課程名稱︰熱力學
課程性質︰必修
課程教師︰陳瑤明
開課學院：工學院
開課系所︰機械系
考試日期（年月日）︰2013/11/7
考試時限（分鐘）：120min
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1.please answer the following question:(35%)
(a)what's zeroth law of thermodynamics? how do we use it?
(b)what's a thermodynamic property? explain the difference between heat
and internal energy
(c)what's the principles of corresponding states?
(d)what's the physical significance of the two constants that appear in
the van der Waal eq. of state? on whatbasis are they determined?
(e)what's a thermocouple? what's its operating principles?
(f)what are the mechanisms of heat transfer? what's Fourier's law?
what's Newton's law of cooling?
(g)what are the definitions of Cv, Cp? how can they be measured?
2.A supply line carries a two-phase liquid-vapor mixure of a
steam at 2 MPa. a samll fraction of the flow in the line is diverted
through a throttling calorimeter and exhausted to the atmosphere at
100kPa. the temperature of the echaust steam is measured as 125*C.
determine the quality of the steam in the supply line.(15%)
3.nitrogen gas flows through a long, constant diameter adiabatic pipe.
it enters at 700kPa and 50*C and leaves at 350kPa and 20*C. calculate
the velocity of the nitrogen at the pipe's inlet and outlet. the
specific heat of nitrogen a the room temperature is Cp=1.039kJ/kgK.
(15%)
4.an insulated rifid tank is initially evacuated. a valve is opened,
and atmospheric air at 95kPa and 17*C enters the tank until the
pressure in the tank reaches 95kPa, at which point the valva is closed.
determine the final temperature of the air in the tank. assume constant
specific heats. the specific heat ratio for air at room temperature is
k=1.4 . (15%)
5.argon is contained in a cylinder device fitted with a piston.
Initially the argon is at 100kPa and 27*C and occupies a volume of 0.4
m^3. The argon is first compressed while tje temperature is held
constant until the volume is 0.6m^3.
(a)Sketch both processes on a single P-V diagram showing the direction
of the processes and label the end states as1, 2and3.
(b)Deterine the total amount of net heat transferres to the argon,
in kJ, during the combines processes.
The properties of argon are R=0.2081kJ/kgK and Cv=0.3122kJ/kgK. (20%)
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