The composite insulation shown, which was described in Chapter 1 (Problem 1.86e), is being considered as a ceiling material. It is proposed that the outer and inner slabs be made from low-density particle board of thicknesses L 1 = L 3 = 12.5 mm and that the honeycomb core be constructed from a high-density particle board. The square cells of the core are to have length L 2 = 50 mm , width W = 10 mm , and wall thickness t = 2 mm . The emissivity of both particle boards is approximately 0.85, and the honeycomb cells are tilled with air at 1-atm pressure. To assess the effectiveness of the insulation, its total thermal resistance must be evaluated under representative operating conditions for which the bottom (inner) surface temperature is T s , i = 25 ° C and the top (outer) surface temperature is T s , i = − 10 ° C . To assess the effect of free convection in the air space, assume a cell temperature difference of 20°C and evaluate air properties at 7.5°C. To assess the effect of radiation across the air space, assume inner surface temperatures of the outer and inner slabs to be −5 and 15°C, respectively.
The composite insulation shown, which was described in Chapter 1 (Problem 1.86e), is being considered as a ceiling material. It is proposed that the outer and inner slabs be made from low-density particle board of thicknesses L 1 = L 3 = 12.5 mm and that the honeycomb core be constructed from a high-density particle board. The square cells of the core are to have length L 2 = 50 mm , width W = 10 mm , and wall thickness t = 2 mm . The emissivity of both particle boards is approximately 0.85, and the honeycomb cells are tilled with air at 1-atm pressure. To assess the effectiveness of the insulation, its total thermal resistance must be evaluated under representative operating conditions for which the bottom (inner) surface temperature is T s , i = 25 ° C and the top (outer) surface temperature is T s , i = − 10 ° C . To assess the effect of free convection in the air space, assume a cell temperature difference of 20°C and evaluate air properties at 7.5°C. To assess the effect of radiation across the air space, assume inner surface temperatures of the outer and inner slabs to be −5 and 15°C, respectively.
Solution Summary: The diagram shows the kinematic properties of air at the ambient temperature of stackrel, i=25°C.
The composite insulation shown, which was described in Chapter 1 (Problem 1.86e), is being considered as a ceiling material.
It is proposed that the outer and inner slabs be made from low-density particle board of thicknesses
L
1
=
L
3
=
12.5
mm
and that the honeycomb core be constructed from a high-density particle board. The square cells of the core are to have length
L
2
=
50
mm
, width
W
=
10
mm
, and wall thickness
t
=
2
mm
. The emissivity of both particle boards is approximately 0.85, and the honeycomb cells are tilled with air at 1-atm pressure. To assess the effectiveness of the insulation, its total thermal resistance must be evaluated under representative operating conditions for which the bottom (inner) surface temperature is
T
s
,
i
=
25
°
C
and the top (outer) surface temperature is
T
s
,
i
=
−
10
°
C
. To assess the effect of free convection in the air space, assume a cell temperature difference of 20°C and evaluate air properties at 7.5°C. To assess the effect of radiation across the air space, assume inner surface temperatures of the outer and inner slabs to be −5 and 15°C, respectively.
Lightweight epoxy composite with thermal insulation properties is required. Use a hollow glass ball as a stabilizer. Glass balls 1/16 inch in diameter and 0.001 inch in wall thickness. It weighs one foot and has a density of 0.65 g / cm3 The glass ball epoxy of any weight trying to produce a composite to do more? The density of glass is 2.5 g / cm3 and that of epoxy is 1.25 g / cm3
Thank you for you assist
You are asked to design an insulated stud timber wall and have the following materials available:
Outer skin materials.
●
Plasterboard 8 mm thick (k= 0.3 W/m.K)
Plasterboard 12.5 mm thick (k = 0.3 W/m.K)
Insulated Plasterboard 25 mm thick (k = 0.2 W/m.K)
Timber studs available (k = 0.1 W/m.K)
50 mm x 100 mm
50 mm x 120 mm
50 mm x 150 mm
Insulation layers
Glass fibre insulation (k= 0.05 W/m.K)
● Polyisocyanurate insulation (k= 0.025 W/m.K)
Sheeps wool insulation (k= 0.04 W/m.K)
●
Wall construction should consist of two outer plasterboard skins, followed by an appropriate
stud/insulation infill layer. Studs can be placed vertically at 400 mm or 600 mm intervals and you
may ignore any requirement for horizontal studding.
1) Draw a plan (top view) cross section of your wall indicating dimensions, spacing and
material choices.
2) Calculate the thermal resistance of your wall.
3) If the internal convective heat transfer coefficient in room one is 10 W/m²K and in the
second room it is 15…
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
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