《【2017年整理】第三章 理想气体的性质与热力过程》由会员分享，可在线阅读，更多相关《【2017年整理】第三章 理想气体的性质与热力过程（8页珍藏版）》请在金锄头文库上搜索。
1、第三章 理想气体的性质和理想气体的热力过程英文习题1. Mass of air in a roomDetermine the mass of the air in a room whose dimensions are 4 m5 m6 m at 100 kPa and 252. State equation of an ideal gasA cylinder with a capacity of 2.0 m3 contained oxygen gas at a pressure of 500 kPa and 25 initially. Then a leak developed and was
2、 not discovered until the pressure dropped to 300 kPa while the temperature stayed the same. Assuming ideal-gas behavior, determine how much oxygen had leaked out of the cylinder by the time the leak was discovered.3. Two tanks are connected by a valve. One tank contains 2 kg of carbon monoxide gas
3、at 77C and 0.7 bar. The other tank holds 8 kg of the same gas at 27C and 1.2 bar. The valve is opened and the gases are allowed to mix while receiving energy by heat transfer from the surrounding. The final equilibrium temperature is 42 Using the ideal gas model, determine (a) the final equilibrium
4、pressure, in bar, and (b) the heat transfer for the process, in kJ.4. Electric heating of air in a house The electric heating systems used in many houses consist of a simple duct with resistance wires. Air is heated as it flows over resistance wires. Consider a 15-kW electric system. Air enters the
5、heating section at 100 kPa and 17C with a volume flow rate of 150 m3/min. If heat is lost from the air in the duct to the surroundings at a rate of 200 W, determine the exit temperature of air. CP=1.005 kJ/(kg. K).5. Evaluation of the u of an ideal gasAir at 300 K and 200 kPa is heated at constant p
6、ressure to 600 K. Determine the change in internal energy of air per unit mass, using (a) data from the air table, (b) the functional form of the specific heat, and (c) the average specific heat value. 6. Properties of an ideal gasA gas has a density of 1.875 kg/m3 at a pressure of 1 bar and with a
7、temperature of 15C. A mass of 0.9 kg of the gas requires a heat transfer of 175 kJ to raise its temperature from 15C to 250C while the pressure of the gas remains constant. Determine (1) the characteristic gas constant of the gas, (2) the specific heat capacity of the gas at constant pressure, (3) t
8、he specific heat capacity of the gas at constant volume, (4) the change of internal energy, (5) the work transfer.Carbon Mxide2kg, 7C0.bar Carbon Mxide8kg, 27C1.barvaleTnk 1 Tnk 2FIGURE 3-1FIGURE 3-2FIGURE 3-7. Freezing of chicken in a boxA supply of 50 kg of chicken at 6 contained in a box is to be
9、 frozen to -18 in a freezer. Determine the amount of heat that needs to be removed. The latent heat of the chicken is 247 kJ/kg, and its specific heat is 3.32 kJ/kg. above freezing and 1.77 kJ/kg. below freezing. The container box is 1.5 kg, and the specific heat of the box material is 1.4 kJ/kg. Al
10、so, the freezing temperature of chicken is -2.8.8. Closed- system energy balanceA rigid tank which acts as a perfect heat insulator and which has a negligible heat capacity is divided into two unequal parts A and B by a partition. Different amounts of the same ideal gas are contained in the two part
11、s of the tank. The initial conditions of temperature T, pressure p, and total volume V are known for both parts of the tank. Find expressions for the equilibrium temperature T and pressure P reached after removal of the partition. Calculate the entropy change for A and B and the total entropy change
12、 of the tank. Assume that Cv,m is constant, 9. Thermal processes of an ideal gasAn air receiver has a capacity of 0.85 m3 and contains air at a temperature of 15 and a pressure of 275 kN/m3. An additional mass of 1.7 kg is pumped into the receiver. It is then left until the temperature becomes 15 on
13、ce again. Determine (1) the new pressure of the air in the receiver, (2) the specific enthalpy of the air at 15 if it is assumed that the specific enthalpy of the air is zero at 0. Take cp=1.005 kJ/kg.K, cc=0.715 kJ/kg.K.10. Air is compressed steadily by a reversible compressor from an inlet state o
14、f 100KPa and 300K to an exit pressure of 900 kPa. Determine the compressor work per unit mass for isentropic compression with k=1.4, (1) isentropic compression with k=1.4, (2) polytropic compression with n=1.3, (3) isothermal compression, and (4) ideal two-stage compression with intercooling with a
15、polytropic exponent of 1.3. 11. A rigid cylinder contains a “floating” piston, free to move within the cylinder without friction. Initially, it divided the cylinder in half, and on each side of the piston the cylinder holds 1 kg of the same ideal gas at 20C, and 0.2 MPa . An electrical resistance he
16、ater is installed on side A of the cylinder, and it is energized slowly to PA2=PB2=0.4 MPa. If the tank and the piston are perfect heat insulators and are of negligible heat capacity, cv=0.72 kJ/(kgK). Calculate（1 ）the final temperatures, volumes of A,B sides, （2）the amount of heat added to the system by the resistor. (3）the entropy changes of A,B sides, （4）the total entropy change of the cylinder. 工程热力学与传热学第三章 理想气体的性质和热力过程 习题习 题0.2MPa3K0.1m3A0.1MPa3K0
