Quizsummary
0 of 20 questions completed
Questions:
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
Information
MASS TRANSFER TEST 2
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
0 of 20 questions answered correctly
Your time:
Time has elapsed
You have reached 0 of 0 points, (0)
Average score 

Your score 

Categories
 Not categorized 0%
Pos.  Name  Entered on  Points  Result 

Table is loading  
No data available  
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 Answered
 Review

Question 1 of 20
1. Question
1 pointsConsider a circular pipe of inner diameter D= 0.5 in. whose inner surface is covered with a thin layer of liquid water as a result of condensation. In order to dry the pipe, air at 540 R and 1 atm is forced to flow through it with an average velocity of 4 ft/s. Using the analogy between heat and mass transfer, determine the mass transfer coefficient inside the pipe for fully developed flow.(ANSWER UPTO THREE DECIMAL)
Correct
0.024 ft/s
Incorrect
0.024 ft/s

Question 2 of 20
2. Question
1 pointsDry air at 15°C and 92 kPa flows over a 2mlong wet surface with a free stream velocity of 4 m/s. Determine the average mass transfer coefficient.(answer upto five decimal)
Correct
0.00514 m/s
Incorrect
0.00514 m/s

Question 3 of 20
3. Question
1 pointsConsider a 5m x 5m wet concrete patio with an average water film thickness of 0.3 mm. Now wind at 50 km/h is blowing over the surface. If the air is at 1 atm, 15°C, and 35 percent relative humidity, determine how long it will take for the patio to dry completely.(answer upto one decimal)
Correct
18.6 min
Incorrect
18.6 min

Question 4 of 20
4. Question
1 pointsA 2in.diameter spherical naphthalene ball is suspended in a room at 1 atm and 80°F. Determine the average mass transfer coefficient between the naphthalene and the air if air is forced to flow over naphthalene with a free stream velocity of 15 ft/s. The Schmidt number of naphthalene in air at room temperature is 2.35.(answer upto four decimal)
Correct
0.0525 ft/s
Incorrect
0.0525 ft/s

Question 5 of 20
5. Question
1 pointsA glass bottle washing facility uses a wellagitated hot water bath at 55°C with an open top that is placed on the ground. The bathtub is 1 m high, 2 m wide, and 4 m long and is made of sheet metal so that the outer side surfaces are also at about 55°C. The bottles enter at a rate of 800 per minute at ambient temperature and leave at the water temperature. Each bottle has a mass of 150 g and removes 0.6 g of water as it leaves the bath wet. Makeup water is supplied at 15°C. If the average conditions in the plant are 1 atm, 25°C, and 50 percent relative humidity, and the average temperature of the surrounding surfaces is 15°C, determine the amount of heat and water removed by the bottles themselves per second
Correct
61,337 W
Incorrect
61,337 W

Question 6 of 20
6. Question
1 pointsA glass bottle washing facility uses a wellagitated hot water bath at 55°C with an open top that is placed on the ground. The bathtub is 1 m high, 2 m wide, and 4 m long and is made of sheet metal so that the outer side surfaces are also at about 55°C. The bottles enter at a rate of 800 per minute at ambient temperature and leave at the water temperature. Each bottle has a mass of 150 g and removes 0.6 g of water as it leaves the bath wet. Makeup water is supplied at 15°C. If the average conditions in the plant are 1 atm, 25°C, and 50 percent relative humidity, and the average temperature of the surrounding surfaces is 15°C, determine the rate of heat loss from the top surface of the water bath by radiation, natural convection, and evaporation;
Correct
1480 W
Incorrect
1480 W

Question 7 of 20
7. Question
1 pointsA glass bottle washing facility uses a wellagitated hot water bath at 55°C with an open top that is placed on the ground. The bathtub is 1 m high, 2 m wide, and 4 m long and is made of sheet metal so that the outer side surfaces are also at about 55°C. The bottles enter at a rate of 800 per minute at ambient temperature and leave at the water temperature. Each bottle has a mass of 150 g and removes 0.6 g of water as it leaves the bath wet. Makeup water is supplied at 15°C. If the average conditions in the plant are 1 atm, 25°C, and 50 percent relative humidity, and the average temperature of the surrounding surfaces is 15°C, determine the rate of heat loss from the side surfaces by natural convection and radiation;
Correct
3773 W
Incorrect
3773 W

Question 8 of 20
8. Question
1 pointsA glass bottle washing facility uses a wellagitated hot water bath at 55°C with an open top that is placed on the ground. The bathtub is 1 m high, 2 m wide, and 4 m long and is made of sheet metal so that the outer side surfaces are also at about 55°C. The bottles enter at a rate of 800 per minute at ambient temperature and leave at the water temperature. Each bottle has a mass of 150 g and removes 0.6 g of water as it leaves the bath wet. Makeup water is supplied at 15°C. If the average conditions in the plant are 1 atm, 25°C, and 50 percent relative humidity, and the average temperature of the surrounding surfaces is 15°C, determine the rate at which heat and water must be supplied to maintain steady operating conditions. Disregard heat loss through the bottom surface of the bath and take the emissivities of sheet metal and water to be 0.61 and 0.95, respectively
Correct
79,960 W, 44.9 kg/h
Incorrect
79,960 W, 44.9 kg/h

Question 9 of 20
9. Question
1 pointsOne way of increasing heat transfer from the head on a hot summer day is to wet it. This is especially effective in windy weather, as you may have noticed. Approximating the head as a 30cmdiameter sphere at 30°C with an emissivity of 0.95, determine the total rate of heat loss from the head at ambient air conditions of 1 atm, 25°C, 40 percent relative humidity, and 25 km/h winds if the head is dry Take the surrounding temperature to be 25°C.(answer upto one decimal)
Correct
40.6 W
Incorrect
40.6 W

Question 10 of 20
10. Question
1 pointsOne way of increasing heat transfer from the head on a hot summer day is to wet it. This is especially effective in windy weather, as you may have noticed. Approximating the head as a 30cmdiameter sphere at 30°C with an emissivity of 0.95, determine the total rate of heat loss from the head at ambient air conditions of 1 atm, 25°C, 40 percent relative humidity, and 25 km/h winds if the head is wet Take the surrounding temperature to be 25°C.
Correct
352 W
Incorrect
352 W

Question 11 of 20
11. Question
1 pointsConsider a glass of water in a room at 25°C and 100 kPa. If the relative humidity in the room is 70 percent and the water and the air are at the same temperature, determine the mole fraction of the water vapor in the room air.(answer in two decimal)
Correct
2.22 percent
Incorrect
2.22 percent

Question 12 of 20
12. Question
1 pointsConsider a glass of water in a room at 25°C and 100 kPa. If the relative humidity in the room is 70 percent and the water and the air are at the same temperature, determine the mole fraction of the water vapor in the air adjacent to the water surface, (answer upto two decimal)
Correct
3.17 percent
Incorrect
3.17 percent

Question 13 of 20
13. Question
1 pointsConsider a glass of water in a room at 25°C and 100 kPa. If the relative humidity in the room is 70 percent and the water and the air are at the same temperature, determine the mole fraction of air in the water near the surface.
Correct
1.34 x 10^5 percent
Incorrect
1.34 x 10^5 percent

Question 14 of 20
14. Question
1 pointsA carbonated drink is fully charged with CO2 gas at 17°C and 600 kPa such that the entire bulk of the drink is in thermodynamic equilibrium with the CO2–water vapor mixture. Now consider a 2L soda bottle. If the CO2 gas in that bottle were to be released and stored in a container at 25°C and 100 kPa, determine the volume of the container(answer upto one decimal)
Correct
12.7 L
Incorrect
12.7 L

Question 15 of 20
15. Question
1 pointsThe oxygen needs of fish in aquariums are usually met by forcing air to the bottom of the aquarium by a compressor. The air bubbles provide a large contact area between the water and the air, and as the bubbles rise, oxygen and nitrogen gases in the air dissolve in water while some water evaporates into the bubbles. Consider an aquarium that is maintained at room temperature of 25°C at all times. The air bubbles are observed to rise to the free surface of water in 2 s. If the air entering the aquarium is completely dry and the diameter of the air bubbles is 4 mm, determine the mole fraction of water vapor at the center of the bubble when it leaves the aquarium. Assume no fluid motion in the bubble so that water vapor propagates in the bubble by diffusion only.(answer upto two decimal)
Correct
3.13 percent
Incorrect
3.13 percent

Question 16 of 20
16. Question
1 pointsNaphthalene is commonly used as a repellent against moths to protect clothing during storage. Consider a 1cmdiameter spherical naphthalene ball hanging in a closet at 25°C and 1 atm. Considering the variation of diameter with time, determine how long it will take for the naphthalene to sublimate completely. The density and vapor pressure of naphthalene at 25°C are 0.11 Pa and 1100 kg/m³ and 11 Pa, respectively, and the mass diffusivity of naphthalene in air at 25°C is DAB 0.61 x 10^5 m² /s.(answer upto one decimal)
Correct
45.7 days
Incorrect
45.7 days

Question 17 of 20
17. Question
1 pointsA thick part made of nickel is put into a room filled with hydrogen at 3 atm and 85°C. Determine the hydrogen concentration at a depth of 2mm from the surface after 24 h.
Correct
4.1 x 10^7 kmol/m³
Incorrect
4.1 x 10^7 kmol/m³

Question 18 of 20
18. Question
1 pointsThe top section of an 8ftdeep 100ft x 100ft heated solar pond surface is maintained at a constant temperature of 80°F at a location where the atmospheric pressure is 1 atm. If the ambient air is at 70°F and 100 percent relative humidity and wind is blowing at an average velocity of 40 mph, determine the rate of heat loss from the top surface of the pond by forced convection. Take the average temperature of the surrounding surfaces to be 90°F
Correct
299,400 Btu/h
Incorrect
299,400 Btu/h

Question 19 of 20
19. Question
1 pointsThe top section of an 8ftdeep 100ft x 100ft heated solar pond surface is maintained at a constant temperature of 80°F at a location where the atmospheric pressure is 1 atm. If the ambient air is at 70°F and 100 percent relative humidity and wind is blowing at an average velocity of 40 mph, determine the rate of heat loss from the top surface of the pond by radiation. Take the average temperature of the surrounding surfaces to be 90°F
Correct
1,057,000 Btu/h
Incorrect
1,057,000 Btu/h

Question 20 of 20
20. Question
1 pointsThe top section of an 8ftdeep 100ft x 100ft heated solar pond surface is maintained at a constant temperature of 80°F at a location where the atmospheric pressure is 1 atm. If the ambient air is at 70°F and 100 percent relative humidity and wind is blowing at an average velocity of 40 mph, determine the rate of heat loss from the top surface of the pond by evaporation.Take
the average temperature of the surrounding surfaces to be 60°FCorrect
3,396,000 Btu/h
Incorrect
3,396,000 Btu/h