Question

A heat exchanger has been designed with heat transfer surface area of ‘A’ and overall heat transfer coefficient ‘U’, handling two different fluids of heat capacities $ C_{\text{min}} $ and $ C_{\text{max}} $. The parameter NTU used in the analysis of heat exchanger is specified as:

• A. \( \frac{A U}{C_{\text{max}}} \)
• B. \( \frac{C_{\text{max}}}{A U} \)
• C. \( \frac{A U}{C_{\text{min}}} \)
• D. \( \frac{C_{\text{min}}}{A U} \)

Hint:

When analyzing heat exchangers, use the relation \( \text{NTU} = \frac{A U}{C_{\text{min}}} \) for counterflow heat exchangers to estimate the number of transfer units.

Answer 1

The Correct Option is C

Step 1: NTU Definition
The number of transfer units (NTU) in heat exchanger analysis is defined as: \[ \text{NTU} = \frac{A U}{C_{\text{min}}} \] Where: \( A \) is the heat transfer area,
\( U \) is the overall heat transfer coefficient,
\( C_{\text{min}} \) is the minimum heat capacity rate.
Step 2: Conclusion
Thus, the correct expression for NTU is \( \boxed{\frac{A U}{C_{\text{min}}}} \).