第7章汽动力值环 P232263 7-2朗肯循环 朗肯循环定量计算 循环净功 wmet=91-92=(h-h4)-(h2-h) Wnet Ws,1-2 Ws3-4 h 91 91 泵功一般很小，占0.81%，忽略 h-h2 7,≈ h-hs 30℃ (1bar,125.8kJ/kg;5bar,126.1kJ/kg;10ba r,126.6kJ/kg;20bar,127.5kJ/kg
h s 1 3 4 2 net ,1 2 ,3 4 t 1 1 w w w s s q q η − − − = = 泵功一般很小，占0.8~1%，忽略 1 2 1 3 t h h h h η − ≈ − ( ) ( ) 1 2 1 4 2 3 w q q h h h h 循环净功 net = − = − − − 30℃ (1bar,125.8kJ/kg;5bar,126.1kJ/kg;10ba r,126.6kJ/kg;20bar,127.5kJ/kg 第 章 P232~263 7 7-2 朗肯循环 朗肯循环定量计算
第☑章慕汽劲力葡环 P232263 7-2朗肯循环 汽耗率：反映设备尺寸、装置经济性指标。 汽耗率：蒸汽动力装置每输出1kW.h 3600 0 功量所消耗的蒸汽量kg W net Wnet的单位是kJ/kg 1kW=1 kJ/s kg kg 3600kg 3600 kW×h kJ xh kJ Wnet 1 h 3600
汽耗率：反映设备尺寸、装置经济性指标。 汽耗率：蒸汽动力装置每输出1kW.h 功量所消耗的蒸汽量kg net 3600 d w = wnet的单位是kJ/kg 1kW=1 kJ/s net 3600 3600 1 3600 kg kg kg kg d kW h kJ kJ kJ w h h s h = = = = × × × 第 章 P232~263 7 7-2 朗肯循环
举例1a p1=3MPa,ta=300°C,p2=0.006MPa,t6=500°C 求：91=？92=？；w=?wn=? wne=?X3=?;7=?;d=? 解：查表 p1=3MPa;ta=300°C ha=2992.4kJ/kg S1a =6.5371kJ/kg.K
举例1a p MPa t a C p MPa t b C 3 , 300 , 0.006 , 500 1 = 1 = 2 = 1 = ? ?; ?; ? ?; ?; ?; ?; 2 1 2 = = = = = = = = w x d q q w w net T p η 求： p MPa t a C 1 = 3 ; 1 = 300 解：查表 s kJ kg K h kJ kg a a 6.5371 / . 2992.4 / 1 1 = = 1 4 3 2a T s 2b 1b 1a
S2a S1a =6.5371kJ/kg.K p2=0.006MPa =0.5208kJ/kg.K;s"=8.3283kJ/kg.K S2a' 6.5371-0.5208 X2a =0.77058 8.3283-0.5208 h'=151.47kJ/kg h"=2566.48kJ/kg ha x2gh"+(1-x2a)h' =2566.48×0.77058+(1-0.77058)×151.47 =2012.43kJ/kg
s ′ = 0.5208kJ / kg.K;s ′′ = 8.3283kJ / kg.K p MPa s a s a kJ kg K 0.006 6.5371 / . 2 2 1 = = = 0.77058 8.3283 0.5208 2 6.5371 0.5208 2 = − − = ′′ − ′ − ′ = s s s s x a a h kJ kg h kJ kg 2566.48 / 151.47 / ′′ = ′ = kJ kg h a x ah x a h 2012.43 / 2566.48 0.77058 (1 0.77058) 151.47 (1 ) 2 2 2 = = × + − × = ′′ + − ′ 2a 4 3 2a T s 2b 1b 1a
s3=s'=0.5208kJ/kg.K h,=h'=151.47kJ/kg S4=S3=0.5208kJ/kg.K P=3MPa h4=154.82kJ1kg 汽轮机作功 w,=h-h 2992.4-2012.43=979.97kJ/kg 水泵作功 wp =hs -hs =154.28-151.47=3.35kJ/kg
3 h h kJ kg s s kJ kg K 151.47 / 0.5208 / . 3 3 = ′ = = ′ = 4 p MPa s s kJ kg K 3 0.5208 / . 4 4 3 = = = h4 =154.82kJ / kg 汽轮机作功 kJ kg wt h h 2992.4 2012.43 979.97 / 1 2 = − = = − 水泵作功 kJ kg wp h h 154.28 151.47 3.35 / 4 3 = − = = −