噓 afflic :你po這什麼豪洨文 我抓! 11/13 21:49
課程名稱︰熱力學
課程性質︰系定必修
課程教師︰蘇金佳
開課學院：工學院
開課系所︰機械系
考試日期（年月日）︰081113
考試時限（分鐘）：├←50分→┼← 60分 →┤
│openbook│close book│
第一部分:███████████
第二部份: ██████
是否需發放獎勵金：是
試題 :
第一部份
1. A 0.5m^3 adiabatic rigid container is divided into two equal volumes by a
thin membrane. Initially, one of these chambers is filled with air at 500kPa
and 50 degrees Centigrade while the other chamber is evacuated. Determine
the internal energy change of the air when the membrane is ruptured and the
final air pressure in the container. (10%)
2. An oil pump is drawing 52kW of electric power while pumping oil with
ρ=830kg/m^3 at a rate of 0.15m^3/s. The inlet and outlet diameters of thep
pipe are 10cm and 15cm, respectively. If the pressure rise of oil in the
pump is measured to be 380kPa and the motor efficiency is 89%, determine the
mechanical efficiency of the pump. (15%)
3. A steam turbine operates with 1.8MPa and 360 degrees Celsius steam at its
inlet and saturated vapor at 40 degrees Celsius at its exit. The mass flow
rate of the steam is 15kg/s, and the turbine produves 8400kW of power.
Determine the rate at which heat is lost through the casting of this
turbine.
第二部份
4. What is wrong with the following differentiation of work in thermodynamic
analysis? (10%)
dW = d(PV) = (dP)V + P(dV)
5. Explain the difference between thermal and mechanical equilibriums of a
system. (5%)
6. Explain the reason that, instead of internal energy, enthalpy is often used
in control-volume analysis. (10%)
7. Explain the following terms: (a) compressibilith factor, (b) latent heat,
(c) heating value of fuels, (d) triple point and (e) critical point.
(5%each, 25%total)
8. Schematically draw a P-v diagram of a pure substance. On the diagram show
two isothermal lines of different temperatures and indicate the following
regionsL saturated liquid, saturated vapor, wet region and compressed
liquid. (10%)
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