Heat Exchanger

Question 1

For a counterflow heat exchanger with hot oil in the other tube and cool water in the inner tube, how do you solve the system?

Answer 1

1. Find Energy Lost by Hot liquid
2. Heat lost by hot = heat gained by cool. Find new temperature of cool liquid
3. Take logarythmic mean temperature.
4. Find Reynolds Number for both flows. (Manipulate formula to get mass flux term in it.)
5. Use Forced Internal Convection Charts to get Nusselt Numbers for both flows
6. Find Convection Coefficient for both flows using Nusselt Numbers
7. Find Required Length

Question 2

How do you solve a Shell and Tube Condensor Using the NTU method?

Answer 2

1. Find Exiting Temperature using energy balance
2. Find Reynolds Number and Apply Appropriate Nusselt Correlation
3. Find C_min, C_max, and C_min / C_max to decide what graph to use
4. Find Epsilon, and then use the Graph to find correct NTU value
5. Use NTU formula to find required length