Question

Double-pipe heat exchangers are used for cases where the heat transfer area requirement is around

• A. 10 to 20 m$^2$
• B. 100 to 200 m$^2$
• C. 500 to 1000 m$^2$
• D. 5000 to 10000 m$^2$

Hint:

Use double-pipe heat exchangers when space is limited and the required heat duty or area is relatively low — ideal up to about 20 m$^2$.

Answer 1

The Correct Option is A

Double-pipe heat exchangers are a type of heat exchanger where one fluid flows through the inner pipe and the other flows through the annular space between the two pipes.
These are generally used for small heat transfer applications, particularly when:
- The required heat transfer area is low
- There are relatively small flow rates
- Cleaning or maintenance access is important
Typically, double-pipe heat exchangers are preferred when the heat transfer area required is up to 20 m$^2$.
For higher area requirements, like 100 m$^2$ and above, shell and tube or plate-type heat exchangers become more economical and efficient.
Option evaluation:
Option 1: 10 to 20 m$^2$ — Correct, standard range for double-pipe design.
Option 2: 100 to 200 m$^2$ — typically handled by shell-and-tube exchangers.
Option 3: 500 to 1000 m$^2$ — large-scale applications beyond the scope of double-pipe designs.
Option 4: 5000 to 10000 m$^2$ — industrial-grade units like large condensers or multi-pass exchangers are used.
Hence, double-pipe heat exchangers are best suited for applications needing around 10 to 20 m$^2$ of area.