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TEMPERATURE MEASUREMENT :fire: BY : NAIF SHAHMI BIN SUKHAIMI(2018679698) …
TEMPERATURE MEASUREMENT
:fire:
BY : NAIF SHAHMI BIN SUKHAIMI(2018679698)
Most widely measured quantity
INTRODUCTION
Zeroth Law
2 bodies are in equilibrium with 3rd body, then they all in thermal equilibrium each other
Example : Thermometer
LAW
APPLICATIONS
Propulsion systems
Gas turbines
Steam Raising
Carnot cycle:
T1/T2=Q1/Q2
i) Fahrenheit
ii) Celcius
Kelvin :
T = t + 273.15
TEMPERATURE SCALES
Thermocouple remain main themperature sensor(half of industrial application)
METHODS
Temperature measurement method
Non-electrical method
Radiation method
Electrical method
Temperature sensing techniques
(f)Changes in chemical phase
Liquid crystal
Fusible Indicator
(e) Changes in emitted thermal radiation
Infrared pyrometer
Total radiation pyrometers
(d) Semiconductor junction technology
Integrated circuits
Diodes
(c) Changes in electrical properties
Thermistors
Thermocouples
Application : diesel engines
Disadvantage : The output signal requires amplification
Advantage : Good accuracy
2 categories : I) Base metal
ii) Rare metal
Choice factors : I) Ability withstand the temperature
ii) Corrosion Resistance
iii) Linearity characteristics
Different alloys = Different range
I) Consists two dissimilar conductors
ii) Produces a voltage
iii) Produce an electrical potential related to temperature
Resistance thermometers
Quartz thermometers
Disadvatage : Limited range 40C to 230C
Provides high accuracy
Advantage : Highly linear output
Quartz Crystal Oscillator
(a) Changes in physical dimensions
Bimetallic thermometers
Brass
Comprises 2 metals to prevent motion
Advantage : low cost
Application : Thermostat in air conditioner
Disadvantage : Inability to measure rapidly changing temperature
Liquid in glass thermometers
(b) Change in vapor or gas pressure
Constant volume gas thermometers
Pressure thermometers