PPT: Introduction to Heat Exchangers | Heat Transfer - Mechanical Engineering PDF Download

 Page 2


What are heat exchangers for?
q Heat exchangers are practical devices used to transfer
energy from one fluid to another
q To get fluid streams to the right temperature for the next
process
– reactions often require feeds at high temp.
q To condense vapours
q To evaporate liquids
q To recover heat to use elsewhere
q To reject low-grade heat
q To drive a power cycle
Page 3


What are heat exchangers for?
q Heat exchangers are practical devices used to transfer
energy from one fluid to another
q To get fluid streams to the right temperature for the next
process
– reactions often require feeds at high temp.
q To condense vapours
q To evaporate liquids
q To recover heat to use elsewhere
q To reject low-grade heat
q To drive a power cycle
Application: Power cycle
Steam Turbine
Boiler
Condenser
Feed water
Heater
Page 4


What are heat exchangers for?
q Heat exchangers are practical devices used to transfer
energy from one fluid to another
q To get fluid streams to the right temperature for the next
process
– reactions often require feeds at high temp.
q To condense vapours
q To evaporate liquids
q To recover heat to use elsewhere
q To reject low-grade heat
q To drive a power cycle
Application: Power cycle
Steam Turbine
Boiler
Condenser
Feed water
Heater
Main Categories Of
Exchanger
q Most heat exchangers have two streams, hot and cold, but
some have more than two
Heat exchangers
Recuperators Regenerators
Wall separating streams Direct contact
Page 5


What are heat exchangers for?
q Heat exchangers are practical devices used to transfer
energy from one fluid to another
q To get fluid streams to the right temperature for the next
process
– reactions often require feeds at high temp.
q To condense vapours
q To evaporate liquids
q To recover heat to use elsewhere
q To reject low-grade heat
q To drive a power cycle
Application: Power cycle
Steam Turbine
Boiler
Condenser
Feed water
Heater
Main Categories Of
Exchanger
q Most heat exchangers have two streams, hot and cold, but
some have more than two
Heat exchangers
Recuperators Regenerators
Wall separating streams Direct contact
Recuperators/Regenerators
qq Recuperative: Recuperative:
Has separate flow paths for each fluid
which flow simultaneously through the
exchanger transferring heat between
the streams
qq Regenerative Regenerative
Has a single flow path which the hot
and cold fluids alternately pass
through.