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Forced Convection

Convection is a natural process and occurs to some extent when gases or liquids are present. Sometimes however the amount of convection is insufficient - especially when dangerous gases need to be dispersed or an area needs to be ventilated so that people can breathe. In such cases, ventilation can be speeded up using a fan or heat source. A very simple example is shown below.

Forced convection like this must be used in coal mines, to prevent the accumulation of dangerous gases, and ensure that there is enough oxygen to enable coal miners to breathe. It is also used on airplanes and manned spacraft, where carbon dioxide must be continously removed and replaced with oxygen. In spacecraft the air is passed over 'scrubbers' to removed carbon dioxide before the air is returned to the living quarters.

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