Question

The ............. are the device in which hot and cold fluid alternately flow over the surface.

• A. Regenerator
• B. Recuperator
• C. Economizer
• D. Mixed tpye

Hint:

Remember:
- Alternating/sequential flow = Regenerator (stores heat in a matrix).
- Simultaneous/continuous flow = Recuperator (heat passes directly through walls).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Heat exchangers are categorized based on their design, construction, and the path of the heat-transferring fluids.

Step 2: Detailed Explanation:
Let us define the primary types of heat exchangers:
1. Regenerator: A storage-type heat exchanger where a solid matrix is heated by a hot fluid and then cooled by a cold fluid alternately.
The hot and cold fluids pass through the same flow channels sequentially, storing thermal energy in the solid matrix during the hot cycle and releasing it to the cold fluid during the cold cycle.
2. Recuperator: A continuous-type heat exchanger where the hot and cold fluids flow simultaneously through separate channels separated by a solid wall. The fluids never mix.
3. Economizer: A specialized recuperative heat exchanger used to preheat a fluid (typically boiler feed-water) using waste heat from flue gases.

Step 3: Final Answer:
A heat exchanger in which hot and cold fluids alternately pass over the same heat storage surface is called a Regenerator.