sec15-031210-NOTES-example

# sec15-031210-NOTES-example - ChE 120B Example of Heat...

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ChE 120B 15 - 1 Example of Heat Exchange 9 F 10 F 70 F 5 f±/s ²enzene 180 F 750 lb/hr Wa±er o o o o Inside pipe is schedule 40, 1 ¼ inches steel Outside diameter is 1.66 inches = .138 ft Inside diameter is 1.38 inches = .115 ft Area for flow is .0104 ft 2 Outside pipe is 2 inches, schedule 40 steel pipe Inside diameter is 2.07 inches = .172 ft Design Equations 00 l n QUAT    ,1 ,2 ,2 c h cp c c hp h h Qw C T T w  Express 0 0 2a n d / 2 Ar L A L r  We need to estimate 0 U , which is given by 1 0 0 0 ln / 11 1 i ii rr U h K r h     Can be written as 1 0 0 0 ln / 2/ i A U hA LK h A L L

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ChE 120B 15 - 2 2) We need to evaluate 0 , i hh to evaluate 0 U 180 100 140 2 m T  Evaluate properties at near temperature. 3 lb 52.3 ft m b Btu .085 hr ft F b K 4 62 f f 2 .39 2.6 10 lb /ft-s 8.1 10 lb s/ft lb 32ft related by lb bp m c m C g s     x x Btu .45 lb F b m p C 5 K b b r b p C p  4 lb Btu .45 2.6 10 lb F ft-s Btu hr .085 hr ft F 3600s 4.96 careful with units m m x lb lb 7500 2.08 hr s mm w 2 4 i bb D wU , Re bbi UD 2 4 i w D U , 2 Re 4 ii w DD 4 Re i w D 4 4 lb 4 2.08 s Re 8.9 10 lb .115ft 2.6 10
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## This note was uploaded on 03/22/2011 for the course CHE 120B taught by Professor Zasadinski during the Winter '10 term at UCSB.

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sec15-031210-NOTES-example - ChE 120B Example of Heat...

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