Question

What happens to the air in a cooling and dehumidification process?

• A. Temperature and humidity increase
• B. Temperature increases, humidity decreases
• C. Temperature and humidity decrease
• D. Only humidity increases

Hint:

In cooling and dehumidification, air is cooled to condense moisture — both temperature and humidity drop as a result.

Answer 1

The Correct Option is C

In air-conditioning and psychrometric applications, cooling and dehumidification is a commonly employed process to improve indoor air quality and comfort.
This process involves passing warm and humid air over a cold surface, such as the cooling coil in an air conditioner.
As the warm moist air comes into contact with the cold surface:
- The temperature of the air decreases due to heat transfer to the cold surface.
- Simultaneously, as the air cools below its dew point, moisture condenses out, reducing the humidity of the air.
Thus, both the dry-bulb temperature (actual air temperature) and the humidity ratio (amount of water vapor per kg of dry air) decrease.
Explanation of incorrect options:
- (1) Temperature and humidity increase: This contradicts the purpose of cooling and dehumidification.
- (2) Temperature increases, humidity decreases: Cooling implies temperature should drop, not rise.
- (4) Only humidity increases: Actually, humidity decreases, not increases.
Hence, the correct understanding of the process leads us to the conclusion: Temperature and humidity decrease.