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thermodynamics热力学internalenergy内能butane丁烷ethane乙烷methane甲烷Isentropic等熵Compressibleflows可压缩流体combustion燃烧britishthermalunit英热单位controlvolume控制体Inflammabilitylimits可燃范围Laminarflow层流condensation凝结Reynoldsnumber雷诺数convectionheattransfer对流换热kineticenergy动能Isothermal等温potentialenergy势能heatingvalue热值isolatedsystem孤立系统surroundings环境boundary边界isothermalprocess等温过程iso-baricprocess等压过程isometricprocess等熵过程specificvolume比容cycle循环saturationtemperature饱和温度subcooledliquid过冷液体compressedliquid压缩液体flame火焰thermalefficiency热效率cycleefficiency循环效率physicalquantity物理量fluidmechanics流体力学flowfield流场pathlines迹线streamlines流线lowercalorificvalue低热值netcalorificvalue净热值viscousflow/inviscidflow粘性、非粘性流体velocitygradient速度梯度steadyflow/unsteadyflow稳定、非稳定流boundarylayer边界层heattransfer热传递heat-transferrate传热速率temperaturegradient温度梯度proportionalityconstant比例常数thermalconductivity热传导Celsiusdegree摄氏度conductionheattransfer导热convectionheattransfer对流换热radiationheattransfer辐射换热blackbody黑体emissivity发射率viewfactor角系数heatexchanger热交换condenser冷凝器absolutepressure绝对压力absolutetemperature绝对温度air-fuelratio空燃比combustionair助燃空气temperaturedifference温差combustionproducts燃烧产物excessair过剩空气exothermicreaction放热反应fuelgasloss燃气损失oxygen氧气heatefficiency热效率ignitiontemperature点火温度inchesofwatercolumn英寸水柱lowerheatingvalue低热值perfectcombustion完善燃烧completecombustion完全燃烧specificgravity比重watergas水煤气naturalgas天然气coalgasification煤的气化molecularweight分子量specificheat比热compressibilityfactor压缩因数viscosity粘度latentheatofvaporization气化潜热boilingpoint沸点grossheatingvalue高热值gas-airignitionlimit点火极限normalpressure标准压力kitchenVentilation厨房通风minorLosses局部损失/较小损之reversibleprocess可逆过程viscouseffect粘滞作用fuelgas燃气primaryair一次空气secondaryair二次空气13页第二段332行Theflowregimedependsonthreephysicalparametersdescribingtheflowconditions.流动状态依赖于三个描述流动条件的物理参数。15页第二段Whenatemperaturegradientinabody，experiencehasshownthatthereisanenergytransferfromthehigh-temperatureregiontothelow-temperatureregion.Wesaythattheenergyistransferredbyconductionandthattheheat-transferrateperunitareaisproportion¬altothenormaltemperaturegradient：.Whentheproportionalityconstantisinsertedwhereqistheheat-transferrateandisthetemperaturegradientinthedirectionoftheheatflow.Thepositiveconstantλiscalledthethermalconductivityofthematerial，andtheminussignisinsertedsothatthesecondprincipleofthermodynamicswillbesatisfied；i.e.，heatmustflowdownhillonthetemperaturescale.Equation(1-3)iscalledFourier＇slawofheatconductionaftertheFrenchmathematicalphysicistJosephFourier，whomadeverysig¬nificantcontributionstotheanalyticaltreatmentofconductionheattransfer.ItisimportanttonotethatEquation(1-3)isthedefiningequationforthethermalconductivityandthatλhastheunitsofwattspermeterperCelsiusdegreeinatypicalsystemofunitsinwhichtheheatflowisexpressedinwatts.当物体内部存在温度梯度时，经验表明，就有能量从高温区向低温区传递。我们说，此时的能量通过传导进行传递，单位面积上的传热速率与法向温度梯度成正比，即。引入比例系数，则有其中q是热流量，是热流方向上的温度梯度，正常数称为材料的导热系数。方程中插入的负号表示热传导过程应满足热力学第二定律，即热量必须沿温度降低的方向传递。式(1-3)称为傅立叶导热定律，以法国数理学家约瑟夫傅立叶的名字命名，傅立叶在导热的分析处理方面做出了极其重大的贡献。值得注意的是，式(1-3)也是导热系数的定义式，在典型的单位体系中，当热流量q的单位为W时，的单位为℃)。56页最后一段（不包括57页）Gasappliancesaresoflexibleindesignthattheygivesatisfactoryoperationunderallaveragepressures(Table9-10and9-11)listed.Manyappliancesareequippedwithpressureregulatorsandarethereforenearlyindependentofgaslinepressurevariations.Incannotbeassumed,however,thatinapplianceswithoutregulatorssatisfactoryoperationwillbeobtainedathighandlowextremitiesiffluctuationsfromtheaverageadjustmentpressureareasmuchas±50percent.Operationwillbesatisfactoryaslongaspressureismaintainedclosetothatatwhichtheappliancewasadjusted.气体电器设计灵活,在所有列出的平均压力(表9和9-11)下都可顺利运行。许多电器配有压力调节器,使其近独立于气体管路压力变化。然而,如果平均调整压力的波动达±50%，我们不能假定，在没有监管机构顺利地操作下的系统将会达到或高或低两个极端。只要压力保持在该装置调整的压力，操作将是令人满意的