課程名稱︰ 熱力學 課程性質︰ 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）︰ 99.11.11 考試時限（分鐘）： 120分鐘 是否需發放獎勵金：是 （如未明確表示，則不予發放） open book (60min) close book (60min) 60分鐘後才會發下第二部分考題 第一部分 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 pressure os 2.70 MPa, the calorimeter pressure is 0.1 MPa, 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 a 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 transferred 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) flowing 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 supply line that carries air at 0.20 MPa and 300℃. Now the valve is opened, and air is allowed to flow into the tank until the pressure reaches 0.20 MPa, at which point the valve is closed. Determine the flow work of the work of the air in the supply line and the final temperature of the air in the tank. (15%) 第二部分 5. Schematically draw the T-v diagram illustrating the three regions of states of liquid water and steam. Then explain the variation of the substance with temperature under constant pressure. 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, and (d) quality of a pure substance. (5%@,20 total) 8. What os the definition of a pure substance? Can air be treated as a pure substance? Why? (10%) --

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