Student Name: ___________________________________

HW #4 CHE 540 due Tue. Oct. 25, 2011

Here we finish up Chapter 4. Then read Chapter 5.1-5.5 and review handouts from Rawlings and Ekerdt textbook. Review provided example MATLAB programs and functions. Use MATLAB for any numerical calculations you need to do and hand in print outs of “diary files” and all script files (.m files) for work done using MATLAB. ----------------------------------------------------------------------------------------------------------------- Problem (1) = 3pts. Dynamic CSTR/MFR = Mixed flow reactor startup: Modified Exercise 4.5 pg. 175 Use MATLAB to simulate the start up of a CSTR by solving for CA(t) in the specific example given in Part (c) for the initial condition described in Part (b) = initially filled with solvent, no A. Use a feed concentration equal to 6.76 mol/liter and use units of liters for volume and minutes for time. Be careful of other units used in the textbook. Simulate the dynamics up to 300 minutes, a time period long enough to be able to predict the final steady-state concentration of component A. In the same program that solves for CA(t), plot it with appropriate axis labels and title, including your name and date. What would be the fractional conversion of A, XA, at the new steady-state ? XA,final = ________ Problem (2) = 3pts. Example 4.5: Alternative formulations of PFR equations for benzene pyrolysis Simulate a PFR using a MATLAB program which solves this problem using ODEs for molar flow rates (4 ODEs shown in Example 4.5). The extent of reactions solution (2 ODEs shown in Example 4.6) was presented as an example in class to create plots similar to Figures 4.20 and 4.21 on page 152. Hand in copies of your two plots (with name and date). Note the results for two methods should be the same (as noted on the bottom of page 153) and compare the computer time required for your solution to the handout 0.2964 s for solving the 2 ODE system on my home computer. Problem (3) = 4pts. Exercise 4.7 modified = startup of two MFRs in series. Simulate the startup of these two reactors in series when they are initially filled only with solvent. Set the volume of each to be 15 liters and the volumetric feed rate equal to 1.0 liters per minute, thus a mean residence time of 15 minutes for each. Simulate for 150 minutes, which is long enough that you "reach" the final steady state concentrations in both reactors. Make two plots, one for each reactor, showing the concentrations of A, B, C and D and hand these in with a copy of your program. Plot titles should include your name and date as well as the problem number, e.g. HW4 Problem 3, Benny Beaver, Oct. 21, 2011. Use concentrations as “states”, so you will be solving 8 ODEs in this problem.