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Plate Heat Exchanger Applications and working principle hvac heat transfer

WEBVTT
Kind: captions
Language: en

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Hey there, guys.
00:00:05.083 --> 00:00:07.020
Paul here from TheEngineeringMindset.com.
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In this video,
00:00:07.853 --> 00:00:09.520
we'll be discussing the applications
00:00:09.520 --> 00:00:10.750
of plate heat exchangers.
00:00:10.750 --> 00:00:13.390
We'll be covering both
gasket and brazed plate type
00:00:13.390 --> 00:00:14.570
as well as some micro plate
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and very briefly welded plate type also.
00:00:17.480 --> 00:00:18.880
I just want to take a quick moment
00:00:18.880 --> 00:00:21.020
to thank Danfoss for
sponsoring this video.
00:00:21.020 --> 00:00:22.080
If you're watching this channel,
00:00:22.080 --> 00:00:23.450
I'm going to go ahead and assume
00:00:23.450 --> 00:00:25.560
that you enjoy learning
about engineering topics.
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If that's the case,
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including more information
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about heat exchangers of all kinds.
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Okay, a quick test for you.
00:00:52.400 --> 00:00:53.830
And I want you to tell me your answers
00:00:53.830 --> 00:00:55.770
in the video description below.
00:00:55.770 --> 00:00:57.860
Why do fluids in plate heat exchangers
00:00:57.860 --> 00:01:00.340
typically flow in opposite directions?
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Let me know your answers below
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and I'll give you the answer
at the end of the video.
00:01:04.410 --> 00:01:06.310
In our previous videos on heat exchangers,
00:01:06.310 --> 00:01:07.680
we've looked in great detail
00:01:07.680 --> 00:01:09.640
about how gasket plate
heat exchangers work
00:01:09.640 --> 00:01:11.540
and also micro plate heat exchangers.
00:01:11.540 --> 00:01:14.140
I highly recommend you watch
those if you haven't already.
00:01:14.140 --> 00:01:16.510
Links are in the video description below.
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Okay, let's just briefly recap
on what a heat exchanger is
00:01:19.350 --> 00:01:21.280
and how these plate types work.
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A heat exchanger is a device used
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to transfer thermal energy
from one fluid to another.
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Both fluids are completely
separated by the heat exchanger.
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They never meet or mix.
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The fluids can be anything,
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such as water, oil, refrigerants, etc.
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The fluids much be at
different temperatures
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to transfer heat
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and heat always flows from hot to cold.
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There are two main types
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There's gasket type and brazed plate type.
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Let's look at gasket type first.
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Gasket type heat exchangers
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consist of multiple sheets of thin metal
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arranged to create channels.
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The gaskets sit between each
of the plates and form a seal.
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The seal prevents the fluids
from mixing and leaking.
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They also dictate
00:02:01.360 --> 00:02:03.890
which channels each
fluid can flow through.
00:02:03.890 --> 00:02:05.200
Gasket plate heat exchangers
00:02:05.200 --> 00:02:08.470
can increase or decrease their
heating or cooling capacity
00:02:08.470 --> 00:02:10.960
by adding or removing internal plates.
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They can also be dismantled
for cleaning and maintenance.
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The materials used in
the plate heat exchangers
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will vary depending on the fluids used,
00:02:18.307 --> 00:02:20.810
but the plates are typically
made from stainless steel,
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sometimes titanium,
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and the end plates are
usually made from mild steel.
00:02:24.470 --> 00:02:27.010
Meanwhile the gaskets are
usually made from rubber.
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Applications of gasket
plate heat exchangers.
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You're going to find these in
many heavy-duty applications
00:02:32.250 --> 00:02:35.460
for HVAC as well as industrial
and process engineering.
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Let's have a look at
some examples of these.
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District heating and cooling.
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You'll find these type of heat exchangers
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used to connect buildings
00:02:42.250 --> 00:02:44.440
to district heating and cooling networks.
00:02:44.440 --> 00:02:46.460
The district heating and cooling center
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distributes the hot and cold fluids
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around some central
pipes to form a network.
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Buildings are then connected
to these central networks
00:02:53.570 --> 00:02:55.770
to make use of the heating
and cooling fluids.
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To connect the buildings to the networks,
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gasket plate heat exchangers
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are typically installed
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between the building's
central plant circuit
00:03:02.460 --> 00:03:03.730
and the district network.
00:03:03.730 --> 00:03:06.160
The central plant circuit
pulls heat or coolth
00:03:06.160 --> 00:03:07.920
out of the network as required,
00:03:07.920 --> 00:03:11.160
usually through a heat meter
to measure the consumption.
00:03:11.160 --> 00:03:11.993
HVAC.
00:03:11.993 --> 00:03:13.820
Now you're going to find
00:03:13.820 --> 00:03:15.910
used in many HVAC applications
00:03:15.910 --> 00:03:18.300
to indirectly connect chillers, boilers,
00:03:18.300 --> 00:03:20.860
and cooling towers to
central plant systems.
00:03:20.860 --> 00:03:22.970
They're also for economizer circuits
00:03:22.970 --> 00:03:24.390
and heat recovery circuits
00:03:24.390 --> 00:03:26.950
to reduce the cooling
load on the chillers.
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Industry and manufacturing.
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Many industrial plants will
use plate heat exchangers
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for things such as pasteurization
and waste heat recovery.
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For example,
00:03:35.273 --> 00:03:37.480
a manufacturing plant
may use chilled water
00:03:37.480 --> 00:03:40.750
to cool down a hot, newly
manufactured beverage product.
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The hot finished liquid product
00:03:42.310 --> 00:03:44.180
needs to be cooled down before bottling.
00:03:44.180 --> 00:03:46.180
So it passes through a
plate heat exchanger,
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which is connected to a
cooling circuit of a chiller.
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This extracts the unwanted heat
00:03:50.300 --> 00:03:52.140
without the two fluids mixing.
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If we just consider some
of the pros and cons
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to using gasket type,
00:03:55.530 --> 00:03:58.490
well the pros are that it can
be dismantled for cleaning,
00:03:58.490 --> 00:04:01.050
the heating and cooling
capacity can be changed,
00:04:01.050 --> 00:04:04.280
and parts can quickly be
replaced if the unit was damaged.
00:04:04.280 --> 00:04:07.100
The cons the really consider
are that leaks are rare
00:04:07.100 --> 00:04:09.117
but they're more likely
due to the gaskets.
00:04:09.117 --> 00:04:11.440
And also this unit will
have a higher pressure drop
00:04:11.440 --> 00:04:13.850
than the shell and tube heat exchanger.
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Welded plate and frame.
00:04:15.630 --> 00:04:17.960
There's a variation of the
plate and frame heat exchanger
00:04:17.960 --> 00:04:19.800
that I just want to briefly cover.
00:04:19.800 --> 00:04:21.830
That's the welded plate and frame type.
00:04:21.830 --> 00:04:22.663
In this type,
00:04:22.663 --> 00:04:25.190
the plates are all welded
together in one block.
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They therefore cannot be dismantled
00:04:27.080 --> 00:04:29.850
and the heating and
cooling capacity is fixed.
00:04:29.850 --> 00:04:30.683
However,
00:04:30.683 --> 00:04:32.630
they do allow for much higher pressure
00:04:32.630 --> 00:04:34.280
and temperature fluids to be used
00:04:34.280 --> 00:04:36.070
and they minimize the risk of leakage
00:04:36.070 --> 00:04:38.150
so hazardous fluids can be used.
00:04:38.150 --> 00:04:40.640
You'll find these mostly
in heavy industrial sites,
00:04:40.640 --> 00:04:43.910
power plants, and oil
refinery applications.
00:04:43.910 --> 00:04:45.780
Brazed plate heat exchangers.
00:04:45.780 --> 00:04:48.440
Now these are typically used
in smaller applications.
00:04:48.440 --> 00:04:50.120
However, in recent years,
00:04:50.120 --> 00:04:51.490
this has started to change
00:04:51.490 --> 00:04:53.210
and larger units are being produced
00:04:53.210 --> 00:04:54.510
and applied to industry.
00:04:54.510 --> 00:04:57.300
These heat exchangers also
use thin plates of metal
00:04:57.300 --> 00:04:58.610
to separate the fluids.
00:04:58.610 --> 00:05:00.830
Although the plates are brazed together
00:05:00.830 --> 00:05:02.490
to completely seal the unit.
00:05:02.490 --> 00:05:04.900
No gaskets are used in this design.
00:05:04.900 --> 00:05:07.050
The brazing and the
alignment of the plates
00:05:07.050 --> 00:05:09.750
forms the seal and dictates
which of the channels
00:05:09.750 --> 00:05:11.570
each fluid can flow into.
00:05:11.570 --> 00:05:12.670
Materials used.
00:05:12.670 --> 00:05:14.200
Well, the plates and the casing
00:05:14.200 --> 00:05:16.300
are typically made from stainless steel.
00:05:16.300 --> 00:05:19.000
But the brazing which joins
each of the plates together
00:05:19.000 --> 00:05:20.430
is usually made from copper.
00:05:20.430 --> 00:05:22.157
Sometimes it'll also be stainless steel,
00:05:22.157 --> 00:05:24.470
but the materials used for this type
00:05:24.470 --> 00:05:25.570
will vary depending on
00:05:25.570 --> 00:05:28.580
which fluid is being
used in the application.
00:05:28.580 --> 00:05:30.850
00:05:30.850 --> 00:05:32.360
00:05:32.360 --> 00:05:33.760
The heat interface units,
00:05:33.760 --> 00:05:36.310
which connect individual
apartments or homes
00:05:36.310 --> 00:05:37.850
to heating and cooling networks,
00:05:37.850 --> 00:05:41.030
will usually use a brazed
plate type heat exchanger.
00:05:41.030 --> 00:05:43.620
Sometimes large brazed
plate heat exchangers
00:05:43.620 --> 00:05:45.300
are used to connect the buildings
00:05:45.300 --> 00:05:47.640
to the district or heating network.
00:05:47.640 --> 00:05:49.740
However, the majority of these used
00:05:49.740 --> 00:05:52.100
are still currently gasket type.
00:05:52.100 --> 00:05:53.060
Heat pumps.
00:05:53.060 --> 00:05:54.520
Now heat pumps will often use
00:05:54.520 --> 00:05:56.180
brazed plate type heat exchangers
00:05:56.180 --> 00:05:58.660
to connect the separated loops together.
00:05:58.660 --> 00:06:00.640
This is quite common in
water source heat pumps
00:06:00.640 --> 00:06:02.010
with brazed plates being used
00:06:02.010 --> 00:06:04.180
for both the condenser and the evaporator.
00:06:04.180 --> 00:06:06.320
This separates the
different circuits of water,
00:06:06.320 --> 00:06:08.380
refrigerant, and water/glycol mixtures,
00:06:08.380 --> 00:06:10.120
allowing only the thermal energy
00:06:10.120 --> 00:06:12.770
to indirectly transfer between them.
00:06:12.770 --> 00:06:13.603
Chillers.
00:06:13.603 --> 00:06:15.100
Chillers have begun to be produced
00:06:15.100 --> 00:06:17.070
using brazed plate heat exchangers.
00:06:17.070 --> 00:06:18.150
On an air-cooled chiller,
00:06:18.150 --> 00:06:20.050
the evaporator can often be replaced
00:06:20.050 --> 00:06:21.310
with brazed plate type,
00:06:21.310 --> 00:06:22.640
and in water-cooled chillers,
00:06:22.640 --> 00:06:24.620
both the evaporator and the condenser
00:06:24.620 --> 00:06:26.660
can be replaced with brazed plate type
00:06:26.660 --> 00:06:29.197
depending on the size of the cooling load.
00:06:29.197 --> 00:06:31.340
Calorifiers and hot water tanks.
00:06:31.340 --> 00:06:33.270
Now calorifiers and hot water tanks
00:06:33.270 --> 00:06:35.920
are often indirectly
connected to heating circuits
00:06:35.920 --> 00:06:37.840
through brazed plate heat exchangers.
00:06:37.840 --> 00:06:38.950
This separates the two
00:06:38.950 --> 00:06:41.830
and allows instantaneous
hot water to be provided,
00:06:41.830 --> 00:06:44.500
or hot water can be drawn
from the storage vessel
00:06:44.500 --> 00:06:47.290
depending on the building's
demand for hot water.
00:06:47.290 --> 00:06:48.610
So what are the pros and cons
00:06:48.610 --> 00:06:51.020
to using a brazed plate
type heat exchanger?
00:06:51.020 --> 00:06:53.130
Well, the pros are that
it's less likely to leak
00:06:53.130 --> 00:06:55.050
because it doesn't have
a gasket seal in between.
00:06:55.050 --> 00:06:57.120
The whole unit is sealed as one.
00:06:57.120 --> 00:06:59.320
It's also gonna have a
slightly higher efficiency
00:06:59.320 --> 00:07:01.890
because there's no rubber
gaskets used in between.
00:07:01.890 --> 00:07:02.980
All the material used
00:07:02.980 --> 00:07:04.910
is there just to transfer heat.
00:07:04.910 --> 00:07:06.640
And the lack of gaskets also allows
00:07:06.640 --> 00:07:09.360
for a more compact design
than the gasket type.
00:07:09.360 --> 00:07:10.193
The cons,
00:07:10.193 --> 00:07:11.610
well it's gonna be harder to clean
00:07:11.610 --> 00:07:13.500
because you cannot take this unit apart.
00:07:13.500 --> 00:07:15.260
Additionally, if the unit was damaged,
00:07:15.260 --> 00:07:16.830
then the whole thing must be replaced
00:07:16.830 --> 00:07:19.164
because you cannot get
replacement parts for these.
00:07:19.164 --> 00:07:21.181
Micro plate heat exchangers.
00:07:21.181 --> 00:07:22.890
Micro plate heat exchangers
00:07:22.890 --> 00:07:25.660
can be either gasket
or brazed plate design.
00:07:25.660 --> 00:07:28.270
They are the next evolution
of plate heat exchangers,
00:07:28.270 --> 00:07:31.560
providing the greatest heat
exchanger efficiency to date.
00:07:31.560 --> 00:07:32.600
It's actually the plate
00:07:32.600 --> 00:07:34.950
which characterizes this
type of heat exchanger.
00:07:34.950 --> 00:07:36.900
Usually the heat exchanger has a pattern
00:07:36.900 --> 00:07:38.510
like a chevron or a fish bone,
00:07:38.510 --> 00:07:39.980
which is pressed into the plate
00:07:39.980 --> 00:07:41.540
to increase the heat transfer.
00:07:41.540 --> 00:07:44.720
instead used small dimples.
00:07:44.720 --> 00:07:47.050
There are a number of reasons
why this is a great design.
00:07:47.050 --> 00:07:47.883
Firstly,
00:07:47.883 --> 00:07:50.230
this allows the fluids to
spread across the plates
00:07:50.230 --> 00:07:51.760
much more evenly.
00:07:51.760 --> 00:07:54.620
This maximizes the heat
transfer surface area.
00:07:54.620 --> 00:07:57.770
This also causes the fluids
to flow much more turbulently,
00:07:57.770 --> 00:07:59.800
which again increases the heat transfer.
00:07:59.800 --> 00:08:02.140
The small dimples
increase the surface area
00:08:02.140 --> 00:08:04.990
allowing more opportunities
for heat to transfer.
00:08:04.990 --> 00:08:06.240
These design improvements
00:08:06.240 --> 00:08:09.600
allow lighter and smaller
heat exchangers to be used.
00:08:09.600 --> 00:08:12.100
Applications for micro
00:08:12.100 --> 00:08:14.060
You can find these type
of plate heat exchangers
00:08:14.060 --> 00:08:16.330
being used in heat pumps, VRF units,
00:08:16.330 --> 00:08:19.310
and also chiller
evaporators and condensers.
00:08:19.310 --> 00:08:20.730
00:08:20.730 --> 00:08:22.600
for the micro plate heat exchanger?
00:08:22.600 --> 00:08:24.900
it's lighter and smaller,
00:08:24.900 --> 00:08:26.870
also has a reduced refrigerant charge,
00:08:26.870 --> 00:08:29.090
and it has a higher heat
transfer efficiency.
00:08:29.090 --> 00:08:29.923
00:08:29.923 --> 00:08:30.930
well it's harder to clean,
00:08:30.930 --> 00:08:33.170
although it's rarely needed
because of the fluids used
00:08:33.170 --> 00:08:35.600
and also the turbulence
caused by the design,
00:08:35.600 --> 00:08:38.000
the whole unit must be
replaced if it was damaged
00:08:38.000 --> 00:08:39.520
for the brazed plate type,
00:08:39.520 --> 00:08:40.353
and again,
00:08:40.353 --> 00:08:42.670
you can't increase or
decrease the capacity
00:08:42.670 --> 00:08:44.770
for the brazed plate type either.
00:08:44.770 --> 00:08:46.110
Okay, before we wrap up,
00:08:46.110 --> 00:08:47.610
I just want to remind you to sign up
00:08:47.610 --> 00:08:49.820
for a free Danfoss Learning profile.
00:08:49.820 --> 00:08:51.120
Doing so gets you access
00:08:51.120 --> 00:08:53.870
to literally hundreds of
engineering-focused e-lessons,
00:08:53.870 --> 00:08:56.210
including several about heat exchangers.
00:08:56.210 --> 00:08:58.490
It also enables you to
earn certifications,
00:08:58.490 --> 00:08:59.810
so go give it a try now.
00:08:59.810 --> 00:09:02.070
00:09:02.070 --> 00:09:03.250
At the beginning of the video,
00:09:03.250 --> 00:09:05.500
I asked you why do fluids typically flow
00:09:05.500 --> 00:09:07.020
in opposite directions?
00:09:07.020 --> 00:09:08.840
Well, there are two common configurations,
00:09:08.840 --> 00:09:11.400
which are parallel and
counter flow design.
00:09:11.400 --> 00:09:12.640
In parallel flow,
00:09:12.640 --> 00:09:14.770
the fluids both flow
in the same direction.
00:09:14.770 --> 00:09:17.010
So the temperature difference
in large at the beginning
00:09:17.010 --> 00:09:18.610
but diminishes along the length
00:09:18.610 --> 00:09:21.150
until both fluids are
at the same temperature,
00:09:21.150 --> 00:09:23.260
then no more heat can be transferred.
00:09:23.260 --> 00:09:25.230
However, in counter flow design,
00:09:25.230 --> 00:09:27.450
the two fluids flow in opposite directions
00:09:27.450 --> 00:09:29.790
resulting in a lower inlet
temperature difference.
00:09:29.790 --> 00:09:33.070
But as the two fluids travel
through the heat exchanger
00:09:33.070 --> 00:09:34.590
in opposite directions,
00:09:34.590 --> 00:09:37.420
the fluids constantly passes newer fluids
00:09:37.420 --> 00:09:39.470
which is a higher or lower temperature.
00:09:39.470 --> 00:09:40.440
This is what causes
00:09:40.440 --> 00:09:42.310
the nearly constant temperature difference
00:09:42.310 --> 00:09:44.540
along the entire length
of the heat exchanger,
00:09:44.540 --> 00:09:46.490
making it much harder for the two fluids
00:09:46.490 --> 00:09:47.900
to reach the same temperature.
00:09:47.900 --> 00:09:49.480
That means that the thermal energy
00:09:49.480 --> 00:09:51.380
is being refreshed constantly,
00:09:51.380 --> 00:09:54.310
allowing more time for
more heat to transfer over
00:09:54.310 --> 00:09:56.310
and for smaller and more
efficient heat exchangers
00:09:56.310 --> 00:09:57.390
to be designed.
00:09:57.390 --> 00:09:58.960
Okay guys, that's it for this video.
00:09:58.960 --> 00:10:00.140
Thank you very much for watching.
00:10:00.140 --> 00:10:01.720
I hope you've enjoyed this
and it has helped you.
00:10:01.720 --> 00:10:02.553
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