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Đề thi giữa kì môn Cân Bằng Vật Liệu của Professor G.Higgins trường UC Davis sẽ giúp các hiểu sâu hơn về sự chuyển dịch các chất có trong sơ đồ của nhà máy lọc hóa dầu, các chu trình làm mát, làm hóa lỏng, sự thay đổi áp suất khi cho 1 các chất thêm vào trong quá trình lọc dầu. Hy vọng các bạn sẽ vượt qua môn Cân bằng vật liệu ( balance materials ) 1 cách xuất sắc nhất
�������������������������������������� ������ ����������������� ������������������������ ���������������������������������������������������� ���������������������� ��������������� Total Mass Balance ⅆ ⅆ� ρ ⅆ� + (�) ρ (� - �) · � ⅆ � = � (�) Species Mass Balance (no reactions) ⅆ ⅆ� ρ� ⅆ � + (�) ρ� (�� - �) · � ⅆ � = �� � = �� �� …� � (�) ��������������������� The species mass density of a three-component (A, B, and C) liquid mixture are: acetone, ρA = 326.4 kgm3 , acetic acid ρB = 326.4 kgm3 , and ethanol ρC = 217.6 kgm3 Determine the following for this mixture: (a) the mass fraction of each species in the mixture (b) the mole fraction of each species in the mixture (c) the mass of each component required to make one cubic metter of the mixture Note that the molecular masses of the three species are MWA = 58.08 g/mol, MWB = 60.05 g/mol, MWC = 46.07 g/mol ��������������������� A variety of devices, such as ram pumps, hydraulic jacks, and shock absorbers, make use of moving solid cylinders to generate a desired fluid motion In the Figure below we have illustrated a cylindrical rod entering a cylindrical cavity in order to force the fluid out of the cavity In order to determine the force acting on the cylindrical rod, we must know the velocity of the fluid in the annular region If density of the fluid can be treated as a constant, the velocity can be determined by application of the macroscopic mass balance and in this problem you are asked to develop a general representation for the fluid velocity 2 ��� ECH51FirstPracticeExam_2016.nb ��������������������� In a four stage evaporation system shown in Figure below, a 50% by weight sugar solution is concentrated to 75% by weight in the liquid stream leaving the fourth evaporator Pure water leaves each evaporator with a mass flow rate of mB The mass flow rate entering the system is 100 kg/min, and you are asked to determine the composition of the sugar solution leaving the second evaporator In your analysis, let the sugar be species A and the water be species B Assume that a degree-of-freedom analysis has been carried out and that the problem is well-posed � � � � � � � � Problem (15 points) Liquid acetone (C3 H6 O, species A) is fed (Stream #1) a rate of 0.400 m3 /min into a heated evaporator, where it evaporates into a nitrogen stream that enters the evaporator as Stream #2 The gas mixture leaving the evaporator Stream #3 is diluted by another nitrogen stream (Stream #4) flowing at a measured rate of 419 m3 (STP)/min The combined gases (Stream #5) are then compressed together and leave the compressor at a total pressure of 5550 mm Hg and temperature of 325°C (Stream #6) The partial pressure of acetone in the exit stream (Stream #6) is pA = 500 mm Hg The ambient pressure is 763 mm Hg A schematic of the flow is shown below ECH51FirstPracticeExam_2016.nb ��� ������� (i) What are the molar flow rates of N2 and acetone in the stream leaving the compressor (Stream #6)? (ii) What is the volumetric flow rate of nitrogen entering the evaporator (Stream #2) if the temperature and pressure of this stream are 27°C and 1238 mm Hg ? Data given: mol =0.0224 m3 (STP) , ρA = 0.791 gcm3 , A = 58.06 g/mol The partial pressure is related to the total pressure by: pA = yA P, where yA is the mole fraction of species A Yopu may assume that all the gas streams behave as ideal gas mixture, and the ideal gas law is PV=n RT, where n is the number of moles ... volumetric flow rate of nitrogen entering the evaporator (Stream #2) if the temperature and pressure of this stream are 27°C and 1238 mm Hg ? Data given: mol =0.0224 m3 (STP) , ρA = 0.791 gcm3 , A =