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Temperature vs time plots, showing the Mpemba Effect. The Mpemba effect is the name given to the observation that a liquid (typically water) which is initially hot can freeze faster than the same liquid which begins cold, under otherwise similar conditions. There is disagreement about its theoretical basis and the parameters required to produce ...
Provided the air was calm and not too far above freezing, heat gain from the surrounding air by convection was low enough to allow the water to freeze. [37] [38] [3] In Iran, this involved making large flat ice pools, which consisted of a reflection pool of water built on a bed of highly insulative material surrounded by high walls. The high ...
Globally. Food in a refrigerator with its door open. A refrigerator, commonly fridge, is a commercial and home appliance consisting of a thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to its external environment so that its inside is cooled to a temperature below the room ...
Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. A heat pump is a mechanical system that transmits heat from one location (the "source") at a certain temperature to another location (the "sink" or "heat sink") at a higher temperature. [ 1]
A defrost timer taken out of a household refrigerator. The defrost mechanism in a refrigerator heats the cooling element (evaporator coil) for a short period of time and melts the frost that has formed on it. [ 1] The resulting water drains through a duct at the back of the unit. Defrosting is controlled by an electric or electronic timer.
Blast chilling is a method of cooling food quickly to a low temperature that is relatively safe from bacterial growth. Bacteria multiply fastest between +8 and +68 °C (46 and 154 °F). By reducing the temperature of cooked food from +70 to +3 °C (158 to 37 °F) or below within 90 minutes, the food is rendered safe for storage and later ...
A 3He/4He dilution refrigerator is a cryogenic device that provides continuous cooling to temperatures as low as 2 mK, with no moving parts in the low-temperature region. [ 1][ 2] The cooling power is provided by the heat of mixing of the helium-3 and helium-4 isotopes.
An absorption refrigerator is a refrigerator that uses a heat source to provide the energy needed to drive the cooling process. Solar energy, burning a fossil fuel, waste heat from factories, and district heating systems are examples of convenient heat sources that can be used. An absorption refrigerator uses two coolants: the first coolant ...