The cooling is often realized by way of a refrigeration cycle, but occasionally evaporation or free of charge cooling is utilised. Air conditioning devices will also be built determined by desiccants (chemical substances which take away moisture with the air). Some AC units reject or keep warmth in subterranean pipes.[two] https://drive.google.com/drive/folders/1DwQcVWGr5RtTFleX78g087Tcbb3eCLQO