Thermal Engineering

• Principles and Characteristics of Humidity Transducers:
• Statement 1: True; measure gaseous moisture content.
• Statement 3: True; resistive hygrometers utilize electrical resistance changes in moisture-absorbing conductive polymers.
• Statement 4 is false: Relative humidity sensors are inherently temperature sensitive, requiring active thermal compensation.
• Conclusion: 1, 3 only (Option 3).

Correct option: (3) 1,3 only

• FSSAI Preservative Standards for Sulphur Dioxide in Fruit Juices:
• Regulatory Thresholds:
• Under the Food Safety and Standards (Food Products Standards and Food Additives) Regulations, Sulphur Dioxide (added as Potassium Metabisulphite, KMS) is permitted in ready-to-serve fruit juices up to a maximum limit of $70\text{ ppm}$ ($\text{mg/kg}$).
• Acts as an antioxidant and antimicrobial agent, inhibiting polyphenol oxidase browning and microbial fermentation.
• Conclusion: 70 ppm (Option 2).

Correct option: (2) 70

Arranging the sequence correctly for Continuous and composite control modes:

The correct chronological order is Option 1: Proportional Control — Integral Control + Derivative Control.

Correct option: (1) Proportional Control — Integral Control + Derivative Control