研究生用-化工热力学-补充习题参考资料

1、蒁化工热力学习题腿研究生用肅第一章习题33螁 1-1. A 4-m storage tank containing 2 m of liquid is to be pressurized with air from a large, high-p ressure reservoir through a valve at the top of the tank to rap id ejectio n of the liquid(see figure) the air in the reservoir is mai ntai ned at 100 bar and 300K. The gas sp a

2、ce above the liquid contains in itially air at 1 bar and 280K. When the pressure in the tank reaches 5 bar, the liquid transfer valve is opened3and the liquid ejected at the rate of 0.2 m /min while tank pressure is maintained at 5 bar. What is the air temp erature whe n the p ressure reaches 5 bar

3、and whe n the liquid has bee n drained comp letely?Neglect teat in teract ions at the gad-liquid and gas tank boun daries. It may beassumed that the gasabove the liquid is well mixed and that air is an ideal gaswith a con sta nt value of CV = 20.9 J/mol K衿 1-2. We have liquid etha ne at 1 bar p ress

4、ure what is the maximum temp erature the liquid ethane can be heated before it reaches the limits of stability? Use the Pen g-Rob inson equati on of state with the followi ng data肆 Tc = 305.4 K肄 Pc= 48.8 bar荿 3=0.098虿 Tb=184.5 K(at 1.013 bar).节 1-3. From the report of a thermodynamicist: ” while rel

5、axing near a large tank of2nitrogen gas (A) at 687 kN/m and 298K, I began reviewing some of my kno wledge in thermod yn amics. A rather in teresti ng exp erime nt suggested itself and I thought I would compare theory with real data(see figure).2莀 I first filled B with nitroge n gas at 101 kN/ m and

6、298K and conn ected it as show n. Then work ing quickly, I opened valve C (with D closed ) and allowed the pressures in B to its original pressures in Band A to equalized. Then, working quickly, then, I quickly closed C and opened D to flow down vessel B to its original pressure.I repeated this sequ

7、encea number of times. Tank A was so large that I did not cause any sig ni fica nt drop in p ressure in it by my exp erime nts. Secon d, I p ressurized and blew B so rap idly that little heat tran sfer p robably occurred during this time” . Nitrogen ha a value of Cp=29.33 J/moh K and is an ideal gas

8、, so Cp-Cv =R.羅 a)Guess the temp erature of the gas in B after the sec ond p ressurizati on and afterthe sec ond blowdow n.薄 b) What do you think these temperatures were after a very large number of cycles?祎 1-4. An all-quartz Dewar flask is filled initially with liquid hydrogen at 1 bar (see figure

9、). The inner walls cool to the no rmal boili ng point of hydroge n 20.6K. the liquid is then quickly poured out and the flask evacuated to a very low p ressure. Assume that at the end of the evacuati on the walls are still at 20.6K. The Dewar is then connected to a large tank of helium at 2 bar and

10、300K and p ressurized very rap idly to a large tank of helium at 2 bar and 300K and p ressurized very rap idly to 2 bar. After p ressurizati on, the connecting line is left open to allow additi onal flow to occur in order to mai ntai n a p ressure of 2 bar. There is heat tran sfer betwee n the heliu

11、m gas and inner Dewar walls, but assume no heat tran sfer by radiati on conv ecti on, or con ducti on across the walls of the Dewar.羆 The enthaIpy of quartz, H(J/g), can be approximated as a function of tem perature(K) from 20 to 100 K by the relatio n.2蚃 logH=-11.43+10.64log T - 2.215(logT)2袁 How m

12、any moles of helium are there in the Dewar after all flow has ceased?薆 Data: Cp (helium)=20.9 J/mol K-33袁 Helium is an ideal gas Dewar flask volume=8.206*10 m inner walls of Dewar =1000g, temperature of the environment =300K螅莇 1-5.袅 a) The heat of fusion Hfus for the ice-water phase transition is 80

13、 cal/g at 0 C and 1 atm. The density of water is 1.000g/cc at these conditions, and that of ice is 0.915g/cc. Develop an expression for the change the melting, temperature of ice with pressure.膃 b) the heat of vaporization for the steam-water phase transition is 539 cal/g at 100C and 1 atm. Develop

14、an expression for the change in the boiling temperature of water with pressure.螀 c) compute the normal freezing and boiling points of water in Denver, Colorado, where the mean atmospheric pressure is 635 mm of Hg.羆 6.The following data are available for water节 lnpsub (ice) = 24.00- 6140.1/T p in mmH

15、g膀 lnpvaP (water) = 21.4- 5432.8TT in K袈 a)Compute the triple point temperature pressure of water.螄b)Compute the heat of vaporization, the heat sublimation, and the heat of fusion water at its triple point.1-7.1-8.蕿 We are faced with handling a stream of pure carbon monoxide at 300 atm and 197 K. We

16、 would like to liquefy as great a fraction as possible, but there seems to be some disagreement about the process to be used. One suggestion has been to expand this high-pressure fluid across a Joule-Thompson valve and take what liquid is formed (see figure a ).节Another suggestion is to expand the v

17、apor in an adiabatic turbine to thesaturati on curve and the n follow with a Joule-Thoms on expan sior(see figure b).袇 The two-ste p op erati on has bee n suggested to avoid erosi on of the turb ine袁 blades with a two-p hase mixture.蚂 Evaluate these methods in order in to in dicate the fractio n of

18、in itial gas one might be exp ected to liquefy carb on mono xide that will give a larger fraction liquefied. We wish we could supply you with thermod yn amic prop erty data but unfortunately, we do not have access to any at the present time. Use any estimati on methods you can find.聿 1-8. We have co

19、n sta nt-volume, closed vessel filled with vapor and would like to know how the sp ecific entropy of the vapor varies with p ressure, Derive a general relation to allow one to calculate the derivative, ( ?S/?p)v assuming that we know the total volume of the vessel, the moles of vapor, Cp as a fun ct

20、i on cT and p, and an equati on of state.蚄 Illustrate your result at the start of the heat ing p rocess, whereT = 365.8K, p = 16.5 bar, and total volume = 1.51 咒10 m . assume that at this condition, Cp = 94.9 J/mol K and the Redlich-Kwong equation of state is applicable with a = 20.839 JK/mol2, b =

21、6.72510-10 m3/mol.賺第二章习题2-1.2-2.=-中的B值，并作出位r能函数曲线。B=B1（偶极静电作用）+B2 （诱导作用）+B3 （色散作用）蝿试验算NH3、H2O分子对的相互作用位能蚅 2-2.乙醚分子量比丙酮大，但沸点（346C）比丙酮（565C）低，乙醇分子量更大，但沸点（78.5C）更高，试用分子间力解释之。2-3.2-4.莂20C,邻位和对位硝基苯酚于水中的溶解度之比为0.39，在苯中则为 1.93，试说明原因。2-4.2-5.薀试解释下列化合物的沸点顺序蕿Tb ,C2H5OH Tb( CH3)2NH Tb C3H8CH3)2 NH 7.5 C ， C2H5OH

22、 78.5CC3H8-42.1C薄第三章习题袂 3-1.Estimate the equilibrium p ressure and isobute ne vapor-p hase mole fracti on as a function of liquid composition for the isobutane-furfural system at 37.8C . At this temperature the vapor pressure of furfural is 3.7 mmHg and that of isobutene is 3628 mmHg.葿3-2 To evaluat

23、e the potential use of carbon dioxide in tertiary oil recovery, it is necessaryto estimate the vapor-liquid equilibrium between carbon dioxide and reservoir petroleum, which we will take to be n-hexane, at oil well conditions, typically 2000 psia and 170 F. Make this estimate as best you can.薅Temper

24、ature (C)68.793131.7羁 Vapor pressure of n-hexane (atm)薆 3-3. One way to remove a dissolved gas from a liquid is by vaporizing a small amount of the liquid in such a way that the vapor formed is continually withdrawn from the system. This process is called differential distillation.蚇 a) if N is the t

25、otal number of moles liquid, x the instantaneousmole fraction of dissolved gas, and y the gas mole fraction of the vapor in equilibrium with the liquid, show that dx/dN = (y-x)/N莃 b) if the mole fraction of the dissolved gas is low, then芇 where H is the Henry s law constant for the g-assolvent combi

26、nation, and p is the total pressure above the liquid. Under this circumstance show that蒄 x/ x0 = (N/N0) (H-p) /por, equivalently N/N0 = ( x/ x0) p / (H-p)蒂 where No and x0 are the in itial moles of soluti on and dissolved gas mole fractio n, respectively.羁 c) The Henry s law constant for carbon diox

27、ide in carbon disulfide was computed to be 265 atm at 25 C . At a total pressure of 1 atm, how much liquid should be vaporized from a solution saturated in carbon dioxide to decrease the CO2 concentration to 1% of its equilibrium value? To 0.01% of its equilibrium value?薅 3-4. Calculate the fugacity

28、 for each species in the following gases at 209 K and 800 atm.a)b)c)d)e)f)袄 pure oxygen莁 pure n itroge n螈 Oxygen and nitrogen in a 30 mole percent O2, 70 mole percent N2 mixture using the Lewis-Randall ruleg)h)薇 Oxygen and nitrogen in the mixture above using Kaysrules for the pseudo-critical constan

29、ts羂 e) oxygen and nitrogen in the mixture above using the Prausnitz-Gunn rules for the pseudo-critical constants.蒈3-5. The fugacity of methane dissolved in a light oil is given by Henrys law. At200 K and 30 atm, the Henrys-law constant Hi for methane in the (liquid) oil is 200atm. At the same condit

30、ions, the gas phase in equilibrium with the oil is found to contain 95 mole percent of methane. Making reasonable assumption (state them explicitly and give your justification), determine the equilibrium mole fraction of methane in the liquid phase at 200 K, and 30 atm. At 200 K, the second virial c

31、oefficie nt of pure metha ne is -05 cm/mol.艿第四章习题蒆4-1. A mixture of 80 mole percent acetoneand 20 mole percent water is to be transported on a pipeline within a chemical plant. This mixture can be transported as either a liquid or gas.蒃 a) A reciprocating pump would be used with a liquid mixture. Th

32、is pump will vapor-lock and ceasefunctioning if any vapor is present. Compute the minimum pressurewhich must be maintained at the pump inlet so that no vapor is formed when the liquid temperature is 100C .虿 b) A cen trifugal pump would be used with a gas mixture. To p reve nt erosi on of the pump blades, only vapor should be present. If the pump effluent is 100C, compute the maximum pump effluent pressure so that no liquid is formed.蒇 Temperature (C)56.678.6113.0薁 Va