Introduction

A refrigerator is any kind of enclosure (like a box, cabinet, or room) whose interior

temperature is kept substantially lower than the surrounding environment.

The term "refrigerator" was coined by a Maryland engineer, Thomas Moore, in

1800. Moore's device would now be called an "ice box" — a cedar tub, insulated

with rabbit fur, filled with ice, surrounding a sheet metal container. Moore designed

it as as a means for transporting butter from rural Maryland to Washington, DC. Its

operating principle was the latent heat of fusion associated with melting ice.

The term "air conditioning" was coined by Stuart Cramer in 1905 to describe his

system for regulating the temperature and humidity inside a textile factory in the

South (the humidity regulation was seen as more important than the temperature

regulation). Willis Carrier also designed climate control systems for industry.

One of the first uses of air conditioning for personal comfort was in 1902 when the

New York Stock Exchange's new building was equipped with a central cooling as

well as heating system. Alfred Wolff, an engineer from Hoboken, New Jersey who is

considered the forerunner in the quest to cool a working environment, helped

design the new system, transferring this budding technology from textile mills to

commercial buildings.

In 1906, Stuart Cramer first used the term "air conditioning" as he explored ways to

add moisture to the air in his southern textile mill. He combined moisture with

ventilation to actually "condition" and change the air in the factories, controlling the

humidity so necessary in textile plants.

An early pioneer who did much to promote "controlled air" was Willis Carrier, a

mechanical engineer who worked at the Buffalo Forge Company in Buffalo, New

York. Subsequent subsidiary companies carrying his name helped conquer the

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temperature-humidity relationship, marrying theory with practicality. Starting in

1902, he designed a spray-type temperature and humidity controlled system. His

induction system for multi-room office buildings, hotels, apartments and hospitals

was just another of his air-related inventions. Many industry professionals and

historians consider him the "father of air conditioning."

There are several basic refrigeration techniques:

1. ice box (or dry ice box)

2. cold air systems

3. vapor-compression: the current standard method of refrigeration used in

home refrigerators, home air conditioners and heat pumps (Kelvin's idea,

refrigerate the environment in the winter, store "cold" in the ground for use

in the summer)

4. vapor-absorption: the Electrolux refrigerator with no moving parts

5. thermoelectric

SCIENCE EXPERIMENTS RELATED TO PHYSICS

Physics science experiments explore the structure and behavior of

energy and matter. Science experiments in physics concern the principles of energy

and matter, as they function separately or together. Project ideas include basic

physics experiments on the structure and behavior of matter such as liquid. In

addition, specialized fields related to physics such as astronomy and forensic

science also offer room for experimentation.

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Creating a Comet

o Suited to all grade levels, experiments that create comets provide students

with lessons in the composition of matter in space. The experiment covers

comet structure and material composition but can also be used for lessons on

comet orbit and sublimation where objects transform from solids to gases.

Using a recipe created by Dr. Dennis Schatz from the Pacific Science Center,

students make 6-inch comets with water, dry ice and ammonia. Due to the

dangers of improperly handling ammonia and dry ice, students should wear

rubber gloves when forming their comets.

Heat Transfer

o Heat transfer involves the molecular interaction and movement of matter and

occurs in four ways known as conduction, evaporation, radiation and

convection. Experiments on heat transfer by cooling a can of soda involve

conduction and convection. Students place open cans of room temperature

soda in a freezer, refrigerator, ice bath and ice water bath. At timed intervals,

students measure the temperature of each soda to compare the level of

cooling for each type of device. At the end of the experiment, students

compare the results to see which method of heat transfer was most effective.

Surface Tension of Liquids

o Surface tension involves the level of energy needed to expand a liquid surface

area. Science experiments on the surface tension of liquid compare the energy

needed to remove an object from different types of liquid. Using a beam

balance, students measure water surface tension using a needle that is floated

in a bowl of water. Students determine the amount of surface tension by

analyzing the force needed to extract the needle from the water. The greater

the water surface tension, the more force is needed to remove the needle.

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Different surface tensions are created for analysis by comparing regular

water, cooking oil, rubbing alcohol and liquid detergent.

Splatter Analysis

o Forensic science involves various types of scientific analysis including

principles of physics to analyze crime scene evidence such as the dispersion

of blood spatter. Blood spatter is evaluated based on velocity and allows

forensic scientists to determine the position of a body during attack and the

rate at which it fell. Forensic science experiments related to physics measure

the spatter of water from water-filled balloons to imitate variations in spatter

patterns. Balloons are filled with equal amounts of water and must have a

similar weight with no more than a 10 percent difference. Balloons are

dropped to the ground from different heights. Students record the weight,

height of drop and time duration of the drop to calculate velocity. Students

then analyze the size and shape of the spatter pattern when the balloon

breaks to determine which velocity created the largest dispersion of liquid.

ADVANTAGES AND DISADVANTAGES OF REFRIGERATOR?

ADVANTAGES

Your refrigerator keeps food cold, preserves it and keeps it safe from dangerous

bacterial growth until you have a chance to eat it. Imagine life without one of these

appliances in today's world may be difficult, but all the news on refrigerators is not

good news. A few disadvantages exist to owning a refrigerator. Hardly anyone

would consider that the downside of having a refrigerator is worse than not having

one at all, but there are some "cold" realities associated with the appliance.

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DISADVANTAGES

Energy Requirements

Perhaps the biggest disadvantage of the refrigerator is the cost to run it.

According to the California Energy Commission website, approximately one-

sixth of electricity used in the typical American home is consumed by the

refrigerator and freezer, and this is a sizeable improvement over the

refrigerators your parents used. Since 1990, refrigerators have become much

more energy efficient, using 60 percent less power today than they did back

then. Refrigerators are such an energy hog that they come with two kinds of

price tags. They have the retail purchase price and the estimation of what

they'll cost you to run each year. Often the energy cost is enough to make up

for the additional amount you have to pay for better built models.

Disposal Concerns

One of the disadvantages of refrigerators is that they are environmentally

unfriendly and dangerous if not disposed of properly. If doors are not

removed from old refrigerators with locking doors, they pose a hazard to

children who may get trapped inside. The refrigerator also contains

refrigerant that can be damaging to the environment because of

chlorofluorocarbon (CFC) content. This material should be recycled.

Otherwise the CFCs can escape into the air. This material is suspected to be

the cause of depletion of the earth's ozone layer.

Common Repairs

Repairs can be a disadvantage of refrigerators because of the many common

problems that the appliance can have over its lifetime. While the owner can

do some repairs at no significant cost, others may require out-of-pocket

expense and payments to repair technicians. A person who owns a

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refrigerator likely will encounter one of the common refrigerator problems

over the life of the appliance. Among the common repairs made to

refrigerators include leaks and icing, icemaker malfunction, cooling problems

and replaced fan motors. Some owners may not see repairs as a major

problem and may never have a serious issue throughout the life of the unit

while others may have to fix their refrigerator on a regular basis.

REFERENCE

Rebecca Macken, eHow Contributor

www.setaram.com

WWW.ask.com

www.wikipeadia.com

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