Question

Your firm has designed a new 2m double-paned window which consists of two 5 mm thick plates of glass (k = 0.75 W/mK) separated by a 14 mm thick layer of xenon gas with an unknown thermal conductivity, which you intend to determine through an experiment. You use a heater that provides 100 W of heat to maintain one side of the window at 80 °C while the other 2 side is exposed to the air in the room with T = 20 °C (h = 15 W/m K). ∞

(a) Determine the thermal conductivity of the xenon layer

(b) Determine the temperature of the surface of the glass exposed to the room air in your experiment

Answer #1

1.
Consider a 1.8-m high and 1.5 m-wide double-pane window
consisting of two 4-mm thick layers of glass (k = 0.78 W/m°C)
separated by a 10-mm wide stagnant air space (k = 0.026 W/m°C). The
room is maintained at 20°C while the temperature of the outdoors is
-10°C. Take the convective heat transfer coefficients on the inner
and outer surfaces of the window to be 10 W/m2°C and 40 W/m2°C,
respectively.
Determine the steady rate of heat transfer through this...

A clever student decides to produce and sell windows that
consist of two 5.9-mm thick glass panes ( thermal conductivity of 1
W/m-K) separated by a 0.9-cm thick layer of aerogel, which has a
thermal conductivity of 10-4 W/m-K). Assuming the
temperature inside is 19.5˚ C, and the temperature outside is
-4.7˚C, what is the approximate heat loss in units of Watts through
such a window with area 1 m2?

16a) A triple glazed window consists of 3 clear glass
panes of 4 mm thickness each, separated by two
air cavities of 13 mm each in thickness. The
window area is 1.0 m2
. If the thermal conductivity
of the glass panes is 0.8 W•m-1•K-1 and of the air
cavities is 0.026 W•m-1•K-1 what is the total
thermal resistance of the window?
(A) 2.452 K•W-1
(B) 0.015 K•W-1
(C) 1.015 K•W-1
(D) 6004 K•W-1
16b)A heater provides 305 W of...

A picture window has dimensions of 1.40 m×2.50 m and is made of
glass 5.10 mm thick. On a winter day, the outside temperature is
-15.0 ∘C , while the inside temperature is a comfortable 21.0 ∘C
.
Part B
At what rate would heat be lost through the window if you
covered it with a 0.750 mm-thick layer of paper (thermal
conductivity 0.0500 W/m⋅K)?
**I'm getting 6713 W but it saying im wrong. Please help

An 80.0 cm × 1.25 m glass window has a thickness of 2.34 mm. If
the indoor temperature is 22.0°F and the outdoor temperature is
98.5°F, What is the rate at which heat is conducted through the
glass in this window? (thermal conductivity of glass is 0.75
W/(m•K))

Constants A picture window has dimensions of 1.40 m×2.50 m and
is made of glass 5.80 mm thick. On a winter day, the outside
temperature is -15.0 ?C , while the inside temperature is a
comfortable 20.5 ?C . a)At what rate is heat being lost through the
window by conduction? b)At what rate would heat be lost through the
window if you covered it with a 0.750 mm-thick layer of paper
(thermal conductivity 0.0500 W/m?K)?

71 mm thick horizontal plate made of an opaque material of
thermal conductivity k= 25 W/m-K. At the bottom, water flows at a
temperature of T∞,w = 25C, whereas air flows at the top of the
plate at T∞,a = 710 C having convection coefficient of ha= 71
W/m2-K. Assuming a diffused top of the plate that receives an
irradiated flux of 7100W/m2, of which 30% is reflected back. The
top and bottom surface temperatures are maintained at 43 C...

a) A 12 mm diameter mild steel sphere (k = 42.5 W/m K) is
exposed to cooling airflow at 27 0C resulting in the convective
coefficient, h = 114 W/ m2 K. The relevant properties of mild steel
are given as follows: Density , /7850 2 mkg Specific heat K kgJc
p / 475 and thermal diffusivity hr m /043.0 2 Determine: (i)
Time required to cool the sphere (lumped parameter system) from 540
0C to 950C. [7...

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