In psychrometrics, cooling air with no change in its specific humidity (humidity ratio) is termed what process?

Introduction / Context:
Air-conditioning processes are often described on the psychrometric chart. Distinguishing sensible versus latent processes is essential for sizing coils and understanding coil bypass factor, apparatus dew point, and comfort control strategies.

Given Data / Assumptions:

• Specific humidity (humidity ratio) remains constant.
• Air dry-bulb temperature decreases.

Concept / Approach:
Sensible cooling reduces dry-bulb temperature without removing moisture. On the psychrometric chart, the state point moves horizontally to the left at constant humidity ratio. Latent cooling would move the point down-left as moisture condenses. Evaporative cooling typically increases humidity ratio while reducing dry-bulb toward wet-bulb, not keeping humidity ratio constant.

Step-by-Step Solution:

Verification / Alternative check:
Coil models with 100% bypass (hypothetical) or heat exchangers that do not reach dew point show purely sensible temperature change, matching the constant-humidity path.

Why Other Options Are Wrong:

• Latent cooling requires moisture removal; humidity ratio decreases.
• Evaporative cooling increases humidity ratio; not constant.
• Adiabatic saturation and isothermal humidification describe different moisture–temperature interactions.

Common Pitfalls:
Assuming any cooling coil always dehumidifies; only when coil surface is below dew point will latent cooling occur.

Final Answer:
Sensible cooling