Heat And Mass Transfer Tutorial 2
UNIVERSITI TUNKU ABDUL RAHMAN
Faculty
Course
:
Engineering and Science
Unit Code
:
:
Bachelor of Engineering (Hons)
Chemical / Mechanical Engineering
Unit Title
:
Academic
:
Year
Session
:
Lecturer
2014/2015
:
UEME 3213
Heat and Mass
Transfer
Dr. Mah Shee Keat/
Mr. Chong Kok Chung
201501
Tutorial 2
1) A one dimensional plane wall of thickness 2L = 80 mm experiences uniform thermal energy generation of ?̇ = 1000 W/m3 and is convectively cooled at ? = ±40 mm by an ambient fluid characterized by ?∞ = 30℃. If the steady state temperature distribution within the wall is ?(?) = ?(?2 − ? 2 ) + ? where a = 15 ºC/m2 and b = 40 ºC, what is the thermal conductivity of the wall? What is the value of the convection heat transfer coefficient, h?
2) The rear window of an automobile is defogged by passing warm air over its inner surface.
If the warm air is at T∞,i = 40oC and the corresponding convection coefficient is hi =30
W/m2.K, what are the inner and outer surface temperatures of 4 mm thick window glass, if the outside ambient air temperature is T∞,o = -10oC and the associated convection coefficient is ho = 65 W/m2.K?
3) The steady-state temperature distribution in a one-dimensional wall of thermal conductivity 50 W/m.K and thickness 50 mm is observed to be ?(℃) = ? + ?? 2 , where a = 200 ºC, b = -2000 ºC/m2, and x is in meters.
a)
What is the heat generation rate (?̇ ) in the wall?
b)
Determine the heat fluxes at the two wall faces. In what manner are these heat fluxes related to the heat generation rate?
4) A long, circular aluminum rod is attached at one end to a heated wall and transfers heat by convection to a cold fluid.
a) If the diameter of the rod is doubled, by how much would the rate of heat removal change? b) If a copper rod of the same diameter is used in place of the aluminum, by how much would the rate of heat removal change?
1 UEME 3213 Heat and Mass Transfer
5) One dimensional, steady state conduction with uniform internal energy
Faculty
Course
:
Engineering and Science
Unit Code
:
:
Bachelor of Engineering (Hons)
Chemical / Mechanical Engineering
Unit Title
:
Academic
:
Year
Session
:
Lecturer
2014/2015
:
UEME 3213
Heat and Mass
Transfer
Dr. Mah Shee Keat/
Mr. Chong Kok Chung
201501
Tutorial 2
1) A one dimensional plane wall of thickness 2L = 80 mm experiences uniform thermal energy generation of ?̇ = 1000 W/m3 and is convectively cooled at ? = ±40 mm by an ambient fluid characterized by ?∞ = 30℃. If the steady state temperature distribution within the wall is ?(?) = ?(?2 − ? 2 ) + ? where a = 15 ºC/m2 and b = 40 ºC, what is the thermal conductivity of the wall? What is the value of the convection heat transfer coefficient, h?
2) The rear window of an automobile is defogged by passing warm air over its inner surface.
If the warm air is at T∞,i = 40oC and the corresponding convection coefficient is hi =30
W/m2.K, what are the inner and outer surface temperatures of 4 mm thick window glass, if the outside ambient air temperature is T∞,o = -10oC and the associated convection coefficient is ho = 65 W/m2.K?
3) The steady-state temperature distribution in a one-dimensional wall of thermal conductivity 50 W/m.K and thickness 50 mm is observed to be ?(℃) = ? + ?? 2 , where a = 200 ºC, b = -2000 ºC/m2, and x is in meters.
a)
What is the heat generation rate (?̇ ) in the wall?
b)
Determine the heat fluxes at the two wall faces. In what manner are these heat fluxes related to the heat generation rate?
4) A long, circular aluminum rod is attached at one end to a heated wall and transfers heat by convection to a cold fluid.
a) If the diameter of the rod is doubled, by how much would the rate of heat removal change? b) If a copper rod of the same diameter is used in place of the aluminum, by how much would the rate of heat removal change?
1 UEME 3213 Heat and Mass Transfer
5) One dimensional, steady state conduction with uniform internal energy