Definition check in psychrometry The temperature indicated by a thermometer not affected by air moisture content is called:

Mechanical Engineering Heat Transfer, Refrigeration and Air Conditioning Difficulty: Easy
Choose an option
  • A
    Wet-bulb temperature
  • B
    Dry-bulb temperature
  • C
    Dew-point temperature
  • D
    Adiabatic saturation temperature
  • E
    Sphere temperature

Answer

Correct Answer: Dry-bulb temperature

Explanation

Introduction / Context:Psychrometric properties are essential in HVAC design and analysis. Distinguishing between dry-bulb, wet-bulb, and dew-point temperatures is fundamental for chart reading and load calculations.

Given Data / Assumptions:

  • Standard atmospheric air mixture with water vapour.
  • Thermometer measuring in free air without a wetted wick.

Concept / Approach:Dry-bulb temperature (T_db) is the ordinary air temperature measured by a standard thermometer shielded from radiation and without evaporative effects. Wet-bulb temperature uses a wetted wick and airflow to register evaporative cooling. Dew-point temperature is the saturation temperature corresponding to the partial pressure of water vapour.

Step-by-Step Solution:Identify measurement without moisture effects → dry-bulb.Recognize that wet-bulb requires a wetted wick and airflow.Dew-point is not directly measured by a dry thermometer; it is inferred from moisture content.

Verification / Alternative check:On the psychrometric chart, dry-bulb is the horizontal axis, reaffirming its role as the basic temperature measure independent of immediate moisture interaction at the sensor.

Why Other Options Are Wrong:Wet-bulb explicitly depends on evaporation; dew-point is a moisture property; adiabatic saturation temperature is a process temperature found by a specific apparatus.

Common Pitfalls:Exposing dry-bulb thermometers to radiation or poor shielding leads to biased readings; ensure proper shielding and airflow.

Final Answer:Dry-bulb temperature

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