00:00this is a turbo core chiller
00:03it's packed with technology from a
00:05variable frequency drive
00:07a soft starter dual impellers an
00:10electronic expansion valve
00:12and even magnetic bearings which
00:14levitate the shaft of the compressor
00:17so we're going to learn the basics of
00:20in this video which is sponsored by
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00:46down below like any refrigeration system
00:52we have the main parts being the
00:55the condenser the expansion valve and
00:58the evaporator the evaporator is usually
01:01covered with insulation
01:03to help increase efficiency the
01:05compressor will push
01:06refrigerant between these main
01:08components to remove the unwanted heat
01:12in this example we also find a filter
01:15on a small diameter pipe entering the
01:18rear of the compressor
01:20this is transporting refrigerant into a
01:23to cool down the compressor and the
01:27the evaporator and condenser are shell
01:30and tube type heat exchangers
01:33the refrigerant typically fills the
01:35shell and surrounds the tubes
01:37water is then pumped through the tubes
01:40to either heat the refrigerant
01:41or cool it down which will cause it to
01:45between a liquid and a gas we'll see how
01:48that works a little later in this video
01:51valves are usually found on the
01:53evaporator and condenser
01:55to allow these parts to be manually
01:58for example during the replacement of a
02:02the compressor is the heart of the
02:04system and pushes the refrigerant around
02:06the inside of the chiller
02:08it sucks in low pressure low temperature
02:11slightly superheated vapor refrigerant
02:15via the suction line the compressor
02:18squeezes this into a smaller volume so
02:22leaves via the discharge line as a high
02:25high temperature superheated vapour
02:28instead of a piston compression chamber
02:31the turbo core chiller actually uses an
02:33impeller and the loot
02:35to manipulate the refrigerant's velocity
02:38and static pressure we'll see that later
02:42the refrigerant is a specially designed
02:44fluid which can easily
02:46change between a liquid and a gas
02:50it has a very low boiling point inside
02:53we find the power electronics we have
02:57phase ac input terminals then we find
03:00the silicon controlled rectifiers
03:03which is converting the high voltage ac
03:06high voltage dc this will then travel
03:09along the dc bus bars we
03:12also find a soft starter this reduces
03:16the inrush current when the compressor
03:18first turns on it sends a signal to the
03:22telling it to slowly allow more current
03:25into the dc bus bars connected to the
03:29are some large capacitors which are
03:31mounted to the side of the compressor
03:34these will smooth out the rippled dc
03:37produced by the rectifiers to ensure
03:41dc electricity is supplied to the
03:45we also have some small snubber
03:48which remove the noise and harmonics
03:51before the high voltage dc enters the
03:55the inverter is located underneath the
03:59it consists of some igbts which
04:02convert the clean high voltage dc into
04:06a variable frequency three-phase supply
04:09this is sent to the electrical motor
04:11inside the compressor
04:13to control the rotational speed of the
04:16we'll see that in just a moment
04:18alongside the inverter
04:20we find the high voltage dc to dc
04:24this is used to change the dc voltage
04:27level and supply the different
04:29electrical control circuits of the
04:32it receives the high voltage dc and
04:35into a much lower voltage we have 24
04:40for the control circuit board and around
04:44for the magnetic bearings signal
04:48on this side of the unit we find the
04:52there's the backplane which physically
04:55connects all the different control
04:58the serial driver module which controls
05:01the various stepper motors
05:02solenoid valves and expansion valves and
05:06it contains relays for compressor run
05:09etc next we find the bearing motor
05:12compressor controller
05:14module this uses the feedback data from
05:17various sensors to control the
05:19electromagnetic bearing
05:21and shaft position it also controls the
05:25as well as ensuring the compressor is
05:27operating within its design limits
05:30the final module is the bearing pulse
05:33amplifier this uses high voltage
05:37which turn on and off extremely fast at
05:41to control the current to the
05:43electromagnetic bearings
05:44inside the chiller these are controlled
05:47by the bearing motor compressor
05:49controller module then as we look inside
05:53at the mechanical parts we see the inlet
05:57at the front on the suction inlet these
05:59blades can vary their position
06:01and cause a refrigerant to swirl as it
06:04enters the compressor impeller
06:06these are driven by an internal stepper
06:09the serial driver module controls this
06:12and the bearing motor compressor
06:14controller determines when
06:17and how much to rotate them these are
06:21cooling loads to improve the efficiency
06:24chiller surge but in normal operation
06:27they are usually left open then we have
06:30the two stage impellers
06:32these rotate together the refrigerant
06:35through the first impeller and then
06:37through a small channel
06:39and into the second impeller before
06:41entering the veloute
06:43from here it will be ejected from the
06:46the refrigerant pressure increases each
06:50through an impeller the impellers are
06:52attached to the shaft
06:54which runs the length of the compressor
06:56the shaft passes through the electrical
07:00the shaft contains permanent magnets in
07:04these will interact with the
07:06electromagnetic field produced
07:08by the stator coils of the motor and
07:11because magnets attract and repel each
07:14to force the rotor to rotate the
07:17variable frequency drive
07:19controls the speed of rotation the
07:22bearing motor compressor controller
07:24determines the required speed the shaft
07:28by three bearings the first two are
07:32and the rear is an axial bearing these
07:35three bearings are magnetic
07:37and have no moving parts so there is no
07:41and thus they do not require oil they
07:43create strong electromagnetic fields
07:46which levitate the shaft proximity
07:50monitor the position of the shaft and
07:52the pulse width modulation module
07:55sends signals to alter the magnetic
07:58and keep the shaft aligned and central
08:01the heat generated by the compressor
08:03is removed by diverting some refrigerant
08:07channel around the motor and also
08:10underneath the power
08:15this is a water cooled chiller meaning
08:19is cooled by pumping water through it we
08:23air cooled turbo core chillers where the
08:26by moving ambient outdoor air over the
08:30around the building we have a number of
08:33and also fan coil units these contain
08:37fans and heat exchangers the fans
08:40distribute and recirculate air within
08:43the room or the zone
08:45this is forced through the heat
08:48chilled water through the heat
08:50exchangers and this will absorb the
08:52unwanted heat from the air
08:54so warm air from the room enters the
08:58and the air re-enters the room much
09:01the water enters cold it collects the
09:04and then leaves warmer this relatively
09:08returns to the chiller and enters the
09:11the evaporator is typically a shell and
09:14tube type heat exchanger
09:16with the water flowing through the tubes
09:18and the refrigerant surrounding the
09:20outside of the tubes
09:21the refrigerant has a very low boiling
09:24so the temperature of the water is
09:26enough to cause a refrigerant to boil
09:29and evaporate the refrigerant is
09:31absorbing the thermal energy from the
09:34this energy passes through the tube wall
09:37the refrigerant and the water
09:39never meet or mix the water therefore
09:42enters warm and leaves cooler this
09:45chilled water is then sent around the
09:47building to pick up more unwanted heat
09:50the vapor refrigerant which is
09:52evaporating is sucked into the
09:55the compressor's impeller increases the
09:58the diffuser then slows this down the
10:02is converted to pressure and the
10:04temperature increases
10:06this is then sent to the condenser and
10:08released into the shell
10:10another stream of water is flowing
10:12through the condenser
10:13known as the condenser water as this
10:16water flows through it
10:18it absorbs the thermal energy of the
10:21this removal of thermal energy causes
10:24the refrigerant to condense into a
10:26and accumulates at the bottom of the
10:28condenser the condenser water
10:31therefore enters cool and exits warm
10:34this is then sent to the cooling tower
10:37which is usually located on the roof
10:40the cooling tower uses a large fan to
10:42force ambient outdoor air through it
10:45the condenser water is typically then
10:48sprayed into this airstream
10:50the air will absorb the thermal energy
10:54and carry this away into the atmosphere
10:56this means the condenser water
10:58enters warm and excess cooler then heads
11:01back to the condenser
11:03to collect more thermal energy the
11:06enters cool and exits warm
11:10in this type of chiller the expansion
11:12valve is typically used to control the
11:15in the condenser or sometimes the
11:17evaporator by monitoring the liquid
11:21alternatively it could control the level
11:23of superheat on the compressor
11:25suction line although this isn't
11:27recommended for this type of chiller
11:29it will try to maintain a certain level
11:33which basically means the refrigerant
11:35has been heated past its boiling point
11:37so that no liquid can exist that's
11:40important because compressors can only
11:43gas liquids cannot be compressed
11:48the turbocore compressor can pass a
11:50small amount of liquid with the gas
11:52but if too much liquid enters the
11:55compressor will stop
11:57to maintain the required level of
11:58superheat the expansion valve opens
12:01and closes small amounts to increase or
12:05the amount of refrigerant entering the
12:08it uses an internal stepper motor to
12:10achieve very precise control
12:13by the way we have covered how
12:15electronic expansion valves work
12:17in detail in our previous video do check
12:20links can be found in the video
12:21description down below
12:23the unwanted heat of the room has
12:25therefore been collected
12:27by the chilled water and transported to
12:31the refrigerant absorbed this and the
12:33compressor transferred this
12:35to the condenser the condenser water
12:37absorbed the thermal energy
12:39and transported this to the cooling
12:42it was removed from the system and
12:44released to the atmosphere
12:49turbo core compressors are currently the
12:52most advanced type of compressor
12:55they are also the most efficient this is
12:58it has so much technology built into it
13:01first of all we find a two-stage
13:04the evaporator is low pressure the
13:08high pressure the compressor increases
13:11and instead of a single large impeller
13:15two smaller impellers which work
13:17together increasing the pressure in
13:20stage 1 increases the pressure to
13:22roughly half the difference
13:25stage 2 increases the pressure the
13:28refrigerant is pulled in through the
13:31guide veins and into the impeller
13:33of the first stage this will exert a
13:37onto the refrigerant particles forcing
13:39them to increase in velocity
13:41and move towards the outer edge of the
13:44this then passes through a diffuser
13:48the high velocity refrigerant down as it
13:51the velocity is converted into pressure
13:54and this is then pulled
13:55into the second stage this second
13:59sucks in the higher pressure refrigerant
14:02increases the velocity the refrigerant
14:06at a high velocity and accumulates in
14:10the veloute is a chamber which spirals
14:12around the edge of the impeller
14:14the veloute chamber starts off small and
14:17increases in diameter
14:18as it reaches the exit the increasing
14:22causes the refrigerant to slow down
14:24which will increase the pressure
14:27as more refrigerant exits the impeller
14:29this will be forced out
14:31through the discharge line and into the
14:34the capacity of the compressor is mainly
14:38by the rotational speed of the impellers
14:41the inlet guide vanes
14:42located at the suction inlet also
14:45provide capacity control
14:47but usually only in periods of low
14:51they can vary their angle between fully
14:53open and fully closed
14:55and a small internal stepper motor will
14:59these triangular shaped veins will guide
15:01the flow of refrigerant gas
15:03swirling it into the eye of the impeller
15:06efficient angle and also in the same
15:10rotational direction as the impeller
15:13this makes it easier for the impeller
15:15during the low cooling loads when the
15:17refrigerant flow rate is decreased
15:20the two impellers are mounted to the
15:22shaft which runs the length of the
15:25this passes through three bearings two
15:28will provide radial support
15:30and a rear bearing provides axial
15:33these work together to hold the shaft in
15:37these bearings use electromagnets to
15:40and suspend it freely sensors on the
15:44will monitor the position of the shaft
15:47and feed this information back to the
15:50the controller will make adjustments to
15:52the strength of multiple
15:54small electromagnets which around the
15:57this will alter the position of the
15:59shaft and keep it perfectly aligned
16:02when the unit is off the rotor
16:05and rests on some mechanical bearings
16:08the motor consists of permanent magnets
16:12and a number of separated coils of
16:15in the stator each coil is connected to
16:18a different phase from the inverter
16:21the bearing motor compressor controller
16:23module sends signals
16:25to control the on off time of the igbts
16:28allowing the inverter to vary the output
16:32and voltage to the coils when the
16:35through the coils they generate
16:37electromagnetic fields
16:38which interact with the permanent
16:40magnets inside the rotor
16:42this forces the rotor to rotate
16:46and by varying the output frequency from
16:49we can change the rotational speed of
16:52which varies the capacity of the chiller
16:55in the event of a power failure to the
16:59the permanent magnets within the rotor
17:01induce a current in the stator coils
17:04effectively turning this into an
17:06electrical generator
17:07this is then used to charge the
17:09capacitors for a short amount of time
17:12but long enough to safely shut down the
17:14chiller and prevent damage
17:16check out one of the videos on screen
17:18now to continue learning about
17:20refrigeration engineering
17:21as this is the end of the video don't
17:24forget you can follow us on facebook
17:26linkedin and instagram and of course the
17:30engineeringmindset.com
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