作者sky207 (squarebook)
看板ChemEng
標題[問題] 熱傳鰭片問題
時間Sun Nov 10 17:13:33 2013
A 2-in OD stainless steel tube has 16 longitudinal fins
spaced around its outside surface as shown.
The fin are 1/16 in.thick and extend 1-in from the outside surface
of the tube.
Q:If the outside surface of the tube wall at 250°F, the surrounding
air is at 80°F, and h is 8 Btu/hr ft^2°F,let W=1ft
問鰭片g為多少?
我用內差求出stainless steel的 K=9.80 Btu/hr ft°F
再用鰭片第三種case end of fin is unknow
也求出鰭片g的公式，都代入後算出來全部鰭片的q=2241 Btu/hr
但教授給的答案是2842 Btu/hr 不知是想法哪邊有問題
希望有高人能幫小弟解惑
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◆ From: 61.56.181.97
1F：推 GOKU81271:as shown ?圖在哪... 114.39.34.18 11/10 22:44
2F：→ sky207:sorry圖是一個圓外圍接16個fin 為成一圈 61.56.181.97 11/10 23:27
3F：推 GOKU81271:let W=1ft W?? 114.39.43.52 11/11 12:05
4F：→ sky207:應該是鰭片的寬度吧 61.56.181.97 11/11 12:58
5F：推 GOKU81271:The fin are 1/16 in.thick 這才是寬八 114.39.40.136 11/11 13:29
6F：→ GOKU81271:可能要請你把題目描述清楚 才有辦法解.. 114.39.40.136 11/11 13:30
7F：→ sky207:我是用鰭片寬=1/16in 高=1ft 長=1 in算 61.56.181.97 11/11 14:16
8F：→ sky207:這是原文書後面的題目 我是照抄的 61.56.181.97 11/11 14:18