Editing Refrigerator (section)

===Compressor refrigerators===
A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers. In this cycle, a circulating refrigerant such as [[R134a]] enters a compressor as low-pressure vapor at or slightly below the temperature of the refrigerator interior. The vapor is compressed and exits the compressor as high-pressure superheated vapor. The superheated vapor travels under pressure through coils or tubes that make up the ''condenser''; the coils or tubes are passively cooled by exposure to air in the room. The condenser cools the vapor, which liquefies. As the refrigerant leaves the condenser, it is still under pressure but is now only slightly above room temperature. This liquid refrigerant is forced through a metering or throttling device, also known as an expansion valve (essentially a pin-hole sized constriction in the tubing) to an area of much lower pressure. The sudden decrease in pressure results in explosive-like flash evaporation of a portion (typically about half) of the liquid. The latent heat absorbed by this flash evaporation is drawn mostly from adjacent still-liquid refrigerant, a phenomenon known as ''auto-refrigeration''. This cold and partially vaporized refrigerant continues through the coils or tubes of the evaporator unit. A fan blows air from the compartment ("box air") across these coils or tubes and the refrigerant completely vaporizes, drawing further latent heat from the box air. This cooled air is returned to the refrigerator or freezer compartment, and so keeps the box air cold. Note that the cool air in the refrigerator or freezer is still warmer than the refrigerant in the evaporator. Refrigerant leaves the evaporator, now fully vaporized and slightly heated, and returns to the compressor inlet to continue the cycle.

Modern domestic refrigerators are extremely reliable because motor and compressor are integrated within a welded container, "sealed unit", with greatly reduced likelihood of leakage or contamination.  By comparison, externally-coupled refrigeration compressors, such as those in automobile air conditioning, inevitably leak fluid and lubricant past the shaft seals.  This leads to a requirement for periodic recharging and, if ignored, possible compressor failure.

====Dual compartment designs====
Refrigerators with two compartments need special design to control the cooling of refrigerator or freezer compartments. Typically, the compressors and condenser coils are mounted at the top of the cabinet, with a single fan to cool them both. This arrangement has a few downsides: each compartment cannot be controlled independently and the more humid refrigerator air is mixed with the dry freezer air.<ref name=sear-dual>{{cite web |title=What is Dual-Cooling Technology? |url=https://www.sears.com/articles/appliances/refrigerators/what-is-dual-cooling-in-refrigerators.html |website=www.sears.com |language=en |access-date=13 May 2020 |archive-date=6 August 2020 |archive-url=https://web.archive.org/web/20200806175607/https://www.sears.com/articles/appliances/refrigerators/what-is-dual-cooling-in-refrigerators.html |url-status=dead }}</ref>

{{anchor|Dual compressor refrigerators}}Multiple manufacturers offer dual compressor models.  These models have separate freezer and refrigerator compartments that operate independently of each other, sometimes mounted within a single cabinet.  Each has its own separate compressor, condenser and evaporator coils, insulation, thermostat, and door.{{Citation needed|date=August 2021}}

A hybrid between the two designs is using a separate fan for each compartment, the Dual Fan approach. Doing so allows for separate control and airflow on a single compressor system.{{Citation needed|date=August 2021}}