pr=Prs)
hshell = (shell_Nu * ks) / dext
friction_factor_darcy = (1.82 * math.log10(REt) - 1.64)**(-2)
tube_nu = ht.conv_internal.turbulent_Gnielinski(Re=REt,
Pr=Prt,
fd=friction_factor_darcy)
htube = (tube_nu * kt) / dint
invU = (1 / hshell) + (1 / hsf) + (dext /
(2 * k)) * (math.log(dext / dint)) + (
(dext / dint) / htf) + (
(dext / dint) / htube)
U = 1 / invU
A = UA / U
number_of_tubes = A / (tubes_length * 3.14 * dint)
return {
'UA': UA,
'U': U,
'A': A,
'Ft': Ft,
'LMTD': LMTempDiff,
'Shell number': N,
'Number of tubes': number_of_tubes,
'tubes_length': tubes_length
}
def test_LMTD_vect():
dTlms = [ht.LMTD(T, 60., 30., 40.2) for T in [100, 101]]
dTlms_vect = ht.vectorized.LMTD([100, 101], 60., 30., 40.2)
assert_allclose(dTlms, dTlms_vect)