Home refrigerators do not have external exhaust systems like portable AC units or clothes dryers because they operate on a different principle and have different cooling requirements.
Refrigerators work based on a closed-loop refrigeration cycle that involves compressing and expanding refrigerant gases to remove heat from the interior of the fridge. The removed heat is then expelled from the refrigerator through a heat exchanger located at the back or bottom of the unit. This heat exchanger, often referred to as the condenser, dissipates the heat into the surrounding room.
The reason refrigerators do not require external exhaust is that the amount of heat they generate is relatively small compared to the heat produced by air conditioners or clothes dryers. Refrigerators are designed to operate efficiently within the confines of a room without the need for external venting. The heat dissipated by the condenser is typically dispersed into the surrounding air, and the room's natural ventilation is sufficient to dissipate it.
On the other hand, air conditioners and clothes dryers are designed to actively remove heat from the environment and require a dedicated exhaust to expel the hot air. Air conditioners extract heat from indoor spaces and expel it outside to cool the room. Clothes dryers generate a significant amount of heat during the drying process and need to vent it outside to prevent overheating and humidity buildup.
In summary, refrigerators do not have external exhaust systems because they produce a relatively small amount of heat that can be dissipated into the room without requiring dedicated venting.