推 gj942l41l4 :宅馬XD 11/04 01:04
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）︰2011/11/03
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 :
1.(40%) Please answer the following questions.
(a) The concept of a continuum was used to describe the limit of
macroscopic thermodynamic analysis. Describe "continuum" in your
own words.
(b) What is the zeroth law of thermodynamics? Why is the zeroth law
important in thermometry?
(c) What is the principle of corresponding states?
(d) What are the mechanisms of heat transfer?
(e) What is throttling process? Would you expect the temperature of air to
drop as it undergoes a steady flow throttling process? Explain.
2.(20%)
A piston-cylinder device initially contains air at 150 kPa and 27℃.
At this state, the piston is resting on a pair of stops, and the
enclosed volume is 400 L. The mass of the piston is such that a 350 kPa
pressure is required to move it. The air is now heated until its volume
has doubled.
Determine (a) the final temperature
(b) the work done by the air, and
(c) the total heat transferred to the air
(the gas constant for air: R = 0.287 kJ/kg‧K )
3.(20%)
An adiabatic gas turbine expands air at 1300 kPa and 500℃ to 100 kPa and
127℃. Air enters the turbine through a 0.2 m^2 opening with an average
velocity of 40 m/s, and exhausts through a 1 m^2 opening.
Determine (a) the mass flow rate of air through the turbine and
(b) the power produced by the turbine.
4.(20%)
An air-conditioning system is to be filled from a rigid container that
initially contains 5 kg of liquid R-134a at 24℃. The valve connecting this
container to the air-conditioning system is now opened until the mass in the
container is 0.25 kg, at which time the valve is closed. During this time,
only liquid R-134a flows from the container. Presuming that the process is
isothermal while the valve is open, determine the final quality of the
R-134a in the container and the total heat transfer.
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