Particles on the order of 10 μm or less are called PM10 (or coarse particulate matter). The refrigerant picks up the heat from the air, changing its state into a low-temperature and low-pressure gas, and goes back to the compressor again. The heat of the indoor air moves to the refrigerant and the air is cooled. The refrigerant turned into a low-temperature and low-pressure liquid at the expansion valve is transferred to the evaporator (heat exchanger), where heat is exchanged between the refrigerant and indoor air. Depressurized refrigerant expands, dropping the temperature and changing its state into a liquid of low temperature and pressure. The liquefied refrigerant moves to the expansion valve that decreases the pressure of the refrigerant. Releasing the heat, the refrigerant changes its state to a medium-temperature and high-pressure liquid. This releases the heat of the refrigerant into the outdoor air. The gaseous refrigerant is transferred to the condenser (heat changer), where heat is exchanged between the refrigerant and outdoor air. The temperature of the gas increases, whereby making the refrigerant gaseous at high temperature and pressure. When the cooling process starts, the refrigerant at low temperature and pressure is compressed by the compressor. Then, the Kyoto Protocol agreed in 1997 set the broad outlines of emissions targets of GHGs. In the 1990s, HCFCs and HFCs were classified into a subset of a larger group of climate-changing greenhouse gases (GHGs). These international frameworks encouraged the use of CFC alternatives, such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). The Vienna Convention for the Protection of the Ozone Layer signed in 1985 and the Montreal Protocol agreed in 1987 provided frameworks for international reductions in the production and trade of chlorofluorocarbons. CFCs became the culprits mainly responsible for man-made chemical ozone depletion. However, ozone depletion came up to the surface as a global issue in the 1970s. Thomas Midgley, Jr created the first chlorofluorocarbon gas (CFC) in 1928.īeing chemically stable, non-flammable, and easily liquefied, fluorocarbons had been in use everywhere, as, e.g., refrigerants for air conditioners and refrigerators, foaming agents for heat-insulating materials, cleaning agents for precision parts, and aerosol propellants. The first air conditioners and refrigerators in the early 20th century employed toxic or flammable gases, such as ammonia, methyl chloride, or propane, that could result in fatal accidents when they leaked. The refrigerant circulates through the indoor and outdoor units of the air conditioner to carry heat, and cools or warms the indoor air.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |