Transcript علم سیستمهای تهویه مطبوع

‫علم سیستمهای تهویه مطبوع‬
‫تهیه کننده‪ :‬محسن اشکذری‬
‫‪Himech.wordpress.com‬‬
What is 'Air
Conditioning'?
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Air Conditioning is the simultaneous
control of Temperature, Humidity,
Motion & Purity of the atmosphere in
confined Space. What are the
Requirements of comfort Air
Conditioning?
Supply of Oxygen & removal of
Carbon-di-oxide.
Removal Of heat dissipated by the
occupants.
Removal of moisture dissipated by the
occupants.
To provide sufficient air movement &
air distribution in the confined space.
To maintain the purity of air by
removing odor & dust
What is Air Conditioning
load?

Any heat generated with in the
space to be air-conditioned
forms a load on the air
conditioning system.
Examples: Occupants, Lights,
Fans, Photocopier, Stabilizers,
Computers, TV's etc.., Heat also
enters the enclosed space from
outside through walls, glass
windows, roof, open doors, etc.
What are the types of Air
Conditioning?
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Summer Air Conditioning - To reduce
the heat & moisture Content of the air
by cooling De-humidification.
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Winter Air Conditioning - To increase
the heat & moisture content of air by
heating Humidification.
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Year Round Air Conditioning - To
control temperature & moisture
content of the air throughout the year
as per the climatic changes.
What are the types of Air
Conditioning systems?
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Unitary air Conditioning Systems
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Window Air Conditioner
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Split Air Conditioner
Central Air Conditioning Systems
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Package Unit
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Central Plants
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What do you mean by Ton of
Refrigeration (TR)? Ton of
refrigeration is the amount of heat
removed to convert 1000Kgs of water
at ' zero' degrees Celsius into Ice in
24 hrs. In other words. Ton of
refrigeration is the capacity to
remove 3000 Kilo Calories (12,000
Btu) of heat per hour from the
conditioned space.
What is BTU? The British Thermal
Unit (BTU) is defined as the
amount of heat required to raise or
lower one pound of water to one
degree Fahrenheit.
What is Kilo Calorie? It is the
amount of heat required to raise the
temperature of 1000 grams of water
by 1 degree C.
What is Comfort AirConditioning?
1. Temperature : 24 + 2 Degree
Celsius DBT.
2. RH : 50 + 10% RH.
What do you mean by Dry Bulb Temperature
(DBT), Wet Bulb Temperature (WBT), and
Relative Humidity (RH)?
1. Dry Bulb Temperature: The temperature of air
measured by ordinary thermometer is known as
Dry Bulb Temperature.
2. Wet Bulb Temperature: The temperature
measured by the thermometer when its bulb is
covered with Wet Cloth & exposed to airflow is
known as Wet Bulb When the difference between
DBT and WBT is Zero, the air becomes fully
saturated (100 % RH).
3. Relative Humidity : The relative humidity is
defined as the ratio of actual mass of water vapor
in a given volume to the mass of water vapor if
the air is saturated at the same temperature. RH
= Mass of the water vapor actually present in a
volume of air at T degree C. Mass of the water
vapor required to saturate the same volume of air
at T degree C .
What are the basic
components in an Air
Conditioner?
1. Compressor - It is heart of the air conditioning system. Its
function is to suck the refrigerant vapor from the evaporator, and
to raise its temperature & pressure by compression to a point
such that it can be condensed with the available atmospheric air.
2.Condenser - The function of condenser is to provide a heat
transfer surface through which heat passes from hot refrigerant
vapor to the atmospheric air. In condenser high temperature
vapor is converted in to high temperature liquid by removal of
latent heat .
3.Strainer - Strainer is normally fitted in between a condenser &
Capillary tube to remove moisture & foreign particles from the
refrigerant. The moisture & foreign particles if allowed to enter
may choke the capillary tube thereby restricting the flow of
refrigerant resulting in less cooling / no cooling.
4.Capillary Tube - It is a tube with a very small orifice and its
function is to meter the proper amount of refrigerant to the
evaporator and reduce the temperature & pressure of liquid
refrigerant entering the evaporator. Hence, this low temperature
liquid will vaporize in the evaporator and take out sufficient
amount of heat from room air 5.Evaporator - Its operation is
similar to that of condenser. Here Liquid refrigerant is converted
to low temperature vapor by taking the heat from the room air. It
is at the evaporator cooling is produced and room is conditioned
What is Refrigerant?
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Refrigerant is a substance that absorbs heat
through expansion or vaporization and loses
the same through condensation in a
refrigeration system.
In what way refrigerant helps in achieving
cooling in a confined space?
 Refrigerant flowing through the closed cycle
absorbs heat from the space to be cooled &
rejects heat to the outside surrounding by
continuously changing its phase from liquid
to vapor & Vice-versa.
Does the use of R-22 affect the ozone layer?
 Ozone layer is normally affected by the
presence of chlorine molecules (two atoms)
Since R-22 has only one atom of chlorine, the
effect of refrigerant on ozone is very less.
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What is CFM?
The Volume flow rate of air
(Volume of air handled) is
measured by Cubic Feet Per
Minute (CFM)
What is EER?
Energy Efficiency Ratio =Cooling Capacity
(BTU/Hr.) /Power consumption (Watts/Hr.)
What are the functions of
various components used in an
air conditioner?
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Thermostat - Its function is to controls the room temperature as per
the settings by cutting in & off the compressor.
Rotary switch - It is through the rotary switch the desired mode of
operation is selected (i.e.) Off, Fan, Super quiet, Normal, High cool
etc.
Running Capacitor - The Function of running capacitor is to store
the current & thereby maintain constant supply of current to the
compressor.
Starting Capacitor - The function of starting capacitor is to increase
the starting torque of the compressor.
Starting relay - The function of starting relay is to disconnect the
starting capacitor from the circuit as soon as the compressor reaches
the rated speed.
Fan Blower - The function of starting relay is to disconnect the
starting capacitor from the circuit as soon as the compressor reaches
the rated speed.
Condenser Fan Blade - It sucks the atmospheric air through sides of
the outer cabinet and the same is made to pass through the
condenser to take the heat from the refrigerant flowing through it.
Fan Motor - It rotates the condenser fan blade and blower for
handling the air at condenser and evaporator side. In case of split air
conditioner two fan motors are used. (One at the condensing unit
and the other at the evaporator unit)
Oscillation Motor - This helps to circulate the cold air uniformly into
the room with the help of the oscillation louvers.
What are types of
compressors normally
used?.
. Reciprocating Compressor
. Rotary Compressor
. Centrifugal compressor
What types of compressor is
normally used in Window / Split Air
Conditioner?.
. Reciprocating Compressor
. Rotary Compressor
‫مقایسه بین کمپرسورهای پیستونی و روتاری‬
‫‪ROTARY‬‬
‫‪RECIPROCATING‬‬
‫حرکت دورانی یک غلطک گاز را حرکت رفت و برگشتی پیستون گاز‬
‫را متراکم میکند‪.‬‬
‫متراکم میکند‪.‬‬
‫فقط تک سیلندر ساخته میشود‪.‬‬
‫میتواند تک یا چند سیلندر ساخته‬
‫شود‪.‬‬
‫برای کاربرد های خانگی ساخته‬
‫میشود‪.‬‬
‫برای کاربردهای خانگی و هم تجاری‬
‫ساخته میشود‪.‬‬
‫سیم پیچ در معرض گاز گرم دیسشارژ‬
‫قرار گرفته است‪.‬‬
‫سیم پیچ کمپرسور با گاز برگشتی‬
‫خنک میشود‪.‬‬
‫قابل تعمیر و تجدید نیستند‪.‬‬
‫در نوع هرمتیک نباید تعمیر و مجدد‬
‫استفاده گردد ولی انواع نیمه‬
‫هرمتیک و باز آن در سیستمهای‬
‫تجاری قابل تعمیر است‪.‬‬
What is the need for having fins in
condenser and evaporator?
Fins are provided to increase the
heat transfer area and thereby to
improve the efficiency of the unit.
What is the advantage of having
grooved copper tubes?
The advantage of grooved copper
tubes over ordinary tubes is that
it increases the resistance to the
flow of refrigerant and thereby
increasing the heat transfer rate.
Where split air conditioners
can be installed?
1. It can be installed where
window AC's cannot be
installed.
2. It can be installed in places
where the aesthetics is the first
priority.
3. It can be installed in places
where the noise level is to be
minimum.
Explain how an Air
Conditioner works?
When the compressor is started it sucks the
refrigerant vapor at low temperature and low
pressure from the evaporator through the suction
line. After compressing, it discharges the
refrigerant at high temperature and high
pressure in vapor state to condenser through the
discharge line. Here the vapor is condensed at
high pressure by lowering down the temperature
of refrigerant with the help of atmospheric air,
which was circulated by condenser fan. This
liquid flows towards capillary tube through the
liquid line & strainer. When the liquid passes
through the capillary tube, its pressure and
temperature are lowered and enters into the
evaporator. Here this liquid refrigerant gets
vaporized by absorbing the heat from the room
air, which is being sucked by the blower through
the evaporator coil. Hence the room air gets
cooled and the same is discharged to the room.
The compressor sucks the vaporized refrigerant
at low temperature and low pressure. This cycle
is repeated till the compressor works.
THE END
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