2. What is the transfer of vibrational energy due to collisions between neighbouring atoms and molecules in a solid called? a. Conduction b. Convection Radiation c. d. Latent Heat

Structural Analysis
6th Edition
ISBN:9781337630931
Author:KASSIMALI, Aslam.
Publisher:KASSIMALI, Aslam.
Chapter2: Loads On Structures
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Heat Transfer
1. If you have a piece of extruded polystyrene insulation that has an R-value of 5
hr ft?.°F/Btu per inch [or RSI = 0.8805 (m² · K)/W)]. How many inches of
extruded polystyrene do you need in your wall if you want it to have an R-value
of 20 hr ft2.°F/Btu [or RSI = 3.522 (m² · K)/W)]? L= 4"
2. What is the transfer of vibrational energy due to collisions between neighbouring
atoms and molecules in a solid called?
a. Conduction
b. Convection
c. Radiation
d. Latent Heat
Radiant Energy
3. Absorptance is a measure of the relative amount of radiant energy absorbed by a
surface. Does a shiny and smooth polished aluminum surface have a high
absorptance (closer to 1), or a low absortptance (closer to 0)? Absorptance is a
ratio of the radiation absorbed to the radiation received, and thus is dimensionless.
What about reflectance? Are absorptance and reflectance related?
4. Emissivity is a measure of the relative amount of radiant energy emitted by a
surface. Does a shiny and smooth polished aluminum surface have a high
emissivity (closer to 1), or a low emissivity (closer to 0)? Emissivity is a ratio
and thus is dimensionless.
5. When radiant energy hits a surface (such the sun's rays hitting a window), there
are 3 different things that can happen to this radiant energy at the surface, can you
name all or any of these?
Transcribed Image Text:Heat Transfer 1. If you have a piece of extruded polystyrene insulation that has an R-value of 5 hr ft?.°F/Btu per inch [or RSI = 0.8805 (m² · K)/W)]. How many inches of extruded polystyrene do you need in your wall if you want it to have an R-value of 20 hr ft2.°F/Btu [or RSI = 3.522 (m² · K)/W)]? L= 4" 2. What is the transfer of vibrational energy due to collisions between neighbouring atoms and molecules in a solid called? a. Conduction b. Convection c. Radiation d. Latent Heat Radiant Energy 3. Absorptance is a measure of the relative amount of radiant energy absorbed by a surface. Does a shiny and smooth polished aluminum surface have a high absorptance (closer to 1), or a low absortptance (closer to 0)? Absorptance is a ratio of the radiation absorbed to the radiation received, and thus is dimensionless. What about reflectance? Are absorptance and reflectance related? 4. Emissivity is a measure of the relative amount of radiant energy emitted by a surface. Does a shiny and smooth polished aluminum surface have a high emissivity (closer to 1), or a low emissivity (closer to 0)? Emissivity is a ratio and thus is dimensionless. 5. When radiant energy hits a surface (such the sun's rays hitting a window), there are 3 different things that can happen to this radiant energy at the surface, can you name all or any of these?
Heat Flow
6. Heat Flow (measured in Watts) through a building wall is proportional to the
following items;
the overall effective thermal resistance of the wall
the area of the wall
the difference between the indoor and outdoor temperatures
a. Increasing the effective thermal resistance of the wall to heat flow, what
happens to the amount of heat flow, it increases or decreases?
b. Decreasing the area of the wall, what happens to the amount of heat flow, it
increases or decreases?
c. Decreasing the temperature difference between the inside and outside
temperature, what happens to the amount of heat flow, it increases or decreases?
Heat Flow Through Building Assemblies
7. The indoor air temperature is +20°C, and the outdoor air temperature is -10°C.
The outside surface temperature of an uninsulated wall is -5°C. If you add 89
mm of fibreglass batt insulation to the inside of this wall section, what will
happen to the outside surface temperature?
a. it be warmer than -5°C
b. it will remain at -5°C
c. it will be colder than -5°C and warmer than -10°C
d. it will be -10°C
e. it will be colder than -10°C
8. What material has a greater thermal resistance, a, b, c, or d?
а. 50mm coрper
b. 50mm glass
c. 50mm common brick
d. 50mm pine
Transcribed Image Text:Heat Flow 6. Heat Flow (measured in Watts) through a building wall is proportional to the following items; the overall effective thermal resistance of the wall the area of the wall the difference between the indoor and outdoor temperatures a. Increasing the effective thermal resistance of the wall to heat flow, what happens to the amount of heat flow, it increases or decreases? b. Decreasing the area of the wall, what happens to the amount of heat flow, it increases or decreases? c. Decreasing the temperature difference between the inside and outside temperature, what happens to the amount of heat flow, it increases or decreases? Heat Flow Through Building Assemblies 7. The indoor air temperature is +20°C, and the outdoor air temperature is -10°C. The outside surface temperature of an uninsulated wall is -5°C. If you add 89 mm of fibreglass batt insulation to the inside of this wall section, what will happen to the outside surface temperature? a. it be warmer than -5°C b. it will remain at -5°C c. it will be colder than -5°C and warmer than -10°C d. it will be -10°C e. it will be colder than -10°C 8. What material has a greater thermal resistance, a, b, c, or d? а. 50mm coрper b. 50mm glass c. 50mm common brick d. 50mm pine
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