chapter 5

CC608 BUILDING SERVICES

PN. FAIZATUL HARLINA BT MUHAMAD SHAH019-4884240

CHAPTER 5

AIR CONDITIONING

SYSTEM

AIR CONDITIONING SYSTEM5.1 Learn the basic principle of air conditioning system5.1.1 Describe the basic principle of air conditioning

system.

Air conditioning is the process of altering the properties of air (primarily temperature and humidity) to more conditions.

More generally, air conditioning can refer to any form of technological cooling, heating, ventilation, or disinfection that modifies the condition of air.

AIR CONDITIONING SYSTEM An air conditioner is a major or home appliance, system, or

mechanism designed to change the air temperature and humidity within an area (used for cooling and sometimes heating depending on the air properties at a given time).

The cooling is typically done using a simple refrigeration cycle, but sometimes evaporation is used, commonly for comfort cooling in buildings and motor vehicles.

In construction, a complete system of heating, ventilation and air conditioning is referred to as "HVAC".

AIR CONDITIONING SYSTEM

Air-conditioning is the process of cooling the air in a building to

provide a comfortable temperature.

AIR CONDITIONING SYSTEM5.1 Learn the basic principle of air conditioning system5.1.2 Illustrate the functional parts in air conditioning

system.The major parts of an air conditioner manage refrigerant and move air in two directions (indoors and outside):

1.Evaporator - Receives the liquid refrigerant

2.Condenser - Facilitates heat transfer

3.Expansion valve - Regulates refrigerant flow into the evaporator

4.Compressor - A pump that pressurizes refrigerant

AIR CONDITIONING SYSTEM5.1 Learn the basic principle of air conditioning system5.1.3 Identify the cycles and its function.


1. Liquids absorb heat when changed from liquid to gas.2. Gases give off heat when changed from gas to liquid.3. For an air conditioning system to operate with economy, the

refrigerant must be used repeatedly. 4. For this reason, all air conditioners use the same cycle of

compression, condensation, expansion, and evaporation in a closed circuit.

5. The same refrigerant is used to move the heat from one area, to cool this area, and to expel this heat in another area.

6. The refrigerant comes into the compressor as a low-pressure gas, it is compressed and then moves out of the compressor as a high-pressure gas.

Basic cycles of air conditioning system

AIR CONDITIONING SYSTEM7. The gas then flows to the condenser. Here the gas condenses to a

liquid, and gives off its heat to the outside air.8. The liquid then moves to the expansion valve under high pressure.

This valve restricts the flow of the fluid, and lowers its pressure as it leaves the expansion valve.

9. The low-pressure liquid then moves to the evaporator, where heat from the inside air is absorbed and changes it from a liquid to a gas.

10. As a hot low-pressure gas, the refrigerant moves to the compressor where the entire cycle is repeated.

11. Note that the four-part cycle is divided at the centre into a high side and a low side This refers to the pressures of the refrigerant in each side of the system

AIR CONDITIONING SYSTEM Air conditioning system will have these two heat transfer cycles:

air cycle & refrigeration cycle

Two other cycles found in some systems are : the chilled water cycle & the cold (cooling water) water cycle

Understanding the heat transfer cycles will help in the understanding the syllabus air conditioning systems.

There are two air cycles involved in any air-conditioning system i.e.

the internal air cycle & the external air cycle

AIR CONDITIONING SYSTEM5.2 Know the principle of the cooling substance5.2.1 Describe the air and water cycle and its functions in cooling system.

Air cycleAir cycle

Refrigeration cycle Refrigeration cycle

Water cycleWater cycle

The cooling substance !

!

AIR CONDITIONING SYSTEMAir cycleAir cycle

The internal air cycle involves the conditioning, delivery and the distribution of air in the building. The conditioning of air is the control of the temperature, humidity and quality of air. The delivery of air involves the fan moving the conditioned air and used air through the ducting system. But some system do not have a ducting system and therefore rely on the natural air circulation within the room for air delivery. The distribution of conditioned air involved the local control of temperature and volume of air at the outlet. At the outlet temperature control is possible by using a cooling coil damper and volume control is by regulating the outlet fan.

the internal air cycle and the external air cycle

AIR CONDITIONING SYSTEMThe external air cycle involves the transfer of heat from the air-conditioning system to the outside air.

The air-conditioning system releases the heat to the outside air.

The heat is dissipated into the larger volume of air.

Cooler air is produced and can then goes back to receive heat again

from the air – conditioning system.

AIR CONDITIONING SYSTEMRefrigeration cycle Refrigeration cycle

The system by which air conditioners provide cooling is called the Refrigerant Cycle.

This system has four major components common to all air-conditioning systems (see figure).


In the Evaporator, the cold liquid refrigerant under low pressure absorbs heat from the air cycle thus cooling the air.

The refrigerant turns into a low pressure gas due to the absorbed heat.

1. Evaporation1. Evaporation

2. Compression2. Compression

The low pressure gas is then compressed by the compressor so that the gas now becomes hotter and has high pressure.

Because of the high pressure, the boiling point of the refrigerant is increased.

Thus the gas refrigerant is carrying excess heat but could not release it due to the insulated pipe


The hot high pressure gas passes through the condenser. The condenser is a coiled pipe exposed to the out side air.

Excess heat and latent heat is transferred to the lower temperature outside air and the gas changes into high pressure liquid at room temperature.

3. Condensation3. Condensation

4. Expansion4. Expansion

The pressure of the liquid is lowered after passing through the expansion valve.

This causes the lowering of the boiling point of the liquid refrigerant and make it a cold liquid under low pressure.

It goes back to step no 1 to continue the cycle.

AIR CONDITIONING SYSTEMWater cycleWater cycle

the chilled water cycle and the cold (cooling water) water cycle

The chilled water cycle and

In some air conditioning system, The RC indirectly cools the air to be conditioned.Chilled water is produced by passing water over the evaporator coil of the refrigerant plant. This chilled water is then piped to the air handling units (AHUs) at various parts of the building. Air from the ducting diverted into the AHU and is cooled by flowing over a coil of piped water containing chilled (very cold) water in the Air Handling Unit (AHU).

AIR CONDITIONING SYSTEM The heat is transferred from the air to the water. This raises the water

temperature and cools the air. The cooled air is then fed into the room via the supply register. The less

chilled water pumped back to pass over the Evaporator Coil where the heat is transferred to the RC from the water.

Thus the water becomes chilled again. The water flows back to the AHU for air cooling. The Cycle is thus repeated.

AIR CONDITIONING SYSTEMThe cold (cooling water) water cycle

In some air conditioning system, the refrigeration cycle transfers the heat to the outside air indirectly.

Heat is transferred to the water which flows over the condenser of the heated water is piped and pumped to the cooling tower.

In the tower, the heated water is showered so that it comes into contact with the cooler outside air.

Heat is transferred from the heated water to the cooler air (see the external air cycle). The air-cooled water is piped back to the condenser to repeat the cycle again.

Spraying the water is a good way of releasing heat from the water to the outside air because the water droplets gives a greater surface area for the heat to the escape.


But a small portion of the water will also evaporate into the air or will be blown out of the cooling tower. Thus, in order to replace the lost water, this cold water pipe is connected to a replenishing water tank specially meant for the air conditioning system.

AIR CONDITIONING SYSTEM5.2 Know the principle of the cooling substance

5.2.2 Relate air and water cycles and cooling substances.

Try to describe the relation

between three of this.

AIR CONDITIONING SYSTEM5.3 Understand the process of the air conditioning system5.3.1 State the factors to consider in choosing type of air conditioning system.

1. Energy effectiveness2. Funds3. Atmosphere4. Vacant dish5. Automatic resume6. Portable unit


1. Energy effectiveness: It means how much energy it takes while in working and this is the

most important thing to consider for consumers they don't afford too much billing. So take that conditioner which has Energy saving star ratings.

2. Funds: This is the important thing while purchasing conditioner. You want

that conditioner which not breaks your budget and gives you comfortable feel when you are at home.


3. Atmosphere: You always want that conditioner that is according to environment. Mostly portable air conditioning unit use CFC refrigerant but use chooses that one which filters all the air before entering into your room.

4. Vacant dish: Many people working for a long hours so they always want that appliance you never have to empty. You don't want that appliance which fills your entire home with water when you. come back to your home after working.1..


5. Automatic resume: Always buy that conditioner which have automatic restart option if you're room is too hot in summer and automatically adjust temperature according to your need.

6. Portable unit: If you are living in a house i.e. on rent than portable conditioning is a great choice.come back to your home after working.1..

AIR CONDITIONING SYSTEM5.3 Understand the process of the air conditioning system5.3.2 Differentiate types of air conditioning system

AIR CONDITIONING SYSTEMa. Centralized unit

Central air conditioning plants are used for applications like big hotels, large buildings having multiple floors, hospitals, etc, where very high cooling loads are required.

The central air conditioning plants or the systems are used when large buildings, hotels, theaters, airports, shopping malls etc are to be air conditioned completely.

In the central air conditioning systems there is a plant room where large compressor, condenser, thermostatic expansion valve and the evaporator are kept in the large plant room.


They perform all the functions as usual similar to a typical refrigeration system. However, all these parts are larger in size and have higher capacities.

The compressor is of open reciprocating type with multiple cylinders and is cooled by the water just like the automobile engine.

The compressor and the condenser are of shell and tube type. While in the small air conditioning system capillary is used as the expansion valve, in the central air conditioning systems thermostatic expansion valve is used.

AIR CONDITIONING SYSTEMThe chilled is passed via the ducts to all the rooms, halls and other

spaces that are to be air conditioned. Thus in all the rooms there is only the duct passing the chilled air and there are no individual cooling coils, and other parts of the refrigeration system in the rooms.

What is we get in each room is the completely silent and highly effective air conditions system in the room. Further, the amount of chilled air that is needed in the room can be controlled by the openings depending on the total heat load inside the room.

AIR CONDITIONING SYSTEMThere are two types of central air conditioning plants or systems:

1. Direct expansion or DX central air conditioning plant:

In this system the huge compressor, and the condenser are housed in the plant room, while the expansion valve and the evaporator or the cooling coil and the air handling unit are housed in separate room.

The cooling coil is fixed in the air handling unit, which also has large blower housed in it. The blower sucks the hot return air from the room via ducts and blows it over the cooling coil.

The cooled air is then supplied through various ducts and into the spaces which are to be cooled. This type of system is useful for small buildings.


Showing view of Air Conditioning Plant Room

AIR CONDITIONING SYSTEM2. Chilled water central air conditioning plant:

This type of system is more useful for large buildings comprising of a number of floors. It has the plant room where all the important units like the compressor, condenser, throttling valve and the evaporator are housed.

The evaporator is a shell and tube. On the tube side the Freon fluid passes at extremely low temperature, while on the shell side the brine solution is passed. After passing through the evaporator, the brine solution gets chilled and is pumped to the various air handling units installed at different floors of the building. The air handling units comprise the cooling coil through which the chilled brine flows, and the blower.


The blower sucks hot return air from the room via ducts and blows it over the cooling coil. The cool air is then supplied to the space to be cooled through the ducts.

The brine solution which has absorbed the room heat comes back to the evaporator, gets chilled and is again pumped back to the air handling unit.

To operate and maintain central air conditioning systems we need to have good operators, technicians and engineers. Proper preventative and breakdown maintenance of these plants is vital.


Central air conditioning – Chilled water system


Advantages of Central air conditioning :Noise in rooms is usually reduced if plant room is away from occupied spaces.The whole building can be controlled from a central control station. This means that optimum start and stop can be used and a weather compensator can be utilised. Also time clocks can bring air conditioning on and off at appropriate times.Maintenance is centralised in the plant room. Plant is easier to access.


Disadvantages of Central air conditioning :Expensive to install a complete full comfort air-conditioning system throughout a building. Space is required for plant and to run ductwork both vertically in shafts and horizontally in ceiling spaces.Individual room control is difficult with central plant. Many systems have been tried such as Variable Air Volume (VAV), dual duct systems and zone re-heaters. Zone re-heaters are probably more successful than the rest.

AIR CONDITIONING SYSTEMb. Split unit

The window and split air conditioners are used for single rooms or small office spaces. If the whole building is to be cooled it is not economically viable to put window or split air conditioner in each and every room. Further, these small units cannot satisfactorily cool the large halls, auditoriums, receptions areas etc.

Split air conditioners have two main parts, the outdoor unit is the section which generates the cold refrigerant gas and the indoor unit uses this cold refrigerant to cool the air in a space.

The outdoor unit uses a compressor and air cooled condenser to provide cold refrigerant to a cooling coil in the indoor unit.

A fan then blows air across the cooling coil and into the room.

The indoor unit can either be ceiling mounted (cassette unit), floor mounted or duct type, above ceiling unit with provision for duct connections and high level indoor unit.

AIR CONDITIONING SYSTEMVarious Types of Split Unit Air Conditioners (Indoor Units).

Ceiling mounted

(cassette unit)

Floor mounted or duct type

Above ceiling unit with

provision for duct connections

High levelIndoor unit.

AIR CONDITIONING SYSTEMThe photographs below show a ceiling mounted cassette and an outdoor unit.

AIR CONDITIONING SYSTEMAdvantages of Split unit :Cheaper to install.Individual room control.Works well where rooms have individual requirements.No long runs of ductwork.Can be used to heat as well as cool if a reversing valve is fitted.

AIR CONDITIONING SYSTEMDisadvantages of Split unit :

Sometimes the indoor unit fan becomes noisy.Noisy compressor in outdoor unit.Each unit or group of units has a filter, compressor and refrigeration pipework that needs periodic maintenance and possible re-charging. Units have course filters therefore filtration is not as good as with AHU’s.The installation may require long runs of refrigerant pipework which, if it leaks into the building, can be difficult to remedy.Not at robust as central plant.The majority of room air conditioners just recirculate air in a room with no fresh air supply although most manufacturers make units with fresh air capability.Cooling output is limited to about 9 kW maximum per unit; therefore many units would be required to cool rooms with high heat gains.

AIR CONDITIONING SYSTEM5.4 Understand the effects of air conditioning system to

the environment5.4.1 Identify the latest product of environmental friendly

air condition.

1. Solar Hybrid Air Conditioner2. Green AC3. Geothermal Heat Pumps (Geothermal Heating and

Cooling)


Solar Hybrid Air Conditioner

Comfort living without the guilt of destroying the environment is now made possible by LG with their first eco-friendly air conditioner that has its debut in Korea.

The Hybrid conditioner of LG has solar modules attached on top of the outer unit of the air conditioner that collects sunrays and convert it into electric power of up to 70 watts per hour.

With this ability, the LG solar hybrid air conditioner will be able to reduce carbon emission of up to 212kg over 10 years, which is equivalent to 780 pine trees.

With this product, using your air conditioner can now be more comfortable and at the same time will set your mind free from worries about destroying the environment.


Green AC

To design a more than just ordinary air conditioner, LED lights were introduced behind the front cover enabling illumination of the room with a soft background light.

This is giving the customer the unique possibility to incorporate the stylish design into the home styling.

You can controly our air conditioner unit with applications created for smart phones. These applications communicate with your product, so that you can control your AC when you

are away from home. With the applications you can do everything that you can do with the remote control; adjust

the airflow, the temperature, use the timer and turn on the light if the unit has one.


The application will have the same functions as the remote control, in the function, Air flow, you can adjust the temperature, select Swing-mode or Eco-mode.


Geothermal Heat Pumps (Geothermal Heating and Cooling)

Why it’s cool: Similar to how caves regulate temperature, Geothermal Heat Pumps use the earth’s steady temperature to cool and heat water. Each system has an indoor and outdoor unit that transfers water into the ground and pumps it back inside. For cooling, water is piped into the ground, where the soil extracts excess heat, significantly reducing the amount of electricity needed in conventional cooling methods.

Drawbacks: Installation costs run higher than conventional methods, but the energy savings usually make up the difference in three to ten years.


Geothermal heat pumps have gotten more attention over the last few years than any other single source of home heating and cooling. Why? Because they’re extremely efficient AND the federal government is willing to pay for 30% of the cost to install them in your home!


Geothermal heat pump installation

AIR CONDITIONING SYSTEMGeothermal Cooling :In the cooling mode, the heating process is reversed - creating cool, conditioned air throughout the home.Instead of extracting heat from the ground, heat is extracted from the air in your home and either moved back into the earth loop, or used to preheat the water in your hot water tank.

Geothermal vs. Geoexchange: what's in a name? :Geothermal energy has been used to heat and air condition buildings for several decades, and during that time these geothermal systems have been called many different things. Some of the more popular variations include geo-thermal, geoexchange, ground-water, ground-water assisted, ground-water-source, water-to-water, and even our company name, water furnace heating and cooling.

AIR CONDITIONING SYSTEMBe An Eco-Friendly User Of Your Air Conditioner1. Find The Energy Star Label And High SEER. The importance and significance of the Energy

Star label and SEER are mentioned earlier. What you need to realize is that air conditioner units with these certifications and ratings are able to use 10-50% less energy than regular AC units. By choosing this type of system, you will be able to save more money on your utility bills since it reduces the amount of energy consumed. These eco-friendly units will also have a timer and thermostat which will help you control the temperature of the unit.

2. Buy The Right Air Conditioner Size. When buying an eco-friendly AC unit, you must consider the space of your home or room. Some of the factors you need to consider include:

The number of windows in your home Home shading Your home insulation The heat generated by the residents in the house and the appliances being used

If you are getting a window unit, you can get the BTU size that is big enough to cool the entire room.

AIR CONDITIONING SYSTEM3. Program The Thermostat And Install A Fan. When choosing an air conditioning system, you

must find one with a programmable thermostat. You can then set your thermostat higher since doing so will consume less energy. Another useful tip is to install a ceiling fan, as this will lead to even air circulation in the room, and it doesn’t use as much energy.

4. Shade Your Air Conditioner. When installing the cooling system, you must choose areas with bushes and trees so that the sun won’t be able to easily beat down on it. Doing this is more energy-efficient since shaded air is about six degrees cooler than air that’s not shaded.

Eco-friendly air conditioning systems can be quite expensive, but investing in such systems is worth it. These units can help you save more in the future; thus, if you want to avoid paying expensive energy bills but you do not want to compromise your comfort, you must invest in a reliable eco-friendly unit.

AIR CONDITIONING SYSTEM5.4 Understand the effects of air conditioning system to

the environment5.4.2 Recognized the effect of air conditioning gases to

global warming.


Global warming (also called the greenhouse effect) describes the gradual increase of the air temperature in the earth's lower atmosphere.

Why is global warming called the greenhouse effect? Greenhouses are not common in Africa, so don't be surprised if you have never seen one! They are used mainly in the cooler northern hemisphere to grow vegetables and flowers.

A greenhouse is made entirely of glass. When sunlight (shortwave radiation) strikes the glass, most of it passes through and warms up the plants, soil and air inside the greenhouse. As these objects warm up they give off heat, but these heat waves have a much longer wavelength than the incoming rays from the sun. This long wave radiation cannot easily pass through glass, it is re- radiated into the greenhouse, causing everything in it to heat up.

What is the global warming ???

AIR CONDITIONING SYSTEMWhat is the global warming (greenhouse effect) gases ???1. Water vapour is the main greenhouse gas. Human activities are not known to have had a

significant influence on the atmospheric concentration of water vapour.2. Carbon dioxide (CO2) is the pollutant most responsible for increased global warming. It is

released into the atmosphere mainly through burning of fossil fuels (e.g. coal, petrol, diesel). In addition, widespread destruction of natural vegetation, particularly forests, has contributed to increased atmospheric CO2 levels (see Enviro Facts "Deforestation"). This has occurred for two reasons. First, plants take up CO2 through the process of photosynthesis. The destruction of vegetation, as occurs in deforestation, reduces the amount of CO2 that is removed from the atmosphere. Second, when forests are cleared, and burnt or left to rot, CO2 is released.

3. Methane (CH4) has doubled in concentration, mainly as a result of agricultural activities, between 1750 and 1990.

4. Nitrous oxide (N2O), also a product of burning fossil fuel, has increased by 8% over the same period.

5. Chlorofluorocarbons (CFCs), in addition to damaging the ozone layer, are potent greenhouse gases. Their concentrations in the atmosphere are increasing by about 4% every year.

AIR CONDITIONING SYSTEMWhat is the effect of air conditioning gases to global warming???

The average global temperature is about 0,5 degrees centigrade warmer than it was 100 years ago.

1990 is the warmest year on record, 1988 the second warmest, and 1980, 1981, 1983 and 1986 were all warmer than any other years in the last century. Preliminary analyses of 1991 temperature records indicate that this year was also above average.

Snow and ice-cover have decreased this century, deep ocean temperatures have increased, and cloud cover over North America has also increased over this period. The latter indicates increased atmospheric water vapour.

Over the last century, global sea levels have risen by between 100 mm and 200 mm.

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