Figure 3 shows a wall that is constructed from a thick
fiberglass insulation (k = 0.035
W/m.οC) sandwiched between two layers of 1 mm thick sheet metal (k
= 15.1 W/m.οC).
The thickness of the side wall is as shown in Figure 3 while the
height is 1 m and the
width is 1 m. The average heat transfer coefficients at the inner
and outer surfaces of the
wall are 4 W/m2.οC and 9 W/m2.οC respectively. If the air in the
inside of the wall is
maintained at 3οC and the temperature of the surrounding air is
25οC, answer the
following questions:
What is the function of the fiberglass and could it be replaced
with other material?
(
b) Determine the convection heat transfer from the outer surface of
the wall Q COV using
newton’s law of cooling
1 (58.45 KiB) Viewed 15 times
Surrounding air 25°C 20°C 1 mm Sheet metal Insulation -L- Figure 3 Refrigerated space 3°C Tin ||1 mm
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