As usual,I would appreciate your help and advice here,am currently stuck and helpless

[Geminiman7]

# -*- coding: utf-8 -*-
"""
Created on Sun Aug  4 20:12:52 2024

@author: ENGR. OGBORU REWARD
"""

import tespy
import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
from tespy.networks import Network
from tespy.components import Sink, Source, Pump, HeatExchangerSimple, Valve, Compressor, CycleCloser,Condenser
from tespy.connections import Connection, Bus
from tespy.tools.characteristics import CharLine
from tespy.tools.characteristics import load_default_char as ldc

# Define the working fluid
fluid_list = ['R404A']

# Network setup
network = Network(fluids=fluid_list, T_unit='C', p_unit='bar', h_unit='kJ / kg', m_unit='kg / s')


# Define components
storage_tank = HeatExchangerSimple('Evaporator')
condenser =HeatExchangerSimple('Condenser')
expansion_valve = Valve('Expansion Valve')
compressor = Compressor('Compressor')
air_cooler = HeatExchangerSimple('Air Cooler')

# Cycle Closer to ensure the fluid returns to the cycle
cycle_closer = CycleCloser('Cycle Closer')
# Connecting components together

#R404A enters the compressor
conn_cycle_closer_compressor = Connection(cycle_closer , 'out1', compressor, 'in1')

# From compressor to condenser
conn_compressor_condenser = Connection(compressor, 'out1', condenser, 'in1')

# From condenser to expansion valve
conn_condenser_valve = Connection(condenser, 'out1', expansion_valve, 'in1')

# From expansion valve to air cooler
conn_valve_air_cooler = Connection(expansion_valve, 'out1', air_cooler, 'in1')

# Air cooler to ice storage tank
conn_air_cooler_storage_tank = Connection(air_cooler, 'out1', storage_tank, 'in1')

# Ice storage tank to sink (closing the loop)
conn_storage_tank_cycle_closer = Connection(storage_tank, 'out1', cycle_closer , 'in1')


# Add connections to the network
network.add_conns( conn_cycle_closer_compressor,conn_compressor_condenser, conn_condenser_valve,
                  conn_valve_air_cooler, conn_air_cooler_storage_tank, conn_storage_tank_cycle_closer)

# Define Components Geometry

# Set compressor parameters
compressor.set_attr(eta_s=0.85)

# Set condenser parameters
condenser.set_attr(pr=0.98, Q=200)

# Set expansion valve parameters
expansion_valve.set_attr(pr=0.6)

# Set storage tank parameters
storage_tank.set_attr(pr=0.98,Q=-200)

# Air cooler parameters
air_cooler.set_attr(pr=0.98)

# Set source and sink conditions
conn_cycle_closer_compressor.set_attr(T=25, p=16.3)
conn_cycle_closer_compressor.set_attr(fluid={'R404A': 50.7})
# Set attributes for the connection from compressor to condenser
#conn_compressor_condenser.set_attr(p=14.3)

# Set attributes for the connection from condenser to expansion valve
conn_condenser_valve.set_attr(T=-25)


network.solve('design')
network.print_results()

# Reference state for exergy analysis
T0 = 298.15  # Reference temperature (K)
p0 = 1.013  # Reference pressure (bar)

for conn in network.conns.all():
    h = conn.h.val_SI  # Enthalpy (J/kg)
    s = conn.s.val_SI  # Entropy (J/(kg K))
    exergy = (h - 0) - T0 * (s - 0)  # Simplified exergy calculation (assuming h_ref and s_ref are zero)
    print(f'Exergy at connection {conn.label}: {exergy} J/kg')

I keep getting these errors,please guys if anything is wrong with my flow attributes,just show me the way out

[fwitte]

@Geminiman7, the issue here is that you do not actually iterate over the connection objects. You can do this by modifying the for loop:

for conn in network.conns["object"]:

Apart from that, if you are expecting help from people here, you should

• actually ask questions and not just put something in the title
• use a meaningful title
• provide context to what your problem is (what do you want to model, what is the problem)