ipc project (2)

8/13/2019 Ipc Project (2)

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Temperature sensors

Team Members

Imtisal-e-Noor

Arooj Fatima

Taibah Jaffery

Farhan YaqoobAyaz Naveed


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temperature

Temperature

Energy level of matter

Evidenced by some physical change in matter

Temperature sensorMeasure temperature by some change in physical

characteristic.

Critical parameter for several processes andoperations


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Two basictypes oftemperature

sensors

Contact

type:

Measure their owntemperature.

Makes use ofconduction

Non-contact

type:

se convection andradiation to monitor

changes in temperature

Type of temperature sensors


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Thermocouple

!esistive temperature devices" !T#s and thermistors$

%imetallic devices

&i'uid e(pansion devices

Molecular change of state sensor

)ilicon diode temperature sensor

*nfrared temperature sensor

Contact Type Temperature )ensors

Non-contact Type Temperature )ensor


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WORKING PRINCIPLE: Converts thermal energyinto electrical energy.

%ased on the difference inthe conductivities of the two

wire metals that thethermocouple is made of+ at

a given temperature.This conductivity differenceincreases at highertemperatures andconversely+ the conductivitydifference decreases atlower temperatures.

)everal types based on thecombination of metals used

Thermocouple


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Advantage:)elf powered

)imple

*ne(pensive

,ide temperature range

isadvantages:Cold unction compensation

&east sensitive

&east stable

E(tension leads re'uired


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oltage

arying parameter

/st order 0dy1dt 2 y 3 k4"t$

5rder

-678 to /798 C

!ange

6-9 sec

!esponse time

)teel industry Thermoelectric cooling )afety

pplication


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WORKING PRINCIPLE: converts thermalenergy to resistance

,orkingChange in resistance with

change in temperatureTwo types ; !T# igher initial cost than thermocouples

&ess rugged in high vibration environments.


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.aryingparameter

!esistance

5rder !T#-linearThermistor-&inearoverashortrange?rdorderbeyondthisrange-)teinhart->artE'uation

!ange

!T#:-688to988CThermistor:-@8to6A8C

!esponsetime

!T#:6-9secThermistor:/-6sec

pplication Te(tileindustriesChemicalindustries4oodindustries


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WORKING PRINCIPLE: converts temperaturescale into motion.

,orkingMade of two pieces of

metal are put together orglued together into one.Every metal has differentcoefficient of e(pansion+ ifthe two pieces of metalthat has united thedifferent e(pansion

coefficients of the secondoint of the metal will bendwhen heated.

%imetallic devices


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Advantages:*ne(pensive

=ortable

)imple construction without leads

No power supply re'uired

isadvantages:&imited accuracy and sensitivity

alues cannot be easily recorded

Easily de-calibrated due to mechanical shock


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aryingparameter

E(pansion

pplicationMechanical clock

Thermostats

>eat engine

Circuit breaker

Electric *ron

5rder&inear

!ange

-/8 to //8 C

!esponse tim4ast


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WORKING PRINCIPLE:smiconductor diodes havetemperature-sensitive voltage vs. current characteristics

,orking*f two identical transistors areoperated at different but

constant collector currentdensities+ then the differencein their base-emitter voltagesis proportional to the absolutetemperature of the transistors.This voltage difference is thenconverted to a single endedvoltage or a current. n offsetmay be applied to convert thesignal from absolutetemperature to Celsius or4ahrenheit.

)ilicon diode temperature sensor


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Advantages:

Cryogenic temperature sensorEasy to interface with other electronics for display and

control

ccurate

*ne(pensive

ra!ba"#s:&imited temperature range "-@8 to 2/68BC typical$

)ome devices are inclined to oscillate unless

precautions are taken


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!ange

-99 to /98 C


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WORKING PRINCIPLE: li'uid e(pands as it get warmer

,orkingElements and compoundse(pand as their

temperature increases.&i'uids or solids thate(pand at a constant rateover the desiredtemperature range areused so that the amountthey have e(panded can

be measured andcompared against knowne(pansion rates todetermine the temperature

Thermometers


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dvantagesCheap

#urable

Easily calibrated

#isadvantages#isplay is harder to read

)low response

4ragile

Cant be used for thermograph

#oes not work below freeing point


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WORKING PRINCIPLE: )tate of material changes dueto change in temperature.

%asically these sensorsmeasure the change instate of a material due to avariation in temperature.These are non electric

devices and serve auni'ue purpose.Commercially availabledevices of this type are inthe form of labels+ pellets+crayons+ or lac'uers.

Change-of-state labelsindicate temperature in B4and BC.

Change of state sensors


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Advantages:,hen re'uirement is a non-reversing indication they are 'uite useful

small+ rugged+ indicator that continuously updates temperature )implest devices employed for fast measurement of temperature.

vailable in variety of shapes+ sies and forms.

Comparatively cheaper than other temperature sensors.

Measure a wide range of temperature.

ra!ba"#s: !esponse time is comparatively slow

Not as accurate as some other types

Most of these devices are meant for one time use only


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.aryingparameter)tate

change

5rderModerately

linear

!esponsetimeslow

pplicationChemical%iological

sensing


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WORKING PRINCIPLE: at specific temperature +certainintensity of infrared radiations emits

Every form of matterwith a temperatureabove absolute eroemits infrared radiation.

The cause of this is theinternal mechanicalmovement ofmolecules. The intensityof this movement

depends on thetemperature of theobect.

*nfrared sensors


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*nfraredintensity

aryingparameter

=lancks&aw

E(ponential

5rder

-98 to ?888C

!ange

4ast

!esponse time

%rewing Meteorolog

y

Climatologypplication


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Comparison 5f %asic Temperature Types


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Comparison 5f %asic Temperature Types


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Conclusion

The sensors we have discussed above all have their

own uni'ue features.

the decision of which one to use will be based upon the

re'uirement )ince most sensor choices overlap in temperature

range and accuracy+ selection of the sensor will depend

on how it will be integrated into a system.


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ipc project (2)

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