西安建筑科技大学：《工程热力学 Engineering Thermodynamics》课程双语教学资源（PPT课件讲稿）第七章 湿空气 Moist Air

Chapter 7, moist Ai (第7章湿空气) 471 Introduction(介绍) 72 Properties of moist air(湿空气的参数) 473H- d Diagram of Moist Air(湿空气的H-d图) 7. 4 Thermodynamic Process of moist Air (湿空气的热力过程)

Chapter 7. Moist Air (第７章 湿空气） 7.1 Introduction (介绍) 7.2 Properties of Moist Air （湿空气的参数） 7.3 H-d Diagram of Moist Air （湿空气的H-d 图) 7.4 Thermodynamic Process of Moist Air （湿空气的热力过程）

71 Introduction(介绍) 空调、通风、烘干、冷却塔、储存 Atmospheric air 湿空气=(干空气+水蒸气) Dry air 理想混合气体 分压低 p=pat p 湿空气与一般理想混合气体的最大区别是:水蒸气的成分可 能变化

湿空气＝（干空气＋水蒸气） 空调、通风、烘干、冷却塔、储存 湿空气与一般理想混合气体的最大区别是：水蒸气的成分可 能变化。 理想混合气体 分压低 a v p p p = + Dry air Atmospheric air 7.1 Introduction (介绍)

1. Definition of Atmospheric Air(湿空气的定义) Dry air Water vapor(moisture) EAtmospheric Air (含有水蒸汽的空气称为湿空气。) Air that contains no water vapor is called dry air. (完全不含水蒸汽的空气称为干空气。) 2. Characteristics of Moisture Air(湿空气的特点) Atmospheric air contains a very small amount of water vapor. The partial pressure of water vapor is very low so that water vapor in the atmospheric air is always at superheated state Thus water vapor can be treated as ideal gas, (湿空气中水蒸汽含量很小,分压力很低,常处于过热状态,可以当 作理想气体来处理。)

1. Definition of Atmospheric Air（湿空气的定义） Dry air + Water vapor (Moisture) =Atmospheric Air (含有水蒸汽的空气称为湿空气。) Air that contains no water vapor is called dry air. (完全不含水蒸汽的空气称为干空气。) 2. Characteristics of Moisture Air (湿空气的特点) Atmospheric air contains a very small amount of water vapor. The partial pressure of water vapor is very low so that water vapor in the atmospheric air is always at superheated state. Thus, water vapor can be treated as ideal gas. (湿空气中水蒸汽含量很小，分压力很低，常处于过热状态，可以当 作理想气体来处理。)

Atmospheric air can be treated as a binary mixture(二元混合物) of ideal gases, dry air and moisture Dry air: Paav= marat Ra=83144l/289645=287.055J(kgK) Water vapor: pV=mdar t Rn=831441/1801528=461.520J/(kgK)

Atmospheric air can be treated as a binary mixture (二元混合物） of ideal gases, dry air and moisture Rda = 8314.41/28.9645 = 287.055 J/(kg·K) Rw = 8314.41/18.01528 = 461.520 J/(kg·K) Dry air: pdaV= mdaRdaT Water vapor: pwV= mdaRwT

3. Saturated Air and Unsaturated Air (未饱和空气和饱和空气) Superheated vapor过热蒸汽 Water vapor Saturated vapo饱和蒸汽 (1)未饱和湿空气( Unsaturated air) Dry air+ Superheated water vapor 干空气 T Unsaturated air p、未饱和湿空气 过热水蒸气 p、<Ps(T) 加入水蒸气,n

Saturated vapor 饱和蒸汽 (1) 未饱和湿空气(Unsaturated Air): Dry air+ Superheated water vapor Superheated vapor过热蒸汽 Water vapor 干空气 ＋ 过热水蒸气 pv < ps (T) T s pv ps 加入水蒸气，pv 3. Saturated Air and Unsaturated Air (未饱和空气和饱和空气) Unsaturated air 未饱和湿空气

(2)饱和湿空气 Saturated air) Saturated Air: Dry air+ Saturated water vapor (饱和湿空气:干空气和饱和水蒸汽的混合物。) Saturated air 干空气 饱和湿空气 + T 饱和水蒸气 py=D、(T) 温度一定,不能再加入水蒸气 If the temperature is fixed, no more water vapor it can absorb

(2) 饱和湿空气(Saturated air) 干空气 ＋ 饱和水蒸气 pv ＝ ps (T) T s ps 温度一定，不能再加入水蒸气 If the temperature is fixed, no more water vapor it can absorb. Saturated Air: Dry air+Saturated water vapor (饱和湿空气：干空气和饱和水蒸汽的混合物。) Saturated air 饱和湿空气

(3)从未饱和到饱和的途径 A.(T加水蒸气P b >C C.p、不变,T T Ps 结露 b T露点温度

(3)从未饱和到饱和的途径 T s pv ps A. T 加水蒸气, pv b a C. pv 不变，T a b a d d c B. pv ，T a c D. v a e e 结露 Td 露点温度 B. B. ppv ，T v ，T A. A. T 加水蒸气, pv A. T 加水蒸气, pv A. T 加水蒸气, pv A. T 加水蒸气, pv A. T 加水蒸气, pv A. T 加水蒸气, pv , pv

72湿空气的参数 Properties of Moist Air 1. Pressure of atmospheric air p= pa t py The barometric pressure of atmospheric air vary considerably with altitude as well as with local geographic and weather conditions

7.2 湿空气的参数 Properties of Moist Air p = pa + pv The barometric pressure of atmospheric air vary considerably with altitude as well as with local geographic and weather conditions. 1. Pressure of atmospheric air

500 「107478 101325 500 95461 1000 89875 1500 84.55 2000 79495 2500 74682 3000 70.108 4000 61.640 5000 54020 6000 47.181 7000 4106l 8000 35.600 9000 3071 10000 26.436 12000 19.284 114000 13.786 16000 19632 18000 20000 4.328

-500 107.478 0 101.325 500 95.461 1000 89.875 1500 84.556 2000 79.495 2500 74.682 3000 70.108 4000 61.640 5000 54.020 6000 47.181 7000 41.061 8000 35.600 9000 30.742 10000 26.436 12000 19.284 14000 13.786 16000 9.632 18000 6.556 20000 4.328

The partial pressure of water vapor is also called vapor pressure, 2.干球温度(Dry- bulb temperature) It is the temperature of moist air. The dry-bulb temperature of water vapor and dry air is the same. It is denoted as t' 3露点温度(Dew- point Temperature It is defined as the temperature at which condensation begins when the air is cooled at constant pressure In other words, it is the saturation temperature of water corresponding to the vapor pressure. t d=ta (pu)

⚫ The partial pressure of water vapor is also called vapor pressure. 2.干球温度 (Dry-bulb temperature) It is the temperature of moist air. The dry-bulb temperature of water vapor and dry air is the same. It is denoted as ‘t’ . 3.露点温度(Dew-point Temperature) It is defined as the temperature at which condensation begins when the air is cooled at constant pressure. In other words, it is the saturation temperature of water corresponding to the vapor pressure. ( ) d sat pv t = t