The temperature function with respect to time in a household fridge after the power is off follows a curve that depends on various factors, including the initial temperature inside the refrigerator, the surrounding ambient temperature, the insulation of the fridge, and the amount and type of food stored inside.
When the power is turned off, the refrigerator's cooling mechanism (compressor and fans) stops running, and the cooling process ceases. As a result, the temperature inside the fridge begins to rise gradually. The rate at which the temperature increases depends on the factors mentioned above.
In the first few hours after power loss, the temperature may rise relatively slowly, especially if the refrigerator is well-insulated and has a lower initial temperature. However, over time, the rate of temperature increase may become faster as the fridge starts to reach equilibrium with the surrounding room temperature.
If the fridge is full of food and well-insulated, it will tend to retain cold for a more extended period compared to an empty fridge with poor insulation. The type of food stored inside can also influence how quickly the temperature rises, as items with higher thermal mass, like large containers of water or frozen food, will help to maintain lower temperatures for a more extended period.
After several hours without power, depending on the factors mentioned above, the temperature inside the fridge may approach or equalize with the surrounding room temperature.
It's essential to keep food safety in mind during power outages. Perishable items such as meat, dairy, and certain fruits and vegetables may reach unsafe temperatures after an extended power outage, leading to potential spoilage and foodborne illness risk. If you suspect that the food inside the fridge has been at unsafe temperatures for an extended period, it's best to discard it to avoid potential health hazards.