課程名稱︰化工熱力學甲一
課程性質︰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）︰101/12/4
考試時限（分鐘）：100
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1. a) Show that for an open system kept under constant pressure and chemical
optential, its temperature reaches minimum at equilibrium. To simplify
the problem, consider one mass flow stream only and no shaft work(10 pts)
b) Show that at equilibrium the temperatur, pressure, and chemical potential
does not vary with location in the previous system. (5 points)
2. The van der waals equation of state is P= (RT)/(V-b)-a/V^2
a) Show that the compressibility at the critical poiint is a constant 0.375
(6 opints)
b) Determone the departure finctions for enthalpy, entropym abd Gibbs free
energy. Express your results in terms of dimensionless quantities,
Z=PV/RT, A=Pa/(RT)^2, and B=Pb/RT (9 points)
Note that:
(H-H(Ideal))@ T, P = RT(Z-1)+ S (T(dp/dt)-P)dV
(S-S(Ideal))@ T, P = RT(lnZ)+ S (dP/dT-R/V) dV
(dp/dt in under constant molar volume)
(V: molar volume)
c) Write down the procedure of calculating the departure functions (based on
Van der Waals EOS) for a fluid (i.e., a and b are known)@ given
temperature T1 and molar volume V1. (5 points)
d) Write down the procedure of calculating the departure functions (based on
Van der waals EOS) for a fluid (i.e., a and b are known)@ given
temperature T1 and pressure P1. (5 points)
3. Ethylene at T1, P1 passes thriugh a heater-expander and emerges at a higher
temperature T2 and lower pressure P2. There is no flow work into or out of
the heater-expander but heat is supplied,
----------------
T1, P1 → : heater : → T2, P2
----------------
↑ Q
Suppose ethlyene has a constant constant-pressure heat capacity Cp,
determine the heat supplied per mole of ethylene assuming
(a) ethylene us an ideal gas(10 points)
(b) ethylene obeys the van der waals equation of state (write down the
procedure fir the part you cannot calculate without a calculator).
(10 points)
4. The change Helmholtz energy (A) of some fluid as a function of molar volume
(V) at constant temperature (below critical temperature) is shown below.
(a) Sketch this figure on your answer sheet and indicate the molar volumes
of the two phases that can coesist at temperature T. (5 points)
(b) Explain the reason of your answer to (a). (10 points)
(c) Suppose the fluid initially at point I is compressed slowly and
carefully to point F isothermally. Plot the change in the Helmholtz free
energy of the fluid during the compression process. (10 points)
(d) Plot the change in pressure during the compression process of (c).
(5 points)
圖: http://ppt.cc/abuK
5. The following data for a certain chemical is obtainedfrom experiment:
Triple point: 175K and 3 Pa
The normal boiling point: 330K
The normal melting point: 176K
The vapor pressure : @170K = 1 Pa
From these data, please estimate the following properties of the chemical
(a) the heat of sublimation (5 points)
(b) the heat of vaporization (5 points)
(c) the heat of fusion (5 points)
(d) the change in molar volume as the solud melts (5 points)
total: 110 points
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※ 編輯: cxzdsa 來自: 140.112.24.77 (12/08 12:16)