Tuesday, March 19, 2019
The Physics of Cooling Techniques :: thermodynamics physics refrigerator
There are many reasons for wanting to coolheaded things, but whatever the reason, the southward Law of Thermodynamics dictates that chill something will eat effort (sorry, no spontaneously cool sodas). Different techniques have been develop to address this issue, each having its own limitations and ideal uses. The around commonly employ method acting of cooling is with vapor-compression bouts, because it is fairly easy to construct a cooling device employing this method and the cost is low. In fact, conventional refrigerators use this method of cooling to keep your leftovers and drinks chilled Air conditioners also employ a vapor-compression rhythm method to cool the ambient air temperature in a room. Basically, vapor-compression refrigeration employs a high temperature engine elapse backwards, so heat energy is interpreted from a cold reservoir and deposited into a hot reservoir. By the Second Law of Thermodynamics, heat energy does not spontaneously transfer fr om a cold to a hot reservoir. In order to have heat transfer in that direction (and not from from hot to cold, as the agreement is naturally inclined to do), it is necessary to do work 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 through the system and undergoes allege changes (from liquid to fellate and back). The latent heat of vaporization of the refrigerant is apply to transfer large amounts of heat energy, and changes in pressure are utilize to control when the refrigerant expels or absorbs heat energy. However, for a refrigeration cycle that has a hot reservoir at around room temperature (or a bit higher) and a cold reservoir that is desired 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 ammonia, Freon (and other chlorofluorocarbon refrigerants, aka CFCs), and HFC-134a (a non-toxic hydrofluorocarbon). Stages of the Vapor-Compression infrigidation Cycle The Vapor-Compression Refrigeration Cycle is comprised of four steps. The conceptual figure of the process shows the PV changes during each part. voice 1 Compression In this stage, the refrigerant enters the compressor as a gas under low pressure and having a low temperature.