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Home work Assignment No # 1 ChE 333: Mass Transfer Department of Chemical and Materials Engineering Faculty of Engineering King Abdulaziz University Jeddah, KSA Name of the student : Student Number : Comments: Instructor : Dr Sharif Zaman Submission date : 18-9-2015. Question 1 :
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Home work Assignment No # 1 ChE 333: Mass Transfer Department of Chemical and Materials Engineering Faculty of Engineering King Abdulaziz University Jeddah, KSA Name of the student : Student Number : Comments: Instructor : Dr Sharif Zaman Submission date : 18-9-2015
Question 1 : A mixture 1.0 mol % O2 (species A) in a helium carrier gas (species B) enters the micro scale chamber. The chamber consists of a channel that is 5.0 mm (microns) in diameter. The total system pressure within the chamber is 300 Pa, which is very small. The chamber temperature is maintained at 100 oC. The molecular weight of oxygen is 32 g/g mol and helium is 4.0 g/g mol. a. What is the molar concentration of oxygen gas at the entrance to the micro chamber? b. What is the effective diffusion coefficient of O2 (DAe) within the micro chamber?
Question 2 : Benzene (species A) is often added to ethanol to denature the ethanol (species B). Estimate the liquid-phase diffusion of benzene in ethanol and ethanol in benzene at 288 K by The Wilke–Chang equation and The Scheibel equation. Does DAB = DBA?
Question 3: An absorption tower has been proposed to remove selectively two pollutants, hydrogen sulfide (H2S) and sulfur dioxide (SO2), from an exhaust gas stream containing H2S -3 Vol% SO2 -5 vol% N2 - 92 vol% Estimate the diffusivity of hydrogen sulfide in the gas mixture at 350 K and 1.013 x 105 Pa: The critical temperature (TC) of H2S is 373.2 K and the critical volume (VC) of H2S is 98.5 cm3/mol.
Question 4: Steam reforming of hydrocarbons is one way to make hydrogen gas (H2) for fuel cells. However, the product gas contains H2 contaminated with carbon monoxide (CO), which must be further enriched in H2 in order for the fuel cell to work better. It is desired to separate a mixture of CO and H2 using a microporousceramic membrane. The average pore diameter of the porous membrane material is 15 nm, and the void fraction e= 0.10. The system operates at 5.0 atm total system pressure and 400 OC. Determine the effective diffusion coefficient of CO in the gas mixture within the microporous membrane. Is Knudsen diffusion important? (Calculate Knudsen number) Assumption: You may assume that the CO is dilute in the gas mixture.