西安建筑科技大学：《工程热力学》课程教学资源（思考与习题）英语习题

Chapter 1 Basic Concepts 1. a gas in a piston-cylinder device is compressed and as a result its temperature rises is this a heat or work interaction? the process curve represent the area under 2. On a p-v diagram what does 3. Determine the energy required to accelerate a 2000-kg car from 20 to 70 km/h on an uphill road with a vertical rise of 40m

Chapter 1 Basic Concepts 1. A gas in a piston-cylinder device is compressed, and as a result its temperature rises. Is this a heat or work interaction? 2. On a P-v diagram, what does the area under the process curve represent? 3. Determine the energy required to accelerate a 2000-kg car from 20 to 70 km/h on an uphill road with a vertical rise of 40m

4 Consider a device with one inlet and one exit if the volume flow rates at the inlet and at the exit are the same is the flow through the device necessarily steady? Why? 5. A2 m rigid tank contains nitrogen gas at 500kPa and 300k now heat is transferred to the nitrogen in the tank and the pressure of nitrogen rises to 800kPa. The work done during this process is (A)600k(B)1000k](C)0k (D)500kJ(E)1600k

4. Consider a device with one inlet and one exit. If the volume flow rates at the inlet and at the exit are the same, is the flow through the device necessarily steady？ Why? 5. A 2 m3 rigid tank contains nitrogen gas at 500kPa and 300K. Now heat is transferred to the nitrogen in the tank and the pressure of nitrogen rises to 800kPa. The work done during this process is (A) 600 kJ (B) 1000 kJ (C) 0 kJ (D) 500 kJ (E) 1600 kJ

6. A2 m'ngid tank contains nitrogen gas at 500kPa and 300k now heat is transferred to the nitrogen in the tank and the pressure of nitrogen rises to 800kPa. The work done during this process is (A)600k](B)1000k](C)0k (D)500k](E)1600k

6. A 2 m3 rigid tank contains nitrogen gas at 500kPa and 300K. Now heat is transferred to the nitrogen in the tank and the pressure of nitrogen rises to 800kPa. The work done during this process is (A) 600 kJ (B) 1000 kJ (C) 0 kJ (D) 500 kJ (E) 1600 kJ

CHAPTER 2 PROPERTIES OF PURE SUBSTANCES 21 arigid tank contains 5kg of an ideal gas at aatm and 40C. Now a valve is opened, and half of mass of the gas is allowed to escape. If the final pressure in the tank is 1.5atm. the final temperature in the tank is [a]-38℃C[b]30℃C [c]40℃C [d]53℃C [e]144C 2.2A 5-m rigid vessel contains steam at 20 MPa and 400 C The mass of the steam is [a]5.0kg[b]0.322Kg[c]322kg[]503kg e680kg

CHAPTER 2 PROPERTIES OF PURE SUBSTANCES 2.1 A rigid tank contains 5kg of an ideal gas at 4atm and 40℃.Now a valve is opened, and half of mass of the gas is allowed to escape .If the final pressure in the tank is 1.5atm.the final temperature in the tank is [a] -38 ℃ [b]30 ℃ [c]40 ℃ [d] 53 ℃ [e]144 ℃ 2.2 A rigid vessel contains steam at 20 MPa and 400 ℃.The mass of the steam is [a] 5.0kg [b] 0.322kg [c] 322kg [d] 503kg [e]680kg 3 5 − m

2.3 A 500-m' rigid tank is filled with saturated liquid-vapor mixture of water at 200kPa. If 20 percent of the mass is liquid and the 80 percent of the mass is vapor the total mass in the tank [a]705kg[b]500kg [C]258kg[d]635kg [e]2809

2.3 A rigid tank is filled with saturated liquid-vapor mixture of water at 200kPa.If 20 percent of the mass is liquid and the 80 percent of the mass is vapor ,the total mass in the tank is [a] 705kg [b] 500kg [c]258kg [d] 635kg [e]2809 3 500 − m

Chapter 3 The first Law of Thermodynamics 1. a reversible cycle plots as a perfect circle on a T-S diagram with maximum and minimum temperatures 600 k and 300K and a maximum and minimum entropy of 600 k/K and 300k]/. 600K 300K 300kJ/K 600kJ/K

Chapter 3 The first Law of Thermodynamics 1. A reversible cycle plots as a perfect circle on a T-S diagram with maximum and minimum temperatures 600 K and 300K and a maximum and minimum entropy of 600 kJ/K and 300kJ/K

a what is the net work of this cycle? b indicate the path in the cycle along which heat is rejected How do you know? (A sentence or two is required perhaps bolstered by an equation) c)What is the thermodynamic efficiency of this cycle?

a) What is the net work of this cycle? b) Indicate the path in the cycle along which heat is rejected. How do you know?(A sentence or two is required, perhaps bolstered by an equation). c) What is the thermodynamic efficiency of this cycle?

2. The sketch below shows a perfectly insulated container with two compartments separated by a non-adiabatic, frictionless piston Both compartments are at the same pressure (pa= PB)and contain an equal amount of the same gas( ma =mB). Initially compartment a is at a higher temperature than compartment B(TA>TB

2. The sketch below shows a perfectly insulated container with two compartments separated by a non-adiabatic, frictionless piston. Both compartments are at the same pressure (PA= PB) and contain an equal amount of the same gas ( mA =mB ). Initially compartment A is at a higher temperature than compartment B(TA>TB)

A gas properties: cn C, R insulation fric chinless initially ston PA=PB TA>TE

aa Which way, if at all, does the piston move? Indicate by an arrow on a drawing in your exam book(a sentence or two is expected perhaps bolstered by some equations ) a b is the final internal energy Ufinal of the system (both compartments together) lower, equal or higher than initial internal energy Initial of the system? Why? (a sentence or two is expected, perhaps bolstered by some equations

 a) Which way, if at all, does the piston move? Indicate by an arrow on a drawing in your exam book (A sentence or two is expected, perhaps bolstered by some equations).  b) Is the final internal energy Ufinal of the system (both compartments together) lower, equal or higher than initial internal energy Uinitial of the system? Why? (A sentence or two is expected, perhaps bolstered by some equations.)