class TestCompressedAirIn: def setup(self): """Set up air compressor.""" self.Tamb = 20 self.pamb = 1 fluids = ['Air'] # compressor part self.nw = Network(fluids=fluids) self.nw.set_attr(p_unit='bar', T_unit='C', h_unit='kJ / kg') # components amb = Source('air intake') cp = Compressor('compressor') cooler = HeatExchangerSimple('cooling') cas = Sink('compressed air storage') # power input bus self.power_in = Bus('power input') self.power_in.add_comps({'comp': cp, 'char': 1, 'base': 'bus'}) # compressed air bus (not sure about this!) self.cas_in = Bus('massflow into storage') self.cas_in.add_comps({'comp': cas}, {'comp': amb, 'base': 'bus'}) self.nw.add_busses(self.power_in, self.cas_in) # create connections amb_cp = Connection(amb, 'out1', cp, 'in1') cp_cool = Connection(cp, 'out1', cooler, 'in1') cool_cas = Connection(cooler, 'out1', cas, 'in1') self.nw.add_conns(amb_cp, cp_cool, cool_cas) # component parameters cp.set_attr(eta_s=1) cooler.set_attr(pr=1) # connection parameters amb_cp.set_attr(m=2, T=self.Tamb, p=self.pamb, fluid={'Air': 1}) cool_cas.set_attr(T=self.Tamb, p=10) # solve network self.nw.solve('design') convergence_check(self.nw.lin_dep) def test_exergy_analysis_bus_conversion(self): """Test exergy analysis at product exergy with T < Tamb.""" self.nw.exergy_analysis(self.pamb, self.Tamb, E_P=[self.cas_in], E_F=[self.power_in]) 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
class TestCompressedAirOut: def setup(self): """Set up air compressed air turbine.""" self.Tamb = 20 self.pamb = 1 fluids = ['Air'] # turbine part self.nw = Network(fluids=fluids) self.nw.set_attr(p_unit='bar', T_unit='C', h_unit='kJ / kg') # components cas = Source('compressed air storage') reheater = HeatExchangerSimple('reheating') turb = Turbine('turbine') amb = Sink('air outlet') # power ouput bus self.power_out = Bus('power output') self.power_out.add_comps({'comp': turb, 'char': 1}) # compressed air bus self.cas_out = Bus('exergy in') self.cas_out.add_comps({ 'comp': cas, 'base': 'bus' }, { 'comp': reheater, 'base': 'bus' }) # exergy loss bus self.ex_loss = Bus('exergy loss') self.ex_loss.add_comps({'comp': amb, 'base': 'component'}) self.nw.add_busses(self.power_out, self.cas_out) # create connections cas_reheater = Connection(cas, 'out1', reheater, 'in1') reheater_turb = Connection(reheater, 'out1', turb, 'in1') turb_amb = Connection(turb, 'out1', amb, 'in1', label='outlet') self.nw.add_conns(cas_reheater, reheater_turb, turb_amb) # component parameters turb.set_attr(eta_s=1) reheater.set_attr(pr=1) # connection parameters cas_reheater.set_attr(m=2, T=self.Tamb, p=10, fluid={'Air': 1}) reheater_turb.set_attr() turb_amb.set_attr(p=self.pamb, T=self.Tamb) # solve network self.nw.solve('design') convergence_check(self.nw.lin_dep) def test_exergy_analysis_bus_conversion(self): """Test exergy analysis at product exergy with T < Tamb.""" self.nw.exergy_analysis(self.pamb, self.Tamb, E_P=[self.power_out], E_F=[self.cas_out], E_L=[self.ex_loss]) 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 = ('Exergy efficiency must be equal to 1.0 for this test but is ' + str(round(self.nw.epsilon, 4)) + '.') assert round(self.nw.epsilon, 4) == 1, msg c = self.nw.get_conn('outlet') c.set_attr(T=self.Tamb - 20) self.nw.solve('design') convergence_check(self.nw.lin_dep) self.nw.exergy_analysis(self.pamb, self.Tamb, E_P=[self.power_out], E_F=[self.cas_out], E_L=[self.ex_loss]) msg = ( 'Exergy destruction must be equal to 0.0 for this test but is ' + str(round(self.nw.E_D, 4)) + '.') assert round(self.nw.E_D, 4) == 0, msg msg = ('Exergy loss must be equal to ' + str(round(c.Ex_physical, 4)) + ' for this test but is ' + str(round(self.nw.E_L, 4)) + '.') assert round(self.nw.E_L, 4) == round(c.Ex_physical, 4), msg
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])
class TestRefrigerator: def setup(self): """Set up simple refrigerator.""" self.Tamb = 20 self.pamb = 1 fluids = ['R134a'] self.nw = Network(fluids=fluids) self.nw.set_attr(p_unit='bar', T_unit='C', h_unit='kJ / kg') # create components va = Valve('expansion valve') cp = Compressor('compressor') cond = HeatExchangerSimple('condenser') eva = HeatExchangerSimple('evaporator') cc = CycleCloser('cycle closer') # create busses # power output bus self.power = Bus('power input') self.power.add_comps({'comp': cp, 'char': 1, 'base': 'bus'}) # cooling bus self.cool = Bus('heat from fridge') self.cool.add_comps({'comp': eva}) # heat input bus self.heat = Bus('heat to ambient') self.heat.add_comps({'comp': cond}) self.nw.add_busses(self.power, self.cool, self.heat) # create connections cc_cp = Connection(cc, 'out1', cp, 'in1', label='from eva') cp_cond = Connection(cp, 'out1', cond, 'in1', label='to cond') cond_va = Connection(cond, 'out1', va, 'in1', label='from cond') va_eva = Connection(va, 'out1', eva, 'in1', label='to eva') eva_cc = Connection(eva, 'out1', cc, 'in1') self.nw.add_conns(cc_cp, cp_cond, cond_va, va_eva, eva_cc) # component parameters cp.set_attr(eta_s=0.9) cond.set_attr(pr=0.97) eva.set_attr(pr=0.96) # connection parameters cc_cp.set_attr(m=1, x=1, T=-25, fluid={'R134a': 1}) cond_va.set_attr(x=0, T=self.Tamb + 1) # solve network self.nw.solve('design') convergence_check(self.nw.lin_dep) def test_exergy_analysis_bus_conversion(self): """Test exergy analysis at product exergy with T < Tamb.""" # no exergy losses in this case self.nw.exergy_analysis(self.pamb, self.Tamb, E_P=[self.cool], E_F=[self.power]) self.nw.print_exergy_analysis() 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