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課程名稱︰質能平衡甲
課程性質︰系定必修
課程教師︰林祥泰
開課學院：工學院
開課系所︰化工系
考試日期（年月日）︰97.03.25
考試時限（分鐘）：110分鐘
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
Note:Data needed for the calculations are provided in the back of this paper.
Credit for each problem is given in the square brackets []. Be sure to write
down how you reach the answers. No credit will be given to answers without
providing sufficient explanation.
1.The health limit of contaminant carbon tetrachloride(CCl4) in drinking water
is 5 ppb. What is this value in terms of mass fraction, mole fraction, molarity
, and molality?[10pts]
2.In the degrees-of-freedom analysis, what are the sources of relations that
can be used to solving the unknowns in a non-reactive process? Briefly explain
your answer.[10pts]
3.Shown below is a flowchart of a process in which acetic acid(A) is extracted
from a mixture of acetic acid and water(W) into 1-hexanol(H), a liquid
immiscible with water.
. .
mH(g C6H13OH/min) mE(g/min)
────────→╭┬─┬╮─────────────→
. ││ ││. 0.096g CH3COOH/g
mF(g/min) ││ ││mR(g/min) 0.904g C6H13OH/g
────────→╰┴─┴╯────────→
0.200g CH3COOH/g 0.005g CH3COOH/g
0.800g H2O/g 0.995g H2O/g
a)What is the maximum number of independent material balances that can be
written for this process?[5pts]
b)Suppose we wish to recover acetic acid from the extract(i.e.,the mE stream)
at a rate of 100g/min. Determine the mass flow rates mH,mF,mE, and mR.[10pts]
4.A material containing 75wt% water and 25wt% solid is fed to a granulator at a
rate of 4000kg/hr. The feed is premixed in the granulator with recycled product
from a dryer which follows the granulator(to reduce the water concentration of
the overall material in the granulator to 50wt% water, 50wt% solid). The
produce that leaves the dryer is 16.7wt% water. In the dryer, air is passed
over the solid being dried. The air entering the dryer contains 3wt% water, and
the air leaving the dryer contains 6wt% water.
air
────┐
↓
feed ┌─────┐ ┌───┐ air
────→│granulator├────→│dryer ├────→
│ │ │ ├──┬─→
└─────┘ └───┘ │ product
↑ │
└───────────────┘
a)Draw and complete the flowchart of this process, and label all the unknowns.
[10pts]
b)Circle the subsystems that can be used for analyzing this problem.[5pts]
c)Perform degrees-of-freedom analysis on all the subsystems.[10pts]
d)determine the mass flow rate of air entering the dryer.[10pts]
5.An inclined manometer(shown below) is used to measure small pressure
difference
┌─────1───2─────┐
└────┐┌──┐┌────┘
＼╱╱﹍﹍╱╱
L ╱╱﹉ ◢◤﹉﹉↑
＼╱╱﹍﹍◢◤θ ↓h
◢◤﹉ ◢◤﹉﹉﹉﹉
████◤
a)Derive a formula for h(liquid-level difference) in terms of L(reading) and θ
(angle of inclination)?[5pts]
b)Suppose the manometer fluid is mercury(SG=13.6), the process fluid is water,
the inclination of the manometer is θ=20.0°, and a reading of L=10.0cm is
obtained. What is the pressure difference between the two points 1 and 2?[5pts]
6.The values of diffusivity of methane in zeolite were measured to be
1.9×10^-11 and 20.1×10^-11 m^2/s at 200.K and 300.K, respectively. Suppose
the temperature dependence of diffusivity follows the Arrhenius equation:
D=D0exp(-E/RT) where R is gas constant 8.314J/mol K.
a)Determine the value and unit of D0 and E.[10pts]
b)Derive the formula for D in AES units(e.g.D in ft^2/s, T in °R).[10pts]
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