D2L Assignment Flashcards
(25 cards)
which flow arrangement will the two fluid temps approach eachother and reach equilibrium somewhere between two starting temps?
parallel flow
which flow arrangement is it possible for each fluid to reach inlet temperature of the opposing fluid given enough time?
Counter Flow
which flow path arrangement has the greatest efficiency?
Counter Flow
what is the purpose of the fins on a finned tube heat exchanger?
To increase surface area!
which of the following heat exchanger designs allows surface area and capacity to be increased?
plate exchanger
what is the major benefit of the spiral heat exchanger?
turbulent flow and large surface area
how do cooling towers lower the temperature of process water?
evaporation of parts of the water
what is the purpose of the zinc anodes in a shell and tube heat exchanger?
to prevent galvanic corrosion of exchanger materials
what is the purpose of cooling tower mist eliminators?
to reduce water losses
which type of heat exchanger baffle is used to reduce erosion damage cause by high velocity fluids?
impingement baffle
what is the purpose of segmental or disc and doughnut baffles?
to prevent dead bypass areas and support the tube bundle
how many longitudinal shell side baffles are required to achieve four passes of shell side fluid?
3 longitudinal shell side baffles
how many passes does the tube side fluid make if the channel head of a fix tube exchanger has two baffles and the rear has one ?
the tube side would make 4 passes
which of the following shell and tube exchanger designs is limited to flushing or chemical cleaning of the shell side?
fixed tubed sheet is limited
what is the reason for using a “ floating head” design?
to eliminate thermal stresses
in which of the following heat exchanger is it most difficult to clean the TUBE SIDE surfaces ?
u-tube exchanger ( due to the dirty little bend )
which of the following heat exchangers is most likely to suffer damage due to thermal stress?
fixed tube exchanger
which of the following heat exchanger designs is used in applications where mixing of the tube side and shell side fluids must be prevented?
double tube sheet
( double the protection;) )
which of the following properties is of primary importance for materials used in heat exchanger construction?
high thermal conductivity
as a general rule’ which fluid should be on the “ tube side” of a u tube exchanger?
clean fluid
(as it’s hard to clean the bend of the inside of the tubes)
which of these are indications of heat exchanger fouling ?
a drop in efficiency and an increased pressure drop
which methods of cleaning are suitable for tubes?
hot wash oil
mechanical
chemical
high pressure wate
how should a tube bundle be supported when it’s lifted?
under tube sheet and baffles
what pressure is used when hydrostatic testing a heat exchanger for leaks?
1.5x it’s working pressure
