WorksheetsFinal Examination in ME 413 (Problem-Solving - Part 1)
Total questions: 10
Worksheet time: 50mins
Name
Class
Date
1.
Calculate the specific volume of an air-vapor mixture in cubic meters per kilogram of dry air when the following conditions prevail: t = 30°C, ω = 0.015 kg/kg, and Pt = 90 kPa.
a)
0.69 m³/kga
b)
0.89 m³/kga
c)
0.79 m³/kga
d)
0.99 m³/kga
2.
A 4 m x 4 m x 4 m room has a relative humidity ratio of 80%. The pressure in the room is 120 kPa and temperature is 35°C (Psat = 5.628 kPa). What is the mass of vapor in the room? Use Rvapor = 0.4615 kN-m/kg- K.
a)
2.03 kgv
b)
5.03 kgv
c)
3.03 kgv
d)
1.03 kgv
3.
The mass of an outside air at 50°C in an air conditioning unit is 60 kg. Find the temperature after mixing if the outside air mixed with 40 kg with recirculated air at 35°C.
a)
55°C
b)
65°C
c)
44°C
d)
35°C
4.
In an air conditioning system, if the re-circulated air is three times the outside air and the mass of supply air is 20 kg/s, what is the mass of the outside air?
a)
5 kg/s
b)
5.5 kg/s
c)
6 kg/s
d)
0 kg/s
5.
A room being air conditioned is being held at 25°C dry bulb and 50% relative humidity. A flow rate of 5 m³/s of supply air at 15°C dry bulb and 80% RH is being delivered to the room to maintain that steady condition at 100 kPa. What is the sensible heat absorbed from the room air in kW?
a)
60.5 kW
b)
88 kW
c)
60.5 hP
d)
214.2 kW
6.
If the latent and sensible heat loads are 20 kW and 80 kW respectively, what is the sensible heat ratio?
a)
1
b)
0.5
c)
2
d)
0.8
7.
In an auditorium maintained at a temperature not to exceed 24°C and relative humidity not to exceed 60%, a sensible heat load of 132 kW and 78 kg of moisture per hour to be removed. Air is supplied to the auditorium at 18°C. How many kilograms of air must be supplied per hour?
a)
79200 kg/hr
b)
79002 kg/hr
c)
97200 kg/hr
d)
72900 kg/hr
8.
Determine the approximate load on a cooling tower if the entering and leaving temperatures are 96°F and 88°F, respectively and the flow rate of the water over the tower is 30 gpm.
a)
2000 kW
b)
2000 hP
c)
2000 BTU/min
d)
2000 BUT/s
9.
The natural draft cooling tower has a 400 ton heat rejection load. The temperature of the water entering the cooling tower is 90°F and leaving at 82°F. Compute the approach, range and cooling tower efficiency when the outdoor wet-bulb temperature is 75°F.
a)
R = 8°C, A = 7°C, e = 53.33%
b)
R = 8°C, A = 8°C, e = 53.33%
c)
R = 7°C, A = 7°C, e = 53.33%
d)
R = 7°C, A = 8°C, e = 53.33%
10.
Copra enters a dryer containing 60% water and 40% of solids and leaves with 5% water and 95% solids. Find the weight of water removed based on each pound of original product.
a)
0.85 lb
b)
0.24 lb
c)
0.58 lb
d)
0.42 lb
100 %
