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HVAC Heat Exchangers Explained The basics working principle how heat exchanger works

WEBVTT
Kind: captions
Language: en

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Hey there guys.
00:00:05.758 --> 00:00:07.310
Paul here from theengineeringmindset.com.
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In this video, we're
going to be discussing
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the different types of heat
exchangers used in HVAC
00:00:11.670 --> 00:00:14.480
and building services
applications for both residential
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as well as commercial properties.
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We'll also look at how these are applied
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to system components to
condition the build environment.
00:00:20.700 --> 00:00:23.540
Before we dive into HVAC heat
exchangers and how they work,
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I just want to take a moment
to thank our partner Danfoss
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for sponsoring this video.
00:00:27.420 --> 00:00:29.510
Danfoss has a wide
range of heat exchangers
00:00:29.510 --> 00:00:32.780
including micro plate and
micro channel heat exchangers.
00:00:32.780 --> 00:00:34.690
Whatever HVAC system you're working with,
00:00:34.690 --> 00:00:36.640
they've got what you
need to boost efficiency,
00:00:36.640 --> 00:00:39.120
reduce refrigerant charge and save space.
00:00:39.120 --> 00:00:40.590
Head on over to their website to see
00:00:40.590 --> 00:00:42.080
all the options available to you
00:00:42.080 --> 00:00:44.210
and how they can improve your HVAC system.
00:00:44.210 --> 00:00:46.700
You can find the link in
the video description below.
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Okay, I have a quick test view
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and I want you to tell me your answers
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in the comment section below.
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I'll give the answers
at the end of the video.
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There are three heat
exchangers shown on the screen.
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Now, can you name all of them?
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No cheating, just give you your best shot
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and see how you get on.
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Firstly, what is a heat exchanger?
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A heat exchanger is exactly
what the name implies,
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a device used to transfer thermal energy.
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Heat exchangers are
either given a hot fluid
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to provide heating or a cold
fluid to provide cooling.
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A fluid can be either a liquid or a gas.
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Heat always flows from hot to cold
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and there must be a temperature
difference for heat to flow.
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How is heat exchanged?
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Thermal energy is transferred
via three methods,
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conduction, convection and radiation.
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Most heat exchangers for HVAC purposes
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uses convection and conduction.
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Radiation heat transfer does occur
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but it makes up only a small percent.
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Conduction occurs when two materials
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of different temperatures
physically touch.
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For example, if we place a
hot cup of coffee onto a table
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for a few minutes and remove the cup,
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the table will have conducted
some of this thermal energy.
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Convection occurs when fluids move
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and carry the thermal energy away.
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This can occur naturally
or by mechanical force
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such as using a fan.
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An example of this is when you blow
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onto a hot spoon of soup,
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you blow onto the spoon
to cool the soup down
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and the air carries this heat away.
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Radiation occurs when a surface
emits electromagnetic waves.
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Everything including you,
emits some thermal radiation.
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The hotter the surface is,
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the more thermal radiation it will emit.
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An example of this would be the sun,
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the heat from the sun travels
with electromagnetic waves
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through space and reaches
us with nothing in between.
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Fluids used, the fluids
used in HVAC systems
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typically include water,
steam, air, refrigerant or oil
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as the transfer mediums.
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HVAC heat exchangers usually
do one of two things.
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They either heat or cool water or air.
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Some are used to cool or heat equipment
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for performance reasons
but the majority are used
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just to conditioned air or water.
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Types of heat exchangers.
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Most heat exchangers
follow one of two designs.
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Either coil or plate design.
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Let's have a look at the basics
of how both of these work
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and then see how they're applied
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to common heat exchangers and systems.
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Coil heat exchangers
in their simplest form
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use one or more tubes
which run back and forth
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a number of times.
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The tube separates the two fluids.
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One fluid flows in the inside of the tube
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and another flows on the outside.
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Let's have a look at a heating example.
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Heat is transferred
from the hot inner fluid
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to the tube wall via convection.
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It then conducts through the
pipe wall to the other side
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and the outer fluid which is cooler
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then carries this away through convection.
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Plate heat exchangers use
a thin plates of metal
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to separate the two fluids.
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The fluids generally flow
in opposite directions
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to improve the heat transfer.
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The heat of the hottest fluid is convected
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onto the plate wall and conducted
through to the other side.
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The other fluid which is
entering as a lower temperature
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then carries this away from convection.
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Thin tube coil for fluids.
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Thin tubes are often referred
to simply as the coil,
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eg the heating or cooling coil.
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These are extremely common.
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You'll find these in air
handling units, fan coil units,
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ductwork systems,
evaporators and condensers
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of air conditioning systems,
on the back of refrigerators,
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in trench heaters, the
list really goes on and on.
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For these heat exchangers,
water refrigerant or steam
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usually flows through
the inside and air flows
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on the outside.
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For example, when used for
heating air using heated water
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the hot water flows inside the tube
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and transfers its thermal
energy via convection
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to the tube wall.
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There is a temperature
difference between the hot water
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and the air so that the heat is conducted
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through the tube wall.
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The air passing on the outside
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carries this away via convection.
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The fins usually connect
between all the pipes.
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These sit directly in the
path of the flow of air
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and helps pull the heat out of the pipe
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and get it into the air because
this acts as an extension
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to the surface area of the pipe.
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Duct plate the heat exchanger.
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Duct plate heat exchangers
are used in air handling units
00:04:57.510 --> 00:05:00.040
to exchange thermal
energy between the intake
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and exhaust air streams without
moisture being transferred
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and without air streams being mixed.
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The heat exchanger is made
from thin sheets of metal,
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typically aluminium with the two fluids
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of different temperatures flowing
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in opposite diagonal directions.
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Usually, air is used in
both but the exhaust gases
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from something like a CHP
engine can also be used.
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The heat from one stream is convected
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into the thin sheets of metal
which separates the streams.
00:05:26.830 --> 00:05:28.870
This is then conducted through the metal
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where it is carried away
by forced convection
00:05:31.240 --> 00:05:32.573
into the other stream.
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Trench heaters, trench
heaters are installed
00:05:36.660 --> 00:05:38.300
around the perimeter of a building,
00:05:38.300 --> 00:05:40.280
usually under a window or glass wall
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and are very common in
new commercial buildings.
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Trench heaters are
installed into the floor
00:05:45.530 --> 00:05:47.750
and their purpose is
to reduce the heat loss
00:05:47.750 --> 00:05:48.583
through the glass
00:05:48.583 --> 00:05:51.290
as well as preventing
condensation forming.
00:05:51.290 --> 00:05:54.541
They do this by creating a wall
of convecting air currents.
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Trench heaters usually use hot water
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or electric heating
elements to heat the air.
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Their position at the floor
level means they have access
00:06:02.530 --> 00:06:04.860
to the coldest air in the room.
00:06:04.860 --> 00:06:07.680
The heat exchanger
transfers the heat into this
00:06:07.680 --> 00:06:09.350
via the thin tube.
00:06:09.350 --> 00:06:11.520
This causes the cold air to heat up
00:06:11.520 --> 00:06:13.440
and rise towards the ceiling.
00:06:13.440 --> 00:06:16.410
As it rises up, cold air
in the room will rush in
00:06:16.410 --> 00:06:17.770
to take its place.
00:06:17.770 --> 00:06:20.670
This creates a convective
current and a thermal boundary
00:06:20.670 --> 00:06:22.423
between the glass and the room.
00:06:23.510 --> 00:06:26.570
Duct electric heater, open coil element.
00:06:26.570 --> 00:06:28.890
Open coil heating elements are used mostly
00:06:28.890 --> 00:06:33.090
in ductwork applications,
furnaces and sometimes fan coils.
00:06:33.090 --> 00:06:35.660
These operate using exposed live coils
00:06:35.660 --> 00:06:38.500
of highly resistive
metal to generate heat.
00:06:38.500 --> 00:06:40.660
These heat exchanges are placed directly
00:06:40.660 --> 00:06:44.097
into the flow of air and as the
air passes across the coils,
00:06:44.097 --> 00:06:47.400
the thermal energy is
transferred via convection.
00:06:47.400 --> 00:06:50.310
These provide uniform heating
across the air stream,
00:06:50.310 --> 00:06:53.290
although these are only used
where it is safe to do so
00:06:53.290 --> 00:06:55.823
and the coils cannot easily be accessed.
00:06:57.409 --> 00:06:58.567
Microchannel heat exchangers.
00:06:58.567 --> 00:07:01.310
Microchannel heat exchangers
are an advancement
00:07:01.310 --> 00:07:04.490
on the thin tube coil, providing
superior heat exchange,
00:07:04.490 --> 00:07:06.670
although these are only
used for refrigeration
00:07:06.670 --> 00:07:08.540
and air conditioning systems.
00:07:08.540 --> 00:07:10.270
You can find this type of heat exchangers
00:07:10.270 --> 00:07:13.550
on air-cooled chillers,
condensing units, residential AC,
00:07:13.550 --> 00:07:15.220
air dryers, cabinet cooling
00:07:15.220 --> 00:07:17.870
and rooftop units et etcera et cetera.
00:07:17.870 --> 00:07:20.800
These type of heat exchangers
also work using convection
00:07:20.800 --> 00:07:23.030
as their main method of heat transfer.
00:07:23.030 --> 00:07:26.130
The micro channel heat
exchanger has a simple design.
00:07:26.130 --> 00:07:27.770
On each side is a header.
00:07:27.770 --> 00:07:30.290
Running between each
header are some flat tubes
00:07:30.290 --> 00:07:31.910
with fins in between.
00:07:31.910 --> 00:07:34.470
Air passes through the
fins between the gaps
00:07:34.470 --> 00:07:36.470
to carry the thermal energy away.
00:07:36.470 --> 00:07:38.270
The refrigerant enters through the header
00:07:38.270 --> 00:07:40.220
and then passes through the flat tubes
00:07:40.220 --> 00:07:42.130
until it reaches the other header.
00:07:42.130 --> 00:07:44.260
The headers contain baffles which control
00:07:44.260 --> 00:07:46.190
the direction of flow of refrigerant
00:07:46.190 --> 00:07:48.920
and are used to loop the
refrigerant through the tubes
00:07:48.920 --> 00:07:51.840
a number of times to increase
the time spent inside
00:07:51.840 --> 00:07:54.330
and thus increase the opportunity
00:07:54.330 --> 00:07:56.550
to transfer thermal energy.
00:07:56.550 --> 00:07:59.600
Inside each flat tube are
a number of small holes
00:07:59.600 --> 00:08:02.150
and then there's microchannels
which run the entire length
00:08:02.150 --> 00:08:03.800
of each flat tube.
00:08:03.800 --> 00:08:07.050
These microchannels dramatically
increase the surface area
00:08:07.050 --> 00:08:09.950
of the heat exchanger which
allows more thermal energy
00:08:09.950 --> 00:08:11.680
to get out of the refrigerant
00:08:11.680 --> 00:08:14.460
and into the heat
exchanger's metal casing.
00:08:14.460 --> 00:08:16.560
The temperature difference
between the refrigerant
00:08:16.560 --> 00:08:18.800
and air cause the heat to conduct
00:08:18.800 --> 00:08:21.970
through the flat tube
casing and into the fins.
00:08:21.970 --> 00:08:23.740
As the air passes through the gaps,
00:08:23.740 --> 00:08:26.883
it carries the thermal
energy away via convection.
00:08:27.860 --> 00:08:29.710
Furnace evaporator coil.
00:08:29.710 --> 00:08:32.690
Furnace evaporators are
commonly found in large homes
00:08:32.690 --> 00:08:36.130
and small commercial properties
with small ducted systems.
00:08:36.130 --> 00:08:39.120
You can get larger coils that
work on a similar principle
00:08:39.120 --> 00:08:41.850
but for larger systems, mostly for AHUs
00:08:41.850 --> 00:08:44.300
in medium to large commercial buildings.
00:08:44.300 --> 00:08:47.120
The coil inside the furnace
evaporator works the same
00:08:47.120 --> 00:08:49.990
as a thin tube heat exchanger
and uses a refrigerant
00:08:49.990 --> 00:08:53.300
on the inside with ducted
air on the outside.
00:08:53.300 --> 00:08:56.300
The air passes across the
tubes and transfers its heat
00:08:56.300 --> 00:08:57.980
via force convection.
00:08:57.980 --> 00:08:59.490
This is then transferred
00:08:59.490 --> 00:09:01.810
through the tube wall through conduction.
00:09:01.810 --> 00:09:04.560
The refrigerant on the
inside carries this heat away
00:09:04.560 --> 00:09:06.170
through force convection.
00:09:06.170 --> 00:09:09.453
The refrigerant boils and
evaporates away to the compressor.
00:09:10.700 --> 00:09:14.010
Radiators, these are very
common especially across Europe
00:09:14.010 --> 00:09:17.620
and North America in homes and
older commercial buildings.
00:09:17.620 --> 00:09:20.040
They are mounted two walls,
typically under a window
00:09:20.040 --> 00:09:21.800
to provide space heating.
00:09:21.800 --> 00:09:23.360
Their function is very simple,
00:09:23.360 --> 00:09:25.590
they are usually connected
to a hot water pipe
00:09:25.590 --> 00:09:28.150
which is fed water from a boiler.
00:09:28.150 --> 00:09:30.420
The water enters through
a small diameter pipe
00:09:30.420 --> 00:09:33.050
and flows to the inside of the radiator.
00:09:33.050 --> 00:09:36.240
Internal area of the radiator
is larger than the pipe
00:09:36.240 --> 00:09:39.390
which slows the water velocity
down and allows more time
00:09:39.390 --> 00:09:41.160
for the heat to be transferred.
00:09:41.160 --> 00:09:44.170
The heat of the water is
transferred by conduction
00:09:44.170 --> 00:09:46.210
to the metal walls of the radiator.
00:09:46.210 --> 00:09:49.590
On the outside of the radiator
is the air of the room.
00:09:49.590 --> 00:09:52.240
When this air comes into
contact with the hot surface
00:09:52.240 --> 00:09:55.560
of the radiator, the heat
will transfer into the air
00:09:55.560 --> 00:09:58.520
and this will cause the
air to expand and rise.
00:09:58.520 --> 00:10:01.040
Colder air then moves
in to replace this air
00:10:01.040 --> 00:10:03.600
causing a continuous cycle of moving air
00:10:03.600 --> 00:10:04.910
which heats the room.
00:10:04.910 --> 00:10:08.163
This moving air is therefore
convection heat transfer.
00:10:10.260 --> 00:10:11.680
Water heating element.
00:10:11.680 --> 00:10:14.390
The water heating element is
usually found in calorifiers
00:10:14.390 --> 00:10:15.630
and water heaters.
00:10:15.630 --> 00:10:18.970
It's also sometimes used in the
basin of open cooling towers
00:10:18.970 --> 00:10:21.280
to prevent the water
from freezing in winter.
00:10:21.280 --> 00:10:23.370
These use a metal coil along the tube
00:10:23.370 --> 00:10:25.350
which has a high resistance value.
00:10:25.350 --> 00:10:27.290
This resistance generates heat.
00:10:27.290 --> 00:10:30.180
The coil is insulated to
contain the flow of current
00:10:30.180 --> 00:10:32.220
but permit the flow of thermal energy.
00:10:32.220 --> 00:10:34.730
The heating element is
submerged in a tank of water
00:10:34.730 --> 00:10:36.970
and the heat is conducted
out of the element
00:10:36.970 --> 00:10:38.270
and into the water.
00:10:38.270 --> 00:10:40.830
The water which comes into
contact with the heating element
00:10:40.830 --> 00:10:43.460
is therefore heated and
this causes it to rise
00:10:43.460 --> 00:10:44.560
within the tank.
00:10:44.560 --> 00:10:46.950
Cooler water then flows in to replace this
00:10:46.950 --> 00:10:49.883
this heated water where this
cycle will then continue.
00:10:50.990 --> 00:10:53.970
Rotary wheel, this type of heat exchangers
00:10:53.970 --> 00:10:56.250
are usually found within
the air handling units
00:10:56.250 --> 00:10:59.710
between the supply and
extract ducted air streams.
00:10:59.710 --> 00:11:01.840
They work by using a small electric motor
00:11:01.840 --> 00:11:04.330
connected to a pulley
belt to slowly rotate
00:11:04.330 --> 00:11:07.990
the heat exchanger disc which
sits directly in the airflow
00:11:07.990 --> 00:11:11.030
between both the exhaust
and fresh air intake.
00:11:11.030 --> 00:11:12.950
The air passes straight through the disc
00:11:12.950 --> 00:11:15.170
but as it does so it comes into contact
00:11:15.170 --> 00:11:17.050
with the material of the wheel.
00:11:17.050 --> 00:11:19.370
The material of the heat exchanger disc
00:11:19.370 --> 00:11:22.750
absorbs the thermal energy
from one stream of air
00:11:22.750 --> 00:11:26.460
and as it rotates and enters
the second stream of air
00:11:26.460 --> 00:11:29.370
where it will release this
absorbed thermal energy.
00:11:29.370 --> 00:11:32.250
This type of heat exchanger
will result in a small amount
00:11:32.250 --> 00:11:36.480
of fluid mixing between the
intake and exhaust air streams
00:11:36.480 --> 00:11:39.550
due to the small gaps present
where the wheel rotates.
00:11:39.550 --> 00:11:42.300
Therefore, it can't be
used where strong odors
00:11:42.300 --> 00:11:44.350
or toxic fumes are used.
00:11:44.350 --> 00:11:47.150
These heat exchangers can
be used in the winter months
00:11:47.150 --> 00:11:49.611
to reclaim heat from the
building's exhaust system.
00:11:49.611 --> 00:11:52.360
This heat is captured by the thermal wheel
00:11:52.360 --> 00:11:55.510
and transferred into the
fresh air intake stream
00:11:55.510 --> 00:11:59.110
which will be much cooler than
the air inside the building.
00:11:59.110 --> 00:12:01.700
These heat exchangers can also
be used in the summer months
00:12:01.700 --> 00:12:04.730
to recover cold air from
the building's exhaust
00:12:04.730 --> 00:12:08.109
and use this to cool down
the fresh air intake.
00:12:08.109 --> 00:12:11.460
Water boiler, you find
large boilers like this
00:12:11.460 --> 00:12:13.780
mostly in medium to large
commercial buildings
00:12:13.780 --> 00:12:15.370
in cooler climates.
00:12:15.370 --> 00:12:18.700
Homes and smaller buildings
will use much smaller versions
00:12:18.700 --> 00:12:20.400
which are usually wall-mounted.
00:12:20.400 --> 00:12:24.190
Both have many variations
but this type is very common.
00:12:24.190 --> 00:12:26.860
Fuel is combusted in
the combustion chamber,
00:12:26.860 --> 00:12:30.460
usually through gas or oil
and the hot exhaust gases
00:12:30.460 --> 00:12:32.640
are forced through a number of tubes
00:12:32.640 --> 00:12:34.610
until they reach the flue and are released
00:12:34.610 --> 00:12:35.750
to the atmosphere.
00:12:35.750 --> 00:12:37.530
The tubes and the combustion chamber
00:12:37.530 --> 00:12:39.250
are surrounded by water.
00:12:39.250 --> 00:12:42.450
The heat convex to the tube
walls and is then conducted
00:12:42.450 --> 00:12:44.270
through into the water.
00:12:44.270 --> 00:12:46.670
This is then carried away by convection.
00:12:46.670 --> 00:12:48.340
Depending on the system design,
00:12:48.340 --> 00:12:52.300
the water then leaves as either
heated water or as steam.
00:12:52.300 --> 00:12:55.720
The water is forced through by
a pump, the speed of the pump
00:12:55.720 --> 00:12:57.920
as well as the amount of fuel combusted
00:12:57.920 --> 00:13:00.230
can be varied to change the temperature
00:13:00.230 --> 00:13:01.480
as well as the flow rate.
00:13:02.360 --> 00:13:05.930
Heat pipe, you'll find these
in solar thermal water heaters
00:13:05.930 --> 00:13:08.590
and some heat recovery AHU coils.
00:13:08.590 --> 00:13:10.800
If we look at the solar
thermal application,
00:13:10.800 --> 00:13:12.990
we have a tube made from special glass
00:13:12.990 --> 00:13:16.280
which is evacuated of all
air to create a vacuum
00:13:16.280 --> 00:13:17.520
and is then sealed.
00:13:17.520 --> 00:13:20.270
The inner layer of the
tube has a special coating.
00:13:20.270 --> 00:13:22.230
The coating and the vacuum work together
00:13:22.230 --> 00:13:24.470
to prevent the heat from
being able to leave,
00:13:24.470 --> 00:13:26.050
once it enters the tube.
00:13:26.050 --> 00:13:29.650
It then helps move this to
the heat pipe at the center.
00:13:29.650 --> 00:13:31.850
The heat pipe has a fin on each side
00:13:31.850 --> 00:13:35.120
connected to the tube coating
to pick up the thermal energy.
00:13:35.120 --> 00:13:38.340
The heat pipe is a sealed
long hollow copper pipe
00:13:38.340 --> 00:13:40.610
which runs the length of the glass tube
00:13:40.610 --> 00:13:42.980
and has a protruding bulb at the top.
00:13:42.980 --> 00:13:45.040
The bulb is connected into a header
00:13:45.040 --> 00:13:47.620
and cool water passes through the header
00:13:47.620 --> 00:13:49.840
to pass across the bulb head.
00:13:49.840 --> 00:13:51.910
Inside the heat pipe is a water mixture
00:13:51.910 --> 00:13:53.670
held at very low pressure.
00:13:53.670 --> 00:13:57.010
This low pressure allows the
water to evaporate into steam
00:13:57.010 --> 00:13:58.250
of little heat.
00:13:58.250 --> 00:14:01.500
The steam then rises up into
the bulb where it will give up
00:14:01.500 --> 00:14:04.840
this heat into the water
flowing through the header.
00:14:04.840 --> 00:14:06.420
As the steam gives up its heat,
00:14:06.420 --> 00:14:09.870
it will condense and fall
back down to repeat the cycle.
00:14:09.870 --> 00:14:12.220
The tube absorbs thermal radiation.
00:14:12.220 --> 00:14:14.690
This is then conducted into the tube.
00:14:14.690 --> 00:14:17.906
The water inside convexes up to the bulb,
00:14:17.906 --> 00:14:21.150
the heat is conducted
through the pipe wall
00:14:21.150 --> 00:14:24.823
and is carried away by convection
into the stream of water.
00:14:26.280 --> 00:14:29.490
Chilled beam, there are two
types of chilled beam used,
00:14:29.490 --> 00:14:31.040
passive and active.
00:14:31.040 --> 00:14:33.640
Both are used mostly in
commercial buildings.
00:14:33.640 --> 00:14:36.790
Active chilled beams work
by passing a cool liquid,
00:14:36.790 --> 00:14:40.250
typically water, through a
thin tube heat exchanger.
00:14:40.250 --> 00:14:42.740
Air is then ducted into the chilled beam
00:14:42.740 --> 00:14:45.800
and it exits through a
specially positioned nozzle.
00:14:45.800 --> 00:14:47.560
The air moves over the thin tube
00:14:47.560 --> 00:14:49.970
and blows the cold air into the room.
00:14:49.970 --> 00:14:52.440
Therefore, it uses forced convection.
00:14:52.440 --> 00:14:54.830
Passive chilled beams will also use
00:14:54.830 --> 00:14:57.240
thin tube heat exchangers
but they will not have
00:14:57.240 --> 00:14:59.670
a ducted air supply connected.
00:14:59.670 --> 00:15:02.380
Instead, they create a
natural convection current
00:15:02.380 --> 00:15:05.590
by cooling down the warm
air at the ceiling level.
00:15:05.590 --> 00:15:08.400
This air then sinks and
is replaced by warmer air
00:15:08.400 --> 00:15:09.883
where the cycle will repeat.
00:15:10.860 --> 00:15:14.120
Furnace heater, furnace
heaters are common in homes
00:15:14.120 --> 00:15:15.770
with ducted air conditioning.
00:15:15.770 --> 00:15:18.280
These are very common in North America.
00:15:18.280 --> 00:15:21.040
Furnace heaters use a heat
exchanger placed directly
00:15:21.040 --> 00:15:22.660
into the ducted air stream.
00:15:22.660 --> 00:15:25.180
Fuel is combusted and the hot gas is sent
00:15:25.180 --> 00:15:26.940
through the heat exchanger.
00:15:26.940 --> 00:15:29.580
The heat of this is
convected into the walls
00:15:29.580 --> 00:15:30.960
of the heat exchanger.
00:15:30.960 --> 00:15:33.690
The cooler ducted air passes
across the other side,
00:15:33.690 --> 00:15:35.510
causing a temperature difference.
00:15:35.510 --> 00:15:38.910
So, the heat of the gas is
conducted through the wall
00:15:38.910 --> 00:15:41.013
and will be carried away by convection.
00:15:43.700 --> 00:15:45.220
Plate heat exchanger.
00:15:45.220 --> 00:15:47.630
There are two main types
of plate heat exchangers,
00:15:47.630 --> 00:15:49.970
gasket type and brazed plate type.
00:15:49.970 --> 00:15:53.310
These are both very effective
at transferring thermal energy
00:15:53.310 --> 00:15:56.680
but for even greater
efficiency and compact design,
00:15:56.680 --> 00:15:59.120
you can use a micro plate heat exchanger
00:15:59.120 --> 00:16:00.640
for many applications.
00:16:00.640 --> 00:16:02.570
We've covered all of these heat exchangers
00:16:02.570 --> 00:16:04.380
in great detail, previously.
00:16:04.380 --> 00:16:06.910
Links are in the video description below.
00:16:06.910 --> 00:16:09.310
The basic things to know
about these two types
00:16:09.310 --> 00:16:13.280
of heat exchangers is that
gasket type can be dismantled.
00:16:13.280 --> 00:16:16.110
Its heating or cooling
capacity can be increased
00:16:16.110 --> 00:16:18.840
or decreased simply by adding or removing
00:16:18.840 --> 00:16:20.720
heat transfer plates.
00:16:20.720 --> 00:16:23.810
You'll find these use
especially in large or high-rise
00:16:23.810 --> 00:16:27.580
commercial properties to
indirectly connect chillers,
00:16:27.580 --> 00:16:29.740
boilers and cooling towers to the heating
00:16:29.740 --> 00:16:32.450
and cooling circuits
or to connect buildings
00:16:32.450 --> 00:16:34.550
to district energy networks.
00:16:34.550 --> 00:16:36.910
Brazed plate heat
exchangers are sealed units
00:16:36.910 --> 00:16:38.620
which cannot be dismantled.
00:16:38.620 --> 00:16:41.520
Their heating or cooling
capacity is fixed.
00:16:41.520 --> 00:16:44.240
These are used for applications
such as heat pumps,
00:16:44.240 --> 00:16:46.840
combi boilers, heat interface units,
00:16:46.840 --> 00:16:50.060
connecting calorifires
indirectly et cetera.
00:16:50.060 --> 00:16:52.620
Both work the same
however and pass fluids,
00:16:52.620 --> 00:16:56.430
usually in opposite directions
in adjacent channels.
00:16:56.430 --> 00:16:59.660
The fluids are usually
water and/or refrigerant.
00:16:59.660 --> 00:17:02.690
The thermal energy is
convected onto the plate
00:17:02.690 --> 00:17:04.950
and then conduct through the plate
00:17:04.950 --> 00:17:06.580
and the fluid on the other side
00:17:06.580 --> 00:17:08.613
carries this away through convection.
00:17:10.200 --> 00:17:12.830
Shell and tube, shell
and tube heat exchangers
00:17:12.830 --> 00:17:15.720
are typically found on
chillers for the evaporator
00:17:15.720 --> 00:17:18.540
and/or condenser, sometimes are also used
00:17:18.540 --> 00:17:20.880
for lubricating oil cooler.
00:17:20.880 --> 00:17:24.230
These are possibly the simplest
design of heat exchanger.
00:17:24.230 --> 00:17:27.020
They have an outer container
known as the shell.
00:17:27.020 --> 00:17:29.270
Sitting inside the shell
are a number of pipes
00:17:29.270 --> 00:17:30.900
known as the tubes.
00:17:30.900 --> 00:17:32.450
The tubes contain one fluid
00:17:32.450 --> 00:17:34.660
and the shell contains another fluid.
00:17:34.660 --> 00:17:37.540
The two fluids are always
separated by the tube walls,
00:17:37.540 --> 00:17:39.540
they never meet or mix.
00:17:39.540 --> 00:17:41.410
The fluids will be at
different temperatures
00:17:41.410 --> 00:17:43.890
which causes a thermal
energy to be transferred
00:17:43.890 --> 00:17:46.340
between the fluids and this thermal energy
00:17:46.340 --> 00:17:48.450
will pass through the tube walls.
00:17:48.450 --> 00:17:50.480
When using the evaporator or condenser,
00:17:50.480 --> 00:17:53.360
the two fluids will be
water and refrigerant.
00:17:53.360 --> 00:17:56.190
Depending on the design, the
water can be in the shell
00:17:56.190 --> 00:17:58.840
or the tube and the refrigerant
will be in the other.
00:18:00.370 --> 00:18:03.660
Chillers, a chiller will
use either a shell and tube
00:18:03.660 --> 00:18:06.010
heat exchanger, a plate heat exchanger
00:18:06.010 --> 00:18:08.420
or a thin tube heat exchanger.
00:18:08.420 --> 00:18:10.520
Many chillers will
actually use a combination
00:18:10.520 --> 00:18:11.810
of all of these.
00:18:11.810 --> 00:18:14.420
For example, an air cooled chiller may use
00:18:14.420 --> 00:18:17.630
a shell and tube heat
exchanger for the evaporator,
00:18:17.630 --> 00:18:19.960
a thin tube or microchannel heat exchanger
00:18:19.960 --> 00:18:23.110
for the condenser, a
brazed plate heat exchanger
00:18:23.110 --> 00:18:26.290
for the compressors
oil lubrication cooling
00:18:26.290 --> 00:18:29.460
and a gasket plate heat
exchanger to indirectly connect
00:18:29.460 --> 00:18:31.823
the chiller to the
central cooling circuit.
00:18:34.130 --> 00:18:35.820
Okay, before I wrap things up,
00:18:35.820 --> 00:18:38.610
I just want to say thanks
to Danfoss one last time
00:18:38.610 --> 00:18:40.120
00:18:40.120 --> 00:18:42.760
Don't forget to check out all
their heat exchanger solutions
00:18:42.760 --> 00:18:43.930
over on their website.
00:18:43.930 --> 00:18:46.750
Just click the link in the
video description below.
00:18:46.750 --> 00:18:49.470
The answer to the questions
at the beginning of the video
00:18:49.470 --> 00:18:51.850
is a, shell and tube heat exchanger,
00:18:51.850 --> 00:18:53.830
b, brazed plate heat exchanger
00:18:53.830 --> 00:18:56.300
and c, micro channel heat exchanger.
00:18:56.300 --> 00:18:57.950
Okay guys, that's it for this video.
00:18:57.950 --> 00:18:59.260
Thank you very much for watching.
00:18:59.260 --> 00:19:00.930
I hope you've enjoyed this
and it has helped you.
00:19:00.930 --> 00:19:03.550
If so, please don't forget
to like, subscribe and share
00:19:03.550 --> 00:19:06.090
and don't forget to follow
us on Facebook, Instagram,
00:19:06.090 --> 00:19:09.710
Twitter as well as our website
theengineeringmindset.com.
00:19:09.710 --> 00:19:11.483
Once again, thanks for watching.

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