How to Solve Volumetric Flow Balance Problems in Biomedical Engineering

[sixers786]

***Biomedical Eng. HW Prob! Help!***

Homework Statement

http://img11.imageshack.us/img11/3586/20582546.jpg

Homework Equations

The Attempt at a Solution

all i know is the the sum of flow rate in is equal to the sum of flow rate out
so i did
0.1 mg/ml * 1200 ml/min = 1.5 ml/min*5 mg/ml + mass flow rate blood.
and the m flow rate for blood is equal to 112.5 mg/min
i really don't know what to do next..please help.

 

[sixers786]

can anyone please help?

 

[burningbend]

first do an overall mass balance

V_b=V_f+V_u

then do your component balances

c_u,bV_b=c_u,fV_f+c_u,uV_u
c_d,bV_b=c_d,fV_f+c_d,uV_u

here you only have 3 unknowns. plug and chug, but make sure your units match up since some of your givens are funky.

 

[burningbend]

one other thing to note in this problem is that we're not really doing a mass balance, but a volumetric flow balance. you can ONLY do volumetric flow balances when your density is constant, otherwise you must convert each stream into a mass flow rate!