湿空气学习教案

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1、会计学1湿空气湿空气第一页，共41页。第1页/共41页第二页，共41页。Rda = 8314.41/28.9645 = 287.055 J/(kgK)Rw = 8314.41/18.01528 = 461.520 J/(kgK)Dry air: pdaV= mdaRdaTWater vapor: pwV= mdaRwT第2页/共41页第三页，共41页。饱和饱和(boh)蒸汽蒸汽 (1)未饱和未饱和(boh)湿空气湿空气(Unsaturated Air): Dry air+ Superheated water vapor过热过热( (u u r)r)蒸汽蒸汽水蒸水蒸气气干空气干空气过热过热水蒸气

2、水蒸气pv ps(T) Tspvps加入水蒸气加入水蒸气，pv3. Saturated Air and Unsaturated Air (未饱和空气和饱和空气未饱和空气和饱和空气)未饱和湿空气未饱和湿空气第3页/共41页第四页，共41页。(2)饱和饱和(boh)湿空气湿空气(Saturated air)干空气干空气饱和饱和水蒸气水蒸气pv ps(T) Tsps温度温度(wnd)一定，不一定，不能再加入水蒸气能再加入水蒸气Saturated Air: Dry air+Saturated water vapor (饱和饱和(boh)湿空气：干空气和饱和湿空气：干空气和饱和(boh)水蒸汽的混合物。

3、水蒸汽的混合物。)饱和湿空气饱和湿空气第4页/共41页第五页，共41页。TspvpsA. T 加水蒸气加水蒸气, pvabC. pv 不变，不变，Ta ba ddcB. pv ，Ta cD. va ee结露结露Td 露点露点(ldin)温度温度第5页/共41页第六页，共41页。 The barometric pressure of atmospheric air vary considerably with altitude as well as with local geographic and weather conditions.1. Pressure of atmospheric ai

4、r第6页/共41页第七页，共41页。-500107.4780101.32550095.461100089.875150084.556200079.495250074.682300070.108400061.640500054.020600047.181700041.061800035.600900030.7421000026.4361200019.2841400013.786160009.632180006.556200004.328第7页/共41页第八页，共41页。第8页/共41页第九页，共41页。第9页/共41页第十页，共41页。4.相对湿度相对湿度 (Relative Humidity

5、of Air)定义定义(dngy)：湿空气中实际包含的水蒸汽量与同温度：湿空气中实际包含的水蒸汽量与同温度下最多能包含的水蒸汽量的百分比。下最多能包含的水蒸汽量的百分比。The relative humidity is defined as the ratio of the amount of moisture in the air to the maximum amount of moisture the air can hold at the same temperature. If we use “a”、“v”、“s” denoting dry air, water vapor and

6、saturated water vapor respectively, then (若用下标若用下标“a”、“v”、“s”表示干空气、水蒸汽和表示干空气、水蒸汽和饱和水蒸汽的参数，则有：饱和水蒸汽的参数，则有：)第10页/共41页第十一页，共41页。 1 饱和饱和(boh)湿空气湿空气 ( Saturated Moist Air)在相同在相同(xin tn)的温度下：的温度下： 0 干空气干空气(kngq) (dry air)0 tw tdDry-bulb, Wet-bulb and Dew Point temperature第20页/共41页第二十一页，共41页。7.3 湿空气的焓湿图湿空气

7、的焓湿图The Psychrometric Chart (h-d图图)Saturation Line (饱和湿空气线）饱和湿空气线）In addition, there are other lines(还有下列曲线：）还有下列曲线：）1. Lines of constant enthalpy (定焓线，与定焓线，与y轴成轴成45oC角向下角向下)2. Lines of constant humidity ratio (定含湿量线，垂直直线定含湿量线，垂直直线(zhxin)3.Lines of constant temperature (定温线定温线)4. Lines of constant v

8、olume ( 定容线定容线)5. Lines of constant relative humidity line( 定相对湿度线。定相对湿度线。)6. Lines of constant pv和和d. (水蒸汽分压力水蒸汽分压力pv和和d关系曲线关系曲线 )第21页/共41页第二十二页，共41页。d=0 干空气干空气(kngq)dh(2) h 线线(1) d 线线 人为将人为将 h 旋转旋转135度度 h135度度第22页/共41页第二十三页，共41页。dh(3) t 线线 正斜率正斜率(xil)的的直线直线 h等干球温度线等干球温度线t第23页/共41页第二十四页，共41页。dhht(4

9、) 线线100%ts=99.63oCd第24页/共41页第二十五页，共41页。dhht(5) 线线vp100%dvp第25页/共41页第二十六页，共41页。dhht(6)露点露点(ldin) td100%vppv下饱和湿空气下饱和湿空气1td第26页/共41页第二十七页，共41页。dhht(7) 湿球温度湿球温度tw100%vp绝热饱和绝热饱和(boh)温度温度tdtwt第27页/共41页第二十八页，共41页。The room process line, known also as room ratio line (RRL) is defined by the condition of sup

10、plied air and the desired air condition in the space.The RRL is dependent on both sensible and latent heat load.1.焓湿图的结构焓湿图的结构(jigu)第28页/共41页第二十九页，共41页。dhht热湿比热湿比100%vph-d图上为直线图上为直线(zhxin):0,0hd :0,0hd :0,0hd :0,0hd 角系数角系数(xsh)：过程方向与特：过程方向与特征征第29页/共41页第三十页，共41页。dhht100%vp124000已知初态已知初态1过程斜率过程斜率(xil)

11、已知已知可确定终态可确定终态第30页/共41页第三十一页，共41页。twtd不同不同(b tn)的的B不同不同(b tn)的的h-d图图第31页/共41页第三十二页，共41页。7.4 湿空气的热力过程湿空气的热力过程（Thermodynamic Process of Moist Air ）1. Sensible Heating Process (单纯加热单纯加热(ji r)过程过程)Sensible Heating Process is a process during which Sensible Heating Process is a process during which the d

12、ry-bulb temperature the dry-bulb temperature of air is increasedof air is increased. . The process occurs The process occurs at constant moisture contentat constant moisture content. . The air passes over a hot and dry surface which might be pipe coil using steam The air passes over a hot and dry su

13、rface which might be pipe coil using steam or hot water, electrical resistance or an air-to-air heat recovery unit. or hot water, electrical resistance or an air-to-air heat recovery unit. The load on the heater is:The load on the heater is:BA 加热加热(ji r)过过程程第32页/共41页第三十三页，共41页。Sensible cooling proce

14、ss at constant moisture content is aprocess during which the dry-bulb temperature of air is decreased. If the temperature of the cooling medium is still above its dew point temperature, then(若冷却介质温度若冷却介质温度(wnd)没有降到露点以下，则没有降到露点以下，则过程前后过程前后)：AB冷却冷却(lngqu)过程过程The air passes over a cooling coil which us

15、es chilled water or direct expansion of some refrigerant into the pipe coil. 第33页/共41页第三十四页，共41页。If the air is continuously cooled to a temperature which below its dew-point temperature, then water vapor will condense.(温度下降到露点以后，继续温度下降到露点以后，继续(jx)降温，析出水分，减小含湿量。降温，析出水分，减小含湿量。) CAB3. Sensible Cooling

16、with Dehumidification (冷却冷却(lngqu)去湿去湿)第34页/共41页第三十五页，共41页。4. Humidification Process (加湿过程加湿过程(guchng)由于水的焓值很小，可以忽略不计，所以可以看作由于水的焓值很小，可以忽略不计，所以可以看作(kn zu)(kn zu)加湿之加湿之后焓不变，在后焓不变，在h-dh-d图上是沿着定焓线向图上是沿着定焓线向d d增大的方向进行（过程增大的方向进行（过程1-21-2）。 (1) Adiabatic Humidification Process (绝热加湿过程绝热加湿过程(guchng)第35页/共41

17、页第三十六页，共41页。(2) Isothermal Humidification Process (等温加湿等温加湿)第36页/共41页第三十七页，共41页。5. Mixing of Two Air Streams (混合混合(hnh)过程过程)第37页/共41页第三十八页，共41页。dh12已知空气的已知空气的t1=20oC， p1=0.1MPa将其加热至将其加热至t2=50oC，后送入干燥室，后送入干燥室，从干燥室排出时从干燥室排出时t3=30oC，求：，求：1）2）从干燥室每吸收）从干燥室每吸收(xshu)1kg水分所需水分所需空气量和加热量空气量和加热量h2h13第38页/共41页第

18、三十九页，共41页。dh112h2h13根据根据t1=20oC，p1=0.1MPa，10.6查图查图d1=8.9g水蒸气水蒸气/kg(d.a.)h1=42.8kJ/kg(d.a.)根据根据(gnj)d2=d1, t2=50oC查图查图h2=73.5kJ/kg(d.a.)根据根据(gnj)h3=h2, t3=30oC查图查图30.63d3=17.0g水蒸气水蒸气/kg(d.a.)( )0.622( )ssp tdpp t1.005(2501 1.863 )htdt第39页/共41页第四十页，共41页。dh112h2h13含含1kg干空气干空气(kngq)的湿空气的湿空气(kngq)所吸收水分所吸收水分每吸收每吸收1kg水分水分(shufn)所需干空气所需干空气每吸收每吸收(xshu)1kg水分所需湿空气水分所需湿空气每吸收每吸收1kg水分所需加热量水分所需加热量第40页/共41页第四十一页，共41页。