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Annular steel fins (k=56.7W/m· K) are attached to a steel tube that is 30mm in external...

Annular steel fins (k=56.7W/m· K) are attached to a steel tube that is 30mm in external diameter. The fins are 2mm thick and 15mm long. The tube wall temperature is 350K and the surrounding fluid temperature is 450K with a heat-transfer coefficient of 75W/m2 · K. There are 200 fins per meter of tube length. Calculate:

(a) The fin efficiency.

(b) The fin surface area per meter of tube length.

(c) The prime surface area per meter of the tube length.

(d) The weighted efficiency of the finned surface.

(e) The rate of heat transfer per meter of tube length.

Ans. (a) 85%. (b) 0.9248m2. (c) 0.0565m2. (d) 86%. (e) 6330W.

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