[試題] 99上 蘇金佳 熱力學 期中考
課程名稱︰熱力學
課程性質︰必修
課程教師︰蘇金佳老師
開課學院：工學院
開課系所︰機械系
考試日期（年月日）︰99/11/11
考試時限（分鐘）：open book 60 min and close book 50 min
是否需發放獎勵金：Yes
（如未明確表示，則不予發放）
試題 :
Open book
1.A throttling calorimeter is connected to a desuperheated steam line supplying
steam to the auxiliary feed pump in a steam power plant.The line presure is
2.70MPa,the calorimeter presure is 0.1MPa,and the temperature is 150℃.
Determine the enthalpy and quality of the desuperheated steam.(15%)
2.An ordinary egg can be approximated as a 55 mm-diameter sphere.The egg is
initially at a uniform temperature of 5℃ and is drop into boiling water at
97℃.Taking the properties of the egg to be ρ=1020 kg/m^3 and c=3.32 KJ/kg K
determine how much heat is traansferred to the egg by the time the average
temperature of the egg rises to 85℃.(10%)
3.A heat exchanger is to cool ethylene glycol (c=2.56 kJ/kg K) floeing at a
rate of 4.0 kg/s from 70℃ to 35℃ by water (c=4.18 kJ/kg K) that enters at
25℃ and leaves at 65℃.Determine the mass flow rate of water.(10%)
4.A rigid, insulated tank that is initially evacuated is connected through a
valve to a supply line that carries air at 0.20Mpa and 300℃.Now the valve
is opened,and air is allowed to flow into the tank until the pressure
reaches 0.20MPa,a which points the valve is closed.
Determine the flow work of the air in the supply line and the final
temperature of the air in the tank.(15%)
Close book
5.Schematically draw the T-v diagram illustrating the three regions of state
of liquid water and steam.The explain the variation of the state of the
substance with temperature under constant pressure.(10%)
6.Write down the equation of energy conservation for an open system and
explain the physical meaning of each term in the equation.(10%)
7.Briefly explain the following terms:(a)critical point of a pure substance,
(b)latent heat (c)total energy of a closed system (d)quality of a pure
substance. (5% each,20% total)
8.What is the defination of a pure substance? Can air be treated as a pure
substance? Why?(10%)
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世界上最遙遠的距離不是生與死
而是考試openbook我卻不知道答案在哪一頁
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