Question

With the aid of a simple sketch, explain the "trouble spots" in a basic air conditioning unit and with reference to your sketch, explain the following:

(a) How the problem of increase in humidity of cooled air is overcome?

(b) How discomfort caused by the excessive drying effect of heated air is overcome?

Answer 1

Trouble Spots in a Basic Air Conditioning Unit

Refrigerant Leakage: Commonly occurs at the compressor shaft seal, condenser, dryer, oil separator, evaporator coils, or damaged pipes.
Condenser: Insufficient water or air flow and dirty tubes may cause high-pressure (HP) trip.
Filters: Blocked intake and recirculation filters lead to poor airflow.
Dryer & Expansion Valve: Can experience icing or short cycling, causing system inefficiencies.
Evaporator Coil: Dirt accumulation leads to poor heat transfer and icing.
Electrical Problems: Malfunctioning of LP/HP trips, oil differential pressure switches, thermostats, solenoid valves, motors, or fans.
V-Belts: Wear and breakage can disrupt fan or motor operation.
Expansion Valve Malfunction: Leads to improper cooling.
Compressor Issues: Damage due to liquid refrigerant entering the suction line or inadequate lubrication.

Part (a)

In hot climates, when cooling air, its relative humidity may rise to uncomfortable levels (up to 100%). To address this issue:

De-Humidification Process:

The air is overcooled first to reduce its temperature below the dew point, causing the excess moisture to condense out of the air.
The cooled, dry air is then reheated to bring it back to a comfortable temperature and humidity level suitable for human comfort.
This ensures the air supplied to the space is not excessively humid.

Part (b)

In cold climates or winters, air may become excessively dry when heated, leading to discomfort for occupants. To manage this:

Humidity Control Through Humidification:

A humidifier is fitted inside the Air Handling Unit (AHU).
The humidifier injects steam or water mist into the heated air to maintain a relative humidity of approximately 40%, which is considered comfortable.
This ensures that the heated air does not cause dryness in the indoor environment, improving comfort for occupants.

✓ Verified Model Answer (Text Solution)

In hot climates, when cooling air, its relative humidity may rise to uncomfortable levels (up to 100%). To address this issue:

De-Humidification Process:

In cold climates or winters, air may become excessively dry when heated, leading to discomfort for occupants. To manage this:

Humidity Control Through Humidification: