1. COOLING AIR © Commonwealth of Australia 2010 | Licensed under AEShareNet Share and Return licence

2. Hello, I would like to show you the three most common methods of cooling air. Hello, I would like to show you the three most common methods of cooling air. Usually, the main function of an air conditioning system is to cool the air in the zone to a desirable temperature. In most cases this will mean a room temperature in the range of 23.5 °C to 24.5 °C. Usually, the main function of an air conditioning system is to cool the air in the zone to a desirable temperature. In most cases this will mean a room temperature in the range of 23.5 °C to 24.5 °C. The three most common methods of cooling air are: The three most common methods of cooling air are: direct air cooling with refrigerated cooling coils direct air cooling with refrigerated cooling coils indirect air cooling with chilled water coils indirect air cooling with chilled water coils evaporative cooling. evaporative cooling. © Commonwealth of Australia 2010 | Licensed under AEShareNet Share and Return licence

3. Lets look at a direct air cooling system with refrigerated cooling coils. Direct air cooling systems with refrigerated cooling coils are air conditioners which use a refrigeration system to directly cool the air being supplied to the zone. © Commonwealth of Australia 2010 | Licensed under AEShareNet Share and Return licence

4. In these systems the evaporator would be a finned evaporator with 2–3mm fin spacings. In these systems the evaporator would be a finned evaporator with 2–3mm fin spacings. The evaporator temperature would be expected to have a saturation temperature of approximately 2 °C to 5°C but this could be slightly higher on units which have special applications. The evaporator temperature would be expected to have a saturation temperature of approximately 2 °C to 5°C but this could be slightly higher on units which have special applications. Generally, the lower the evaporator temperature, the more moisture will be removed from the air. Therefore, those systems which have a high latent heat load could have a lower saturation temperature than others to assist in the removal of the moisture from the air. Generally, the lower the evaporator temperature, the more moisture will be removed from the air. Therefore, those systems which have a high latent heat load could have a lower saturation temperature than others to assist in the removal of the moisture from the air. © Commonwealth of Australia 2010 | Licensed under AEShareNet Share and Return licence

5. This water is then pumped to cooling coils which are very similar to an evaporator coil. Air passes through these coils which, at 5°C, are at a similar temperature to what an evaporator would be, and therefore the air gets a similar amount of cooling as it would in a directly refrigerated system. Air passes through these coils which, at 5°C, are at a similar temperature to what an evaporator would be, and therefore the air gets a similar amount of cooling as it would in a directly refrigerated system. Indirect air cooling with chilled water coils is an alternative system to the direct cooling by refrigerated coils. This system has a refrigeration unit to chill an amount of water to a temperature of approximately 5°C. This system has a refrigeration unit to chill an amount of water to a temperature of approximately 5°C. © Commonwealth of Australia 2010 | Licensed under AEShareNet Share and Return licence

6. As the air passes through the water some of the water evaporates thus absorbing latent heat of evaporation, most of which comes from the air. This has the effect of dropping the temperature of the air. As the air passes through the water some of the water evaporates thus absorbing latent heat of evaporation, most of which comes from the air. This has the effect of dropping the temperature of the air. These systems are not suitable for all applications and do not work as efficiently as refrigerated systems. These systems are not suitable for all applications and do not work as efficiently as refrigerated systems. Evaporative cooling systems are very different to those already discussed. These systems pass air through a screen which is wetted with water. Evaporative cooling systems are very different to those already discussed. These systems pass air through a screen which is wetted with water. © Commonwealth of Australia 2010 | Licensed under AEShareNet Share and Return licence