Chemical Engineering - Heat Transfer - Discussion

Discussion Forum : Heat Transfer - Section 1 (Q.No. 50)
50.
A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be
greater than that for uninsulated steam pipe.
less than that of the uninsulated steam pipe.
equal to that of the uninsulated steam pipe.
less than the steam pipe with 5 cms insulation.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
15 comments Page 2 of 2.

Amit shah said:   8 years ago
Explain the formula.

Suraj said:   9 years ago
Also calculated by the formula.

1) without insulation.

2) with insulation.

Nihar said:   1 decade ago
The concept is if the insulation exceeds (rc) critical radius of insulation then the insulation not worthy i.e. we are wasting money. And here if at all the thickness is less than the rc but still it is obvious thing that heat transfer is less in a insulated pipe as compared to non-insulated.

Deekshant said:   1 decade ago
k/d = 0.75 mts.
So critical radius = 75 cm.

But here the radius is 7 cm.
So, ans A must be right.

Omprakash said:   1 decade ago
Radius of insulation is less than that of critical radius. Hence heat loss from ins pipe is more than that in without insulated pipe.


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