Heat Capacities: Example Problems

Try to solve these problems before watching the solutions in the screencasts.

Example Problem 1

A mixture of 70.% benzene and 30.% toluene at 150°C and a flow rate of 540 mol/h is fed to a furnace. What is the outlet temperature if 22 MJ/h are added to the mixture? The heat capacity coefficients, which can be used from 273 to 1500 K are in the table.

Molecule\(A\)\(B x 10^2\)\(C x 10^5\)\(D x 10^9\)
Benzene-36.19348.444-31.54877.753
Toluene-34.36488.887-34.43580.335

\(C_P = A + BT + CT^2 +DT^3\)

where \(C_P\) is in J/mol K and \(T\) is in kelvin.

Example Problem 2

An ammonia stream with a flow rate of 100 mol/min is heated from 375 to 750 K. How much heat must be added per min to this stream? Use the temperature-dependent heat capacity
       CP,i = Ai + BiT + CiT2
which is applicable from 300 to 1500 K. The constants are below.

 A B
 23.6193.75E-02  1.38E-06