def _TwoPhase_Forward(self,w_2phase=1.0,xout_2phase=1.0):
# Update outlet quality field [-]
self.xout_2phase=xout_2phase
# Heat transfer rate based on inlet quality [W]
self.Q_2phase=self.mdot_r*(self.xout_2phase-self.xin_r)*self.h_fg
# Heat flux in 2phase section (for Shah correlation) [W/m^2]
q_flux=self.Q_2phase/(w_2phase*self.A_r_wetted)
#
h_r_2phase=ShahEvaporation_Average(self.xin_r,1.0,self.AS_r,
self.G_r,self.Dh_r,self.pin_r,q_flux,self.Tbubble_r,self.Tdew_r)
self.h_r_2phase = h_r_2phase * self.h_tp_tuning
UA_2phase=w_2phase/(1/(self.h_g*self.A_g_wetted)+1/(self.h_r_2phase*self.A_r_wetted)+self.Rw)
C_g=self.cp_g*self.mdot_g
Ntu_2phase=UA_2phase/(C_g)
#for Cr=0 and counter flow in two-phase:
epsilon_2phase=1-exp(-Ntu_2phase)
Q_2phase_eNTU=epsilon_2phase*C_g*(self.T_g_x-self.Tsat_r)
rho_average=TwoPhaseDensity(self.AS_r,self.xin_r,xout_2phase,self.Tdew_r,self.Tbubble_r,slipModel='Zivi')
self.Charge_r_2phase = rho_average * w_2phase * self.V_r
# Frictional prssure drop component
DP_frict=LMPressureGradientAvg(self.xin_r,xout_2phase,self.AS_r,self.G_r,self.Dh_r,self.Tbubble_r,self.Tdew_r)*w_2phase*self.L
# Accelerational prssure drop component
DP_accel=AccelPressureDrop(self.xin_r,xout_2phase,self.AS_r,self.G_r,self.Tbubble_r,self.Tdew_r)*w_2phase*self.L
self.DP_r_2phase=DP_frict+DP_accel
if self.Verbosity>4:
print (Q_2phase_eNTU-self.Q_2phase)
return Q_2phase_eNTU-self.Q_2phase
def _TwoPhase_Forward(self,xout_r_2phase=0.0):
# **********************************************************************
# TWO-PHASE PART
# **********************************************************************
"""
xout_r_2phase: quality of refrigerant at end of two-phase portion
default value is 0.0 (full two phase region)
"""
## Bubble and dew temperatures (same for fluids without glide)
Tbubble=self.Tbubble
Tdew=self.Tdew
## Mean temperature for use in HT relationships
Tsat_r=(Tbubble+Tdew)/2
h_l = self.h_l #[J/kg]
h_v = self.h_v #[J/kg]
h_fg = h_v - h_l #[J/kg]
# This block calculates the average frictional pressure drop griendient
# and average refrigerant heat transfer coefficient by
# integrating the local heat transfer coefficient between
# a quality of 1.0 and the outlet quality
DPDZ_frict_2phase, h_r_2phase =KM_Cond_Average(xout_r_2phase,1.0,self.AS,self.G_r,self.Dh,Tbubble,Tdew,self.psat_r,self.beta)
self.h_r_2phase=h_r_2phase*self.h_tp_tuning
UA_overall = 1 / (1 / (self.Fins.eta_a * self.Fins.h_a * self.Fins.A_a * self.h_a_tuning) + 1 / (self.h_r_2phase * self.A_r_wetted) + self.Rw);
self.epsilon_2phase=1-exp(-UA_overall/(self.mdot_da*self.Fins.cp_da));
self.w_2phase=-self.mdot_r*h_fg*(1.0-xout_r_2phase)/(self.mdot_da*self.Fins.cp_da*(self.Tin_a-Tsat_r)*self.epsilon_2phase);
#Positive Q is heat input to the refrigerant, negative Q is heat output from refrigerant.
#Heat is removed here from the refrigerant since it is condensing
self.Q_2phase = self.epsilon_2phase * self.Fins.cp_da* self.mdot_da * self.w_2phase * (self.Tin_a-Tsat_r);
self.xout_2phase=xout_r_2phase
# Frictional pressure drop component
DP_frict=DPDZ_frict_2phase*self.Lcircuit*self.w_2phase
#Accelerational pressure drop component
DP_accel=-AccelPressureDrop(self.xout_2phase,1.0,self.AS,self.G_r,Tbubble,Tdew,slipModel='Zivi')*self.Lcircuit*self.w_2phase
# Total pressure drop is the sum of accelerational and frictional components (neglecting gravitational effects)
self.DP_r_2phase=DP_frict+DP_accel
rho_average=TwoPhaseDensity(self.AS,self.xout_2phase,1.0,self.Tdew,self.Tbubble,slipModel='Zivi')
self.Charge_2phase = rho_average * self.w_2phase * self.V_r
if self.Verbosity>7:
print ('2phase cond resid', self.w_2phase-(1-self.w_superheat))
print ('h_r_2phase',self.h_r_2phase)
#Calculate an effective pseudo-subcooling based on the equality
cp_satL=self.cp_satL
self.DT_sc_2phase=-self.xout_2phase*h_fg/(cp_satL)
#If the quality is being solved for, the length of the two-phase and subcooled
# sections should add to the length of the HX. Return the residual
return self.w_2phase-(1-self.w_superheat)
#generate data
x=np.linspace(0,1,1000)
dp_acc_zivi=np.zeros_like(x) #accelerational pressure drop, Zivi slip flow model
dp_acc_hom=np.zeros_like(x) #accelerational pressure drop, homogeneous equilibrium model
dp_lm=np.zeros_like(x) #frictional pressure drop (Lockhardt-Martinelli)
dp_km=np.zeros_like(x) #frictional condensation pressure drop (Kim-Mudawar)
for i in range(len(x)):
#determine inlet/outlet quality
x_in = x[i]
x_out = x_in+DELTA_x
if x_out>1.0: #last point in graph needs to be moved to the left
x_in=1.0-DELTA_x
x_out=1.0
#accelerational pressure drop using ACHP
dp_acc_zivi[i]=-AccelPressureDrop(x_in,x_out,Ref,G_r,Tbubble_r,Tdew_r,None,None,'Zivi')*L
#accelerational pressure drop using homogeneous equilibrium model:
dp_acc_hom[i]=-AccelPressureDrop(x_in,x_out,Ref,G_r,Tbubble_r,Tdew_r,None,None,'Homogeneous')*L
#frictional pressure drop using Lockhart-Martinelli
C=None
satTransport=None
dp_lm[i]=LockhartMartinelli(Ref, G_r, D, x[i], Tbubble_r,Tdew_r,C,satTransport)[0]*L
beta = 1 #channel aspect ratio (=width/height)
dp_km[i]=Kim_Mudawar_condensing_DPDZ_h(Ref, G_r, D, x[i], Tbubble_r,Tdew_r,psat_r,beta,satTransport)[0]*L
#havg=np.trapz(h,x=x)
def plot(KM=None,LM=None,Zivi=None,Hom=None,scl='log',txtx=0.1,txty=5,pos='best'):
pylab.figure(figsize=(7,5))
pylab.text(txtx,txty,'%s\nG=%0.1f kg/m$^2$\nD=%0.3f, L=%0.3f m\nq\"=%0.1f W/m$^2$\np=%0.1f Pa' %(Ref,G_r,D,L,Q,psat_r))
if LM: pylab.plot(x,dp_lm,label="Frictional: Lockhart-Martinelli")
if Zivi: pylab.plot(x,dp_acc_zivi,label="Accelerational: Zivi")
def _TwoPhase_Forward(self, w_2phase):
DWS = DWSVals() #DryWetSegment structure
# Store temporary values to be passed to DryWetSegment
DWS.Fins = self.Fins
DWS.FinsType = self.FinsType
DWS.A_a = self.Fins.A_a * w_2phase
DWS.cp_da = self.Fins.cp_da
DWS.eta_a = self.Fins.eta_a
DWS.h_a = self.Fins.h_a * self.h_a_tuning #Heat transfer coefficient, not enthalpy
DWS.mdot_da = self.mdot_da * w_2phase
DWS.pin_a = self.Fins.Air.p
DWS.Tdew_r = self.Tdew_r
DWS.Tbubble_r = self.Tbubble_r
DWS.Tin_a = self.Tin_a
DWS.RHin_a = self.Fins.Air.RH
DWS.Tin_r = self.Tsat_r
DWS.A_r = self.A_r_wetted * w_2phase
DWS.Rw = self.Rw / w_2phase
DWS.cp_r = 1.0e15 #In the two-phase region the cp is infinite, use 1e15 as a big number;
DWS.pin_r = self.psat_r
DWS.mdot_r = self.mdot_r
DWS.IsTwoPhase = True
#Target heat transfer to go from inlet quality to saturated vapor
Q_target = self.mdot_r * (self.xout_2phase - self.xin_r) * self.h_fg
if Q_target < 0:
raise ValueError('Q_target in Evaporator must be positive')
# Average Refrigerant heat transfer coefficient
try:
if self.AS.name() in 'CarbonDioxide':
h_r = KandlikarEvaporation_average(self.xin_r,
self.xout_2phase, self.AS,
self.G_r, self.ID,
self.psat_r,
Q_target / DWS.A_r,
self.Tbubble_r, self.Tdew_r)
else:
h_r = ShahEvaporation_Average(self.xin_r, self.xout_2phase,
self.AS, self.G_r, self.ID,
self.psat_r, Q_target / DWS.A_r,
self.Tbubble_r, self.Tdew_r)
except:
h_r = ShahEvaporation_Average(self.xin_r, self.xout_2phase,
self.AS, self.G_r, self.ID,
self.psat_r, Q_target / DWS.A_r,
self.Tbubble_r, self.Tdew_r)
DWS.h_r = h_r * self.h_tp_tuning #correct refrigerant side convection heat transfer
#Run the DryWetSegment to carry out the heat and mass transfer analysis
DryWetSegment(DWS)
self.Q_2phase = DWS.Q
self.Q_sensible_2phase = DWS.Q_sensible
self.h_r_2phase = DWS.h_r
self.fdry_2phase = DWS.f_dry
self.Tout_a_2phase = DWS.Tout_a
rho_average = TwoPhaseDensity(self.AS,
self.xin_r,
self.xout_2phase,
self.Tdew_r,
self.Tbubble_r,
slipModel='Zivi')
self.Charge_2phase = rho_average * w_2phase * self.V_r
#Frictional pressure drop component
DP_frict = LMPressureGradientAvg(
self.xin_r, self.xout_2phase, self.AS, self.G_r, self.ID,
self.Tbubble_r, self.Tdew_r) * self.Lcircuit * w_2phase
#Accelerational pressure drop component
try:
if self.AS.name() in 'CarbonDioxide':
DP_accel = AccelPressureDrop(
self.xin_r,
self.xout_2phase,
self.AS,
self.G_r,
self.Tbubble_r,
self.Tdew_r,
D=self.ID,
slipModel='Premoli') * self.Lcircuit * w_2phase
else:
DP_accel = AccelPressureDrop(
self.xin_r,
self.xout_2phase,
self.AS,
self.G_r,
self.Tbubble_r,
self.Tdew_r,
slipModel='Zivi') * self.Lcircuit * w_2phase
except:
DP_accel = AccelPressureDrop(
self.xin_r,
self.xout_2phase,
self.AS,
self.G_r,
self.Tbubble_r,
self.Tdew_r,
slipModel='Zivi') * self.Lcircuit * w_2phase
self.DP_r_2phase = DP_frict + DP_accel
if self.Verbosity > 7:
print(w_2phase, DWS.Q, Q_target, self.xin_r,
"w_2phase,DWS.Q,Q_target,self.xin_r")
return DWS.Q - Q_target
def _TwoPhase_Forward(self,w_2phase):
DWS=DWSVals() #DryWetSegment structure
# Store temporary values to be passed to DryWetSegment
DWS.Fins=self.Fins
DWS.FinsType = self.FinsType
DWS.A_a=self.Fins.A_a*w_2phase
DWS.cp_da=self.Fins.cp_da
DWS.eta_a=self.Fins.eta_a
DWS.h_a=self.Fins.h_a*self.h_a_tuning #Heat transfer coefficient, not enthalpy
DWS.mdot_da=self.mdot_da*w_2phase
DWS.pin_a=self.Fins.Air.p
DWS.Tdew_r=self.Tdew_r
DWS.Tbubble_r=self.Tbubble_r
DWS.Tin_a=self.Tin_a
DWS.RHin_a=self.Fins.Air.RH
DWS.Tin_r=self.Tsat_r
DWS.A_r=self.A_r_wetted*w_2phase
DWS.Rw=self.Rw/w_2phase
DWS.cp_r=1.0e15 #In the two-phase region the cp is infinite, use 1e15 as a big number;
DWS.pin_r=self.psat_r
DWS.mdot_r=self.mdot_r
DWS.IsTwoPhase=True
#Target heat transfer to go from inlet quality to saturated vapor
Q_target=self.mdot_r*(self.xout_2phase-self.xin_r)*self.h_fg
if Q_target<0:
raise ValueError('Q_target in Evaporator must be positive')
# Average Refrigerant heat transfer coefficient
#Shah correlation
#h_r=ShahEvaporation_Average(self.xin_r,self.xout_2phase,self.AS,self.G_r,self.Dh,self.psat_r,Q_target/DWS.A_r,self.Tbubble_r,self.Tdew_r)
#Bertsch correlation
#h_r=Bertsch_MC_Average(self.xin_r,self.xout_2phase,self.AS,self.G_r,self.Dh,Q_target/DWS.A_r,self.Lcircuit,self.Tbubble_r,self.Tdew_r)
#Kandlikar correlation
#h_r=KandlikarEvaporation_average(self.xin_r,self.xout_2phase,self.AS,self.G_r,self.Dh,self.psat_r,Q_target/DWS.A_r,self.Tbubble_r,self.Tdew_r)
#Kim and Mudawar (2013)
DPDZ_frict_2phase, h_r = KM_Evap_Average(self.xin_r,self.xout_2phase,self.AS,self.G_r,self.Dh,self.Tbubble_r,self.Tdew_r,self.psat_r,self.beta,Q_target/DWS.A_r,self.PH_PF)
DWS.h_r=h_r*self.h_tp_tuning #correct refrigerant side convection heat transfer
#Run the DryWetSegment to carry out the heat and mass transfer analysis
DryWetSegment(DWS)
self.Q_2phase=DWS.Q
self.Q_sensible_2phase=DWS.Q_sensible
self.h_r_2phase=DWS.h_r
self.fdry_2phase=DWS.f_dry
self.Tout_a_2phase=DWS.Tout_a
rho_average=TwoPhaseDensity(self.AS,self.xin_r,self.xout_2phase,self.Tdew_r,self.Tbubble_r,slipModel='Zivi')
self.Charge_2phase = rho_average * w_2phase * self.V_r
#Frictional pressure drop component
#Lockhart-Martinelli correlation
#DP_frict=LMPressureGradientAvg(self.xin_r,self.xout_2phase,self.AS,self.G_r,self.Dh,self.Tbubble_r,self.Tdew_r)*self.Lcircuit*w_2phase
#using the pressure gradient of Kim & Mudawar (2013)
DP_frict=DPDZ_frict_2phase*self.Lcircuit*w_2phase
#Accelerational pressure drop component
if self.Ref in 'CarbonDioxide' or 'CO2' or 'R744': #TODO: self.AS.name() is not available yet for all backends, using self.Ref for now
DP_accel=AccelPressureDrop(self.xin_r,self.xout_2phase,self.AS,self.G_r,self.Tbubble_r,self.Tdew_r,D=self.Dh,slipModel='Premoli')*self.Lcircuit*w_2phase
else:
DP_accel=AccelPressureDrop(self.xin_r,self.xout_2phase,self.AS,self.G_r,self.Tbubble_r,self.Tdew_r,slipModel='Zivi')*self.Lcircuit*w_2phase
self.DP_r_2phase=DP_frict+DP_accel;
if self.Verbosity>7:
print (w_2phase,DWS.Q,Q_target,self.xin_r,"w_2phase,DWS.Q,Q_target,self.xin_r")
return DWS.Q-Q_target