SAMChapter5

PropertiesofVaporandItsThermodynamicProcess水蒸氣的性質及其熱力過程工程熱力學

EngineeringThermodynamicsSAM第五章水蒸氣的性質及其熱力過程

PropertiesofVaporandItsThermodynamicProcessKeynotesThermalEnergyEngineeringDepartment5-1§5-3水蒸氣的熱力過程

ThermodynamicProcessesofVapor§5-2水蒸氣熱力性質表和圖

propertydiagramsandtablesofvapor§5-1水蒸氣的發生過程

Theprocessofvaporgenerateing§5-1水蒸氣的發生過程

TheProcessofVaporGeneratingSAMThermalEnergyEngineeringDepartment5-2H2O的p-T相圖：臨界點C(Criticalpoint)是汽液相變極限狀態的標志。不同工質均有自己確定的臨界參數，對水蒸氣：三相點O:p0=0.6112kPa,t0=0.01℃,v0=0.001m3/kgabcde§5-1水蒸氣的發生過程

TheProcessofVaporGeneratingSAMThermalEnergyEngineeringDepartment5-2未飽和水unsaturatedwater過熱蒸汽superheatedvapor飽和水saturatedwater濕蒸汽saturatedmixture干飽和蒸汽saturatedvapor一、水蒸氣的定壓發生過程SAMThermalEnergyEngineeringDepartment5-3ab:preheatingprocess,

p=const,t,vchangesalittlebcd:Vaporizationprocess,p=const,ts

=const,vde:heatingofsaturatedvapor,p

=const,t,vchangesalittle液體熱過冷度latentheatofvaporization

過熱熱量過熱度汽化潛熱SAMThermalEnergyEngineeringDepartment5-4干度若濕蒸汽可看成飽和水與干飽和水蒸氣的混合物x=0saturatedwaterx=1saturatedvaporSAMThermalEnergyEngineeringDepartment5-7水蒸氣定壓產生過程會出現三個階段和五種狀態，且p↑→ts↑、v'↑、v"↓、汽化過程bd縮短。二、p-v,T-sdiagramof

vaporSAMThermalEnergyEngineeringDepartment5-6一點：臨界點C二線：上界線BC、干飽和蒸汽線、x=1；下界線AC、飽和水線、x=0。三區：液態區、濕蒸汽區、汽態區。五態：未飽和水、飽和水、濕飽和蒸汽、干飽和蒸汽、過熱蒸汽。SAMThermalEnergyEngineeringDepartment5-9§5-2水蒸氣熱力性質表和圖

propertydiagramsandtablesofvapor國際水蒸氣性質會議規定：取水的三相點（p=0.6112kPa,t=0.01℃）時飽和水的u0=0kJ/kg、s0=0kJ/（kg.K），則在壓力不高時可近似的認為h0=0kJ/kg。水蒸氣熱力性質表飽和水及干飽和蒸汽表未飽和水與過熱蒸汽表水蒸氣熱力性質圖SAMThermalEnergyEngineeringDepartment5-10飽和水及干飽和蒸汽表（p124及附表p300-301）SAMSAMThermalEnergyEngineeringDepartment5-12未飽和水與過熱蒸汽表表5-3未飽和水及過熱蒸汽表的結構（p125）及附表12SAMSAMThermalEnergyEngineeringDepartment5-13SAMSAMThermalEnergyEngineeringDepartment5-14SAMSAMThermalEnergyEngineeringDepartment5-15SAMSAMThermalEnergyEngineeringDepartment5-15水蒸氣熱力性質圖討論（1）

已知H2O的（t,p）,如何確定其所處狀態？（2）

已知H2O的（t,s）,如何確定其所處狀態？SAMSAMThermalEnergyEngineeringDepartment5-15例5-2試確定壓力為1MPa時，溫度分別為160℃及200℃時水所處的狀態。例5-3試用h-s圖求下列狀態的水蒸汽參數：（1）5MPa，干度＝90％；（2）溫度為200℃的干飽和蒸汽；（3）0.1MPa，300℃。并將上述三個狀態表示在h-s圖上。例5-1若水蒸氣在150℃時，比熵為6.0886kJ/(kgK)，試確定水蒸氣的狀態及其它狀態參數。SAMSAMThermalEnergyEngineeringDepartment5-15例5-4(書上無)根據h-s圖確定壓力為2MPa時水蒸氣的氣化潛熱的數值。SAMSAMThermalEnergyEngineeringDepartment5-15§5-3水蒸氣的熱力過程

ThermodynamicProcessesofVaporConstantVolumeProcessConstantTemperatureProcessConstantPressureProcessConstantEntropyProcessSAMSAMThermalEnergyEngineeringDepartment5-16例5-4某蒸汽鍋爐，給水溫度為150℃，出口蒸汽參數為3.5MPa，溫度為435℃。試確定鍋爐進、出口蒸汽的狀態，并計算每千克水在鍋爐內的吸熱量。SAMSAMThermalEnergyEngineeringDepartment5-17例5-5一剛性容器中裝有1kg汽水混合物，其中蒸汽質量占70％，壓力為0.2MPa。若對容器加熱，使水變成干飽和蒸汽，試求：⑴終態壓力；⑵加入的熱量；（3）終態溫度。SAMSAMThermalEnergyEngineeringDepartment5-17例5-6假定從鍋爐中輸出的過熱蒸汽（3.5MPa，435℃），在汽輪機中可逆絕熱地膨脹