KeyError: 'H2O'

[muhammadbagusd]

Hello!

I am quite new to TESpy and so far I have learned the heat pump and Rankine Cycle Basic from modeling the basic system. I tried to customize the heat pump a bit and connect the condenser to the heat exchanger to store the heat. But somehow I get this KeyError: 'H2O', although I have already defined the fluid properties as in the previous basic model (heat pump and Rankine Cycle).

I would like to ask here and hope to find the answer, thanks in advance and wish you all a nice weekend :)

from tespy.components import (Compressor, Condenser ,SimpleHeatExchanger, HeatExchanger,Pump, Turbine, Valve, CycleCloser, Source, Sink)
from tespy.connections import Connection
from tespy.networks import Network

nw = Network(p_unit='bar', T_unit='C', h_unit='kJ / kg')

hp_compressor = Compressor('HP Compressor')
hp_condenser = Condenser('HP Condenser')  # Transfers heat to hot storage
hp_valve = Valve('HP Expansion Valve')
hp_evaporator = HeatExchanger('HP Evaporator')
hp_closer = CycleCloser('HP Cycle Closer')  # Closes the heat pump loop

hp_ambient_source = Source('hp Ambient Source')
hp_ambient_sink = Sink('hp Ambient Sink')

hp_c1 = Connection(hp_closer, 'out1', hp_evaporator, 'in1')
hp_c2 = Connection(hp_evaporator, 'out1', hp_compressor, 'in1')
hp_c3 = Connection(hp_compressor, 'out1', hp_condenser, 'in1')
hp_c4 = Connection(hp_condenser, 'out1', hp_valve, 'in1')
hp_c5 = Connection(hp_valve, 'out1', hp_closer, 'in1')

nw.add_conns(hp_c1, hp_c2, hp_c3, hp_c4, hp_c5)

storage_interface = HeatExchanger('Storage Interface')

hp_charging_cold = Connection(storage_interface, 'out1', hp_condenser, 'in2')
hp_charging_hot = Connection(hp_condenser, 'out2', storage_interface, 'in1')

nw.add_conns(hp_charging_hot, hp_charging_cold)

storage_so = Source('storage Source')
storage_si = Sink('storage Sink')

connection_so = Connection(storage_so, 'out1', storage_interface, 'in2')
connection_si = Connection(storage_interface, 'out2', storage_si, 'in1')

connection_so.set_attr(T=20, p=1.2, fluid={'water': 1})
connection_si.set_attr(T=30)

nw.add_conns(connection_so, connection_si)

hp_ambient_c1 = Connection(hp_ambient_source, 'out1', hp_evaporator, 'in2')
hp_ambient_c2 = Connection(hp_evaporator, 'out2', hp_ambient_sink, 'in1')
nw.add_conns(hp_ambient_c1, hp_ambient_c2)#, c11, c12)

hp_compressor.set_attr(eta_s=0.85)
hp_condenser.set_attr(pr1=1, pr2=0.98)
hp_valve.set_attr(pr=1)  # Assuming no pressure drop
hp_evaporator.set_attr(pr1=1, pr2=0.98)

hp_c2.set_attr(T=20, x=1, fluid={'R134a': 1})
hp_c4.set_attr(T=80, x=0)

hp_ambient_c1.set_attr(T=25, fluid={'R134a': 1})
hp_ambient_c2.set_attr(T=15)

hp_charging_cold.set_attr(T=70)
hp_charging_hot.set_attr(T=80, fluid={"IF97::H2O": 1})

nw.solve(mode='design')
nw.print_results()

[fwitte]

Hi @muhammadbagusd,

thank you for reaching out, this looks like a bug with a small "but". The but is, that this setup would not work anyway in that part of the system. You form a cycle by connecting the storage interface heat exchanger with a condenser and that back to the storage interface heat exchanger without the use of a cycle closer in between. By modifying your script like this, the error is gone

hp_charging_cold = Connection(storage_interface, 'out1', hp_condenser, 'in2')
hp_charging_hot_cc = Connection(hp_condenser, 'out2', storage_closer, 'in1')
hp_charging_hot = Connection(storage_closer, 'out1', storage_interface, 'in1')

nw.add_conns(hp_charging_hot, hp_charging_hot_cc, hp_charging_cold)

Best

Francesco