A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as
A. ACmin/U
B. U/ACmin
C. AUCmin
D. AU/Cmin
Answer: Option D
Solution (By Examveda Team)
The number of transfer units (NTU) is a dimensionless parameter used in heat exchanger analysis.It is defined as the ratio of the product of the heat transfer surface area (A) and the overall heat transfer coefficient (U) to the minimum heat capacity rate (Cmin) of the two fluids.
In mathematical form, NTU = AU / Cmin.
The NTU method is useful for determining the effectiveness of a heat exchanger when the inlet and outlet temperatures of the fluids are not known.
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