temperature sensors

Views:
 
Category: Education
     
 

Presentation Description

-

Comments

Presentation Transcript

MEMS &NANO TECHNOLOGY:

MEMS &NANO TECHNOLOGY TEMPERATURE SENSORS BY S.MOHAMED FAYAS 2010606109

INTRODUCTION:

INTRODUCTION Temperature is defined as a measure of velocity of fluid particles. It is a property which is used to determine the degree of hotness or coldness or the level of intensity of a body. Temperature sensors are the devices which are used to measure the temperature of an object.

TEMPERATURE SENSORS:

TEMPERATURE SENSORS 1.BIMETALLIC STRIP. 2.RESISTANCE TEMPERATURE DETECTOR. 3.THERMOCOUPLES. 4.THERMOPILES. 5.THERMISTORS. 6.PYROMETER. 7.THERMODIODE& 8.THERMO-TRANSISTORS.

BIMETALLIC STRIP:

BIMETALLIC STRIP PRINCIPLE: It is based on change in dimension of the metal. i.e.expands or contracts when there is a change in a temperature. The expansion or contraction depends upon the thermal expansion coefficient.

BIMETALLIC STRIP:

BIMETALLIC STRIP

WORKING OF BIMETALLIC STRIP:

WORKING OF BIMETALLIC STRIP Two pieces of metal with different coefficients of thermal coefficients are bonded together to form the metallic strip. It is in the form of cantilevar beam. When the strip is subjected to a temperature higher than the bonding temperature ,it will be bent in ine direction. If it is subjected to a temperature lower than the bonding temperature,It will be bent in the other direction.

CALCULATION OF BIMETALLIC STRIP:

CALCULATION OF BIMETALLIC STRIP Where E 1 and h 1 are the Young's Modulus and height of Material One E 2 and h 2 are the Young's Modulus and height of Material Two. ε is the misfit strain, calculated by α 1 is the Coefficient of Thermal Expansion of Material One α 2 is the Coefficient of Thermal Expansion of Material Two. ΔT is the current temperature minus the reference temperature

SELECTION OF BIMETALLIC STRIP:

SELECTION OF BIMETALLIC STRIP High coefficient of expansion. High ductility. High modulus of elasticity.& High electrical conductivity.

VARIOUS MATERIALS USED IN BIMETALLIC STRIP:

VARIOUS MATERIALS USED IN BIMETALLIC STRIP MATERIAL THERMAL CO.OF EXPANSION MODULUS OF ELASTICITY Yellow brass 2.02x10^-5 96.5 invar 1.7x10^-6 147 Stainless steel 1.6x10^-5 193 Monel 400 1.35x10^-5 179 Inconel 702 1.25x10^-5 217 APPLICATION : Clocks Thermostats Thermometers Heat engines Electrical devices

ADVANTAGES &DISADVANTAGES:

ADVANTAGES &DISADVANTAGES ADVANTAGES: 1.Cost is low. 2.Negligible maintanance expence. 3.Stable operation over extended period of time. DISADVANTAGES: 1.Not suitable for more than 400°c. 2.Permanent deformation of metallic strip may occur.

THANK YOU:

THANK YOU

authorStream Live Help