A pin fin is made of an Aluminum (k=235W/m K) rod length 68 cm and diameter...
A pin fin is made of an Aluminum (k=235W/m K) rod length 68 cm and diameter 10 mm. If the heat transfer coefficient is 10 W/m2 K, calculate the fin efficiency.
|
a. |
27% |
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b. |
46% |
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c. |
35% |
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d. |
56% |
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e. |
97% |
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f. |
None of them |
A 2-m-high, 3-m-wide, and 120-cm-thick wall of a house has a thermal resistance of 0.0124 ºC/W. The thermal conductivity of the wall is
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a. |
0.72 W/mºC |
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b. |
1.1 W/mºC |
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c. |
1.6 W/mºC |
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d. |
16 W/mºC |
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e. |
32 W/mºC |
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f. |
None of them |
A grape of 1 cm diameter, initially at 28oC, is placed in a refrigerator in which the air temperature is 3oC. If the heat transfer coefficient is 20 W/m2oC, the time required for the grape temperature to reach 10oC is:
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a. |
25 mins |
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b. |
2.5 mins |
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c. |
7 mins |
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d. |
9 mins |
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e. |
12 mins |
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f. |
None of them |
Homework Answers
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A pin fin is made of an Aluminum (k=235W/m K) rod length 68 cm
and diameter...
3.7 The height and diameter of a pin fin made of 3003 aluminum are 2.3 cm...
3.7 The height and diameter of a pin fin made of 3003 aluminum are 2.3 cm and 0.35 cm, respectively. A fin- base temperature of 65°C is maintained while 10°C air flows around the pin fin, producing a heat-transfer coef- fieient of 35 W/m2·K. Find the heat transfer from the fin.
Problem 2 A 4 mm diameter and 20 cm long aluminum fin (k 240 W/m-K) is...
Problem 2 A 4 mm diameter and 20 cm long aluminum fin (k 240 W/m-K) is attached to a surface. If the heat transfer coefficient is 12 W/m2 K, determine the percent error in the rate of heat transfer from the fin when the infiniely long fin assumption is used nstead of the adiabatic fin tip assumption. D-4 mm L- 10 cm Fig. 2 fin
2. A hot surface at 120°C is cooled by attaching a 6-cm-long, 0.6-cm-diameter pin fin (k...
2. A hot surface at 120°C is cooled by attaching a 6-cm-long, 0.6-cm-diameter pin fin (k 220 W/m K, a 97.1 x 10 m2/s). The temperature of the surrounding air is 15°C, and the heat transfer coefficient on the fin surface is 30 W/m2 K. Assuming one-dimensional heat conduction along the fin, an adiabatic tip, and taking the nodal spacing to be Ax 3 cm, determine the tip temperature.
a rectangular fin (k= 235w/m*K) is attached to a wall and has a length of 5...
a rectangular fin (k= 235w/m*K) is attached to a wall and has a length of 5 cm, a width of 10 cm, and a thickness of 5 mm. the surface temperature of the wall is 350 degrees Celcius and the ambient air is 25 degrees celcius. what is the efficiency, the heat transfer rate, and the fin effectiveness? assume an adiabatic fin tip condition and a convection heat transfer coefficient of 154 W/m^2 * K
Consider a very long aluminum fin (k = 237W/m-K) fin
Consider a very long aluminum fin (k = 237W/m-K) fin, with the temperature at the end of the fin essentially that of the surrounding air. This fin has a diameter of lcm, and is attached to a surface at 80°C. The surface is exposed to ambient air at 22°C with a heat transfer coefficient of 15W/m2-K. Estimate: a) The fin temperature at a distance of 5cm from the base; b) The rate of heat loss from the entire fin; c) The effectiveness of...
A copper pin fin 2.5 mm in diameter protrudes from a wall at 100°C into air...
A copper pin fin 2.5 mm in diameter protrudes from a wall at 100°C into air at 28°C. ( k=396 W/m-K.) The heat transfer is mainly by natural convection with a heat transfer coefficient of 12 W/m2×K. Calculate heat losses from the fin assuming the fin is infinitely long. If there is an array of 10 copper pin fins, how much power do they dissipate?
3.1 The height, length, and thickness of a longitudinal fin of 6061 aluminum are 3.2 cm,...
3.1 The height, length, and thickness of a longitudinal fin of 6061 aluminum are 3.2 cm, 15 cm, and 2 mm, re- spectively. If the fin base is maintained at a temperature of 55°C and the surrounding air temperature is 20°C, where the heat-transfer coefficient is 34 W/m2.K, what is the heat transfer from the fin?
1. A fin with a diameter of 5 mm, a length of 100 mm, and a...
1. A fin with a diameter of 5 mm, a length of 100 mm, and a thermal conductivity of 133 w/m.oC is attached to a base plate, which is at 200 oC. The fin is surrounded by a fluid at 200 C, and has a convection heat transfer coefficient of 30 W/(m·℃). 1.1 compute the temperature of the rod at 20 mm, 60 mm, and 100 mm points from the base 1.2 compute the total heat transfer rate from the...
1. A fin with a diameter of 5 mm, a length of 100 mm, and a...
1. A fin with a diameter of 5 mm, a length of 100 mm, and a thermal conductivity of 133 w/m"C is attached to a base plate, which is at 200 oC. The fin is surrounded by a fluid at 20 ° C, and has a convection heat transfer coefficient of 30 W/(m2. c). 1.1 compute the temperature of the rod at 20 mm, 60 mm, and 100 mm points from the base 1.2 compute the total heat transfer rate...
Consider a rectangular fin (k = 180 W/m-K) of length L =10 mm, thickness i =1...
Consider a rectangular fin (k = 180 W/m-K) of length L =10 mm, thickness i =1 mm, and width w» t. The base temperature of the finis Ty = 150°C, and the finis exposed to a fluid of temperature T, =25°C. Assuming a uniform convection coefficient of h = 110 W/m2.K over the entire fin surface, determine the fin heat transfer rate per unit width 4; efficiency ng: effectiveness es, thermal resistance per unit width and the tip temperature T...
3.7 The height and diameter of a pin fin made of 3003 aluminum are 2.3 cm and 0.35 cm, respectively. A fin- base temperature of 65°C is maintained while 10°C air flows around the pin fin, producing a heat-transfer coef- fieient of 35 W/m2·K. Find the heat transfer from the fin.
Problem 2 A 4 mm diameter and 20 cm long aluminum fin (k 240 W/m-K) is attached to a surface. If the heat transfer coefficient is 12 W/m2 K, determine the percent error in the rate of heat transfer from the fin when the infiniely long fin assumption is used nstead of the adiabatic fin tip assumption. D-4 mm L- 10 cm Fig. 2 fin
2. A hot surface at 120°C is cooled by attaching a 6-cm-long, 0.6-cm-diameter pin fin (k 220 W/m K, a 97.1 x 10 m2/s). The temperature of the surrounding air is 15°C, and the heat transfer coefficient on the fin surface is 30 W/m2 K. Assuming one-dimensional heat conduction along the fin, an adiabatic tip, and taking the nodal spacing to be Ax 3 cm, determine the tip temperature.
3.1 The height, length, and thickness of a longitudinal fin of 6061 aluminum are 3.2 cm, 15 cm, and 2 mm, re- spectively. If the fin base is maintained at a temperature of 55°C and the surrounding air temperature is 20°C, where the heat-transfer coefficient is 34 W/m2.K, what is the heat transfer from the fin?
1. A fin with a diameter of 5 mm, a length of 100 mm, and a thermal conductivity of 133 w/m.oC is attached to a base plate, which is at 200 oC. The fin is surrounded by a fluid at 200 C, and has a convection heat transfer coefficient of 30 W/(m·℃). 1.1 compute the temperature of the rod at 20 mm, 60 mm, and 100 mm points from the base 1.2 compute the total heat transfer rate from the...
1. A fin with a diameter of 5 mm, a length of 100 mm, and a thermal conductivity of 133 w/m"C is attached to a base plate, which is at 200 oC. The fin is surrounded by a fluid at 20 ° C, and has a convection heat transfer coefficient of 30 W/(m2. c). 1.1 compute the temperature of the rod at 20 mm, 60 mm, and 100 mm points from the base 1.2 compute the total heat transfer rate...
Consider a rectangular fin (k = 180 W/m-K) of length L =10 mm, thickness i =1 mm, and width w» t. The base temperature of the finis Ty = 150°C, and the finis exposed to a fluid of temperature T, =25°C. Assuming a uniform convection coefficient of h = 110 W/m2.K over the entire fin surface, determine the fin heat transfer rate per unit width 4; efficiency ng: effectiveness es, thermal resistance per unit width and the tip temperature T...
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