Ejemplo n.º 1
0
class TestReactors:
    def setup(self):
        """Set up network for electrolyzer tests."""
        self.nw = Network(['O2', 'H2', 'H2O'], T_unit='C', p_unit='bar')
        self.instance = WaterElectrolyzer('electrolyzer')

        fw = Source('feed water')
        cw_in = Source('cooling water')
        o2 = Sink('oxygen sink')
        h2 = Sink('hydrogen sink')
        cw_out = Sink('cooling water sink')

        self.instance.set_attr(pr=0.99, eta=1)

        cw_el = Connection(cw_in,
                           'out1',
                           self.instance,
                           'in1',
                           fluid={
                               'H2O': 1,
                               'H2': 0,
                               'O2': 0
                           },
                           T=20,
                           p=1)
        el_cw = Connection(self.instance, 'out1', cw_out, 'in1', T=45)

        self.nw.add_conns(cw_el, el_cw)

        fw_el = Connection(fw, 'out1', self.instance, 'in2', label='h2o')
        el_o2 = Connection(self.instance, 'out2', o2, 'in1')
        el_h2 = Connection(self.instance, 'out3', h2, 'in1', label='h2')

        self.nw.add_conns(fw_el, el_o2, el_h2)

    def test_WaterElectrolyzer(self):
        """Test component properties of water electrolyzer."""
        # check bus function:
        # power output on component and bus must be indentical
        self.nw.get_conn('h2o').set_attr(T=25, p=1)
        self.nw.get_conn('h2').set_attr(T=25)
        power = Bus('power')
        power.add_comps({'comp': self.instance, 'param': 'P', 'base': 'bus'})
        power.set_attr(P=2.5e6)
        self.nw.add_busses(power)

        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        msg = ('Value of power must be ' + str(power.P.val) + ', is ' +
               str(self.instance.P.val) + '.')
        assert round(power.P.val, 1) == round(self.instance.P.val), msg

        # effieciency was set to 100 % with inlet and outlet states of the
        # reaction educts and products beeing identical to reference state
        # therefore Q must be equal to 0
        msg = ('Value of heat output must be 0.0, is ' +
               str(self.instance.Q.val) + '.')
        assert round(self.instance.Q.val, 4) == 0.0, msg

        # reset power, change efficiency value and specify heat bus value
        power.set_attr(P=np.nan)
        self.nw.get_conn('h2o').set_attr(T=25, p=1)
        self.nw.get_conn('h2').set_attr(T=50)
        self.instance.set_attr(eta=0.8)
        # check bus function:
        # heat output on component and bus must be indentical
        heat = Bus('heat')
        heat.add_comps({'comp': self.instance, 'param': 'Q'})
        heat.set_attr(P=-8e5)
        self.nw.add_busses(heat)

        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        msg = ('Value of heat flow must be ' + str(heat.P.val) + ', is ' +
               str(self.instance.Q.val) + '.')
        assert round(heat.P.val, 1) == round(self.instance.Q.val), msg
        self.nw.save('tmp')

        # check bus function:
        # heat output on component and bus must identical (offdesign test)
        Q = heat.P.val * 0.9
        heat.set_attr(P=Q)
        self.nw.solve('offdesign', design_path='tmp')
        convergence_check(self.nw.lin_dep)
        msg = ('Value of heat flow must be ' + str(Q) + ', is ' +
               str(self.instance.Q.val) + '.')
        assert round(Q, 1) == round(self.instance.Q.val), msg

        # delete both busses again
        self.nw.del_busses(heat, power)

        # test efficiency vs. specific energy consumption
        self.nw.get_conn('h2').set_attr(m=0.1)
        self.instance.set_attr(eta=0.9, e='var')
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        msg = ('Value of efficiency must be ' + str(self.instance.eta.val) +
               ', is ' + str(self.instance.e0 / self.instance.e.val) + '.')
        eta = round(self.instance.eta.val, 2)
        eta_calc = round(self.instance.e0 / self.instance.e.val, 2)
        assert eta == eta_calc, msg

        # test efficiency value > 1, Q must be larger than 0
        e = 130e6
        self.instance.set_attr(e=np.nan, eta=np.nan)
        self.instance.set_attr(e=e)
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        # test efficiency
        msg = ('Value of efficiency must be ' + str(self.instance.e0 / e) +
               ', is ' + str(self.instance.eta.val) + '.')
        eta = round(self.instance.e0 / e, 2)
        eta_calc = round(self.instance.eta.val, 2)
        assert eta == eta_calc, msg
        # test Q
        msg = ('Value of heat must be larger than zero, is ' +
               str(self.instance.Q.val) + '.')
        assert self.instance.Q.val > 0, msg

        # test specific energy consumption
        e = 150e6
        self.instance.set_attr(e=np.nan, eta=np.nan)
        self.instance.set_attr(e=e)
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        msg = ('Value of specific energy consumption e must be ' + str(e) +
               ', is ' + str(self.instance.e.val) + '.')
        assert round(e, 1) == round(self.instance.e.val, 1), msg

        # test cooling loop pressure ratio, zeta as variable value
        pr = 0.95
        self.instance.set_attr(pr=pr,
                               e=None,
                               eta=None,
                               zeta='var',
                               P=2e7,
                               design=['pr'])
        self.nw.solve('design')
        shutil.rmtree('./tmp', ignore_errors=True)
        self.nw.save('tmp')
        convergence_check(self.nw.lin_dep)
        msg = ('Value of pressure ratio must be ' + str(pr) + ', is ' +
               str(self.instance.pr.val) + '.')
        assert round(pr, 2) == round(self.instance.pr.val, 2), msg

        # use zeta as offdesign parameter, at design point pressure
        # ratio must not change
        self.instance.set_attr(zeta=np.nan, offdesign=['zeta'])
        self.nw.solve('offdesign', design_path='tmp')
        convergence_check(self.nw.lin_dep)
        msg = ('Value of pressure ratio must be ' + str(pr) + ', is ' +
               str(self.instance.pr.val) + '.')
        assert round(pr, 2) == round(self.instance.pr.val, 2), msg

        # test heat output specification in offdesign mode
        Q = self.instance.Q.val * 0.9
        self.instance.set_attr(Q=Q, P=np.nan)
        self.nw.solve('offdesign', design_path='tmp')
        convergence_check(self.nw.lin_dep)
        msg = ('Value of heat must be ' + str(Q) + ', is ' +
               str(self.instance.Q.val) + '.')
        assert round(Q, 0) == round(self.instance.Q.val, 0), msg
        shutil.rmtree('./tmp', ignore_errors=True)
Ejemplo n.º 2
0
class TestClausiusRankine:
    def setup(self):
        """Set up clausis rankine cycle with turbine driven feed water pump."""
        self.Tamb = 20
        self.pamb = 1
        fluids = ['water']
        self.nw = Network(fluids=fluids)
        self.nw.set_attr(p_unit='bar', T_unit='C', h_unit='kJ / kg')

        # create components
        splitter1 = Splitter('splitter 1')
        merge1 = Merge('merge 1')
        turb = Turbine('turbine')
        fwp_turb = Turbine('feed water pump turbine')
        condenser = HeatExchangerSimple('condenser')
        fwp = Pump('pump')
        steam_generator = HeatExchangerSimple('steam generator')
        cycle_close = CycleCloser('cycle closer')

        # create busses
        # power output bus
        self.power = Bus('power_output')
        self.power.add_comps({'comp': turb, 'char': 1})
        # turbine driven feed water pump internal bus
        self.fwp_power = Bus('feed water pump power', P=0)
        self.fwp_power.add_comps({
            'comp': fwp_turb,
            'char': 1
        }, {
            'comp': fwp,
            'char': 1,
            'base': 'bus'
        })
        # heat input bus
        self.heat = Bus('heat_input')
        self.heat.add_comps({'comp': steam_generator, 'base': 'bus'})
        self.nw.add_busses(self.power, self.fwp_power, self.heat)

        # create connections
        fs_in = Connection(cycle_close, 'out1', splitter1, 'in1', label='fs')
        fs_fwpt = Connection(splitter1, 'out1', fwp_turb, 'in1')
        fs_t = Connection(splitter1, 'out2', turb, 'in1')
        fwpt_ws = Connection(fwp_turb, 'out1', merge1, 'in1')
        t_ws = Connection(turb, 'out1', merge1, 'in2')
        ws = Connection(merge1, 'out1', condenser, 'in1')
        cond = Connection(condenser, 'out1', fwp, 'in1', label='cond')
        fw = Connection(fwp, 'out1', steam_generator, 'in1', label='fw')
        fs_out = Connection(steam_generator, 'out1', cycle_close, 'in1')
        self.nw.add_conns(fs_in, fs_fwpt, fs_t, fwpt_ws, t_ws, ws, cond, fw,
                          fs_out)

        # component parameters
        turb.set_attr(eta_s=1)
        fwp_turb.set_attr(eta_s=1)
        condenser.set_attr(pr=1)
        fwp.set_attr(eta_s=1)
        steam_generator.set_attr(pr=1)

        # connection parameters
        fs_in.set_attr(m=10, p=120, T=600, fluid={'water': 1})
        cond.set_attr(T=self.Tamb, x=0)

        # solve network
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)

    def test_exergy_analysis_perfect_cycle(self):
        """Test exergy analysis in the perfect clausius rankine cycle."""
        ean = ExergyAnalysis(self.nw,
                             E_P=[self.power],
                             E_F=[self.heat],
                             internal_busses=[self.fwp_power])
        ean.analyse(pamb=self.pamb, Tamb=self.Tamb)
        msg = ('Exergy destruction of this network must be 0 (smaller than ' +
               str(err**0.5) + ') for this test but is ' +
               str(round(abs(ean.network_data.E_D), 4)) + ' .')
        assert abs(ean.network_data.E_D) <= err**0.5, msg

        msg = ('Exergy efficiency of this network must be 1 for this test but '
               'is ' + str(round(ean.network_data.epsilon, 4)) + ' .')
        assert round(ean.network_data.epsilon, 4) == 1, msg

        exergy_balance = (ean.network_data.E_F - ean.network_data.E_P -
                          ean.network_data.E_L - ean.network_data.E_D)
        msg = ('Exergy balance must be closed (residual value smaller than ' +
               str(err**0.5) + ') for this test but is ' +
               str(round(abs(exergy_balance), 4)) + ' .')
        assert abs(exergy_balance) <= err**0.5, msg

        msg = (
            'Fuel exergy and product exergy must be identical for this test. '
            'Fuel exergy value: ' + str(round(ean.network_data.E_F, 4)) +
            '. Product exergy value: ' + str(round(ean.network_data.E_P, 4)) +
            '.')
        delta = round(abs(ean.network_data.E_F - ean.network_data.E_P), 4)
        assert delta < err**0.5, msg

    def test_exergy_analysis_plotting_data(self):
        """Test exergy analysis plotting."""
        self.nw.get_comp('steam generator').set_attr(pr=0.9)
        self.nw.get_comp('turbine').set_attr(eta_s=0.9)
        self.nw.get_comp('feed water pump turbine').set_attr(eta_s=0.85)
        self.nw.get_comp('pump').set_attr(eta_s=0.75)
        self.nw.get_conn('cond').set_attr(T=self.Tamb + 3)

        # specify efficiency values for the internal bus and power bus
        self.nw.del_busses(self.fwp_power, self.power)

        self.fwp_power = Bus('feed water pump power', P=0)
        self.fwp_power.add_comps(
            {
                'comp': self.nw.get_comp('feed water pump turbine'),
                'char': 0.99
            }, {
                'comp': self.nw.get_comp('pump'),
                'char': 0.98,
                'base': 'bus'
            })
        self.power = Bus('power_output')
        self.power.add_comps({
            'comp': self.nw.get_comp('turbine'),
            'char': 0.98
        })

        self.nw.add_busses(self.fwp_power, self.power)

        # solve network
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        ean = ExergyAnalysis(self.nw,
                             E_P=[self.power],
                             E_F=[self.heat],
                             internal_busses=[self.fwp_power])
        ean.analyse(pamb=self.pamb, Tamb=self.Tamb)

        exergy_balance = (ean.network_data.E_F - ean.network_data.E_P -
                          ean.network_data.E_L - ean.network_data.E_D)
        msg = ('Exergy balance must be closed (residual value smaller than ' +
               str(err**0.5) + ') for this test but is ' +
               str(round(abs(exergy_balance), 4)) + ' .')
        assert abs(exergy_balance) <= err**0.5, msg

        nodes = [
            'E_F', 'steam generator', 'splitter 1', 'feed water pump turbine',
            'turbine', 'merge 1', 'condenser', 'pump', 'E_D', 'E_P'
        ]

        links, nodes = ean.generate_plotly_sankey_input(node_order=nodes)
        # checksum for targets and source
        checksum = sum(links['target'] + links['source'])
        msg = ('The checksum of all target and source values in the link lists'
               'must be 148, but is ' + str(checksum) + '.')
        assert 148 == checksum, msg

    def test_exergy_analysis_violated_balance(self):
        """Test exergy analysis with violated balance."""
        # specify efficiency values for the internal bus
        self.nw.del_busses(self.fwp_power)
        self.fwp_power = Bus('feed water pump power', P=0)
        self.fwp_power.add_comps(
            {
                'comp': self.nw.get_comp('feed water pump turbine'),
                'char': 0.99
            }, {
                'comp': self.nw.get_comp('pump'),
                'char': 0.98,
                'base': 'bus'
            })
        self.nw.add_busses(self.fwp_power)
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        # miss out on internal bus in exergy_analysis
        ean = ExergyAnalysis(self.nw, E_P=[self.power], E_F=[self.heat])
        ean.analyse(pamb=self.pamb, Tamb=self.Tamb)

        exergy_balance = (ean.network_data.E_F - ean.network_data.E_P -
                          ean.network_data.E_L - ean.network_data.E_D)
        msg = ('Exergy balance must be violated for this test (larger than ' +
               str(err**0.5) + ') but is ' +
               str(round(abs(exergy_balance), 4)) + ' .')
        assert abs(exergy_balance) > err**0.5, msg

    def test_exergy_analysis_bus_conversion(self):
        """Test exergy analysis bus conversion factors."""
        # specify efficiency values for the internal bus
        self.nw.del_busses(self.fwp_power)
        self.fwp_power = Bus('feed water pump power', P=0)
        self.fwp_power.add_comps(
            {
                'comp': self.nw.get_comp('feed water pump turbine'),
                'char': 0.99
            }, {
                'comp': self.nw.get_comp('pump'),
                'char': 0.98,
                'base': 'bus'
            })
        self.nw.add_busses(self.fwp_power)
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        # no exergy losses in this case
        ean = ExergyAnalysis(self.nw,
                             E_P=[self.power],
                             E_F=[self.heat],
                             internal_busses=[self.fwp_power])
        ean.analyse(pamb=self.pamb, Tamb=self.Tamb)

        label = 'pump'
        eps = ean.bus_data.loc[label, 'epsilon']
        msg = ('Pump exergy efficiency must be 0.98 but is ' +
               str(round(eps, 4)) + ' .')
        assert round(eps, 4) == 0.98, msg

        label = 'feed water pump turbine'
        eps = ean.bus_data.loc[label, 'epsilon']
        msg = (
            'Feed water pump turbine exergy efficiency must be 0.99 but is ' +
            str(round(eps, 4)) + ' .')
        assert round(eps, 4) == 0.99, msg

    def test_exergy_analysis_missing_E_F_E_P_information(self):
        """Test exergy analysis errors with missing information."""
        with raises(TESPyNetworkError):
            ExergyAnalysis(self.nw, E_P=[self.power], E_F=[])

        with raises(TESPyNetworkError):
            ExergyAnalysis(self.nw, E_P=[], E_F=[self.heat])

    def test_exergy_analysis_component_on_two_busses(self):
        """Test exergy analysis errors with components on more than one bus."""
        with raises(TESPyNetworkError):
            ean = ExergyAnalysis(self.nw,
                                 E_P=[self.power],
                                 E_F=[self.heat, self.power])
            ean.analyse(pamb=self.pamb, Tamb=self.Tamb)
Ejemplo n.º 3
0
class TestClausiusRankine:
    def setup(self):
        """Set up clausis rankine cycle with turbine driven feed water pump."""
        self.Tamb = 20
        self.pamb = 1
        fluids = ['water']
        self.nw = Network(fluids=fluids)
        self.nw.set_attr(p_unit='bar', T_unit='C', h_unit='kJ / kg')

        # create components
        splitter1 = Splitter('splitter 1')
        merge1 = Merge('merge 1')
        turb = Turbine('turbine')
        fwp_turb = Turbine('feed water pump turbine')
        condenser = HeatExchangerSimple('condenser')
        fwp = Pump('pump')
        steam_generator = HeatExchangerSimple('steam generator')
        cycle_close = CycleCloser('cycle closer')

        # create busses
        # power output bus
        self.power = Bus('power_output')
        self.power.add_comps({'comp': turb, 'char': 1})
        # turbine driven feed water pump internal bus
        self.fwp_power = Bus('feed water pump power', P=0)
        self.fwp_power.add_comps({
            'comp': fwp_turb,
            'char': 1
        }, {
            'comp': fwp,
            'char': 1,
            'base': 'bus'
        })
        # heat input bus
        self.heat = Bus('heat_input')
        self.heat.add_comps({'comp': steam_generator, 'base': 'bus'})
        self.nw.add_busses(self.power, self.fwp_power, self.heat)

        # create connections
        fs_in = Connection(cycle_close, 'out1', splitter1, 'in1', label='fs')
        fs_fwpt = Connection(splitter1, 'out1', fwp_turb, 'in1')
        fs_t = Connection(splitter1, 'out2', turb, 'in1')
        fwpt_ws = Connection(fwp_turb, 'out1', merge1, 'in1')
        t_ws = Connection(turb, 'out1', merge1, 'in2')
        ws = Connection(merge1, 'out1', condenser, 'in1')
        cond = Connection(condenser, 'out1', fwp, 'in1', label='cond')
        fw = Connection(fwp, 'out1', steam_generator, 'in1', label='fw')
        fs_out = Connection(steam_generator, 'out1', cycle_close, 'in1')
        self.nw.add_conns(fs_in, fs_fwpt, fs_t, fwpt_ws, t_ws, ws, cond, fw,
                          fs_out)

        # component parameters
        turb.set_attr(eta_s=1)
        fwp_turb.set_attr(eta_s=1)
        condenser.set_attr(pr=1)
        fwp.set_attr(eta_s=1)
        steam_generator.set_attr(pr=1)

        # connection parameters
        fs_in.set_attr(m=10, p=120, T=600, fluid={'water': 1})
        cond.set_attr(T=self.Tamb, x=0)

        # solve network
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)

    def test_exergy_analysis_perfect_cycle(self):
        """Test exergy analysis in the perfect clausius rankine cycle."""
        self.nw.exergy_analysis(self.pamb,
                                self.Tamb,
                                E_P=[self.power],
                                E_F=[self.heat],
                                internal_busses=[self.fwp_power])
        msg = ('Exergy destruction of this network must be 0 (smaller than ' +
               str(err**0.5) + ') for this test but is ' +
               str(round(abs(self.nw.E_D), 4)) + ' .')
        assert abs(self.nw.E_D) <= err**0.5, msg

        msg = ('Exergy efficiency of this network must be 1 for this test but '
               'is ' + str(round(self.nw.epsilon, 4)) + ' .')
        assert round(self.nw.epsilon, 4) == 1, msg

        exergy_balance = self.nw.E_F - self.nw.E_P - self.nw.E_L - self.nw.E_D
        msg = ('Exergy balance must be closed (residual value smaller than ' +
               str(err**0.5) + ') for this test but is ' +
               str(round(abs(exergy_balance), 4)) + ' .')
        assert abs(exergy_balance) <= err**0.5, msg

        msg = (
            'Fuel exergy and product exergy must be identical for this test. '
            'Fuel exergy value: ' + str(round(self.nw.E_F, 4)) +
            '. Product exergy value: ' + str(round(self.nw.E_P, 4)) + '.')
        assert round(abs(self.nw.E_F - self.nw.E_P), 4) < err**0.5, msg

    def test_entropy_perfect_cycle(self):
        """Test entropy values in the perfect clausius rankine cycle."""
        labels = [
            'turbine', 'feed water pump turbine', 'condenser',
            'steam generator', 'pump'
        ]
        for label in labels:
            cp = self.nw.get_comp(label)
            msg = (
                'Entropy production due to irreversibility must be 0 for all '
                'components in this test but is ' + str(round(cp.S_irr, 4)) +
                ' at component ' + label + ' of type ' + cp.component() + '.')
            assert round(cp.S_irr, 4) == 0, msg
        sg = self.nw.get_comp('steam generator')
        cd = self.nw.get_comp('condenser')
        msg = (
            'Value of entropy production due to heat input at steam generator '
            '(S_Q=' + str(round(sg.S_Q, 4)) + ') must equal the negative '
            'value of entropy reduction in condenser (S_Q=' +
            str(round(cd.S_Q, 4)) + ').')
        assert round(sg.S_Q, 4) == -round(cd.S_Q, 4), msg

    def test_exergy_analysis_violated_balance(self):
        """Test exergy analysis with violated balance."""
        # specify efficiency values for the internal bus
        self.nw.del_busses(self.fwp_power)
        self.fwp_power = Bus('feed water pump power', P=0)
        self.fwp_power.add_comps(
            {
                'comp': self.nw.get_comp('feed water pump turbine'),
                'char': 0.99
            }, {
                'comp': self.nw.get_comp('pump'),
                'char': 0.98,
                'base': 'bus'
            })
        self.nw.add_busses(self.fwp_power)
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        # miss out on internal bus in exergy_analysis
        self.nw.exergy_analysis(self.pamb,
                                self.Tamb,
                                E_P=[self.power],
                                E_F=[self.heat])

        exergy_balance = self.nw.E_F - self.nw.E_P - self.nw.E_L - self.nw.E_D
        msg = ('Exergy balance must be violated for this test (larger than ' +
               str(err**0.5) + ') but is ' +
               str(round(abs(exergy_balance), 4)) + ' .')
        assert abs(exergy_balance) > err**0.5, msg

    def test_exergy_analysis_bus_conversion(self):
        """Test exergy analysis bus conversion factors."""
        # specify efficiency values for the internal bus
        self.nw.del_busses(self.fwp_power)
        self.fwp_power = Bus('feed water pump power', P=0)
        self.fwp_power.add_comps(
            {
                'comp': self.nw.get_comp('feed water pump turbine'),
                'char': 0.99
            }, {
                'comp': self.nw.get_comp('pump'),
                'char': 0.98,
                'base': 'bus'
            })
        self.nw.add_busses(self.fwp_power)
        self.nw.solve('design')
        convergence_check(self.nw.lin_dep)
        # no exergy losses in this case
        self.nw.exergy_analysis(self.pamb,
                                self.Tamb,
                                E_P=[self.power],
                                E_F=[self.heat],
                                internal_busses=[self.fwp_power])
        label = 'pump on bus feed water pump power'
        eps = self.nw.component_exergy_data.loc[label, 'epsilon']
        msg = ('Pump exergy efficiency must be 0.98 but is ' +
               str(round(eps, 4)) + ' .')
        assert round(eps, 4) == 0.98, msg

        label = 'feed water pump turbine on bus feed water pump power'
        eps = self.nw.component_exergy_data.loc[label, 'epsilon']
        eps = self.nw.component_exergy_data.loc[label, 'epsilon']
        msg = (
            'Feed water pump turbine exergy efficiency must be 0.99 but is ' +
            str(round(eps, 4)) + ' .')
        assert round(eps, 4) == 0.99, msg

    def test_exergy_analysis_missing_E_F_E_P_information(self):
        """Test exergy analysis errors with missing information."""
        with raises(TESPyNetworkError):
            self.nw.exergy_analysis(self.pamb,
                                    self.Tamb,
                                    E_P=[self.power],
                                    E_F=[])

        with raises(TESPyNetworkError):
            self.nw.exergy_analysis(self.pamb,
                                    self.Tamb,
                                    E_P=[],
                                    E_F=[self.heat])

    def test_exergy_analysis_component_on_two_busses(self):
        """Test exergy analysis errors with components on more than one bus."""
        with raises(TESPyNetworkError):
            self.nw.exergy_analysis(self.pamb,
                                    self.Tamb,
                                    E_P=[self.power],
                                    E_F=[self.heat, self.power])