CBE 20255

Fall 2005

First Homework

Due September 7, 2005

1. Mass balance formulation for a human

a. Suppose that you wanted to do a mass balance on a human to watch for weight changes. Use a (non) anatomically schematic of a person and identify the input and output streams. For the purposes of this problem, lets use “waste” for the effluent from the urinary and GI tracts.

b. Describe how the mass flow of each of these streams can be measured. Note ones that are difficult.

c. Of course, when we talk about weight gain the first word that is mentioned is “calories” (actually kilocalories if you use the standard definition of a calorie.) Explain why knowledge of the energy balance would be useful if you really wanted to know “why” a person was gaining or loosing weight.

2. Matlab and "Go find it".

a. Use the Antoine equation

log(P)=A-B/(T+C)

to find the normal boiling points of n-hexane, n-octane, n-butane, methyl alcohol, acetone and ethylene oxide. Use an m-file in Matlab that employs a convergence loop. (Turn in a print out of the answers and the m-file.)

b. Plot the vapor pressure for each of these substances on the same plot over a useful range (please use Matlab).

I found some useful information at: http://www.engr.umd.edu/~nsw/ench250/antoine.htm

3. Read some

Read Chapter 2 in Russell and Denn. Explain the rationale for why you expect that q ~ h^1/2. You may use information from EG 112

4. Another draining tank

Do problem 2.4 in Russell and Denn.

5. Yet another draining tank

Do problem 2.9 in Russell and Denn.