7.(a) State THREE functions of air conditioning.
(b) With referance to air conditioning, explain EACH of the following:
(i) absolute humidity;
(ii) relative humidity;
(iii) dew point.
(a) Functions of Air Conditioning (3 marks)
- Control of temperature – maintains a comfortable environment for crew/passengers and prevents overheating of machinery/electronics.
- Control of humidity – reduces excess moisture in the air to avoid condensation, corrosion, and discomfort.
- Purification/filtration of air – removes dust, bacteria, and other contaminants, ensuring good air quality.
(You could also mention ventilation and air circulation as additional functions if required.)
(b) Air Conditioning Terms (7 marks)
(i) Absolute Humidity (2 marks):
- The actual mass of water vapour present in a given volume of air.
- Expressed as grams of water per cubic metre of air (g/m³).
(ii) Relative Humidity (2 marks):
- The ratio of the actual water vapour content of the air to the maximum water vapour capacity of the air at the same temperature, expressed as a percentage.
- Shows how close the air is to being saturated.
(iii) Dew Point (3 marks):
- The temperature at which air becomes saturated with water vapour (100% relative humidity).
- If air is cooled below this temperature, condensation begins (moisture forms as dew or mist).
- Important in air conditioning to prevent condensation on bulkheads, ducts, or machinery.