def Calculate(self):
# AbstractState
AS = self.AS
if hasattr(self,'MassFrac'):
AS.set_mass_fractions([self.MassFrac])
elif hasattr(self, 'VoluFrac'):
AS.set_volu_fractions([self.VoluFrac])
if not 'IncompressibleBackend' in AS.backend_name():
#Figure out the inlet state
AS.update(CP.PQ_INPUTS, self.pin, 0.0)
self.Tbubble=AS.T() #[K]
AS.update(CP.PQ_INPUTS, self.pin, 1.0)
self.Tdew=AS.T() #[K]
else:
#It is a brine
self.Tbubble = None
self.Tdew = None
self.Tin,self.rhoin,self.Phasein=TrhoPhase_ph(self.AS,self.pin,self.hin,self.Tbubble,self.Tdew)
if self.Phasein =='Supercritical': #TO DO: Need to be UPDATED with Petterson et al. (2000) correlation for transcritical CO2
print ("Cauation::Transcritical phase at the inlet of SightGlass during iteration")
self.f_fluid, self.h_fluid, self.Re_fluid=f_h_1phase_Tube(self.mdot, self.ID, self.Tin, self.pin, self.AS)
AS.update(CP.PT_INPUTS, self.pin, self.Tin)
# Specific heat capacity [J/kg-K]
cp=AS.cpmass()
# Density [kg/m^3]
rho=AS.rhomass()
elif self.Phasein =='TwoPhase':
print ("Cauation::two phase at the inlet of SightGlass during iteration")
self.f_fluid, self.h_fluid, self.Re_fluid=f_h_1phase_Tube(self.mdot, self.ID, self.Tin-1, self.pin, self.AS)
AS.update(CP.PT_INPUTS, self.pin, self.Tin-1)
# Specific heat capacity [J/kg-K]
cp=AS.cpmass()
# Density [kg/m^3]
rho=AS.rhomass()
else: #Single phase
self.f_fluid, self.h_fluid, self.Re_fluid=f_h_1phase_Tube(self.mdot, self.ID, self.Tin, self.pin, self.AS)
AS.update(CP.PT_INPUTS, self.pin, self.Tin)
# Specific heat capacity [J/kg-K]
cp=AS.cpmass()
# Density [kg/m^3]
rho=AS.rhomass()
#Pressure drop calculations for single phase refrigerant
v=1./rho
#G=self.mdot/(pi*self.ID**2/4.0)
#Pressure gradient using Darcy friction factor
#dpdz=-self.f_fluid*v*G**2/(2.*self.ID) #Pressure gradient
#self.DP=dpdz*(2*self.B+self.E + self.h) #For total length of sight glass and micromotion only)
#Charge in Sight Glass [kg]
self.SightGlassCharge = pi*self.D**2/4.0*self.h*rho
#Charge in FilterDrier [kg]
self.FilterDrierCharge = self.V*rho
#Charge in MicroMotion [kg]
self.MicroMotionCharge = self.n_Micro*pi*self.D_Micro**2/4.0*self.L_Micro*rho
#Total Chnarge [kg]
self.Charge = self.n_sight*self.SightGlassCharge + self.FilterDrierCharge + self.MicroMotionCharge
def _Subcool_Forward(self):
self.w_subcool=1-self.w_2phase-self.w_superheat
if self.w_subcool<0:
raise ValueError('w_subcool in Condenser cannot be less than zero')
# AbstractState
AS = self.AS
## Bubble and dew temperatures (same for fluids without glide)
Tbubble=self.Tbubble
# Based on the the construction of the cycle model there is guaranteed to be a
# two-phase portion of the heat exchanger
A_a_subcool = self.Fins.A_a * self.w_subcool
mdot_da_subcool = self.mdot_da * self.w_subcool
A_r_subcool = self.A_r_wetted * self.w_subcool
# Friction factor and HTC in the refrigerant portions.
# Average fluid temps are used for the calculation of properties
# Average temp of refrigerant is average of sat. temp and outlet temp
# Secondary fluid is air over the fins
self.f_r_subcool, self.h_r_subcool, self.Re_r_subcool=f_h_1phase_Tube(
self.mdot_r / self.Ncircuits, self.ID, Tbubble-1.0, self.psat_r, self.AS,
"Single")
AS.update(CP.PT_INPUTS, self.psat_r, Tbubble-1)
cp_r = AS.cpmass() #[J/kg-K]
# Cross-flow in the subcooled region.
R_a=1. / (self.Fins.eta_a * self.Fins.h_a * self.Fins.A_a * self.h_a_tuning)
R_r=1. / (self.h_r_subcool * self.A_r_wetted)
UA_subcool = self.w_subcool / (R_a + R_r + self.Rw)
Cmin=min([self.mdot_da*self.Fins.cp_da*self.w_subcool,self.mdot_r*cp_r])
Cmax=max([self.mdot_da*self.Fins.cp_da*self.w_subcool,self.mdot_r*cp_r])
Cr=Cmin/Cmax
NTU=UA_subcool/Cmin
if(self.mdot_da*self.Fins.cp_da*self.w_subcool>self.mdot_r*cp_r):
# Minimum capacitance rate on refrigerant side
epsilon_subcool = 1. - exp(-1. / Cr * (1. - exp(-Cr * NTU)))
else:
# Minimum capacitance rate on air side
epsilon_subcool = 1 / Cr * (1 - exp(-Cr * (1 - exp(-NTU))))
# 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_subcool=-epsilon_subcool*Cmin*(Tbubble-self.Tin_a)
self.DT_sc=-self.Q_subcool/(self.mdot_r*cp_r)
self.Tout_r=Tbubble-self.DT_sc
AS.update(CP.PT_INPUTS, self.psat_r, (Tbubble + self.Tout_r) / 2)
rho_subcool=AS.rhomass() #[kg/m^3]
self.Charge_subcool = self.w_subcool * self.V_r * rho_subcool
# Pressure drop calculations for subcooled refrigerant
v_r=1/rho_subcool
# Pressure gradient using Darcy friction factor
dpdz_r=-self.f_r_subcool*v_r*self.G_r**2/(2*self.ID) #Pressure gradient
self.DP_r_subcool=dpdz_r*self.Lcircuit*self.w_subcool
def _Superheat_Forward(self, w_superheat):
self.w_superheat = w_superheat
DWS = DWSVals() #DryWetSegment structure
AS = self.AS #AbstractState
# 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 * self.h_a_tuning #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.Rw = self.Rw / w_superheat
AS.update(CP.PT_INPUTS, self.psat_r, self.Tdew_r + 2.5)
DWS.cp_r = AS.cpmass(
) #Use a guess value of 6K superheat to calculate cp [J/kg-K]
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.AS, "Single")
# Average Refrigerant heat transfer coefficient
DWS.h_r = self.h_r_superheat
#Run DryWetSegment
DryWetSegment(DWS)
AS.update(CP.PT_INPUTS, self.psat_r, (DWS.Tout_r + self.Tdew_r) / 2.0)
rho_superheat = AS.rhomass() #[kg/m^3]
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 _Superheat_Forward(self, w_superheat):
# Superheated portion
# Mean temperature for superheated part can be taken to be average
# of dew and glycol inlet temps
Tavg_sh_r = (self.Tdew_r + self.Tin_g) / 2.0
self.f_r_superheat, self.h_r_superheat, self.Re_r_superheat = f_h_1phase_Tube(
self.mdot_r, self.ID_i, Tavg_sh_r, self.pin_r, self.AS_r)
# Refrigerant specific heat
self.AS_r.update(CP.PT_INPUTS, self.pin_r, Tavg_sh_r)
cp_r_superheat = self.AS_r.cpmass() #[J/kg-K]
# Overall conductance of heat transfer surface in superheated
# portion
UA_superheat = w_superheat / (1 / (self.h_g * self.A_g_wetted) + 1 /
(self.h_r_superheat * self.A_r_wetted) +
self.Rw)
#List of capacitance rates [W/K]
C = [cp_r_superheat * self.mdot_r, self.cp_g * self.mdot_g]
Cmin = min(C)
Cr = Cmin / max(C)
Ntu_superheat = UA_superheat / Cmin
#for Cr<1 and pure counter flow (Incropera. Table 11.3)
epsilon_superheat = ((1 - exp(-Ntu_superheat * (1 - Cr))) /
(1 - Cr * exp(-Ntu_superheat * (1 - Cr))))
self.Q_superheat = epsilon_superheat * Cmin * (self.Tin_g -
self.Tdew_r)
self.Tout_r = self.Tdew_r + self.Q_superheat / (self.mdot_r *
cp_r_superheat)
# Refrigerant density (supeheated)
self.AS_r.update(CP.PT_INPUTS, self.pin_r,
(self.Tin_g + self.Tdew_r) / 2.0)
rho_superheat = self.AS_r.rhomass() #[kg/m^3]
# Regrigerant charge (supeheated)
self.Charge_r_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.Dh_r) #Pressure gradient
self.DP_r_superheat = dpdz_r * self.L * w_superheat
# Temperature of "glycol" at the point where the refrigerant is at
# a quality of 1.0 [K]
self.T_g_x = self.Tin_g - self.Q_superheat / (self.cp_g * self.mdot_g)
def Calculate(self):
"""
This function is now simply a wrapper around the DryWetSegment()
function in order to decrease the amount of code replication
"""
#Initialize
self.Initialize()
AS_g = self.AS_g
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*self.h_a_tuning #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.Rw=self.Rw
AS_g.update(CP.PT_INPUTS, self.pin_g, (self.Tin_g+DWS.Tin_a)/2.0)
DWS.cp_r=AS_g.cpmass() #[J/kg-K]
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.AS_g, "Single");
# Average Refrigerant heat transfer coefficient
DWS.h_r=self.h_g*self.h_g_tuning
#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
AS_g.update(CP.PT_INPUTS, self.pin_g, self.Tin_g)
v_g=1/AS_g.rhomass() #[m^3/kg]
#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.DP_tuning
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 _Subcool_Forward(self, w_subcool):
# **********************************************************************
# SUPERCRITICAL_LIQUID PART
# **********************************************************************
self.w_subcool = w_subcool
if self.w_subcool < 0:
raise ValueError(
'w_subcool in Gas cooler cannot be less than zero')
#AbstractState
AS = self.AS
DWS = DWSVals() #DryWetSegment structure
# Store temporary values to be passed to DryWetSegment
DWS.A_a = self.Fins.A_a * w_subcool
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_subcool
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.Tcr
DWS.A_r = self.A_r_wetted * w_subcool
AS.update(CP.PT_INPUTS, self.psat_r, self.Tcr - 1)
DWS.cp_r = AS.cpmass() #[J/kg-K]
DWS.pin_r = self.psat_r
DWS.mdot_r = self.mdot_r
DWS.IsTwoPhase = False
# Friction factor and HTC in the refrigerant portions.
# Average fluid temps are used for the calculation of properties
# Average temp of refrigerant is average of sat. temp and outlet temp
# Secondary fluid is air over the fins
self.f_r_subcool, self.h_r_subcool, self.Re_r_subcool = f_h_1phase_Tube(
self.mdot_r / self.Ncircuits, self.ID, self.Tcr - 1.0, self.psat_r,
self.AS, "Single")
# Average Refrigerant heat transfer coefficient
DWS.h_r = self.h_r_subcool
#Run DryWetSegment
DryWetSegment(DWS)
AS.update(CP.PT_INPUTS, self.psat_r, (self.Tcr + DWS.Tout_r) / 2)
rho_subcool = AS.rhomass() #[kg/m^3]
self.Charge_subcool = self.w_subcool * self.V_r * rho_subcool
#Pressure drop calculations for subcooled refrigerant
v_r = 1 / rho_subcool
#Pressure gradient using Darcy friction factor
dpdz_r = -self.f_r_subcool * v_r * self.G_r**2 / (2 * self.ID
) #Pressure gradient
self.DP_r_subcool = dpdz_r * self.Lcircuit * self.w_subcool
# 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_subcool = DWS.Q
self.fdry_subcool = DWS.f_dry
self.Tout_a_subcool = DWS.Tout_a
self.Tout_r = DWS.Tout_r
def Calculate(self):
# AbstractState
if hasattr(self, 'Backend'): #check if backend is given
AS = CP.AbstractState(self.Backend, self.Ref)
if hasattr(self, 'MassFrac'):
AS.set_mass_fractions([self.MassFrac])
else: #otherwise, use the defualt backend
AS = CP.AbstractState('HEOS', self.Ref)
self.AS = AS
if not 'IncompressibleBackend' in AS.backend_name():
# Figure out the inlet state
AS.update(CP.PQ_INPUTS, self.pin, 0.0)
self.Tbubble = AS.T() #[K]
AS.update(CP.PQ_INPUTS, self.pin, 1.0)
self.Tdew = AS.T() #[K]
else:
# It is a brine
self.Tbubble = None
self.Tdew = None
self.Tin, self.rhoin, self.Phasein = TrhoPhase_ph(
self.AS, self.pin, self.hin, self.Tbubble, self.Tdew)
###Solver shows TwoPhase in the first iteration, the following if statement just to avoid ValueError with CoolProp for pseudo-pure refrigerants
if self.Phasein == 'TwoPhase':
self.f_fluid, self.h_fluid, self.Re_fluid = f_h_1phase_Tube(
self.mdot, self.ID, self.Tin - 1, self.pin, self.AS)
AS.update(CP.PT_INPUTS, self.pin, self.Tin - 1)
# Specific heat capacity [J/kg-K]
cp = AS.cpmass()
# Density [kg/m^3]
rho = AS.rhomass()
else: #Single phase
self.f_fluid, self.h_fluid, self.Re_fluid = f_h_1phase_Tube(
self.mdot, self.ID, self.Tin, self.pin, self.AS)
AS.update(CP.PT_INPUTS, self.pin, self.Tin)
# Specific heat capacity [J/kg-K]
cp = AS.cpmass()
# Density [kg/m^3]
rho = AS.rhomass()
# Thermal resistance of tube
R_tube = log(self.OD / self.ID) / (2 * pi * self.L * self.k_tube)
# Thermal resistance of insulation
R_insul = log((self.OD + 2.0 * self.t_insul) /
self.OD) / (2 * pi * self.L * self.k_insul)
# Convective UA for inside the tube
UA_i = pi * self.ID * self.L * self.h_fluid
# Convective UA for the air-side
UA_o = pi * (self.OD + 2 * self.t_insul) * self.L * self.h_air
# Avoid the possibility of division by zero if h_air is zero
if UA_o < 1e-12:
UA_o = 1e-12
# Overall UA value
UA = 1 / (1 / UA_i + R_tube + R_insul + 1 / UA_o)
# Outlet fluid temperature [K]
self.Tout = self.T_air - exp(
-UA / (self.mdot * cp)) * (self.T_air - self.Tin)
# Overall heat transfer rate [W]
self.Q = self.mdot * cp * (self.Tout - self.Tin)
self.hout = self.hin + self.Q / self.mdot
# Pressure drop calculations for single phase refrigerant
v = 1. / rho
G = self.mdot / (pi * self.ID**2 / 4.0)
# Pressure gradient using Darcy friction factor
dpdz = -self.f_fluid * v * G**2 / (2. * self.ID) #Pressure gradient
self.DP = dpdz * self.L
# Charge in Line set [kg]
self.Charge = pi * self.ID**2 / 4.0 * self.L * rho
def Calculate(self):
# AbstractState
AS = self.AS
if hasattr(self, 'MassFrac'):
AS.set_mass_fractions([self.MassFrac])
elif hasattr(self, 'VoluFrac'):
AS.set_volu_fractions([self.VoluFrac])
if not 'IncompressibleBackend' in AS.backend_name():
# Figure out the inlet state
AS.update(CP.PQ_INPUTS, self.pin, 0.0)
self.Tbubble = AS.T() #[K]
AS.update(CP.PQ_INPUTS, self.pin, 1.0)
self.Tdew = AS.T() #[K]
# Check for supercritical state
if self.pin > AS.p_critical():
# Supercritical
self.Tbubble = None
self.Tdew = None
else:
# It is a brine or incompressible
self.Tbubble = None
self.Tdew = None
if hasattr(self, 'LineSetOption'): #check if LineSetOption is given
if self.LineSetOption == 'On':
self.Tin, self.rhoin, self.Phasein = TrhoPhase_ph(
self.AS, self.pin, self.hin, self.Tbubble, self.Tdew)
### Solver shows TwoPhase in the first iteration, the following if statement just to avoid ValueError with CoolProp for pseudo-pure refrigerants
if self.Phasein == 'Supercritical': #TO DO: Need to be UPDATED with Petterson et al. (2000) correlation for transcritical CO2
self.f_fluid, self.h_fluid, self.Re_fluid = f_h_1phase_Tube(
self.mdot, self.ID, self.Tin, self.pin, self.AS)
AS.update(CP.PT_INPUTS, self.pin, self.Tin)
# Specific heat capacity [J/kg-K]
cp = AS.cpmass()
# Density [kg/m^3]
rho = AS.rhomass()
# Specific entropy [J/kg-K]
sin = AS.smass()
elif self.Phasein == 'TwoPhase':
self.f_fluid, self.h_fluid, self.Re_fluid = f_h_1phase_Tube(
self.mdot, self.ID, self.Tin - 1, self.pin, self.AS)
AS.update(CP.PT_INPUTS, self.pin, self.Tin - 1)
# Specific heat capacity [J/kg-K]
cp = AS.cpmass()
# Density [kg/m^3]
rho = AS.rhomass()
# Specific entropy [J/kg-K]
sin = AS.smass()
else: #Single phase
self.f_fluid, self.h_fluid, self.Re_fluid = f_h_1phase_Tube(
self.mdot, self.ID, self.Tin, self.pin, self.AS)
AS.update(CP.PT_INPUTS, self.pin, self.Tin)
# Specific heat capacity [J/kg-K]
cp = AS.cpmass()
# Density [kg/m^3]
rho = AS.rhomass()
# Specific entropy [J/kg-K]
sin = AS.smass()
# Inlet specific entropy
self.sin = sin
# Thermal resistance of tube
R_tube = log(
self.OD / self.ID) / (2 * pi * self.L * self.k_tube)
# Thermal resistance of insulation
R_insul = log((self.OD + 2.0 * self.t_insul) /
self.OD) / (2 * pi * self.L * self.k_insul)
# Convective UA for inside the tube
UA_i = pi * self.ID * self.L * self.h_fluid
# Convective UA for the air-side
UA_o = pi * (self.OD + 2 * self.t_insul) * self.L * self.h_air
# Avoid the possibility of division by zero if h_air is zero
if UA_o < 1e-12:
UA_o = 1e-12
# Overall UA value
UA = 1 / (1 / UA_i + R_tube + R_insul + 1 / UA_o)
# Outlet fluid temperature [K]
self.Tout = self.T_air - exp(
-UA / (self.mdot * cp)) * (self.T_air - self.Tin)
# Overall heat transfer rate [W]
self.Q = self.mdot * cp * (self.Tout - self.Tin)
self.hout = self.hin + self.Q / self.mdot
# Pressure drop calculations for single phase refrigerant
v = 1. / rho
G = self.mdot / (pi * self.ID**2 / 4.0)
# Pressure gradient using Darcy friction factor
dpdz = -self.f_fluid * v * G**2 / (2. * self.ID
) #Pressure gradient
self.DP = dpdz * self.L
# Outlet specific entropy
AS.update(CP.HmassP_INPUTS, self.hout, self.pin + self.DP)
self.sout = AS.smass()
# Charge in Line set [kg]
self.Charge = pi * self.ID**2 / 4.0 * self.L * rho
else: # LineSetOption == 'Off'
print('lineSetOption is off for ' + str(self.Name))
self.Tout = self.Tin
# Inlet specific entropy
AS.update(CP.HmassP_INPUTS, self.hin, self.pin)
self.sin = AS.smass()
# Overall heat transfer rate [W]
self.Q = 0.0
self.hout = self.hin
self.Re_fluid = 0.0
self.h_fluid = 0.0
# Pressure gradient using Darcy friction factor
self.DP = 0.0
# Outlet specific entropy
AS.update(CP.HmassP_INPUTS, self.hout, self.pin + self.DP)
self.sout = AS.smass()
# Charge in Line set [kg]
self.Charge = 0.0
else:
print(str(self.Name) + ' is neglected')
self.Tout = self.Tin
# Inlet specific entropy
AS.update(CP.HmassP_INPUTS, self.hin, self.pin)
self.sin = AS.smass()
# Overall heat transfer rate [W]
self.Q = 0.0
self.hout = self.hin
self.Re_fluid = 0.0
self.h_fluid = 0.0
# Pressure gradient using Darcy friction factor
self.DP = 0.0
# Outlet specific entropy
AS.update(CP.HmassP_INPUTS, self.hout, self.pin + self.DP)
self.sout = AS.smass()
# Charge in Line set [kg]
self.Charge = 0.0
def _Superheat_Forward(self):
# **********************************************************************
# SUPERHEATED PART
# **********************************************************************
#AbstractState
AS = self.AS
#Dew temperature for constant pressure cooling to saturation
Tdew = self.Tdew
Tbubble = self.Tbubble
# Average fluid temps are used for the calculation of properties
# Average temp of refrigerant is average of sat. temp and outlet temp
# Secondary fluid is air over the fins
self.f_r_superheat, self.h_r_superheat, self.Re_r_superheat = f_h_1phase_Tube(
self.mdot_r / self.Ncircuits, self.ID, (Tdew + self.Tin_r) / 2.0,
self.psat_r, self.AS, "Single")
AS.update(CP.PT_INPUTS, self.psat_r, (Tdew + self.Tin_r) / 2)
cp_r = AS.cpmass() #[J/kg-K]
rho_superheat = AS.rhomass() #[kg/m^3]
#Compute Fins Efficiency based on FinsType
if self.FinsType == 'WavyLouveredFins':
WavyLouveredFins(self.Fins)
elif self.FinsType == 'HerringboneFins':
HerringboneFins(self.Fins)
elif self.FinsType == 'PlainFins':
PlainFins(self.Fins)
self.mdot_da = self.Fins.mdot_da
# Cross-flow in the superheated region.
# Using effectiveness-Ntu relationships for cross flow with non-zero Cr.
UA_overall = 1 / (1 / (self.Fins.eta_a * self.Fins.h_a *
self.Fins.A_a * self.h_a_tuning) + 1 /
(self.h_r_superheat * self.A_r_wetted) + self.Rw)
epsilon_superheat = (Tdew - self.Tin_r) / (self.Tin_a - self.Tin_r)
Ntu = UA_overall / (self.mdot_da * self.Fins.cp_da)
if epsilon_superheat > 1.0:
epsilon_superheat = 1.0 - 1e-12
self.w_superheat = -log(1 - epsilon_superheat) * self.mdot_r * cp_r / (
(1 - exp(-Ntu)) * self.mdot_da * self.Fins.cp_da)
# 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 being cooled
self.Q_superheat = self.mdot_r * cp_r * (Tdew - self.Tin_r)
#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
self.Charge_superheat = self.w_superheat * self.V_r * rho_superheat
#Latent heat needed for pseudo-quality calc
AS.update(CP.QT_INPUTS, 0.0, Tbubble)
h_l = AS.hmass() #[J/kg]
AS.update(CP.QT_INPUTS, 1.0, Tdew)
h_v = AS.hmass() #[J/kg]
h_fg = h_v - h_l #[J/kg]
self.xin_r = 1.0 + cp_r * (self.Tin_r - Tdew) / h_fg