Chemical Engineering - Heat Transfer - Discussion
Discussion Forum : Heat Transfer - Section 3 (Q.No. 37)
37.
A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m2.K. The Biot number is
Discussion:
7 comments Page 1 of 1.
Jishnu said:
1 decade ago
Bi = hL/k.
L is the characteristic length.
For cylinder it is radius or diameter/2.
Bi = (1000*0.005/200) = 0.025.
L is the characteristic length.
For cylinder it is radius or diameter/2.
Bi = (1000*0.005/200) = 0.025.
(1)
Ash said:
1 decade ago
Why did you take value of h as 1000 when its given 100 in the question it should be (100*0.005/200) = 0.0025?
(1)
Dhruv Prajapati said:
9 years ago
@Jishnu, Why you have taken h = 1000?
Vincent Chuks Ntichika said:
8 years ago
@Ash.
Dimensional consistency applies. 200W/m.K divide by 0.01m gives 20000W/m2K Bi=((100/20000)/2) = 0.0025.
Dimensional consistency applies. 200W/m.K divide by 0.01m gives 20000W/m2K Bi=((100/20000)/2) = 0.0025.
Philip said:
8 years ago
If we assume that the wire is a cylindrical shape, its characteristic length should be r/2 where r is the radius.
Using this value, my calc answer would be .00125.
Using this value, my calc answer would be .00125.
(2)
Praful said:
7 years ago
Bi = Lh/k.
Lc - Characteristics length.
Lc = V body/A surface,
K - thermal conductivity,
h - heat transfer coefficient.
Lc - Characteristics length.
Lc = V body/A surface,
K - thermal conductivity,
h - heat transfer coefficient.
(1)
Sayan said:
6 years ago
Yeah, you are correct @Philip.
(1)
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