Question

Jack is operating a tubular, water-water heat exchanger when suddenly, the valve controlling the flow rate of the hot-water stream becomes stuck and he is now unable to adjust/control the flow rate of the hot-water stream. Additionally, the tube providing the hot water has become partially clogged, drastically reducing the flow rate of hot water entering the exchanger. How could you adjust the heat exchanger apparatus to maintain the same outlet temperature of the cold-water stream as before the incident?

Select all that apply:

A. Increase the flow rate of the cold-water stream

B. Decrease the flow rate of the cold-water stream

C. Increase the flow rate of the hot-water stream

D. Increase the temperature of the hot-water entering the apparatus

In the heat exchanger experiment, in theory, as the flow rate of the cold-water stream increases, the outlet temperature of the cold-water stream___________.

A. Stays the same

B. Decreases

C. Increases

Answer 1

So for the first part the answer is :

Decrease the flow rate of the cold-water stream :As you will decrease the flow rate of cold water, it will automatically increse the temperarure.

Second option could be Increase the temperature of the hot-water entering the apparatus: As you increase the temperature of hot water, it will carry more heat in less flow and maintain the cold water temperature.

If the flow rate of the cold-water stream increases, the outlet temperature of the cold-water stream Decreases : As it will have less time for heat transfer from the hot water.