Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

Discussion Forum : Heat Transfer, Refrigeration and Air Conditioning - Section 7 (Q.No. 22)
22.
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
25 mm
40 mm
160 mm
800 mm
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
6 comments Page 1 of 1.

Anonumous said:   5 years ago
It's not critical thickness, it is asking for radius. In fact, we cannot find thickness unless a radius is given.

Anome said:   6 years ago
Here, the critical radius: k/h = 0.15/6 = 0.025m or 25mm.

Vishal Agasar said:   7 years ago
k/h = 0.15/6 = 0.025 = 25mm.

Sanet said:   8 years ago
Critical radius of insulation for cylinder =k/h.
K= thermal conductivity of cylinder (not insulation).

Ananth said:   8 years ago
This is critical radius of insulation.

Gaurav said:   1 decade ago
Critical thickness for cylindrical conductor = k/h = 0.15/6 = .025m = 25mm.

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