The Physics of Cooling Techniques :: thermodynamics physics refrigerator

There are some(prenominal) reasons for wanting to cool things, but whatever the reason, the Second Law of Thermodynamics dictates that temperature reduction something will take effort (sorry, no spontaneously cool sodas). different techniques have been developed to address this issue, each having its own limitations and ideal uses. The intimately commonly used method of cooling is with vapor-compression cycles, because it is fairly easy to wee-wee a cooling device chartering this method and the cost is downhearted. In fact, effected refrigerators use this method of cooling to keep your leftovers and drinks chilled Air conditioners also employ a vapor-compression cycle to cool the ambient air temperature in a room. Basically, vapor-compression refrigeration employs a warmness engine run backwards, so heat energy is taken from a cold reservoir and deposited into a zesty reservoir. By the Second Law of Thermodynamics, heat energy does not spontaneously transfer from a cold to a acerbic reservoir. In couch to have heat transfer in that direction (and not from from hot to cold, as the system is naturally inclined to do), it is necessary to do mold on the system. Vapor-Compression infrigidation Cycle This refrigeration cycle is approximately a Rankine cycle run in reverse. A working fluid (often called the refrigerant) is pushed finished the system and undergoes state changes (from liquid to gas and back). The latent heat of desiccation of the refrigerant is used to transfer large amounts of heat energy, and changes in closet are used to control when the refrigerant expels or absorbs heat energy. However, for a refrigeration cycle that has a hot reservoir at approximately room temperature (or a bit higher) and a cold reservoir that is craved to be at around 34F, the boiling point of the refrigerant needs to be fairly low. Thus, various fluids have been identified as practical refrigerants. The most common include ammo nia, Freon (and other chlorofluorocarbon refrigerants, aka CFCs), and HFC-134a (a non-toxic hydrofluorocarbon). Stages of the Vapor-Compression Refrigeration Cycle The Vapor-Compression Refrigeration Cycle is comprised of four steps. The conceptual figure of the influence shows the PV changes during each part.Part 1 Compression In this stage, the refrigerant enters the compressor as a gas under low pressure and having a low temperature.