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Title: Study of various Home Appliances

Introduction:

Refrigerator:In the refrigeration cycle, there are five basic components: fluid refrigerant; a compressor,

which controls the flow of refrigerant; the condenser coils (on the outside of the fridge); theevaporator coils (on the inside of the fridge); and something called an epansion device!

Here"s how they interact to cool your food!

#! $he compressor constricts the refrigerant vapor, raising its pressure, and pushes it into thecoils on the outside of the refrigerator!

%! &hen the hot gas in the coils meets the cooler air temperature of the 'itchen, it becomes a

liuid!

! *ow in liuid form at high pressure, the refrigerant cools down as it flows into the coilsinside the free+er and the fridge!

! $he refrigerant absorbs the heat inside the fridge, cooling down the air!-! .ast, the refrigerant evaporates to a gas, then flows bac' to the compressor, where the

cycle starts all over!

Washing Machine:

A washing machine (laundry machine, clothes washer, or washer) is a machine to wash

laundry, such as clothing and sheets! $he term is mostly applied only to machines that use

water as opposed to dry cleaning (which uses alternative cleaning fluids, and is performed byspecialist businesses) or ultrasonic cleaners! &ashing entails immersing, dipping, rubbing, or

scrubbing in water usually accompanied by detergent, or bleach! $he simplest machines maysimply agitate clothes in water; automatic machines may fill, empty, wash, spin, and heat in a

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cycle! /ost washing machines remove substantial amounts of water from the laundry at theend of a wash cycle, but do not completely dry it!

Operation

.et us see the important parts of the washing machine; this will also help us understand the

wor'ing of the washing machine! 0lea se refer to the image below!

1) Water inlet control valve: *ear the water inlet point of the washing machine there is water inlet control valve! &hen you load the clothes in

washing machine, this valve gets opened automatically and it closes automatically dependingon the total uantity of the water reuired! $he water control valve is actually the solenoid

valve!

2) Water pump: $he water pump circulates water through the washing machine! It wor's in

two directions, re1circulating the water during wash cycle and draining the water during thespin cycle!

3) Tub: $here are two types of tubs in the washing washing machine: inner and outer! $heclothes are loaded in the inner tub, where the clothes are washed, rinsed and dried! $he inner

tub has small holes for draining the water! $he eternal tub covers the inner tub and supports

it during various cycles of clothes washing!

Microwave Oven:

/icrowave oven is one of the most widely used household appliances! /ost of homes andmost of conveniences store and restaurants have microwave oven! $he reason for its

 popularity is that it coo's food in an ama+ingly short amount of time! $hey are also

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etremely efficient in their use of electricity because a microwave oven heats only the foodnothing else! In this article, we"ll discuss the mystery behind the magic of 2meals in a

minute3 with microwave coo'ing!

Operation

A microwave oven consists of:

#) a high voltage power source, commonly a simple transformer or an electronic powerconverter, which passes energy to the magnetron

%) a high voltage capacitor connected to the magnetron, transformer and via a diode to the

case!

) a cavity magnetron, which converts high1voltage electric energy to microwave radiation

) a magnetron control circuit (usually with a microcontroller)

-) a waveguide (to control the direction of the microwaves)

4) a coo'ing chamber

A microwave oven uses microwaves to heat food! /icrowaves are radio waves! In thecase of microwave ovens, the commonly used radio wave freuency is roughly %,-55

megahert+ (%!- gigahert+)! 6adio waves in this freuency range have an interesting

 property : they are absorbed by water, fats and sugars! &hen they are absorbed they areconverted directly into atomic motion and motion is converted into heat!

/icrowaves in this freuency range have another interesting property: they are not

absorbed by most plastics, glass or ceramics! And metal reflects microwaves, which iswhy metals cause spar' in a microwave oven! $he reason that metal reflects microwaves

is that no electronic waves resident in inside of conductor because conductor"s

conductivity is infinity as we studied in our course! $he property in this paragraph is

 possible because the freuency %,-55 megahert+ is resonance freuency of water! .et"sloo' at this in detail! /olecules of all food are consist of a dipole and have positive

charge in one side and have negative charge in another side! If we put electromagnetic

fields in this, all molecules are rearranged: 7charge is to negative! pole and 8charge is to positive pole! In this process molecules heat is produced by friction! $he freuency of

microwave oven is %,-55 megahert+ as we saw before! $hen microwave of this freuency

change the direction of electromagnetic fields %,-55,555,555 times in # second!9onseuently the heat efficiency of a microwave oven is greatly high! ou often hear that

microwave ovens coo' food 2rom the inside out!3 &hat does that mean< If you ba'e a

ca'e in a conventional oven, normally you would ba'e a ca'e at -5degrees or so, butlet"s say you accidentally set the oven at 455 degrees instead of -5! &hat is doing to

happen is that the outside of the ca'e will burn before the inside even gets warm! In a

conventional oven, the heat has to migrate (by conduction) from the outside of the food

toward the middle! ou also have dry, hot air on the outside of the food evaporatingmoisture! So the outside can be crispy and brown while the inside is moist! In microwave

coo'ing, the radio waves penetrate the food and ecite water and fat molecules pretty

much evenly throughout the food! $here is no 2heat having to migrate toward the interior by conduction3! $here is heat everywhere all at once because the molecules are all

ecited together! $here are limits of course! 6adio waves penetrate unevenly in thic'

 pieces of food (they don"t ma'e it all the way to the middle), and there are also2hot spots3 caused by wave interference, but you get the idea! $he whole heating process

is different because you are 2eciting atoms3 rather that 2conducting heat"! In a

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microwave oven, the air in the oven is at room temperature, so there is no way to form a

crust! $hat is because it heats up foods by =microwaves" instead of =heat conduction!"

Precautions:

#) >e careful of handling small euipment?instruments inside the apparatus!

%) >e careful if power is supplied to the apparatus when the casing is 'ept open!

Experimental (emonstration! Procedure:

#) $he rules and regulation were followed for opening an electronic device!

%) 0roper tools were chosen from the toolbo to open the casing of the device!) $he way the 9ourse $eacher or the .ab Instructor demonstrates the appliance were

followed!

References:

#) Howstuffwor's website, Available: www!electronics!howstuffwor's!com%) 9*@$ Asia &ebsite, Available: www!asia!cnet!com

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) @lectronics 6epair &ebsite, Available: http:??www!estineyong!com?