def _Superheat_Forward(self,w_superheat):
self.w_superheat=w_superheat
DWS=DWSVals() #DryWetSegment structure
# Store temporary values to be passed to DryWetSegment
DWS.A_a=self.Fins.A_a*w_superheat
DWS.cp_da=self.Fins.cp_da
DWS.eta_a=self.Fins.eta_a
DWS.h_a=self.Fins.h_a #Heat transfer coefficient
DWS.mdot_da=self.mdot_da*w_superheat
DWS.pin_a=self.Fins.Air.p
DWS.Fins=self.Fins
DWS.FinsType = self.FinsType
# Inputs on the air side to two phase region are inlet air again
DWS.Tin_a=self.Tin_a
DWS.RHin_a=self.Fins.Air.RH
DWS.Tin_r=self.Tdew_r
DWS.A_r=self.A_r_wetted*w_superheat
DWS.cp_r=PropsSI('C','T',self.Tdew_r+2.5, 'P', self.psat_r, self.Ref) #Use a guess value of 6K superheat to calculate cp
DWS.pin_r=self.psat_r
DWS.mdot_r=self.mdot_r
DWS.IsTwoPhase=False
#Use a guess value of 6K superheat to calculate the properties
self.f_r_superheat, self.h_r_superheat, self.Re_r_superheat=f_h_1phase_Tube(self.mdot_r / self.Ncircuits, self.ID,
self.Tdew_r+3, self.psat_r, self.Ref, "Single");
# Average Refrigerant heat transfer coefficient
DWS.h_r=self.h_r_superheat
#Run DryWetSegment
DryWetSegment(DWS)
rho_superheat=PropsSI('D','T',(DWS.Tout_r+self.Tdew_r)/2.0, 'P', self.psat_r, self.Ref)
self.Charge_superheat = w_superheat * self.V_r * rho_superheat
#Pressure drop calculations for superheated refrigerant
v_r=1/rho_superheat
#Pressure gradient using Darcy friction factor
dpdz_r=-self.f_r_superheat*v_r*self.G_r**2/(2*self.ID) #Pressure gradient
self.DP_r_superheat=dpdz_r*self.Lcircuit*self.w_superheat
#Set values
self.Q_superheat=DWS.Q
self.Q_sensible_superheat=DWS.Q_sensible
self.fdry_superheat=DWS.f_dry
self.Tout_a_superheat=DWS.Tout_a
self.Tout_r=DWS.Tout_r
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 #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.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
DWS.h_r=ShahEvaporation_Average(self.xin_r,self.xout_2phase,self.Ref,self.G_r,self.ID,self.psat_r,Q_target/DWS.A_r,self.Tbubble_r,self.Tdew_r)
#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.Ref,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.Ref,self.G_r,self.ID,self.Tbubble_r,self.Tdew_r)*self.Lcircuit*w_2phase
#Accelerational pressure drop component
DP_accel=AccelPressureDrop(self.xin_r,self.xout_2phase,self.Ref,self.G_r,self.Tbubble_r,self.Tdew_r)*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 Calculate(self):
"""
This function is now simply a wrapper around the DryWetSegment()
function in order to decrease the amount of code replication
"""
self.Initialize()
DWS=DWSVals() #DryWetSegment structure
# Store temporary values to be passed to DryWetSegment
DWS.A_a=self.Fins.A_a
DWS.cp_da=self.Fins.cp_da
DWS.eta_a=self.Fins.eta_a
DWS.h_a=self.Fins.h_a #Heat transfer coefficient
DWS.mdot_da=self.Fins.mdot_da
DWS.pin_a=self.Fins.Air.p
DWS.Tin_a=self.Tin_a
DWS.RHin_a=self.Fins.Air.RH
DWS.Fins=self.Fins
DWS.FinsType=self.FinsType #Added to pass FinsType to DryWetSegment
DWS.Tin_r=self.Tin_g
DWS.A_r=self.A_g_wetted
DWS.cp_r=PropsSI('C','T',(self.Tin_g+DWS.Tin_a)/2.0, 'P', self.pin_g, self.Ref_g)#*1000 #Use a guess value of 6K superheat to calculate cp
DWS.pin_r=self.pin_g
DWS.mdot_r=self.mdot_g
DWS.IsTwoPhase=False
#Use a guess value of 6K superheat to calculate the properties
self.f_g, self.h_g, self.Re_g=f_h_1phase_Tube(self.mdot_g / self.Ncircuits, self.ID,
(self.Tin_g+DWS.Tin_a)/2.0, self.pin_g, self.Ref_g, "Single");
# Average Refrigerant heat transfer coefficient
DWS.h_r=self.h_g
#Run DryWetSegment
DryWetSegment(DWS)
#Average mass flux of glycol in circuit
self.G_g = self.mdot_g/(self.Ncircuits*pi*self.ID**2/4.0) #[kg/m^2-s]
#Pressure drop calculations for glycol (water)
Dh_g=self.ID
v_g=1/PropsSI('D','T',self.Tin_g, 'P',self.pin_g,self.Ref_g)
#Pressure gradient using Darcy friction factor
dp_dz_g=-self.f_g*v_g*self.G_g**2/(2*Dh_g)
DP_g=dp_dz_g*self.Lcircuit
self.f_dry=DWS.f_dry
self.DP_g=DP_g
self.Q=DWS.Q
self.Tout_g=DWS.Tout_r
self.Tout_a=DWS.Tout_a
self.hout_a=DWS.hout_a
self.hin_a=DWS.hin_a
self.SHR=self.Fins.cp_da*(DWS.Tout_a-DWS.Tin_a)/(DWS.hout_a-DWS.hin_a)
self.Capacity=DWS.Q-self.Fins.Air.FanPower
def _Superheat_Forward(self,w_superheat,T_inlet_r=-99):
if T_inlet_r==-99: #catch if default case is used
T_inlet_r=self.Tdew_r
self.w_superheat=w_superheat
DWS=DWSVals() #DryWetSegment structure
# Store temporary values to be passed to DryWetSegment
DWS.A_a=self.Fins.A_a*w_superheat
DWS.cp_da=self.Fins.cp_da
DWS.eta_a=self.Fins.eta_a
DWS.h_a=self.Fins.h_a #Heat transfer coefficient
DWS.mdot_da=self.mdot_da*w_superheat
DWS.pin_a=self.Fins.Air.p
DWS.Fins=self.Fins
# Inputs on the air side to two phase region are inlet air again
DWS.Tin_a=self.Tin_a
DWS.RHin_a=self.Fins.Air.RH
DWS.Tin_r=T_inlet_r #default is dew temperature; can change to consider for initial superheat
DWS.A_r=self.A_r_wetted*w_superheat
DWS.cp_r=self.cp_r
DWS.pin_r=self.psat_r
DWS.mdot_r=self.mdot_r
DWS.IsTwoPhase=False
#Use a guess value of 6K superheat to calculate the properties
self.f_r_superheat, self.h_r_superheat, self.Re_r_superheat=f_h_1phase_Tube(self.mdot_r / self.Ncircuits, self.ID,
self.Tdew_r+3, self.psat_r, self.Ref, "Single");
# Average Refrigerant heat transfer coefficient
DWS.h_r=self.h_r_superheat
#Run DryWetSegment
DryWetSegment(DWS)
try:
rho_superheat=Props('D','T',(DWS.Tout_r+self.Tdew_r)/2.0, 'P', self.psat_r, self.Ref)
#members = [attr for attr in dir(DWS()) if not callable(attr) and not attr.startswith("__")]
#print members
except:
print "error in Evaporator, unreasonable inputs?","Inputs to calculate density are DWS.Tout_r,self.Tdew_r,self.psat_r",DWS.Tout_r,self.Tdew_r,self.psat_r,"<<"
print "DWS values are", 'DWS.A_a',DWS.A_a,'DWS.Tin_r',DWS.Tin_r,'DWS.mdot_da',DWS.mdot_da,"DWS.mdot_r",DWS.mdot_r,'DWS.mdot_da',DWS.mdot_da,'DWS.mdot_r',DWS.mdot_r
print "plot DWS vals to figure out what is going on"
raise()
self.Charge_superheat = w_superheat * self.V_r * rho_superheat
#Pressure drop calculations for subcooled refrigerant
v_r=1/rho_superheat
#Pressure gradient using Darcy friction factor
dpdz_r=-self.f_r_superheat*v_r*self.G_r**2/(2*self.ID) #Pressure gradient
self.DP_r_superheat=dpdz_r*self.Lcircuit*self.w_superheat
#Set values
self.Q_superheat=DWS.Q
self.Q_sensible_superheat=DWS.Q_sensible
self.fdry_superheat=DWS.f_dry
self.Tout_a_superheat=DWS.Tout_a
self.Tout_r=DWS.Tout_r
self.omega_out_superheat=DWS.omega_out
def Calculate(self):
"""
This function is now simply a wrapper around the DryWetSegment()
function in order to decrease the amount of code replication
"""
self.Initialize()
DWS = DWSVals() #DryWetSegment structure
# Store temporary values to be passed to DryWetSegment
DWS.A_a = self.Fins.A_a
DWS.cp_da = self.Fins.cp_da
DWS.eta_a = self.Fins.eta_a
DWS.h_a = self.Fins.h_a #Heat transfer coefficient
DWS.mdot_da = self.Fins.mdot_da
DWS.pin_a = self.Fins.Air.p
DWS.Tin_a = self.Tin_a
DWS.RHin_a = self.Fins.Air.RH
DWS.Fins = self.Fins
DWS.Tin_r = self.Tin_g
DWS.A_r = self.A_g_wetted
DWS.cp_r = Props(
'C', 'T', (self.Tin_g + DWS.Tin_a) / 2.0, 'P', self.pin_g, self.
Ref_g) * 1000 #Use a guess value of 6K superheat to calculate cp
DWS.pin_r = self.pin_g
DWS.mdot_r = self.mdot_g
DWS.IsTwoPhase = False
#Use a guess value of 6K superheat to calculate the properties
self.f_g, self.h_g, self.Re_g = f_h_1phase_Tube(
self.mdot_g / self.Ncircuits, self.ID,
(self.Tin_g + DWS.Tin_a) / 2.0, self.pin_g, self.Ref_g, "Single")
# Average Refrigerant heat transfer coefficient
DWS.h_r = self.h_g
#Run DryWetSegment
DryWetSegment(DWS)
#Average mass flux of glycol in circuit
self.G_g = self.mdot_g / (self.Ncircuits * pi * self.ID**2 / 4.0
) #[kg/m^2-s]
#Pressure drop calculations for glycol (water)
Dh_g = self.ID
v_g = 1 / Props('D', 'T', self.Tin_g, 'P', self.pin_g, self.Ref_g)
#Pressure gradient using Darcy friction factor
dp_dz_g = -self.f_g * v_g * self.G_g**2 / (2 * Dh_g)
DP_g = dp_dz_g * self.Lcircuit
self.f_dry = DWS.f_dry
self.DP_g = DP_g
self.Q = DWS.Q
self.Tout_g = DWS.Tout_r
self.Tout_a = DWS.Tout_a
self.hout_a = DWS.hout_a
self.hin_a = DWS.hin_a
self.SHR = self.Fins.cp_da * (DWS.Tout_a - DWS.Tin_a) / (DWS.hout_a -
DWS.hin_a)
self.Capacity = DWS.Q - self.Fins.Air.FanPower
