Thermo Microwave

8/13/2019 Thermo Microwave

http://slidepdf.com/reader/full/thermo-microwave 1/40



Introduction & Overview

Past Microwave Oven

Present Microwave Oven

Future Microwave Oven

Conclusion





Generally, a microwave oven (or microwave) is a kitchenappliance that heats food by bombarding it withelectromagnetic radiation in the microwave spectrum causingpolarized molecules in the food to build up thermalenergy ; food is more evenly heated throughout.

Hence, it is imperative to understand the past, the present aswell as the future technology of microwave and its relationwith the very principles of thermodynamics. The developmentis another important factor to take into account for that

matter.



Figure 1 : Past microwave oven design



Figure 2: The original microwave oven patent by Dr. Percy L.Spencer







When was

microwave

invented?

Who

invented the

microwave?

Where was it

originated

from?

The early

development

process

(How?)



•The microwave oven was accidentally

stumbled upon in 1946 (In the midst of

World War 2 )When

•Dr. Percy Spencer was working as an

engineer with the Raytheon Corporation at

the time.Who

•Howland, Maine, United States.Where



Spencer discovered

something very

unusual one day

while working on a

radar-related

research project.

- A new vacuum

tube known as a

magnetron.

- Concluded that

the observed effects

in each case were all

attributed to

exposure to low-

density microwaveenergy

In late 1946, this

resulted in the

Raytheon

Company's first

patent proposing

that microwaves be

used to cook food



The first commercial microwave oven hit themarket with a cost between $2,000 and$3,000

Finally in 1965, Raytheon introduced the firstcountertop domestic oven, much improved inthe area of size, safety and reliability thanolder models with a cost of $500

In1976, the microwave became a morecommon household appliance.



There is a finite

amount of power in

the microwaves

being produced

Electromagnetic waves

are waves made up of

alternating electric and

magnetic fields. For

this discussion, we’re

more concerned with

the alternating electric

fields because charged

particles readily react

when exposed to them

- That is, when a

positively charged

particle is exposed to an

electric field, it

experiences a force (due

to the field) pointing in

the direction of the field.

- By contrast, when a

negatively charged

particle is exposed to the

same field, it experiences

a force in the directionopposite to the field

How Does It Work?



Now, since an

electromagnetic

wave is made up

of alternating

electric fields, a

charge exposed

to it will

experience forces

regularly

changing in

direction.

- For watermolecules, which are

dipoles, the net effect

would force the

molecules into

rotation.

- Since the fields arealternating, the

rotation will change

from clockwise to

counterclockwise at

regular time intervals

The agitated

water molecules

would then

possess heat

energy that canrub off (much like

friction) to nearby

molecules



If the water molecules are welldistributed in the body subjected to

the microwave (like food, for

example), then the entire body can

heat up quickly – not to mention,

uniformly.





Thecomponents

of themicrowaves

How does itwork?

The lawinvolved



Figure : Schematic diagram of a microwaveoven

Figure 4 : Schematic diagram of a microwave oven



http://www.google.com/imgres?start=124&sa=X&biw=1366&bih=585&tbm=isch&tbnid=edtawF2Z5MKbQM:&imgrefurl=http://hackaday.com/2013/07/12/the-most-advanced-microwave-youll-ever-own/&docid=XYEfO2vnhoSu2M&imgurl=http://hackadaycom.files.wordpress.com/2013/07/raspberry-pi-microwave.jpg?w=580&h=325&w=580&h=326&ei=IyeWUsa4MoWOrQeTkYCIDw&zoom=1&ved=1t:3588,r:30,s:100,i:94&iact=rc&page=8&tbnh=168&tbnw=293&ndsp=18&tx=172&ty=99

http://www.google.com/imgres?biw=1366&bih=585&tbm=isch&tbnid=NVLxGp4T0_KIqM:&imgrefurl=http://www.independent.co.uk/life-style/gadgets-and-tech/features/the-10-best-microwave-ovens-8515680.html&docid=pfCBz7_r-BhizM&imgurl=http://www.independent.co.uk/incoming/article8515648.ece/ALTERNATES/w620/tb1.jpg&w=620&h=465&ei=QiiWUv7SEMijrQee9oHYDg&zoom=1&ved=1t:3588,r:12,s:0,i:115&iact=rc&page=1&tbnh=181&tbnw=228&start=0&ndsp=16&tx=133&ty=102





Microwave cooking is a process of exciting the water molecules infood.

Food substance that does not contain water, such as oil, usuallydoes not get cooked by microwaves.

Water molecules are polar molecules with one end dominated by anegative charge and the other by a positive charge.

The typical frequency of the microwave produced by a microwaveoven is of the order of 2.5 GHz (1 GHz = 1,000,000,000 Hz).

How does it work ?



Since the water molecules are polarized, the water

molecules in the food will also get pulled back and forthat the rate of about 2.5 billion times per second.

This rapid back-and-forth motion between water

molecules creates friction, and hence heat.

In practice, the amount of microwave energy getabsorbed and reflected can be measured for each foodsubstance.

Food substance contains a substantial amount of water

is a good absorber of microwave energy.



First law of thermodynamics

Involving heat transfer◦ Radiation

◦ Conduction

◦ Convection

The law involved



Radiation◦ Unlike conduction and convection, radiation does not require

physical contact between the heat source and the food beingcooked. Instead, energy is transferred by waves of heat orlight striking the food.

Conductiono Heat transfer by means of molecular agitation within a

material without any of the material as a whole.

Convection◦ Convection refers to the transfer of heat through a fluid,

which may be liquid or gas.◦ Convection is actually a combination of conduction and a

mixing in which molecules in a fluid (whether air, water orfat) move from a warmer area to a cooler one.



Microwave cooking relies on radiation generatedand penetrate the food, where it excites water

molecules, creating friction heat.

This energy then spreads throughout the food byconduction (and convection in liquids).

As the water molecules rotate, they bump intoother molecules surrounding them and transfersome of their kinetic energy.

If the particles in the food have more kineticenergy, then the food will be hotter.



Steaming:◦ Water is heated by conduction through the wok.

◦ The internal energy of water increased further whenit changes to steam at 100 C.

◦ When the steam touches the food, it condensatesand releases the latent heat to the food.

◦

The food is hence cooked.



-Micro-waving:◦ In the microwave oven, electrical energy is

converted to microwave energy by magnetron.◦ The microwave is emitted to everywhere inside the

cooking chamber.

◦ When the microwave reaches the food and gets

absorbed by the water molecules there, the food isheated by radiation.

◦ Once the surface of the food is heated, the internalof the food (about 3.5 – 5 cm below the surface)where microwave cannot reach is heated by

conduction.







There are 4 types of future microwave oven can be

designed are such as

Mobile Microwave Oven

Touch Screen Microwave Oven Google Youtube Microwave Oven

Mixture of all above 3 types microwave oven

with some other additional features as well



Mobile

Microwave

Oven

Operate using battery such as :

- Laptops Handphones

Ease for food

products

preparation

Ease for carry and move around

anywhere at anytime :

- Less weight Small in size

Ease for

reheating

process





Google Youtube Microwave Oven

Has free mobile internet connection

Microwave oven made of fully viewable glass screen

Save & fit into user cooking time by having funs Watching movies, playing video games and browsing

web pages on microwave oven front glass screen

Just required an eye tracking while wait food to cook Movie or games will disconnect automatically once the

food is finished cook



The door will release automatically to reheat the food if

the food heated is not reliable

Setting will generate automatically once type of food becook is pressed for various types of food data presented

The recipes of cooking for those types of food will installin the microwave oven

The data presented is divided into

Western section : Italian, Russian, Americans and so on Asian section : Japanese, Chinese, Malay, Indonesian,

Indian, Thai and many more



Operate vary products at one time simultaneously Save time waiting for each product to reheat or cook

Save to consumed very less electricity Lowering the electric bill charge

Environmental friendly

Free from radiation effect

Become user friendly

Use solar, biomass or nuclear energy If electricity is run out

Even totally not using electric energy at all







PAST PRESENT FUTURE

1. Larger size, about the size

of refrigerator.

2. Expensive.3. High- energy consumer

(not environmental

friendly).

4. Water- cooled, so that it

required a good

plumbing job.

5. No timer.

6. The microwave radiation

is produced by the

magnetron.

1. The size is smaller than

the past microwave oven.

(easy to handle)1. Affordable.

2. Multipurpose. (can be

used for many usage

instead of heating)

3. Have timer. (analogue and

digital timer)

4. Use dielectric heating.

1. The size smaller than the

present microwave oven.

(easy to carry)2. Cheap and easy to buy

with variation.

3. Multitask and less energy

consumption. (can

perform many task in

multipurpose)

4. Have timer,( touch screen

digital timer)

5. User friendly. (can save

time)

6. Use biomass, solar or

nuclear energy to operate.

(high and best in function)

7. Various regional food

types recipes are installed

in system.





Documents

Thermo Microwave