TEMPERATURE MEASUREMENGT...TEMPERATURE MEASUREMENGT

A Temperature and Measurement PPT focuses on the fundamental concepts of temperature, its measurement techniques, and various temperature sensors used in different fields. Below is a structured outline for your Temperature and Measurement PPT:

Title Slide
Title: Temperature and Its Measurement
Subtitle: Concepts, Units, Methods, and Applications
Your Name/Institution
1. Introduction to Temperature
Definition of temperature
Importance of temperature in science and engineering
Everyday examples of temperature measurement
2. Temperature Scales
Celsius (°C)
Fahrenheit (°F)
Kelvin (K) – Absolute temperature scale
Rankine (°R) – Used in thermodynamics
3. Methods of Temperature Measurement
Contact Methods:

Thermocouples
Resistance Temperature Detectors (RTDs)
Thermistors
Mercury-in-glass thermometers
Non-Contact Methods:

Infrared thermometers
Pyrometers
4. Types of Temperature Sensors
Mechanical Sensors: Bimetallic strip, liquid expansion thermometers
Electronic Sensors: Thermocouples, RTDs, Thermistors
Optical Sensors: Infrared sensors, fiber optic sensors
5. Working Principles of Temperature Sensors
Thermoelectric effect in thermocouples
Resistance change in RTDs and thermistors
Infrared radiation in non-contact sensors
6. Applications of Temperature Measurement
Weather forecasting
Industrial processes (metallurgy, chemical industry)
Medical field (body temperature measurement, MRI)
Food and beverage industry (storage and processing)
Automotive and aerospace
7. Advantages and Limitations of Temperature Measurement Methods
Accuracy and precision
Response time
Cost-effectiveness
Environmental conditions affecting measurement
8. Conclusion
Summary of key points
Future trends in temperature sensing (IoT-based smart sensors, AI integration)
Q&A session
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1. Mechanical Department 2024-25
Temperature Measurement
Presented by
ABHISHEK S
4PS23ME003

2. Temperature Measurement
✓Temperature measuring device.
✓Resistance Temperature Detectors
✓Thermistor,
✓Thermocouples,
✓CONCLUSION

3. Temperature Scale

4. Electrical Temperature Measuring Instruments
Change in electrical properties of sensor for estimating temperature
1. Resistance Temperature Detectors (RTD)
2. Thermistors
3. Thermocouples and Thermopiles
Resistance Temperature Detectors (RTD)
•Operational Principle: RTDs work on the principle that the electrical resistance of a
metal changes with temperature. Typically, platinum is used due to its stable and
predictable resistance-temperature relationship.
•Range: -200°C to +600°C
•Sensitivity: High; RTDs offer precise, repeatable measurements, making them highly
sensitive to small temperature changes.
•Accuracy: High; more accurate than thermocouples, with an accuracy of ±0.1°C to
±0.5°C.
•Calibration Needs: Requires calibration, but once calibrated, RTDs are stable over
time.
•Cost: Moderate to high, as platinum RTDs are more expensive due to material cost.

5. Resistance Temperature Detectors (RTD)
Material Temperature coefficient of resistance Melting Point Temperature range
(α) Ω/Ω/°C °C °C
Platinum 0.00392 1773 -240 to +650
Nickel 0.00630 1455 -190 to +310
Copper 0.00425 1083 -40 to +250

6. Resistance Temperature Detectors (RTD)
Advantages
1) The sensor can be easily installed and replaced.
2) Good measurement accuracy (± 0.25% of scale range)
3) Fast response and good reproducibility.
4) Resistance to corrosion, chemicals, and oxidation.
5) Wide temperature range. (-180 °C to 760 °C )
6) Remote temperature sensing is possible.
7) No reference junction required.
8) Stable and accurate performance over a long time.
9) No necessity for any temperature compensation.
Disadvantages
1) More expansive than other instruments.
2) Large bulb size compared to thermocouple.
3) Required a separate bridge circuit system.
4) External power source required.
5) The self heating caused by current flow affects the accuracy of the
instrument.

7. Thermistors
•Operational Principle: Thermistors use ceramic or polymer materials that change
resistance with temperature. Negative Temperature Coefficient (NTC) thermistors
decrease resistance with rising temperature, while Positive Temperature Coefficient
(PTC) thermistors increase resistance with rising temperature.
•Range: Typically -55°C to +150°C, though some can go higher.
•Sensitivity: Very high, particularly NTC thermistors, which are very responsive to
small temperature changes.
•Accuracy: High in a narrow range; accuracy can be as high as ±0.05°C in the
optimal range.
•Calibration Needs: Usually require calibration for high-accuracy applications.
•Cost: Low to moderate, generally less expensive than RTDs.

8. Thermistors
Advantages
1) Small size and low cost.
2) Fast temperature response.
3) High sensitivity.
4) Suitable for precise temperature measurement and control.
5) Need simple electric circuitry.
6) No need reference junction.
Disadvantages
1) Response is non linear.
2) Not suitable for measurement of high temperature.
3) Required external power source and bridge circuit.
4) Temperature span is limited.

9. Comparison of RTD and Thermistors
# Characteristic RTD Thermistors
1Change in resistance Positive, Resistance increase Negative, Resistance decreases
with temperature with increase in temperature with increase in temperature
2Temperature resistance Approximately linear
relationship RT = R0 [ 1 + α T]
3Operating range -160°C to 600°C -100°C to 300°C
4Composition Platinum, Copper, NickelMetallic oxides like Manganese,
Nickel, Copper, Iron, Titanium,
Uranium
5Sensitivity Lower Higher
6Cost High Low

10. Thermocouples

11. Thermocouples
Thermo means heat and couple means to make the junction.
Thermocouple works on thermoelectric effect.
It consist of
(1) Sensing element with thermal wall (Sheathing), measuring Junction
(2) Lead wire
(3) Reference junction
(4) Current measuring and indicating device, millivoltmeter or potentiometer
type instrument.

12. Thermocouples
•Operational Principle: Explain the Seebeck effect, where a
temperature difference creates a voltage that can be measured.
•Range: Wide range, typically -200°C to +1800°C, depending on
the type.
•Sensitivity: Moderate; depends on the metal combination.
•Accuracy: Moderate to high but can vary with type and
calibration.
•Calibration Needs: Require periodic calibration to maintain
accuracy.
•Cost: Generally low, though higher for specialized types.

13. Seebeck effect :- When the junctions of two different metals are
maintained at different temperature, the EMF is produced in the
circuit. This is known as Seebeck effect.
The conductor 1 is maintained at
T+∆T temperature (Hot Junction)
The conductor 2 is maintained at
temperature ‘T’. (Cold Junction)
Since the junctions are maintained at
different temperature, the EMF‘U’
flows across the circuit.

14. Thermocouple
Advantages
1) Thermocouple have a better response.
2) They have a higher range of temperature measurements.
3) They sensing elements of thermocouple is easily installed.
4) Cheaper than RTD.
5) Very convenient for measuring the temperature at one particular point in
a piece of apparatus.
Disadvantages
1) Lower accuracy and as such they cannot be used for precision work.
2) Limited life of thermocouple.
3) The circuitry for thermocouple is very complex.
4) Expensive wire.
5) Need known reference.

15. Comparison of Thermocouple and Thermistors
# Characteristic
1 Speed of response
2 Measurement accuracy
3 Use
4 Temperature range
Thermocouple Thermistors
High Low
Good Less
Not much reliable and Very reliable and convenient
complex
-250°C to 2500°C -160°C to 600°C
Comparison of Thermocouple and RTD
# Characteristic Thermocouple RTD
1Response Faster Slower
2Temperature rangeHigher Lower1
3Sensitivity Low High
4Cost and Life Low and shorter High and Longer
5Reference junctionRequired Not required
6Accuracy Lower Higher
7Effect of ambient temp.Effected on accuracyNot effected on accuracy

18. Recommendations
Based on the analysis, recommend the most suitable device for each application and justify each choice
•Monitoring Temperature Variations in a Car Engine Block:
oRecommended Device: Thermocouple
oJustification: Thermocouples are durable and can measure high temperatures at multiple points around the engine block.
They offer fast response times and can withstand harsh conditions, though they need occasional recalibration.
•Monitoring Temperatures in a Furnace of a Power Plant:
oRecommended Device: RTD or Thermocouple (Type K or Type S for high temperatures)
oJustification: For consistent and accurate temperature measurements in high-temperature environments, thermocouples
(particularly high-temperature types) or RTDs are ideal. RTDs offer stable and precise readings, while high-temperature
thermocouples can endure extreme heat within furnaces.

19. THANK YOU