[問題] 熱傳鰭片問題

[sky207 (squarebook)]

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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推 GOKU81271:as shown ?圖在哪...
→ sky207:sorry圖是一個圓外圍接16個fin 為成一圈
推 GOKU81271:let W=1ft  W??
→ sky207:應該是鰭片的寬度吧
推 GOKU81271:The fin are 1/16 in.thick 這才是寬八
→ GOKU81271:可能要請你把題目描述清楚 才有辦法解..
→ sky207:我是用鰭片寬=1/16in 高=1ft 長=1 in算
→ sky207:這是原文書後面的題目 我是照抄的