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Discussion :: Heat and Mass Transfer

  1. An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be

  2. A.

     25 mm

    B.

     40 mm

    C.

     160 mm

    D.

     800 mm

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    Answer : Option A

    Explanation :

    Critical radius of insulation for cylinder
    =k/h.
    K= thermal conductivity of cylinder

    0.15/6 = .025m = 25mm.


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