How Air Conditioning Work

Sunday, February 22, 2009

SANITARY APPLIANCES

SANITARY APPLIANCES
Fitting used for cleansing and disposing of waste product, most sanitary appliances fall into one of two groups, waste appliances ( bidets, wash basins, sinks, showers / baths tubs , drinking fountains ) and soil appliances ( water closet, urinal ). All sanitary appliances are made of non-absorbent, non-corroding, smooth and easily cleaned material and usually made from ceramic ware, vitreous enameled cast iron, vitreous enameled pressed steel, stainless steel or plastics (thermosetting and thermoplastic).

Water Closet
This is the most common type of plumbing appliance and also known as a toilet. It should be vitreous china , except in correctional institutions. It is specifically designed to accept and discharge human waste, including solids. Water closet are usually subdivided according to where they are mounted (floor mounted and wall mounted ) and how they are flushed (tank type and flush valve type ).

AIR CONDITIONING FOR LARGE MULTISTOREY BUILDINGS

AIR CONDITIONING FOR LARGE MULTISTOREY BUILDINGS


DESIGN CONSIDERATION

Most large multistorey buildings are highly centralized air conditioning equipment. The roof and basement are the usual choice for these central station systems. The basement has the advantages of easy utility connections, noise isolation, not being valuable rental area and the fact that structural loads are not a problem. The roof on the other hand, is the ideal location for fresh air intakes and heat rejection to the atmosphere.

TYPES OF AIR CONDITIONING SYSTEMS

Large buildings have so many thermal zones, and there are so many ways to move heat from one place to another, that hundreds of air conditioning systems have been devised. One way to classify air conditioning systems is by the media used to transfer heat. Although thousands of liquids and gases can be used as carrier of heat, the three most common in building applications are air, water and refrigerant. Air conditioning for large buildings have three main system classifications:

a. All-air systems
b. Air and water systems
c. All water systems


ALL-AIR SYSTEMS

The great advantage of all-air systems is that complete control over air quality is possible. The main disadvantage is that all-air systems are very bulky and a significant part of the building volume must be devoted to them. It must be noted that for clarity only the supply ducts are shown on each plan in the following examples. Usually there is also a sizable return duct system on each floor.


AIR-WATER SYSTEMS

The following systems supply both air and water to each zone of a building. Although this increases the complexity of the mechanical systems, it greatly decreases the size of the equipment because of the immense heat-carrying capacity of water as opposed to air. Air is supplied mainly because of the need for ventilation.


AIL-WATER SYSTEMS

Since these systems supply no air, they are appropriate where a large amount of ventilation is either not necessary or where it can be achieved locally by other means such as opening windows.

Wednesday, February 18, 2009

Chiller

A chiller is a machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. A vapor-compression water chiller comprises the 4 major components of the vapor-compression refrigeration cycle (compressor, evaporator, condenser, and some form of metering device).

These machines can implement a variety of refrigerants. Absorption chillers utilize water as the refrigerant and rely on the strong affinity between the water and a lithium bromide solution to achieve a refrigeration effect.

Most often, pure water is chilled, but this water may also contain a percentage of glycol and/or corrosion inhibitors; other fluids such as thin oils can be chilled as well.

Friday, February 13, 2009

AIR CONDITIONING OF SMALL BUILDINGS

AIR CONDITIONING OF SMALL BUILDINGS

INTRODUCTION

Air conditioning systems generally have common basic elements; however, they may differ dramatically in physical appearance and arrangement. Even with the same elements present, the manner in which systems are controlled and operated may also be quite different.

COOLING SYSTEMS

To cool a building, a refrigeration made must pump heat from the variant rooms of a building into a heat sink. The heat sink is usually the outdoor air but can also be a body of water or even the ground. Cooling systems vary mostly by the way heat is transferred from the rooms to the refrigeration machine and from there to the heat sink. The choice of the heat transfer methods depends on building type and size. The four major categories ( based on how heat is transferred from building spaces to refrigeration machine) are direct refrigerant, all-air, all-water and combination air-water.

Direct refrigerant systems

The direct refrigerant system is the simplest because it consists of little more than the basic refrigeration machine plus two fans. The indoor air is blown directly over the condenser coil. Direct refrigerant units are appropriate for cooling small to medium size spaces that require their own separate mechanical units.


All-Air Systems

In an all-air system, air is blown across the cold evaporator coil and then delivered by ducts to the rooms that require cooling. Air systems can effectively ventilate, filter and dehumidify air. The main disadvantage lies in the bulky duct-work that is required.


All-Water Systems

In an all-water system, the water is chilled by the evaporator coil and then delivered to fan-coil units in each space. Although the piping in the building takes up very little space, the fan-coil units in each room do require some space.


Combination Air-Water Systems

An air-water system is a combination of the above mentioned air and water systems. The bulk of the cooling is handled by the water and fan-coil units, while a small air system completes the cooling and also ventilates, dehumidifies and filters the air. Since most of the cooling is accomplished by the water system, the air ducts can be quite small.


AIR CONDITIONING OF SMALL BUILDINGS

In smaller buildings, the heat given off by a refrigeration machine is usually dumped into the atmosphere by blowing outdoor air over the condenser coil. Medium sized building often use a specialized piece of equipment called evaporative condenser to dump heat into the atmosphere by evaporating water. Since the refrigeration lines are limited in length, an evaporative condenser cannot be more than about 60ft from the compressor and evaporator coil. Thus, for large buildings, cooling towers are frequently a better choice.


ROOM AIR CONDITIONERS

For air conditioning single spaces like motel rooms, a window unit is often used. Each of these units essentially consists of a compressive refrigeration machine. The condenser coil, compressor and one fan are on the exterior side of an internal partition. The compressor is on the outside because it is the noisiest part of the equipment. On the interior side of the partition there is the evaporator coil and a fan to blow air over it. The evaporator typically operates below the dew-point temperature of the room air for the purpose of dehumidification, so condensate forms on the coil. It drains to a pan beneath the coil . The capacity of these units may range from about 4000Btu/h (1/3 ton) to 24,000Btu/h (2 tons).


PACKAGED UNITS

Packaged units are pre-engineered self-contained units where most of the mechanical equipment is assembled at the factory. Consequently, they offer low installation, operating and maintenance costs. Usually small buildings are served by one package while larger single-storey buildings get several. Rooftop versions are the most common with each unit serving a separate zone. Packaged units are sometimes also used on the ground, for buildings with crawl spaces or above suspended ceiling when there is enough space below the roof.


SPLIT UNITS

Most homes and some other buildings find the split unit to be most appropriate. In the split unit, the compressor and condenser coils are outdoors while the air handling unit with the evaporator coil are indoors. As in all cooling systems, condensation from the evaporator coil must be drained away.

Thursday, February 12, 2009

COIL BY-PASS FACTOR AND AIR MIXTURES

COIL BY-PASS FACTOR AND AIR MIXTURES

INTRODUCTION
Cooling and dehumidification process involves not only sensible cooling but also latent removal or reduction of moisture content or dehumidification. Therefore the air will have to be cooled below its dew point temperature.


COIL BY-PASS FACTOR
In the proceeding section it is shown that the DB temperature of the air passing over a cooling coil tends to approach the surface temperature of the coil. If all the air passing through the coil come into intimate contact with the cooling surface and remains in contact with it for a sufficient length of time, the DB temperature of the leaving air could be decreased to the temperature of the cooling surface. However, as a practical matter, a certain portion of the total air quantity passing through any heating or cooling coil never comes into contact with the coil surface and therefore is unaffected by its passage through the coil. That is, it leaves the coil in the same condition that it enters the coil.

From the forgoing, it can be assumed that the air leaving the coil is actually a mixture of two air-streams or components . One component is the portion of the air that comes into direct contact with the coil surface and is assumed to leave the coil at a DB temperature equal to the mean surface temperature of the coil (line AB). The other component is the by-pass air, which does not contact the coil surface and it is assumed to leave the coil at the same DB temperature as when entering (line BC). The line AC then, represents the total quantity of the air mixture leaving the coil, which is the sum of the two component air quantities.

Since, in terms of the DB temperature scale, the length of line BC is equal to Tb
- Tc, and the length of line AC is equal to Ta
- Tc, it follows that :-

where, Ta = the DB temperature of the air entering the coil (oC)
Tb = the DB temperature of the air leaving the coil (oC)
Tc = the mean effective temperature of the coil surface (oC)

The BPF (1) increases as the velocity of air over the coil increases; (2) decreases as the pitch of the fin decreases and (3) decreases as the number of rows of the coil increases.

AIR MIXTURES

The mixing of air streams can take place when :-
  1. The fresh air drawn into air handling unit is mixed with re-circulated room air prior to conditioning and supply into the building.
  2. Supply air is blown through supply grilles or diffusers into the room.
  3. Exhaust air is discharged from the building into the external atmosphere.
  4. The discharge air from an external dry or evaporative cooling tower is released into the atmosphere.
  5. Steam from cooking equipment is released.
  6. Opening doors between rooms connects areas held at different temperature, humidity or pressure states.
  7. Air is extracted from different rooms and is mixed in the recirculation ductwork.
  8. Air from different parts of the same room is drawn towards the extract grill and into ductwork.

    Whenever such a mixing process take place, changes occur in the air condition. In comfort air conditioning, room air extracted into the return-air duct may or may not accurately represent the room-air condition around the occupants owing to the relative mixing of air from different parts of the room. It is important to summate mass flow rates for accurate results although an approximation can be made by adding volume flow rates. The inaccuracy here will be due to the changes in air density as the temperature change during the mixing process. The mixed air condition lies on a straight line connecting the two end states. Where,

Q1 = volume flow rates of fresh air (m3/s)

Q2 = volume flow rates of return-air (m3/s)

Q3 = volume flow rates of mixed air (m3/s)

An approximation to the mixed air temperature can be made from the volume flow rates and DB temperatures of the two streams, often with sufficient accuracy for plotting on the psychrometric chart, that is to within 0.5oC DB, by making the assumption that the air densities and specific heat capacities remain practically constant. Divide each side by Q3;

Where;

t1 = DB temperature of fresh air (m3/s)

t2 = DB temperature of return-air (m3/s)

t3 = DB temperature of mixed air (m3/s)

Monday, February 9, 2009

Anly Float Less Level Switch Rosak Atau Tidak

Menentukan sama ada Anly Float Less Level Switch Rosak Atau Tidak?

1. Keadaan Rosak

2. Keadaan Baik

6

5

4

3

6

5

4

3

Floatless Level Switch

Floatless Level Switch

7

8

1

2

7

8

1

2

* kesan kerosakan

* untuk keadaan normal

menunjukkan terminal

terminal 8 dan 1 tiada

8 dan 1 akan ada

bekalan elektrik

bekalan elektrik

(louping) dan

(louping).

indicator light bagi PB OFF

akan berfungsi.

* Pastikan terminal 5 (Live) dan terminal 6 (Neutral)

dipasang sebagai input voltage.


Faktor-Faktor Kejuruteraan Didalam Sistem Bekalan Air

Faktor-Faktor Kejuruteraan Didalam Sistem Bekalan Air

1. Kala rekabentuk
- tempoh 5 tahun, 10 tahun dan sebagainya.
2. Jumlah Permintaan
- kegunaan domestik dan pertanian.
3. Tahap dan Keberkesanan Perkhidmatan
- kuantiti air yang dapat banyak permintaan.
- kualiti air yang dibekalkan.
4. Mengenal Pasti Sumber Air Mentah
5. Kemampuan
- mengolah dan membekalkan.
- dari segi penyimpanan, pemprosesan dan rawatan.

Sunday, February 8, 2009

Kirakan Keamatan Lar, (I)

Diberi Illuminance Pencahayaan, E bersamaan 100 Lux untuk kes diatas ini, kirakan keamatan Lar, I dalam unit cd (Candelar) serta buktikan samada 100 Lux bagi nilai E adalah tepat?

Penyelesaian:

Formulanya ialah



Data yang diberi ;

E = 100 Lux

d = panjang keamatan (Luminius Intensity)

= 3 meter

d x d = 9 meter



maka;

= sudut pada satah (permulaan) iaitu 0 darjah

= cos 0

= 1

100 Lux = (I x 1)/9
I = 900 cd
maka, keamatan lar bagi punca cahaya ini ialah 900 cd.
Pembuktian:
E = (900 x 1)/(9)
= 100 Lux (Terbukti)






Peranan Cahaya Siang

- boleh diperolehi daripada bukaan tingkap.
- berfungsi untuk mendapatkan hiasan yang lebih menarik dalam sesebuah bangunan.
- ia menghasilkan "visual contact".
- ia juga boleh menjimatkan penggunaan elektrik.

Quotation 1205








































































































































































































































































































































































































































































































































































































































































































































































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09000 KHTP KULIM KEDAH










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Kepada : ________________________________




Tarikh :




8/2/2009










Lokasi : N0 1205/Lrg 28/2/Bandar Sri Mahkota
















Bil




Lokasi




Keterangan




Kuantiti




Harga (RM)










1




Porch Area




Pemasangan Lampu Pendaflour 40W




1




3










2




Main Entrance




Pemasangan Lampu Pendaflour 40W




1




3










3




Room No 1




Pemasangan Lampu Pendaflour 40W




1




4.5










4




Room No 2




Pemasangan Lampu Pendaflour 40W




1




3










5




Room No 3




Pemasangan Lampu Pendaflour 40W




1




3










6




Kitchen Area




Pemasangan Lampu Pendaflour 40W




1




3










7




Toilet




Pemasangan Lampu Pendaflour 20W




1




3










8







Aksesori




L/S




21.5










Jumlah Keseluruhan




44
















DISEDIAKAN : ___________________




DI TERIMA:




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IBU PEJABAT : FAMSY ENTERPRISE (PGG 25943936-A)








































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