You work in a chemical plant which recovers gold from gold-plated electrical connectors using heated (Tacid = 55oC) nitric acid. Once the acid is “used up” it gets piped through the plant to a separate facility for disposal. During that time, it passes through a cooling chamber to strip the waste heat off the acid for recovery. The acid passes through the chamber in 6m long, 400mm OD, 360mm ID aluminum tubes. The chamber passes room-temperature air over the tubes at 8 m/s. Approximately 0.45 cubic meters of acid is processed per hour.
You work in a chemical plant which recovers gold from gold-plated electrical connectors using heated (Tacid = 55oC) nitric acid. Once the acid is “used up” it gets piped through the plant to a separate facility for disposal. During that time, it passes through a cooling chamber to strip the waste heat off the acid for recovery.
The acid passes through the chamber in 6m long, 400mm OD, 360mm ID aluminum tubes. The chamber passes room-temperature air over the tubes at 8 m/s. Approximately 0.45 cubic meters of acid is processed per hour.
a) What is the Reynold’s number of the nitric acid passing through the tube? Is it turbulent or laminar?
b) What is the heat transfer coefficient of the nitric acid to the inside of the aluminum tube?
c) What is the heat transfer coefficient of the air over the tube?
d) What is the overall heat rate from the nitric acid to the air?
e) Based on your answers here, in a gas-liquid heat exchanger, which side of the exchanger are the fins usually on? Why?
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