Air Conditioning with explanation

8/22/2019 Air Conditioning with explanation

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Submitted By

C. Blessy


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Introduction The first modern air conditioning system was developed in 1902 by a young

electrical engineer named Willis Haviland Carrier.

It was designed to solve a humidity problem at the Sackett-WilhelmsLithographing and Publishing Company in Brooklyn, N.Y. Paper stock at the

plant would sometimes absorb moisture from the warm summer air, making it

difficult to apply the layered inking techniques of the time.

Carrier realized he'd developed something with far-reaching potential, and itwasn't long before air-conditioning systems started popping up in theaters and

stores, making the long, hot summer months much more comfortable


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Introduction

Contd.. The actual process air conditioners use to reduce the ambient air

temperature in a room is based on a very simple scientific

principle.

The rest is achieved with the application of a few clever

mechanical techniques. Actually, an air conditioner is very

similar to another appliance in your home -- the refrigerator.

Air conditioners don't have the exterior housing a refrigeratorrelies on to insulate its cold box. Instead, the walls in your home

keep cold air in and hot air out.


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Air-conditioning Basics

Air conditioners use refrigeration to chill indoor air, taking advantage of a remarkable

physical law: When a liquid converts to a gas (in a process called phase conversion), it

absorbs heat.

Air conditioners exploit this feature of phase conversion by forcing special chemicalcompounds to evaporate and condense over and over again in a closed system of coils.

The compounds involved are refrigerants that have properties enabling them to change

at relatively low temperatures.

Air conditioners also contain fans that move warm interior air over these cold,

refrigerant-filled coils. In fact, central air conditioners have a whole system of ducts

designed to funnel air to and from these serpentine, air-chilling coils.


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The Parts of an Air Conditioner

Air conditioners monitor and regulate the airtemperature via a thermostat.

They also have an onboard filter that removes airborne

particulates from the circulating air.

Air conditioners function as dehumidifiers. Because

temperature is a key component of relative humidity,

reducing the temperature of a volume of humid air

causes it to release a portion of its moisture.


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Evaporator - Receives the liquid refrigerant

Condenser - Facilitates heat transfer

Expansion valve - regulates refrigerant flow into theevaporator

Compressor - A pump that pressurizes refrigerant

The Parts of an Air Conditioner Contd..


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Window and Split-system AC Units

A window air conditioner unit implements a completeair conditioner in a small space.

The units are made small enough to fit into a standard

window frame. It Consists of

A compressor

An expansion valve

A hot coil (on the outside)

A chilled coil (on the inside)

Two fans

A control unit


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The fans blow air over the coils to improve their ability to dissipate heat

(to the outside air) and cold (to the room being cooled).

When you get into larger air-conditioning applications, its time to start

looking at split-system units.

A split-system air conditioner splits the hot side from the cold side of

the system, as in the diagram below.

The cold side, consisting of the expansion valve and the cold coil, is

generally placed into a furnace or some other air handler.

The air handler blows air through the coil and routes the air

throughout the building using a series of ducts. The hot side, known as

the condensing unit, lives outside the building.

Window and Split-system AC Units Contd..


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BTU - British thermal units Most air conditioners have their capacity rated in British thermal units (Btu).

A Btu is the amount of heat necessary to raise the temperature of 1 pound (0.45

kilograms) of water one degree Fahrenheit (0.56 degrees Celsius).

One Btu equals 1,055 joules. In heating and cooling terms, one ton equals 12,000 Btu.

A typical window air conditioner might be rated at 10,000 Btu.

For comparison, a typical 2,000-square-foot (185.8 square meters) house might have a 5-

ton (60,000-Btu) air conditioning system, implying that you might need perhaps 30 Btu

per square foot. These are rough estimates.

To size an air conditioner accurately for your specific application, you should contact an

HVAC contractor.


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EER - Energy Efficiency Rating The energy efficiency rating (EER) of an air conditioner is its Btu rating over

its wattage. As an example, if a 10,000-Btu air conditioner consumes 1,200

watts, its EER is 8.3 (10,000 Btu/1,200 watts). Obviously, you would like the

EER to be as high as possible, but normally a higher EER is accompanied by ahigher price.

Example for calculating EER:

With roughly 30 days in a month, you're operating the air conditioner:

4 months x 30 days per month x 6 hours per day = 720 hours

[(720 hours x 200 watts) / (1000 watts/kilowatt)] x $0.10/kilowatt hours = $14.40
http://home.howstuffworks.com/watt.htmhttp://home.howstuffworks.com/watt.htm


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Room air conditioners

Central air conditioning systems

Heat pumps Evaporative coolers

TYPES OF AIR CONDITIONERS


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Air Conditioning


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Room air conditioners cool rooms rather than the entire

home.

Less expensive to operate than central units

Their efficiency is generally lower than that of central air

conditioners.

Can be plugged into any 15- or 20-amp, 115-volt household

circuit that is not shared with any other major appliances

Room air conditioner


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Central Air conditioning Circulate cool air through a system of supply and return

ducts. Supply ducts and registers (i.e., openings in the

walls, floors, or ceilings covered by grills) carry cooled air

from the air conditioner to the home.

This cooled air becomes warmer as it circulates through the

home; then it flows back to the central air conditioner

through return ducts and registers


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Types of Central AC split-system

an outdoor metal cabinet contains the condenser

and compressor, and an indoor cabinet contains

the evaporator

Packaged the evaporator, condenser, and compressor are all

located in one cabinet


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Large air conditioning systems Outside air is drawn in, filtered and heated before it

passes through the main air conditioning devices.

The colored lines in the lower part of the diagram

show the changes of temperature and of water

vapor concentration (not RH) as the air flows

through the system.


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Sizing Air Conditioners how large your home is and how many windows it has;

how much shade is on your home's windows, walls, and

roof;

how much insulation is in your home's ceiling and walls;

how much air leaks into your home from the outside; and how much heat the occupants and appliances in your home

generate


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Energy Efficiency Today's best air conditioners use 30% to 50% less

energy than 1970s

Even if your air conditioner is only 10 years old, you

may save 20% to 40% of your cooling energy costs by

replacing it with a newer, more efficient model


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THANK YOU

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Air Conditioning with explanation