Q1.1 A mixture of dray air and water vapour is at a temperature of 20o under a total pressure of 100...

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Q1.1 A mixture of dray air and water vapour is at a temperature of 20o under a total pressure of 100 kPa. The dew-point temperature is 15 o C. Find 1) partial pressure of the water; 2) relative humidity (72.89%); 3) specific humidity XXXXXXXXXX); and 4) specific volume of air per kg of dray air. Q 1.2[1] The refrigerant R-410a is a mixture of R-32 and R125 in a 1:1 mass ratio. Now through a reversible polytropic process, the pressure of R-410a is increased from 100 kPa to 250 kPa, and temperature increased from 290 K to 400 K. Assuming R-410a vapour as an ideal gas with constant specific heats, find 1. the gas coefficient, R XXXXXXXXXXkJ/kg-K), and constant-pressure specific heat, cp, of R410a XXXXXXXXXXkJ/kg-K); and 2. the change in specific volume, specific enthalpy and specific entropy. Assignment 2[2] (Due 11 April XXXXXXXXXXmarks) A wet cooling tower is to cool 40 kg/s of water from 40 to 30 o C. Atmospheric air enters the tower at atmosphere with dry- and wet-bulb temperatures of 22 and 16 o C, respectively, and leaves at 32 o C with a relative humidity of 95%. Assuming adiabatic process in the cooling tower and using the psychrometric chart. Determine 1) the mass flow rate (27.5 m3 /s) o
	
Document Preview: ASSIGNMENT QUESTIONS     AUTUMN 2017 
49322 AIR CONDITIONING 
 
Assignment 1 (Due 4 April 2017)  
(10 marks) 
 
o
Q1.1 A mixture of dray air and water vapour is at a temperature of 20 under a total pressure 
o
of 100 kPa. The dew-point temperature is 15 C. Find 
1) partial pressure of the water; 
2) relative humidity (72.89%); 
3) specific humidity XXXXXXXXXX); and 
4) specific volume of air per kg of dray air. 
 
[1]
Q 1.2  The refrigerant R-410a is a mixture of R-32 and R125 in a 1:1 mass ratio. Now 
through a reversible polytropic process, the pressure of R-410a is increased from 100 kPa to 
250 kPa, and temperature increased from 290 K to 400 K. Assuming R-410a vapour as an 
ideal gas with constant specific heats, find 
1. the gas coefficient, R XXXXXXXXXXkJ/kg-K), and constant-pressure specific heat, c , of R-
p
410a XXXXXXXXXXkJ/kg-K); and 
2. the change in specific volume, specific enthalpy and specific entropy.

[2]
Assignment 2 (Due 11 April 2017) 
(10 marks) 
A wet cooling tower is to cool 40 kg/s of water from 40 to 
o
30 C. Atmospheric air enters the tower at atmosphere with 
o
dry- and wet-bulb temperatures of 22 and 16 C, respectively, 
o
and leaves at 32 C with a relative humidity of 95%. Assuming 
adiabatic process in the cooling tower and using the 
psychrometric chart. Determine 
3
1) the mass flow rate (27.5 m /s) of the air into the cooling 
??
tower; (or 28.6 kg/s if assume m = m ) 
air dryair
2) the volume flow rate of the air into the cooling tower; and 
3) the mass flow rate of the required makeup water (0.56 kg/s).

Assignment 3 (Due 18 April 2017)  
(10 marks)

3
As shown in the schematic diagram above, an air-handling unit mixes 0.3 m /s of fresh air at 
o o o
35 C d.b., 26 C w.b. (state 1) with recirculated room air at 25 C d.b., 50% relative 
1o
humidity (state 2). The mixed air at temperature of 30 C d.b. (state 3) passes through a 
o
chilled-water cooling coil whose dew point is 10 C d.b. (state 4). Incomplete contact...

David · Accepted Answer

Thermo_001.pdf (p.1)
	Thermo_002.pdf (p.2)
	Thermo_003.pdf (p.3)
	Thermo_004.pdf (p.4)
	Thermo_005.pdf (p.5)
	Thermo_006.pdf (p.6)
	Thermo_007.pdf (p.7)
	Thermo_008.pdf (p.8)
	Thermo_009.pdf (p.9)
	Thermo_010.pdf (p.10)

Q1.1 A mixture of dray air and water vapour is at a temperature of 20o under a total pressure of 100 kPa. The dew-point temperature is 15 o C. Find 1) partial pressure of the water; 2) relative...

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