Design of any heat exchanger is manly depend upon the flow configuration.
As discussed before the configuration could be of three type (majourly)
- Parallel Flow
- Counter Flow
- Cross Flow
The compactness increases from Parallel flow to Counter Flow to Cross Flow
While complexity increases in reverse direction.
The superheater has flue gas on one side & Ideal gas on other. As steam has less capacity of carring the heat than water, we have to give more area.
The velocity of steam & flue gas plays a majour role in deciding the compact ness of heat exchanger.
More the velocity, more will be reynold’s number, higher will be nusselt number, higher will be heat transfer co-efficient which leads to higher over all heat transfer co-efficient & hence