• All building needs air conditioning. For smaller buildings, this can be provided by A/C units but once the building reaches a certain size it becomes cost-effective to use a centralized system.
• Centralized systems use “chillers” which are basically giant A/C units but they work slightly differently because of their size.
• Chillers generate chilled water which is used to provide air conditioning in buildings. All building generate a lot of unwanted heat, whether is solar heat gain from the sun beating down on it or from the occupants inside and the equipment they use.
• This heat needs to be removed to keep the people inside at a comfortable temperature but also to make sure electrical and mechanical equipment is kept within certain thermal limits otherwise these will break.
• Chillers are typically located in the basement or on the roof. Rooftop chillers tend to be air cooled whereas basement chillers tend to be water cooled.
• By “cooled” we refer to the method it uses to discard the unwanted heat into the atmosphere which was picked up in the building.
• Water cooled chillers will use cooling towers whereas air cooled chillers will blow air across their condenser, much like an A/C unit, to disperse the unwanted heat into the atmosphere.
• Chillers use refrigerant gas to move the unwanted heat between the evaporator and the condenser.
• The chilled water is generated in the evaporator and this is sent around the building by a pump to collect the unwanted heat and bring it back to the evaporator to be cooled down.
• The refrigerant collects this heat and moves it to the condenser. The condenser puts this unwanted heat into another loop which is sent by a pump to the cooling towers to send it into the atmosphere or it will send it to a cooling coil where a fan blows the heat away, much like you blow onto a hot spoon of soup to cool it down.

SOURCE : theengineeringmindset.com


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