def __init__(self):
"""
Load up the necessary sub-structures to be filled with
the code that follows
"""
self.Compressor = CompressorClass()
#Outdoor coil is a Condenser in cooling mode and evaporator in heating mode
self.Condenser = CondenserClass()
self.Condenser.Fins = FinInputs()
self.Evaporator = EvaporatorClass()
self.Evaporator.Fins = FinInputs()
self.CoolingCoil = CoolingCoilClass()
self.CoolingCoil.Fins = FinInputs()
self.Pump = PumpClass()
#Add both types of internal heat exchangers
self.CoaxialIHX = CoaxialHXClass()
self.PHEIHX = PHEHXClass()
self.LineSetSupply = LineSetClass()
self.LineSetReturn = LineSetClass()
#Make IHX an empty class for holding parameters common to PHE and Coaxial IHX
class struct:
pass
self.IHX = struct()
def __init__(self):
"""
Load up the necessary sub-structures to be filled with
the code that follows
"""
self.Compressor=CompressorClass()
self.Condenser=CondenserClass()
self.Condenser.Fins=FinInputs()
self.Evaporator=EvaporatorClass()
self.Evaporator.Fins=FinInputs()
self.LineSetSupply=LineSetClass()
self.LineSetReturn=LineSetClass()
def __init__(self):
"""
Load up the necessary sub-structures to be filled with
the code that follows
"""
self.Compressor=CompressorClass()
self.Condenser=CondenserClass()
self.Condenser.Fins=FinInputs()
self.CoolingCoil=CoolingCoilClass()
self.CoolingCoil.Fins=FinInputs()
self.PHEHX=PHEHXClass()
self.Pump=PumpClass()
class DXCycleClass():
def __init__(self):
"""
Load up the necessary sub-structures to be filled with
the code that follows
"""
self.Compressor=CompressorClass()
self.Condenser=CondenserClass()
self.Condenser.Fins=FinInputs()
self.Evaporator=EvaporatorClass()
self.Evaporator.Fins=FinInputs()
self.LineSetSupply=LineSetClass()
self.LineSetReturn=LineSetClass()
def OutputList(self):
"""
Return a list of parameters for this component for further output
It is a list of tuples, and each tuple is formed of items:
[0] Description of value
[1] Units of value
[2] The value itself
"""
Output_List=[]
#append optional parameters, if applicable
if hasattr(self,'TestName'):
Output_List.append(('Name','N/A',self.TestName))
if hasattr(self,'TestDescription'):
Output_List.append(('Description','N/A',self.TestDescription))
if hasattr(self,'TestDetails'):
Output_List.append(('Details','N/A',self.TestDetails))
Output_List_default=[ #default output list
('Charge','kg',self.Charge),
('Condensation temp (dew)','K',self.Tdew_cond),
('Evaporation temp (dew)','K',self.Tdew_evap),
('Condenser Subcooling','K',self.DT_sc),
('Primary Ref.','-',self.Ref),
('COP','-',self.COP),
('COSP','-',self.COSP),
('Net Capacity','W',self.Capacity),
('Net Power','W',self.Power),
('SHR','-',self.SHR),
('Imposed Variable','-',self.ImposedVariable),
]
for i in range(0,len(Output_List_default)): #append default parameters to output list
Output_List.append(Output_List_default[i])
return Output_List
def Calculate(self,DT_evap,DT_cond):
"""
Inputs are differences in temperature [K] between HX air inlet temperature
and the dew temperature for the heat exchanger.
Required Inputs:
DT_evap:
Difference in temperature [K] between evaporator air inlet temperature and refrigerant dew temperature
DT_cond:
Difference in temperature [K] between condenser air inlet temperature and refrigeant dew temperature
"""
if self.Verbosity>1:
print 'DTevap %7.4f DTcond %7.4f,' %(DT_evap,DT_cond)
Tdew_cond=self.Condenser.Fins.Air.Tdb+DT_cond#the values (Tin_a,..) come from line 128ff
Tdew_evap=self.Evaporator.Fins.Air.Tdb-DT_evap
psat_cond=Props('P','T',Tdew_cond,'Q',1,self.Ref)
psat_evap=Props('P','T',Tdew_evap,'Q',1,self.Ref)
Tbubble_evap=Props('T','P',psat_evap,'Q',0,self.Ref)
self.Tdew_cond=Tdew_cond
self.Tdew_evap=Tdew_evap
#If the user doesn't include the Mode, fail
assert hasattr(self,'Mode')
if self.Mode=='AC':
if not hasattr(self.Compressor,'mdot_r') or self.Compressor.mdot_r<0.00001:
# The first run of model, run the compressor just so you can get a preliminary value
# for the mass flow rate for the line set
params={ #dictionary -> key:value, e.g. 'key':2345,
'pin_r': psat_evap,
'pout_r': psat_cond,
'Tin_r': Tdew_evap+self.Evaporator.DT_sh,
'Ref': self.Ref
}
self.Compressor.Update(**params)
self.Compressor.Calculate()
params={
'pin': psat_evap,
'hin': Props('H','T',Tdew_evap+self.Evaporator.DT_sh,'P',psat_evap,self.Ref)*1000,
'mdot': self.Compressor.mdot_r,
'Ref': self.Ref
}
self.LineSetReturn.Update(**params)
self.LineSetReturn.Calculate()
params={ #dictionary -> key:value, e.g. 'key':2345,
'pin_r': psat_evap-self.DP_low,
'pout_r': psat_cond+self.DP_high,
'Tin_r': TrhoPhase_ph(self.Ref,psat_evap,self.LineSetReturn.hout,Tbubble_evap,Tdew_evap)[0],
'Ref': self.Ref
}
self.Compressor.Update(**params)
self.Compressor.Calculate()
if self.Verbosity>1:
print 'Comp DP H L',self.DP_low,self.DP_high
params={
'mdot_r': self.Compressor.mdot_r,
'Tin_r': self.Compressor.Tout_r,
'psat_r': psat_cond,
'Ref': self.Ref
}
self.Condenser.Update(**params)
self.Condenser.Calculate()
params={
'pin':psat_cond,
'hin':self.Condenser.hout_r,
'mdot':self.Compressor.mdot_r,
'Ref':self.Ref
}
self.LineSetSupply.Update(**params)
self.LineSetSupply.Calculate()
params={
'mdot_r': self.Compressor.mdot_r,
'psat_r': psat_evap,
'hin_r': self.LineSetSupply.hout,
'Ref': self.Ref
}
self.Evaporator.Update(**params)
self.Evaporator.Calculate()
self.Charge=self.Condenser.Charge+self.Evaporator.Charge+self.LineSetSupply.Charge+self.LineSetReturn.Charge
self.EnergyBalance=self.Compressor.CycleEnergyIn+self.Condenser.Q+self.Evaporator.Q
resid=np.zeros((2))
self.DP_HighPressure=self.Condenser.DP_r+self.LineSetSupply.DP
self.DP_LowPressure=self.Evaporator.DP_r+self.LineSetReturn.DP
resid[0]=self.Compressor.mdot_r*(self.LineSetReturn.hin-self.Evaporator.hout_r)
if self.ImposedVariable=='Subcooling':
resid[1]=self.Condenser.DT_sc-self.DT_sc_target
elif self.ImposedVariable=='Charge':
resid[1]=self.Charge-self.Charge_target
if self.Verbosity>1:
print resid
self.Capacity=self.Evaporator.Capacity
self.Power=self.Compressor.W+self.Evaporator.Fins.Air.FanPower+self.Condenser.Fins.Air.FanPower
self.COP=self.Evaporator.Q/self.Compressor.W
self.COSP=self.Evaporator.Capacity/self.Power
self.SHR=self.Evaporator.SHR
self.DT_sc=self.Condenser.DT_sc
elif self.Mode=='HP':
params={ #dictionary -> key:value, e.g. 'key':2345,
'pin_r': psat_evap-self.DP_low*1,
'pout_r': psat_cond+self.DP_high*1,
'Tin_r': Tdew_evap+self.Evaporator.DT_sh,
'Ref': self.Ref
}
self.Compressor.Update(**params)
self.Compressor.Calculate()
params={
'pin': psat_cond,
'hin': self.Compressor.hout_r,
'mdot': self.Compressor.mdot_r,
'Ref': self.Ref
}
self.LineSetSupply.Update(**params)
self.LineSetSupply.Calculate()
params={
'mdot_r': self.Compressor.mdot_r,
'Tin_r': self.Compressor.Tout_r,
'psat_r': psat_cond,
'Ref': self.Ref
}
self.Condenser.Update(**params)
self.Condenser.Calculate()
params={
'pin': psat_cond,
'hin': self.Condenser.hout_r,
'mdot': self.Compressor.mdot_r,
'Ref': self.Ref
}
self.LineSetReturn.Update(**params)
self.LineSetReturn.Calculate()
params={
'mdot_r': self.Compressor.mdot_r,
'psat_r': psat_evap,
'hin_r': self.LineSetReturn.hout,
'Ref': self.Ref
}
self.Evaporator.Update(**params)
self.Evaporator.Calculate()
self.Charge=self.Condenser.Charge+self.Evaporator.Charge+self.LineSetSupply.Charge+self.LineSetReturn.Charge
self.EnergyBalance=self.Compressor.CycleEnergyIn+self.Condenser.Q+self.Evaporator.Q
resid=np.zeros((2))
resid[0]=self.Compressor.mdot_r*(self.Compressor.hin_r-self.Evaporator.hout_r)
if self.ImposedVariable=='Subcooling':
resid[1]=self.Condenser.DT_sc-self.DT_sc_target
elif self.ImposedVariable=='Charge':
resid[1]=self.Charge-self.Charge_target
self.Capacity=-self.Condenser.Q+self.Condenser.Fins.Air.FanPower
self.DT_sc=self.Condenser.DT_sc
self.Power=self.Compressor.W+self.Evaporator.Fins.Air.FanPower+self.Condenser.Fins.Air.FanPower
self.COP=-self.Condenser.Q/self.Compressor.W
self.COSP=self.Capacity/self.Power
self.SHR=self.Evaporator.SHR
self.DP_HighPressure=self.Condenser.DP_r+self.LineSetSupply.DP
self.DP_LowPressure=self.Evaporator.DP_r+self.LineSetReturn.DP
else:
ValueError("DX Cycle mode must be 'AC', or 'HP'")
if self.Verbosity>1:
print 'DTevap %7.4f DTcond %7.4f Qres % 12.6e DTsc: % 12.6e Charge %10.4f SC: %8.4f' %(DT_evap,DT_cond,resid[0],resid[1],self.Charge,self.Condenser.DT_sc)
self.DT_evap=DT_evap
self.DT_cond=DT_cond
return resid
def PreconditionedSolve(self):
"""
Solver that will precondition by trying a range of DeltaT until the model
can solve, then will kick into 2-D Newton Raphson solve
The two input variables for the system solver are the differences in
temperature between the inlet air temperature of the heat exchanger and the
dew temperature of the refrigerant. This is important for refrigerant blends
with temperature glide during constant-pressure evaporation or condensation.
Good examples of common working fluid with glide would be R404A or R410A.
"""
def OBJECTIVE_DXCycle(x):
"""
A wrapper function to convert input vector for fsolve to the proper form for the solver
"""
try:
resids=self.Calculate(DT_evap=float(x[0]),DT_cond=float(x[1]))#,DP_low=float(x[2]),DP_high=float(x[3]))
except ValueError:
raise
return resids
# Use the preconditioner to determine a reasonably good starting guess
DT_evap_init,DT_cond_init=DXPreconditioner(self)
GoodRun=False
while GoodRun==False:
try:
self.DP_low=0
self.DP_high=0
DP_converged=False
while DP_converged==False:
#Actually run the Newton-Raphson solver to get the solution
x=Broyden(OBJECTIVE_DXCycle,[DT_evap_init,DT_cond_init])
delta_low=abs(self.DP_low-abs(self.DP_LowPressure)/1000)
delta_high=abs(self.DP_high-abs(self.DP_HighPressure)/1000)
self.DP_low=abs(self.DP_LowPressure)/1000
self.DP_high=abs(self.DP_HighPressure)/1000
#Update the guess values based on last converged values
DT_evap_init=self.DT_evap
DT_cond_init=self.DT_cond
if delta_low<1 and delta_high<1:
DP_converged=True
if self.Verbosity>4:
print self.DP_HighPressure/1000,self.DP_LowPressure/1000,'DPHP'
GoodRun=True
except AttributeError:
# This will be a fatal error !! Should never have attribute error
raise
except:
print "-------------- Exception Caught ---------------- "
print "Error of type",sys.exc_info()[0]," is: " + sys.exc_info()[1].message
raise
if self.Verbosity>0:
print 'Capacity: ', self.Capacity
print 'COP: ',self.COP
print 'COP (w/ both fans): ',self.COSP
print 'SHR: ',self.SHR
print 'UA_r_evap',self.Evaporator.UA_r
print 'UA_a_evap',self.Evaporator.UA_a
print 'UA_r_cond',self.Condenser.UA_r
print 'UA_a_cond',self.Condenser.UA_a
class SecondaryCycleClass():
def __init__(self):
"""
Load up the necessary sub-structures to be filled with
the code that follows
"""
self.Compressor=CompressorClass()
#Outdoor coil is a Condenser in cooling mode and evaporator in heating mode
self.Condenser=CondenserClass()
self.Condenser.Fins=FinInputs()
self.Evaporator=EvaporatorClass()
self.Evaporator.Fins=FinInputs()
self.CoolingCoil=CoolingCoilClass()
self.CoolingCoil.Fins=FinInputs()
self.Pump=PumpClass()
#Add both types of internal heat exchangers
self.CoaxialIHX=CoaxialHXClass()
self.PHEIHX=PHEHXClass()
self.LineSetSupply=LineSetClass()
self.LineSetReturn=LineSetClass()
#Make IHX an empty class for holding parameters common to PHE and Coaxial IHX
class struct: pass
self.IHX=struct()
def OutputList(self):
"""
Return a list of parameters for this component for further output
It is a list of tuples, and each tuple is formed of items:
[0] Description of value
[1] Units of value
[2] The value itself
"""
return [
('Charge','kg',self.Charge),
('Condenser Subcooling','K',self.DT_sc),
('Primary Ref.','-',self.Ref),
('Secondary Ref.','-',self.SecLoopFluid),
('Imposed Variable','-',self.ImposedVariable),
('IHX Type','-',self.IHXType),
('COP','-',self.COP),
('COSP','-',self.COSP),
('Net Capacity','W',self.CoolingCoil.Capacity),
('Net Power','W',self.Power),
('SHR','-',self.SHR),
('Condensation temp (dew)','K',self.Tdew_cond),
('Evaporation temp (dew)','K',self.Tdew_evap),
]
def Calculate(self,DT_evap,DT_cond,Tin_CC):
"""
Inputs are differences in temperature [K] between HX air inlet temperature
and the dew temperature for the heat exchanger.
Required Inputs:
DT_evap:
Difference in temperature [K] between cooling coil air inlet temperature and refrigerant dew temperature
DT_cond:
Difference in temperature [K] between condenser air inlet temperature and refrigerant dew temperature
Tin_CC:
Inlet "glycol" temperature to line set feeding cooling coil
"""
if self.Verbosity>1:
print 'Inputs: DTevap %7.4f DTcond %7.4f fT_IHX %7.4f'%(DT_evap,DT_cond,Tin_CC)
#Store the values to save on computation for later
self.DT_evap=DT_evap
self.DT_cond=DT_cond
self.Tin_CC=Tin_CC
#If the user doesn't include the Mode, set it to Air Conditioning
if not hasattr(self,'Mode'):
self.Mode='AC'
if self.Mode=='AC':
self.Tdew_cond=self.Condenser.Fins.Air.Tdb+DT_cond
self.Tdew_evap=self.CoolingCoil.Fins.Air.Tdb-DT_evap
elif self.Mode=='HP':
self.Tdew_cond=Tin_CC+DT_cond
self.Tdew_evap=self.Evaporator.Fins.Air.Tdb-DT_evap
else:
raise ValueError('Mode must be AC or HP')
psat_cond=Props('P','T',self.Tdew_cond,'Q',1,self.Ref)
psat_evap=Props('P','T',self.Tdew_evap,'Q',1,self.Ref)
self.Tbubble_evap=Props('T','P',psat_evap,'Q',0,self.Ref)
self.Tbubble_cond=Props('T','P',psat_cond,'Q',0,self.Ref)
if self.Mode=='AC':
params={ #dictionary -> key:value, e.g. 'key':2345,
'pin_r': psat_evap+self.DP_low,
'pout_r': psat_cond-self.DP_high,
'Tin_r': self.Tdew_evap+self.PHEIHX.DT_sh, # TrhoPhase_ph(self.Ref,psat_evap,self.LineSetReturn.hout,self.Tbubble_evap,self.Tdew_evap)[0],
'Ref': self.Ref
}
self.Compressor.Update(**params)
self.Compressor.Calculate()
params={
'mdot_r': self.Compressor.mdot_r,
'Tin_r': self.Compressor.Tout_r,
'psat_r': psat_cond,
'Ref': self.Ref
}
self.Condenser.Update(**params)
self.Condenser.Calculate()
params={
'mdot': self.Pump.mdot_g,
'hin': Props('H','T',Tin_CC,'P',self.Pump.pin_g,self.SecLoopFluid)*1000,
}
self.LineSetSupply.Update(**params)
self.LineSetSupply.Calculate()
#Now run CoolingCoil to predict inlet glycol temperature to IHX
params={
'mdot_g': self.Pump.mdot_g,
'Tin_g': self.LineSetSupply.Tout,
}
self.CoolingCoil.Update(**params)
self.CoolingCoil.Calculate()
params={
'mdot': self.Pump.mdot_g,
'hin': Props('H','T',self.CoolingCoil.Tout_g,'P',self.Pump.pin_g,self.SecLoopFluid)*1000,
}
self.LineSetReturn.Update(**params)
self.LineSetReturn.Calculate()
if self.IHXType=='Coaxial':
params={
'mdot_g': self.Pump.mdot_g,
'Tin_g': self.CoolingCoil.Tout_g,
'pin_r': psat_evap,
'hin_r': self.Condenser.hout_r,
'Ref_r': self.Ref,
'mdot_r': self.Compressor.mdot_r,
}
self.CoaxialIHX.Update(**params)
self.CoaxialIHX.Calculate()
self.IHX.Charge_r=self.CoaxialIHX.Charge_r
self.IHX.Q=self.CoaxialIHX.Q
self.IHX.Tout_g=self.CoaxialIHX.Tout_g
self.IHX.DP_g=self.CoaxialIHX.DP_g
self.IHX.hout_r=self.CoaxialIHX.hout_r
self.IHX.DP_r=self.CoaxialIHX.DP_r
if hasattr(self,'PHEIHX'):
del self.PHEIHX
elif self.IHXType=='PHE':
params={
'mdot_h': self.Pump.mdot_g,
'hin_h': Props('H','T',self.CoolingCoil.Tout_g,'P',self.PHEIHX.pin_h,self.SecLoopFluid)*1000,
'mdot_c': self.Compressor.mdot_r,
'pin_c': psat_evap,
'hin_c': self.Condenser.hout_r,
}
self.PHEIHX.Update(**params)
self.PHEIHX.Calculate()
self.IHX.Charge_r=self.PHEIHX.Charge_c
self.IHX.Q=self.PHEIHX.Q
self.IHX.Tout_g=self.PHEIHX.Tout_h
self.IHX.DP_g=self.PHEIHX.DP_h
self.IHX.DP_r=self.PHEIHX.DP_c
self.IHX.hout_r=self.PHEIHX.hout_c
if hasattr(self,'CoaxialIHX'):
del self.CoaxialIHX
params={
'DP_g': self.IHX.DP_g+self.CoolingCoil.DP_g+self.LineSetSupply.DP+self.LineSetReturn.DP,
'Tin_g': self.CoolingCoil.Tout_g
}
self.Pump.Update(**params)
self.Pump.Calculate()
self.Charge=self.Condenser.Charge+self.IHX.Charge_r
self.EnergyBalance=self.Compressor.CycleEnergyIn+self.Condenser.Q+self.IHX.Q
self.DT_sc=(Props('H','T',self.Tbubble_cond,'Q',0,self.Ref)*1000-self.Condenser.hout_r)/(Props('C','T',self.Tbubble_cond,'Q',0,self.Ref)*1000)
deltaH_sc=self.Compressor.mdot_r*(Props('H','T',self.Tbubble_cond,'Q',0,self.Ref)*1000-Props('H','T',self.Tbubble_cond-self.DT_sc_target,'P',psat_cond,self.Ref)*1000)
# ## Plot a p-h plot
# Ph(self.Ref,hbounds=(100,500))
# pylab.plot([self.Compressor.hin_r/1000,self.Compressor.hout_r/1000,self.Condenser.hout_r/1000,self.PHEIHX.hin_c/1000,self.Compressor.hin_r/1000],[psat_evap,psat_cond,psat_cond,psat_evap,psat_evap])
# pylab.show()
resid=np.zeros((3))
resid[0]=self.Compressor.mdot_r*(self.Compressor.hin_r-self.IHX.hout_r)
if self.ImposedVariable=='Subcooling':
resid[1]=self.Condenser.DT_sc-self.DT_sc_target
elif self.ImposedVariable=='Charge':
resid[1]=self.Charge-self.Charge_target
# resid[2]=self.IHX.Q-self.CoolingCoil.Q+self.Pump.W
self.residSL=self.IHX.Q-self.CoolingCoil.Q+self.Pump.W+self.LineSetSupply.Q+self.LineSetReturn.Q
resid[2]=self.residSL
if self.Verbosity>7:
print 'Wcomp % 12.6e Qcond: % 12.6e QPHE %10.4f ' %(self.Compressor.W,self.Condenser.Q,self.IHX.Q)
if self.Verbosity>1:
print 'Qres % 12.6e Resid2: % 12.6e ResSL %10.4f Charge %10.4f SC: %8.4f' %(resid[0],resid[1],self.residSL,self.Charge,self.Condenser.DT_sc)
self.Capacity=self.CoolingCoil.Capacity
self.COP=self.CoolingCoil.Q/self.Compressor.W
self.COSP=self.CoolingCoil.Capacity/(self.Compressor.W+self.Pump.W+self.CoolingCoil.Fins.Air.FanPower+self.Condenser.Fins.Air.FanPower)
self.SHR=self.CoolingCoil.SHR
self.Power=self.Compressor.W+self.Pump.W+self.CoolingCoil.Fins.Air.FanPower+self.Condenser.Fins.Air.FanPower
self.DP_high_Model=self.Condenser.DP_r #[Pa]
self.DP_low_Model=self.IHX.DP_r #[Pa]
elif self.Mode=='HP':
if psat_evap+self.DP_low<0:
raise ValueError('Compressor inlet pressure less than zero ['+str(psat_evap+self.DP_low)+' kPa] - is low side pressure drop too high?')
params={ #dictionary -> key:value, e.g. 'key':2345,
'pin_r': psat_evap+self.DP_low,
'pout_r': psat_cond-self.DP_high,
'Tin_r': self.Tdew_evap+self.Evaporator.DT_sh, # TrhoPhase_ph(self.Ref,psat_evap,self.LineSetReturn.hout,self.Tbubble_evap,self.Tdew_evap)[0],
'Ref': self.Ref
}
self.Compressor.Update(**params)
self.Compressor.Calculate()
params={
'mdot': self.Pump.mdot_g,
'hin': Props('H','T',Tin_CC,'P',self.Pump.pin_g,self.SecLoopFluid)*1000,
}
self.LineSetSupply.Update(**params)
self.LineSetSupply.Calculate()
#Now run CoolingCoil to predict inlet glycol temperature to IHX
params={
'mdot_g': self.Pump.mdot_g,
'Tin_g': self.LineSetSupply.Tout,
}
self.CoolingCoil.Update(**params)
self.CoolingCoil.Calculate()
params={
'mdot': self.Pump.mdot_g,
'hin': Props('H','T',self.CoolingCoil.Tout_g,'P',self.Pump.pin_g,self.SecLoopFluid)*1000,
}
self.LineSetReturn.Update(**params)
self.LineSetReturn.Calculate()
params={
'mdot_h': self.Compressor.mdot_r,
'hin_h': self.Compressor.hout_r,
'pin_h': psat_cond,
'mdot_c': self.Pump.mdot_g,
'hin_c': Props('H','T',self.LineSetReturn.Tout,'P',self.PHEIHX.pin_c,self.SecLoopFluid)*1000,
}
self.PHEIHX.Update(**params)
self.PHEIHX.Calculate()
params={
'mdot_r': self.Compressor.mdot_r,
'psat_r': psat_evap,
'hin_r': self.PHEIHX.hout_h,
'Ref': self.Ref
}
self.Evaporator.Update(**params)
self.Evaporator.Calculate()
params={
'DP_g': self.PHEIHX.DP_c+self.CoolingCoil.DP_g,
'Tin_g': self.CoolingCoil.Tout_g
}
self.Pump.Update(**params)
self.Pump.Calculate()
self.Charge=self.Evaporator.Charge+self.PHEIHX.Charge_h
#Calculate an effective subcooling amount by deltah/cp_satL
#Can be positive or negative (negative is quality at outlet
self.DT_sc=self.PHEIHX.DT_sc_h#(Props('H','T',self.Tbubble_cond,'Q',0,self.Ref)*1000-self.PHEIHX.hout_h)/(Props('C','T',self.Tbubble_cond,'Q',0,self.Ref)*1000)
deltaH_sc=self.Compressor.mdot_r*(Props('H','T',self.Tbubble_cond,'Q',0,self.Ref)*1000-Props('H','T',self.Tbubble_cond-self.DT_sc_target,'P',psat_cond,self.Ref)*1000)
resid=np.zeros((3))
resid[0]=self.Compressor.mdot_r*(self.Compressor.hin_r-self.Evaporator.hout_r)
if self.ImposedVariable=='Subcooling':
resid[1]=self.DT_sc-self.DT_sc_target
elif self.ImposedVariable=='Charge':
resid[1]=self.Charge-self.Charge_target
self.residSL=self.PHEIHX.Q+self.CoolingCoil.Q+self.Pump.W+self.LineSetSupply.Q+self.LineSetReturn.Q
resid[2]=self.residSL
if self.Verbosity>1:
print 'Qres % 12.6e Resid2: % 12.6e ResSL %10.4f Charge %10.4f SC: %8.4f' %(resid[0],resid[1],self.residSL,self.Charge,self.DT_sc)
self.Capacity=-self.CoolingCoil.Q+self.CoolingCoil.Fins.Air.FanPower
self.COP=-self.CoolingCoil.Q/self.Compressor.W
self.COSP=self.Capacity/(self.Compressor.W+self.Pump.W+self.CoolingCoil.Fins.Air.FanPower+self.Evaporator.Fins.Air.FanPower)
self.Power=self.Compressor.W+self.Pump.W+self.CoolingCoil.Fins.Air.FanPower+self.Evaporator.Fins.Air.FanPower
self.SHR=-self.CoolingCoil.SHR
self.DP_high_Model=self.PHEIHX.DP_h #[Pa]
self.DP_low_Model=self.Evaporator.DP_r #[Pa]
self.DT_evap=DT_evap
self.DT_cond=DT_cond
return resid
def PreconditionedSolve(self,PrecondValues=None):
'''
PrecondValues = dictionary of values DT_evap, DT_cond and Tin_CC
'''
def OBJECTIVE(x):
"""
Takes the place of a lambda function since lambda functions do not bubble error properly
"""
return self.Calculate(x[0],x[1],x[2])
def OBJECTIVE2(x,Tin):
"""
Takes the place of a lambda function since lambda functions do not bubble error properly
"""
return self.Calculate(x[0],x[1],Tin)
def OBJECTIVE_SL(Tin_CC):
"""
Objective function for the inner loop of the vapor compression system
Using the MultiDimNewtRaph function will re-evaluate the Jacobian at
every step. Slower, but more robust since the solution surfaces aren't
smooth enough
Note: This function is not currently used!
"""
x=MultiDimNewtRaph(OBJECTIVE2,[self.DT_evap,self.DT_cond],args=(Tin_CC,))
# Update the guess values for Delta Ts starting
# at the third step (after at least one update away
# from the boundaries)
if self.OBJ_SL_counter>=0:
self.DT_evap=x[0]
self.DT_cond=x[1]
pass
self.OBJ_SL_counter+=1
return self.residSL
def PrintDPs():
print 'DP_LP :: Input:',self.DP_low,'kPa / Model calc:',self.DP_low_Model/1000,'kPa'
print 'DP_HP :: Input:',self.DP_high,'kPa / Model calc:',self.DP_high_Model/1000,'kPa'
#Some variables need to be initialized
self.DP_low=0 #The actual low-side pressure drop to be used in kPa
self.DP_high=0 #The actual low-side pressure drop to be used in kPa
self.OBJ_SL_counter=0
#Run the preconditioner to get guess values for the temperatures
if PrecondValues is None:
self.DT_evap,self.DT_cond,Tin_CC=SecondaryLoopPreconditioner(self)
else:
self.DT_evap=PrecondValues['DT_evap']
self.DT_cond=PrecondValues['DT_cond']
Tin_CC=PrecondValues['Tin_CC']
#Remove the other, non-used IHX class if found
if self.IHXType=='PHE':
if hasattr(self,'CoaxialIHX'):
del self.CoaxialIHX
else:
if hasattr(self,'PHEIHX'):
del self.PHEIHX
#Remove the condenser if in heating mode and condenser found
if self.Mode=='HP':
if hasattr(self,'Condenser'):
del self.Condenser
iter=1
max_error_DP=999
#Outer loop with a more relaxed convergence criterion
while max_error_DP>0.5:
iter_inner=1
#Inner loop to determine pressure drop for high and low sides
while max_error_DP>0.05 and iter_inner<10:
#Run to calculate the pressure drop as starting point
OBJECTIVE([self.DT_evap,self.DT_cond,Tin_CC])
#Calculate the max error
max_error_DP=max([abs(self.DP_low_Model/1000-self.DP_low),abs(self.DP_high_Model/1000-self.DP_high)])
if self.Verbosity>0:
PrintDPs()
print 'Max pressure drop error [inner loop] is',max_error_DP,'kPa'
#Update the pressure drop terms
self.DP_low=self.DP_low_Model/1000
self.DP_high=self.DP_high_Model/1000
iter_inner+=1
if self.Verbosity > 0:
print "Done with the inner loop on pressure drop"
# Use Newton-Raphson solver
(self.DT_evap,self.DT_cond,Tin_CC)=MultiDimNewtRaph(OBJECTIVE,[self.DT_evap,self.DT_cond,Tin_CC],dx=0.1)
#Calculate the error
max_error_DP=max([abs(self.DP_low_Model/1000-self.DP_low),abs(self.DP_high_Model/1000-self.DP_high)])
if self.Verbosity>0:
PrintDPs()
print 'Max pressure drop error [outer loop] is',max_error_DP,'kPa'
if self.Verbosity>1:
print 'Capacity: ', self.Capacity
print 'COP: ',self.COP
print 'COP (w/ both fans): ',self.COSP
print 'SHR: ',self.SHR
return
Fins.Fins.k_fin = 237 #Thermal conductivity of fin material
Fins.Air.Vdot_ha = 1.7934 #rated volumetric flowrate
Fins.Air.Tdb = 308.15 #Dry Bulb Temperature
Fins.Air.p = 101325 #Air pressure in Pa
Fins.Air.RH = 0.51 #Relative Humidity
Fins.Air.FanPower = 160
params = {
'Ref': 'R410A',
'mdot_r': 0.0708,
'Tin_r': 333.15,
'psat_r': PropsSI('P', 'T', 323.15, 'Q', 1.0, 'R410A'),
'Fins': Fins,
'FinsType':
'WavyLouveredFins', #WavyLouveredFins, HerringboneFins, PlainFins
'Verbosity': 0,
'Backend':
'TTSE&HEOS' #choose between: 'HEOS','TTSE&HEOS','BICUBIC&HEOS','REFPROP','SRK','PR'
}
Cond = CondenserClass(**params)
Cond.Calculate()
print 'Heat transfer rate in condenser is', Cond.Q, 'W'
print 'Heat transfer rate in condenser (superheat section) is', Cond.Q_superheat, 'W'
print 'Heat transfer rate in condenser (twophase section) is', Cond.Q_2phase, 'W'
print 'Heat transfer rate in condenser (subcooled section) is', Cond.Q_subcool, 'W'
print 'Fraction of circuit length in superheated section is', Cond.w_superheat
print 'Fraction of circuit length in twophase section is', Cond.w_2phase
print 'Fraction of circuit length in subcooled section is', Cond.w_subcool
class SecondaryCycleClass():
def __init__(self):
"""
Load up the necessary sub-structures to be filled with
the code that follows
"""
self.Compressor=CompressorClass()
self.Condenser=CondenserClass()
self.Condenser.Fins=FinInputs()
self.CoolingCoil=CoolingCoilClass()
self.CoolingCoil.Fins=FinInputs()
self.PHEHX=PHEHXClass()
self.Pump=PumpClass()
def Calculate(self,DT_evap,DT_cond,Tin_IHX):
"""
Inputs are differences in temperature [K] between HX air inlet temperature
and the dew temperature for the heat exchanger.
Required Inputs:
DT_evap:
Difference in temperature [K] between cooling coil air inlet temperature and refrigerant dew temperature
DT_cond:
Difference in temperature [K] between condenser air inlet temperature and refrigeant dew temperature
Tin_IHX:
Inlet "glycol" temperature to IHX
"""
if self.Verbosity>1:
print 'Inputs: DTevap %7.4f DTcond %7.4f fT_IHX %7.4f'%(DT_evap,DT_cond,Tin_IHX)
#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.Backend = 'HEOS'
self.AS = AS
#AbstractState for SecLoopFluid
if hasattr(self,'Backend_SLF'): #check if backend_SLF is given
AS_SLF = CP.AbstractState(self.Backend_SLF, self.SecLoopFluid)
if hasattr(self,'MassFrac_SLF'):
AS_SLF.set_mass_fractions([self.MassFrac_SLF])
else: #otherwise, use the defualt backend
AS_SLF = CP.AbstractState('HEOS', self.SecLoopFluid)
self.Backend_SLF = 'HEOS'
self.AS_SLF = AS_SLF
"""
The coldest the glycol entering the cooling coil could be would be the
"""
self.Tdew_cond=self.Condenser.Fins.Air.Tdb+DT_cond
self.Tdew_evap=self.CoolingCoil.Fins.Air.Tdb-DT_evap
AS.update(CP.QT_INPUTS,1.0,self.Tdew_cond)
psat_cond=AS.p() #[Pa]
AS.update(CP.QT_INPUTS,1.0,self.Tdew_evap)
psat_evap=AS.p() #[Pa]
AS.update(CP.PQ_INPUTS,psat_evap,0.0)
self.Tbubble_evap=AS.T() #[K]
params={ #dictionary -> key:value, e.g. 'key':2345,
'pin_r': psat_evap,
'pout_r': psat_cond,
'Tin_r': self.Tdew_evap+self.Compressor.DT_sh,
'Ref': self.Ref,
'Backend': self.Backend
}
self.Compressor.Update(**params)
self.Compressor.Calculate()
params={
'mdot_r': self.Compressor.mdot_r,
'Tin_r': self.Compressor.Tout_r,
'psat_r': psat_cond,
'Ref': self.Ref,
'Backend': self.Backend
}
self.Condenser.Update(**params)
self.Condenser.Calculate()
AS.update(CP.QT_INPUTS,0.0,self.Tbubble_evap)
hL=AS.hmass() #[J/kg]
AS.update(CP.QT_INPUTS,1.0,self.Tdew_evap)
hV=AS.hmass() #[J/kg]
xin_r=(self.Condenser.hout_r-hL)/(hV-hL)
AS_SLF.update(CP.PT_INPUTS,300000,Tin_IHX)
h_in = AS_SLF.hmass() #[J/kg]
params={
'mdot_h': self.Pump.mdot_g,
'hin_h': h_in,
'hin_c': self.Condenser.hout_r,
'mdot_c': self.Compressor.mdot_r,
'pin_c': psat_evap,
'xin_c': xin_r
}
self.PHEHX.Update(**params)
self.PHEHX.Calculate()
#Now run CoolingCoil to predict inlet glycol temperature to IHX
params={
'mdot_g': self.Pump.mdot_g,
'Tin_g': self.PHEHX.Tout_h,
}
self.CoolingCoil.Update(**params)
self.CoolingCoil.Calculate()
params={
'DP_g': self.PHEHX.DP_h+self.CoolingCoil.DP_g,
'Tin_g': self.CoolingCoil.Tout_g
}
self.Pump.Update(**params)
self.Pump.Calculate()
self.Charge=self.Condenser.Charge+self.PHEHX.Charge_c
self.EnergyBalance=self.Compressor.CycleEnergyIn+self.Condenser.Q+self.PHEHX.Q
resid=np.zeros((3))
resid[0]=self.EnergyBalance
if self.ImposedVariable=='Subcooling':
resid[1]=self.Condenser.DT_sc-self.DT_sc_target
elif self.ImposedVariable=='Charge':
resid[1]=self.Charge-self.Charge_target
resid[2]=self.PHEHX.Q-self.CoolingCoil.Q
if self.Verbosity>1:
print 'Qres % 12.6e Resid2: % 12.6e ResSL %10.4f Charge %10.4f SC: %8.4f' %(resid[0],resid[1],resid[2],self.Charge,self.Condenser.DT_sc)
self.Capacity=self.CoolingCoil.Capacity
self.COP=self.CoolingCoil.Q/self.Compressor.W
self.COSP=self.CoolingCoil.Capacity/(self.Compressor.W+self.Pump.W+self.CoolingCoil.Fins.Air.FanPower+self.Condenser.Fins.Air.FanPower)
self.SHR=self.CoolingCoil.SHR
return resid
def PreconditionedSolve(self):
# Takes the place of a lambda function since lambda functions do not
# bubble the error up properly
def OBJECTIVE(x):
return self.Calculate(x[0],x[1],x[2])
# Increase DT_evap in increments of 0.5 K until the system solves, and
# two steps cause a sign change in cycle energy balance
# Should give a starting point quite close to the "right" soluton
oldDT_evap=None
oldQresid=None
Tin_IHX=None
for DT_evap in np.linspace(12,25,21):
try:
#Run the cooler to get a good starting inlet temperature for IHX
self.CoolingCoil.mdot_g=self.Pump.mdot_g
self.CoolingCoil.Tin_g=self.CoolingCoil.Fins.Air.Tdb-DT_evap
self.CoolingCoil.Calculate()
Tin_IHX=self.CoolingCoil.Tout_g
resid=self.Calculate(DT_evap,8,Tin_IHX)
except Exception,e:
if self.Verbosity>1:
print 'Failed: ',e.__str__()
raise
pass
else:
#Not set yet, first one that works
if oldQresid==None:
oldQresid=resid[0]
oldDT_evap=DT_evap
#Has been set, and sign changes, use average of old and new DT
elif oldQresid*resid[0]<0:
DT_evap=(DT_evap+oldDT_evap)/2
break
#Run the Newton-Raphson solver to solve the system
x=fsolve(OBJECTIVE,[DT_evap,20,Tin_IHX])
if self.Verbosity>1:
print 'Capacity: ', self.Capacity
print 'COP: ',self.COP
print 'COP (w/ both fans): ',self.COSP
print 'SHR: ',self.SHR