某列管换热器,用100℃水蒸气将物料由20℃加热至80 ℃,传热系数K=100 W/(m2 .℃).经半年运转后,由于污垢的影响,在相同条件下物料出口温度仅为70℃.现欲使物料出口温度仍维持在80℃,问加热蒸气
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![某列管换热器,用100℃水蒸气将物料由20℃加热至80 ℃,传热系数K=100 W/(m2 .℃).经半年运转后,由于污垢的影响,在相同条件下物料出口温度仅为70℃.现欲使物料出口温度仍维持在80℃,问加热蒸气](/uploads/image/z/2179420-52-0.jpg?t=%E6%9F%90%E5%88%97%E7%AE%A1%E6%8D%A2%E7%83%AD%E5%99%A8%2C%E7%94%A8100%E2%84%83%E6%B0%B4%E8%92%B8%E6%B0%94%E5%B0%86%E7%89%A9%E6%96%99%E7%94%B120%E2%84%83%E5%8A%A0%E7%83%AD%E8%87%B380+%E2%84%83%2C%E4%BC%A0%E7%83%AD%E7%B3%BB%E6%95%B0K%3D100+W%2F%28m2+.%E2%84%83%29.%E7%BB%8F%E5%8D%8A%E5%B9%B4%E8%BF%90%E8%BD%AC%E5%90%8E%2C%E7%94%B1%E4%BA%8E%E6%B1%A1%E5%9E%A2%E7%9A%84%E5%BD%B1%E5%93%8D%2C%E5%9C%A8%E7%9B%B8%E5%90%8C%E6%9D%A1%E4%BB%B6%E4%B8%8B%E7%89%A9%E6%96%99%E5%87%BA%E5%8F%A3%E6%B8%A9%E5%BA%A6%E4%BB%85%E4%B8%BA70%E2%84%83.%E7%8E%B0%E6%AC%B2%E4%BD%BF%E7%89%A9%E6%96%99%E5%87%BA%E5%8F%A3%E6%B8%A9%E5%BA%A6%E4%BB%8D%E7%BB%B4%E6%8C%81%E5%9C%A880%E2%84%83%2C%E9%97%AE%E5%8A%A0%E7%83%AD%E8%92%B8%E6%B0%94)
某列管换热器,用100℃水蒸气将物料由20℃加热至80 ℃,传热系数K=100 W/(m2 .℃).经半年运转后,由于污垢的影响,在相同条件下物料出口温度仅为70℃.现欲使物料出口温度仍维持在80℃,问加热蒸气
某列管换热器,用100℃水蒸气将物料由20℃加热至80 ℃,传热系数K=100 W/(m2 .℃).经半年运转后,由于污
垢的影响,在相同条件下物料出口温度仅为70℃.现欲使物料出口温度仍维持在80℃,问加热蒸气温度应取何值?
原qc(80-20)=KAΔ t 1 (1)
Δ t =(80-20)/ln(80/20)=43.28℃
半年后qc(70-20)=K AΔ t 2 (2)
Δ t= 80-30/ln(80/30)=50.98℃
2/1得
70-20/80-20=K Δ t 1/KΔ t2
(K /100)×50.98/43.28
K =70.75 w.m .K
保持原生产能力,即 KAΔ t K AΔ t (2’)
Δ t =KΔ t /K =100×43.28/70.75
=61.17℃ (3’)
Δ t =(T-20)-(T-80)/ln(T-20)/(T-80)
=61.17
∴ 60/61.17ln(T-20)/(T-80)
∴2.667=T-20/T-80
T=115.8℃
某列管换热器,用100℃水蒸气将物料由20℃加热至80 ℃,传热系数K=100 W/(m2 .℃).经半年运转后,由于污垢的影响,在相同条件下物料出口温度仅为70℃.现欲使物料出口温度仍维持在80℃,问加热蒸气
根据饱和蒸汽 压力与温度对照表 试着选两个看看 哪个能达到要求