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The Fundamentals of Cooling I Transcript Slide 1: The
Fundamentals of Cooling I Welcome to The Fundamentals of Cooling I.
Slide 2: Welcome For best viewing results, we recommend that you
maximize your browser window now. The screen controls allow you to
navigate through the eLearning experience. Using your browser
controls may disrupt the normal play of the course. Click the Notes
tab to read a transcript of the narration. Slide 3: Objectives At
the completion of this course, you will be able to:
Explain why cooling in the data center is so critical to high
availability Distinguish between Precision and Comfort Cooling
Recognize how heat is generated and transferred Define basic terms
like Pressure, Volume and Temperature as well as their units of
measurement Describe how these terms are related to the
Refrigeration Cycle Describe the Refrigeration Cycle and its
components
Slide 4: Introduction Every Information Technology professional
who is involved with the operation of computing equipment
needs to understand the function of air conditioning in the data
center or network room. This course explains the function of basic
components of an air conditioning system for a computer room.
Slide 5: Introduction Whenever electrical power is being
consumed in an Information Technology (IT) room or data center,
heat is being generated. We will talk more about how heat is
generated a little later in this course. In the Data Center
Environment, heat has the potential to create significant downtime,
and therefore must be removed from the space. Data Center and IT
room heat removal is one of the most essential yet least understood
of all critical IT environment processes. Improper or inadequate
cooling significantly detracts from the lifespan and availability
of IT equipment. A general understanding of the fundamental
principles of air conditioning and the basic arrangement of
precision cooling systems facilitates more precise communication
among IT and cooling professionals when specifying, operating, or
maintaining a cooling solution. The purpose of precision
air-conditioning equipment is the precise control of both
temperature and humidity.
Slide 6: Evolution Despite revolutionary changes in IT
technology and products over the past decades, the design of
cooling infrastructure for data centers had changed very little
since 1965. Although IT equipment has always required cooling, the
requirements of todays IT systems, combined with the way that those
IT systems are deployed, has created the need for new
cooling-related systems and strategies which were not foreseen when
the cooling principles for the modern data center were developed
over 30 years ago. Slide 7: Comfort vs. Precision Cooling
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Today's technology rooms require precise, stable environments in
order for sensitive electronics to operate at their peak. IT
hardware produces an unusual, concentrated heat load, and at the
same time, is very sensitive to changes in temperature or humidity.
Most buildings are equipped with Comfort Air Conditioning units,
which are designed for the comfort of people. When compared to
computer room air conditioning systems, comfort systems typically
remove an unacceptable amount of moisture from the space and
generally do not have the capability to maintain the temperature
and humidity parameters specified for IT rooms and data centers.
Precision air systems are designed for close temperature and
humidity control. They provide year-round operation, with the ease
of service, system flexibility, and redundancy necessary to keep
the technology room up and running.
As damaging as the wrong ambient conditions can be, rapid
temperature swings can also have a
negative effect on hardware operation. This is one of the
reasons hardware is left powered up, even when not processing data.
According to ASHRAE, the recommended upper limit temperature for
data center environments is 81F (27.22C). Precision air
conditioning is designed to constantly maintain temperature within
1F (0.56C). In contrast, comfort systems are unable to provide such
precise temperature and humidity controls.
Slide 8: The Case for Data Center Cooling A poorly maintained
technology room environment will have a negative impact on data
processing and storage operations. A high or low ambient
temperature or rapid temperature swings can corrupt data processing
and shut down an entire system. Temperature variations can alter
the electrical and physical characteristics of electronic chips and
other board components, causing faulty operation or failure. These
problems may be transient or may last for days. Transient problems
can be very hard to diagnose. Slide 9: The Case for Data Center
Cooling High Humidity High humidity can result in tape and surface
deterioration, condensation, corrosion, paper handling problems,
and gold and silver migration leading to component and board
failure. Low Humidity Low humidity increases the possibility of
static electric discharges. Such static discharges can corrupt data
and damage hardware. Slide 10: The Physics of Cooling Now that we
know that heat threatens availability of IT equipment, its
important to understand the physics of cooling, and define some
basic terminology. First of all, what is Heat? Heat is simply a
form of energy that is transferred by a difference in temperature.
It exists in all matter on earth, in varied quantities and
intensities. Heat energy can be measured relative to any reference
temperature, body or environment. What is Temperature? Temperature
is most commonly thought of as how hot or cold something is. It is
a measure of heat intensity based on three different scales:
Celsius, Fahrenheit and Kelvin. What is Pressure?
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provided are the property of their respective owners.
-
Pressure is a basic physical property of a gas. It is measured
as the force exerted by the gas per unit area on surroundings. What
is Volume? Volume is the amount of space taken up by matter. The
example of a balloon illustrates the relationship between pressure
and volume. As the pressure inside the balloon gets greater than
the pressure outside of the balloon, the balloon will get larger.
Therefore, as the pressure increases, the volume increases. We will
talk more about the relationship between pressure, volume and
temperature a little later in this course. Slide 11: Three
Properties of Heat Energy Now that we know the key terms related to
the physics of cooling, we can now explore the 3 properties of heat
energy. A unique property of heat energy is that it can only flow
in one direction, from hot to cold. For example if an ice cube is
placed on a hot surface, it cannot drop in temperature; it can only
gain heat energy and rise in temperature, thereby causing it to
melt. A second property of heat transfer is that Heat energy cannot
be destroyed. The third property is that heat energy can be
transferred from one object to another object. In considering the
ice cube placed on a hot surface again, the heat from the surface
is not destroyed, rather it is transferred to the ice cube which
causes it to melt. Slide 12: Heat Transfer Methods There are three
methods of heat transfer: conduction convection and radiation.
Conduction is the process of transferring heat through a solid
material. Some substances conduct heat more easily than others.
Solids are better conductors than liquids and liquids are better
conductors than gases. Metals are very good conductors of heat,
while air is very poor conductor of heat. Slide 13: Heat Transfer
Methods Convection is the result of transferring heat through the
movement of a liquid or gas. Radiation related to heat transfer is
the process of transferring heat by means of electromagnetic waves,
emitted due to the temperature difference between two objects.
Slide 14: Heat Transfer Methods For example, blacktop pavement gets
hot from radiation heat by the suns rays. The light that warms the
blacktop from the Sun is a form of electromagnetic radiation.
Radiation is a method of heat transfer that does not rely on any
contact between the heat source and the heated object. If you step
barefoot on the pavement, the pavement feels hot. This feeling is
due to the warmth of the pavement being transferred to your cold
feet by means of conduction. The conduction occurs when two objects
at different temperatures are in contact with each other. Heat
flows from the warmer to the cooler object until they are both the
same temperature. Finally, if you look down a road of paved
blacktop, in the distance, you may see wavy lines emanating up from
the road, much like a mirage. This visible form of convection is
caused by the transfer of heat from the surface of the blacktop to
the cooler air above. Convection occurs when warmer areas of a
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liquid or gas rise to cooler areas in the liquid or gas. As this
happens, cooler liquid or gas takes the place of the warmer areas
which have risen higher. This cycle results in a continuous
circulation pattern and heat is transferred to cooler areas. "Hot
air rises and cool air falls to take its place" - this is a
description of convection in our atmosphere. Slide 15: Air Flow in
IT Spaces As mentioned earlier, heat energy can only flow from hot
to cold. For this reason, we have air conditioners and
refrigerators. They use electrical or mechanical energy to pump
heat energy from one place to another, and are even capable of
pumping heat from a cooler space to a warmer space. The ability to
pump heat to the outdoors, even when it is hotter outside than it
is in the data center, is a critical function that allows
high-power computing equipment to operate in an enclosed space.
Understanding how this is possible is a foundation to understanding
the design and operation of cooling systems for IT
installations.
Slide 16: Heat Generation Whenever electrical power is being
consumed in an Information Technology (IT) room or data center,
heat is being generated that needs to be removed from the space.
This heat generation occurs at various levels throughout the data
center, including the chip level, server level, rack level and room
level. With few exceptions, over 99% of the electricity used to
power IT equipment is converted into heat. Unless the excess heat
energy is removed, the room temperature will rise until IT
equipment shuts down or potentially even fails.
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provided are the property of their respective owners.
-
Slide 17: Heat Generation
Lets take a closer look at heat generation at the server level.
Approximately 50% of the heat energy released by servers originates
in the microprocessor. A fan moves a stream of cold air across the
chip assembly. The server or rack-mounted blade assembly containing
the microprocessors usually draws cold air into the front of the
chassis and exhausts it out of the rear. The amount of heat
generated by servers is on a rising trend. A single blade server
chassis can release 4 Kilowatts (kW) or more of heat energy into
the IT room or data center. Such a heat output is equivalent to the
heat released by forty 100-Watt light bulbs and is actually more
heat energy than the capacity of the heating element in many
residential cooking ovens.
Now that we have learned about the physics and properties of
heat, we will talk next about the Ideal Gas Law. Slide 18: The
Ideal Gas Law Previously, we defined pressure, temperature, and
volume. Further, it is imperative to the
understanding of data center cooling to recognize how these
terms relate to each other. The relation between pressure (P),
volume (V) and temperature (T) is known as the Ideal Gas Law,
which states PV/T= constant . In this equation, P = pressure of
gas, V = volume occupied, and T = temperature. In simpler terms, if
pressure is constant, an increase in temperature results in a
proportional increase in volume. If volume is constant, an increase
in temperature results in a
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provided are the property of their respective owners.
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proportional increase in pressure. Inversely, if volume is
decreased and pressure remains constant, the temperature must
decrease. Basically, pressure and volume are directly proportional
to temperature and inversely proportional to each other.
Slide 19: The Ideal Gas Law Pressure and temperature are both
controlled by the ideal gas law. However, because the volume is
not held constant (that is, the atmosphere can expand and
contract), the relationships between pressure and temperature are
complex. Temperature decreases linearly with increasing altitude,
whereas pressure decreases exponentially. For example, you may have
experienced the outside of an aerosol can becoming colder as you
spray it. This is because the can is a fixed volume, and as the
pressure within the can decreases as it is sprayed, the temperature
also decreases causing the can to feel cold.
Slide 20: The Refrigeration Cycle The refrigeration cycle is a
closed cycle of evaporation, compression, condensation and
expansion,
that has the net effect of moving heat energy away from an
environment and into another environment, in this case, from inside
the data center, to the outdoors.
The working fluid used in the refrigeration cycle is known as
the refrigerant. Modern systems primarily
use fluorinated hydrocarbons that are nonflammable,
non-corrosive, nontoxic, and non-explosive. Refrigerants are
commonly referred to by their ASHRAE numerical designation.
Environmental concerns of ozone depletion may lead to legislation
increasing or requiring the use of alternate refrigerants like
R-134a. Additional legislation related to the use of alternate
refrigerants is under consideration.
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provided are the property of their respective owners.
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Slide 21: The Refrigeration Cycle
Refrigerant changes its physical state from liquid to gas and
back to liquid again each time it traverses the various components
of the refrigeration cycle. As the refrigerant changes state from
liquid to gas, heat energy flows into the refrigerant from the area
to be cooled (the IT environment for example). Conversely, as the
refrigerant changes state from gas to liquid, heat energy flows
away from the refrigerant to a different environment (outdoors or
to a water source).
Slide 22: Evaporation Evaporation is the first step in removing
heat energy from a computer room, and is the first step in the
Refrigeration Cycle. The evaporator coil acts as an automobile
radiator operating in reverse.
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provided are the property of their respective owners.
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Slide 23: Evaporation Warm air from the computer room is blown
across the evaporator coil by a fan, while the tubes comprising the
coil are supplied with the refrigerant exiting the expansion valve.
When the warm computer room air passes through the cold evaporator
coil it is cooled and this cool air is delivered back to the
computer room. Even though the evaporator coil is cold, at
approximately 46F (7.8C), the refrigerant inside is evaporating, or
boiling, changing from liquid to a gaseous state. It is the heat
from the computer room that is boiling the refrigerant, passing
heat energy to the refrigerant in the process. The refrigerant at
this point is a cool gas in a small pipe that is carrying the heat
energy away from the computer room. Slide 24: Compression
Compression is the next step in removing heat energy from a
computer room. The vaporized but cool
refrigerant carrying the heat from the data center is drawn into
a compressor.
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provided are the property of their respective owners.
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Slide 25: Compression This compressor has two important
functions: It pushes the refrigerant carrying the heat energy
around the refrigeration loop. It compresses the gaseous
refrigerant from the evaporator coil, over 200 psi. It is a
fundamental property of gases that the compression of a gas causes
its measured temperature to rise. Therefore, the moving gaseous
refrigerant exiting the compressor is hot, over 125F (52C), as well
as compressed. This temperature rise due to compression is the key
to the ability of the refrigeration cycle to eject heat into the
outdoor environment. Slide 26: Condensation The next stage of the
refrigeration cycle is Condensation. In this stage, the hot
compressed
refrigerant carries the computer room heat energy from the
compressor to the Condenser Coil.
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provided are the property of their respective owners.
-
Slide 27: Condensation The coil is made of small tubes coiled up
into a block of metal fins and resembles an automobile radiator.
This coil transfers heat to the air and operates at a temperature
HIGHER than the air. This means that the air flowing across the
coil is heated by the coil, and that the hot gaseous refrigerant
flowing through the coil is conversely cooled. Heat is flowing from
the refrigerant to the air. The air is typically blown across the
hot coil by a fan which exhausts the hot air to the outdoors. In
this way the heat energy from the computer room has been
transferred to the outdoors. The Condenser coil acts similarly to
the radiator in a car, in that it carries heat from the engine to
the air outside the car. Slide 28: Expansion In the next stage, the
expansion stage, the refrigerant exits the Condenser Coil as a
high-pressure
liquid, although at a lower temperature.
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provided are the property of their respective owners.
-
Slide 29: Expansion The refrigerant then passes through an
expansion valve which has two key functions that are critical to
the refrigeration cycle:
It precisely regulates the flow of high-pressure refrigerant at
a rate that maintains an optimal difference in pressure to ensure
efficient cooling.
Secondly, the refrigerant escapes the expansion valve as a
cooled refrigerant. Slide 30: Expansion Once this cooled
refrigerant has passed through the evaporator coil, it is changed
to a gas. This is because the boiling point of the liquid
refrigerant is extremely low. Therefore as the warm air from the
computer room blows across the coils of the evaporator, the
refrigerant that enters the coil gets heated and starts boiling.
Thus it changes to a gas. In this way, the cold refrigerant absorbs
the heat energy from the air and carries it away from the data
center. At this stage, the refrigeration cycle is repeated, and the
net result of the process is that heat is continuously flowing into
the Evaporator Coil and continuously flowing out of the Condenser
Coil. Slide 31: Summary To summarize, lets review some of the
information that we have covered throughout this course.
When IT equipment is operating, heat is generated, and the
removal of this heat is critical to the
2013 Schneider Electric. All rights reserved. All trademarks
provided are the property of their respective owners.
-
proper functioning of data center environments Precision Cooling
systems are required to provide adequate cooling conditions for IT
spaces Heat, Pressure, Temperature and Volume are interrelated for
gasses Heat is transferred via Conduction, Convection and
Radiation, and it only moves naturally from
areas of high heat to areas of low heat Refrigeration Cycle is a
closed cycle of evaporation, compression, condensation and
expansion
that serves to remove heat from the data center Slide 32: Thank
You! Thank you for participating in this course.
2013 Schneider Electric. All rights reserved. All trademarks
provided are the property of their respective owners.
The Fundamentals of Cooling I TranscriptSlide 1: The
Fundamentals of Cooling IWelcome to The Fundamentals of Cooling
I.
Slide 2: WelcomeFor best viewing results, we recommend that you
maximize your browser window now. The screen controls allow you to
navigate through the eLearning experience. Using your browser
controls may disrupt the normal play of the course. Click the Notes
tab to...
Slide 3: ObjectivesAt the completion of this course, you will be
able to: Explain why cooling in the data center is so critical to
high availability Distinguish between Precision and Comfort Cooling
Recognize how heat is generated and transferred Define basic terms
like Pressure, Volume and Temperature as well as their units of
measurement Describe how these terms are related to the
Refrigeration Cycle Describe the Refrigeration Cycle and its
components
Slide 4: IntroductionEvery Information Technology professional
who is involved with the operation of computing equipment needs to
understand the function of air conditioning in the data center or
network room. This course explains the function of basic components
of an a...
Slide 5: IntroductionWhenever electrical power is being consumed
in an Information Technology (IT) room or data center, heat is
being generated. We will talk more about how heat is generated a
little later in this course. In the Data Center Environment, heat
has the po...
Slide 6: EvolutionDespite revolutionary changes in IT technology
and products over the past decades, the design of cooling
infrastructure for data centers had changed very little since 1965.
Although IT equipment has always required cooling, the requirements
of today...
Slide 7: Comfort vs. Precision CoolingToday's technology rooms
require precise, stable environments in order for sensitive
electronics to operate at their peak. IT hardware produces an
unusual, concentrated heat load, and at the same time, is very
sensitive to changes in temperature or ...As damaging as the wrong
ambient conditions can be, rapid temperature swings can also have a
negative effect on hardware operation. This is one of the reasons
hardware is left powered up, even when not processing data.
According to ASHRAE, the recom...
Slide 8: The Case for Data Center CoolingA poorly maintained
technology room environment will have a negative impact on data
processing and storage operations. A high or low ambient
temperature or rapid temperature swings can corrupt data processing
and shut down an entire system. Temperat...
Slide 9: The Case for Data Center CoolingHigh Humidity High
humidity can result in tape and surface deterioration,
condensation, corrosion, paper handling problems, and gold and
silver migration leading to component and board failure.Low
Humidity Low humidity increases the possibility of static electric
discharges. Such static discharges can corrupt data and damage
hardware.
Slide 10: The Physics of CoolingNow that we know that heat
threatens availability of IT equipment, its important to understand
the physics of cooling, and define some basic terminology.First of
all, what is Heat?Heat is simply a form of energy that is
transferred by a difference in temperature. It exists in all matter
on earth, in varied quantities and intensities. Heat energy can be
measured relative to any reference temperature, body or
environment.What is Temperature?Temperature is most commonly
thought of as how hot or cold something is. It is a measure of heat
intensity based on three different scales: Celsius, Fahrenheit and
Kelvin.What is Pressure?Pressure is a basic physical property of a
gas. It is measured as the force exerted by the gas per unit area
on surroundings.What is Volume?Volume is the amount of space taken
up by matter. The example of a balloon illustrates the relationship
between pressure and volume. As the pressure inside the balloon
gets greater than the pressure outside of the balloon, the balloon
will get larger...We will talk more about the relationship between
pressure, volume and temperature a little later in this course.
Slide 11: Three Properties of Heat EnergyNow that we know the
key terms related to the physics of cooling, we can now explore the
3 properties of heat energy. A unique property of heat energy is
that it can only flow in one direction, from hot to cold. For
example if an ice cube is placed ...A second property of heat
transfer is that Heat energy cannot be destroyed. The third
property is that heat energy can be transferred from one object to
another object. In considering the ice cube placed on a hot surface
again, the heat from the sur...
Slide 12: Heat Transfer MethodsThere are three methods of heat
transfer: conduction convection and radiation.Conduction is the
process of transferring heat through a solid material. Some
substances conduct heat more easily than others. Solids are better
conductors than liquids and liquids are better conductors than
gases. Metals are very good conductors of h...
Slide 13: Heat Transfer MethodsConvection is the result of
transferring heat through the movement of a liquid or gas.Radiation
related to heat transfer is the process of transferring heat by
means of electromagnetic waves, emitted due to the temperature
difference between two objects.
Slide 14: Heat Transfer MethodsFor example, blacktop pavement
gets hot from radiation heat by the suns rays. The light that warms
the blacktop from the Sun is a form of electromagnetic radiation.
Radiation is a method of heat transfer that does not rely on any
contact between the ...
Slide 15: Air Flow in IT SpacesAs mentioned earlier, heat energy
can only flow from hot to cold. For this reason, we have air
conditioners and refrigerators. They use electrical or mechanical
energy to pump heat energy from one place to another, and are even
capable of pumping hea...
Slide 16: Heat GenerationWhenever electrical power is being
consumed in an Information Technology (IT) room or data center,
heat is being generated that needs to be removed from the space.
This heat generation occurs at various levels throughout the data
center, including th...Now that we have learned about the physics
and properties of heat, we will talk next about the Ideal Gas
Law.
Slide 18: The Ideal Gas LawPreviously, we defined pressure,
temperature, and volume. Further, it is imperative to the
understanding of data center cooling to recognize how these terms
relate to each other.The relation between pressure (P), volume (V)
and temperature (T) is known as the Ideal Gas Law, which states
PV/T= constant . In this equation, P = pressure of gas, V = volume
occupied, and T = temperature. In simpler terms, if pressure is
...
Slide 19: The Ideal Gas LawPressure and temperature are both
controlled by the ideal gas law. However, because the volume is not
held constant (that is, the atmosphere can expand and contract),
the relationships between pressure and temperature are complex.
Temperature decrea...
Slide 20: The Refrigeration CycleThe refrigeration cycle is a
closed cycle of evaporation, compression, condensation and
expansion, that has the net effect of moving heat energy away from
an environment and into another environment, in this case, from
inside the data center, to the ...The working fluid used in the
refrigeration cycle is known as the refrigerant. Modern systems
primarily use fluorinated hydrocarbons that are nonflammable,
non-corrosive, nontoxic, and non-explosive. Refrigerants are
commonly referred to by their A...Refrigerant changes its physical
state from liquid to gas and back to liquid again each time it
traverses the various components of the refrigeration cycle. As the
refrigerant changes state from liquid to gas, heat energy flows
into the refrigerant fr...
Slide 22: EvaporationEvaporation is the first step in removing
heat energy from a computer room, and is the first step in the
Refrigeration Cycle. The evaporator coil acts as an automobile
radiator operating in reverse.
Slide 23: EvaporationWarm air from the computer room is blown
across the evaporator coil by a fan, while the tubes comprising the
coil are supplied with the refrigerant exiting the expansion valve.
When the warm computer room air passes through the cold evaporator
coil it...
Slide 24: CompressionCompression is the next step in removing
heat energy from a computer room. The vaporized but cool
refrigerant carrying the heat from the data center is drawn into a
compressor.
Slide 25: CompressionThis compressor has two important
functions: It pushes the refrigerant carrying the heat energy
around the refrigeration loop. It compresses the gaseous
refrigerant from the evaporator coil, over 200 psi. It is a
fundamental property of gases that t...
Slide 26: CondensationThe next stage of the refrigeration cycle
is Condensation. In this stage, the hot compressed refrigerant
carries the computer room heat energy from the compressor to the
Condenser Coil.
Slide 27: CondensationThe coil is made of small tubes coiled up
into a block of metal fins and resembles an automobile radiator.
This coil transfers heat to the air and operates at a temperature
HIGHER than the air. This means that the air flowing across the
coil is heat...
Slide 28: ExpansionIn the next stage, the expansion stage, the
refrigerant exits the Condenser Coil as a high-pressure liquid,
although at a lower temperature.
Slide 29: ExpansionThe refrigerant then passes through an
expansion valve which has two key functions that are critical to
the refrigeration cycle: It precisely regulates the flow of
high-pressure refrigerant at a rate that maintains an optimal
difference in pressure to ensure efficient cooling. Secondly, the
refrigerant escapes the expansion valve as a cooled
refrigerant.
Slide 30: ExpansionOnce this cooled refrigerant has passed
through the evaporator coil, it is changed to a gas. This is
because the boiling point of the liquid refrigerant is extremely
low. Therefore as the warm air from the computer room blows across
the coils of the e...
Slide 31: SummaryTo summarize, lets review some of the
information that we have covered throughout this course. When IT
equipment is operating, heat is generated, and the removal of this
heat is critical to the proper functioning of data center
environments Precision Cooling systems are required to provide
adequate cooling conditions for IT spaces Heat, Pressure,
Temperature and Volume are interrelated for gasses Heat is
transferred via Conduction, Convection and Radiation, and it only
moves naturally from areas of high heat to areas of low heat
Refrigeration Cycle is a closed cycle of evaporation, compression,
condensation and expansion that serves to remove heat from the data
center
Slide 32: Thank You!Thank you for participating in this
course.