Chapt 12

Question 1

What are heat exchangers?

Answer 1

Devices for transferring heat from a hot flowing stream to a cold flowing stream

Question 2

What are the 3 types of heat exchangers?

Answer 2

1) recuperators or through-the-wall nonstoring exchangers
2) direct contact nonstoring exchangers
3) regenerator, accumulator, or heat storing exchanger

Question 3

Why are recuperators used?

Answer 3

When the fluids are not allowed to contact each other, as with gas-gas systems, miscible liquids, dissolving solids or reactive chemicals. The fluids are kept apart by a wall between them

Question 4

What are some examples of a recuperator?

Answer 4

Shell and tube exchanger, plate exchanger, car radiator

Question 5

How does a direct-contact nonstoring exchanger work?

Answer 5

The streams touch each other directly. The heat flows from the hotter stream to the cooler stream. Can only be used with two phases that do not react with each other

Question 6

How do regenerators work?

Answer 6

A hot stream of gas transfers its heat to an intermediary, (usually a solid), which later gives up the stored heat to a second stream of cold gas.