ASSIGNMENT 1
MATERIAL BALANCE PROBLEM
Answer all questions.
Problem 1
A solution of common salt in water is prepared by adding 20 kg of salt to 100 kg of water, to make liquid of density of 1323 kg/m3. Calculate the concentration of salt in this solution as a
a. Weight fraction
b. Weight/volume fraction
c. Mole fraction
Problem 2
If 35 000 kg of whole milk containing 4% of at is to be separated in a 6 hour period into skim milk with 0.45% fat and cream with 45% fat, what are the flow rates of the two output streams from a continuous centrifuge which accomplishes this separation?
Basis 1 hour’s flow of whole milk
Problem 3
An aqueous solution of sodium hydroxide contains 20% NaOH by mass. It is desired to produce an 8% NaOH solution by diluting a stream of the 20% solution with a stream of pure water. What is the flow rate of pure water and outlet stream?
Problem 4
During an air pollution monitoring study, the inlet gas stream to a bag filter is 169920 m3/hr and the dust loading is 4577 mg/m3. The outlet gas stream from the bag filter is 185040 m3/hr and the dust loading is 57 mg/m3. What is the maximum quantity of ash that will have to be removed per hour from the bag filter hopper based on these test results?
Problem 5
Moist air flows along a duct in an air-conditioning plant at a rate of 20 lbm/s and with a specific humidity of 0.004 (Note that the specific humidity is the ratio of the masses of water and dry air in sample). Water is sprayed into the stream at a rate of 0.120 lbm/s and mixes with it, albeit uniformly. At outlet 3, the mass flow rate of air and water are 12.20 lbm/s and 0.130 lbm/s respectively.
a. What are the mass flow rates of dry air and water at point 1?
b. What is the total discharge rate (mass flow rate of dry air and water) and the specific humidity at outlet 4?
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