Since then, the R134a refrigerant became the industry standard in automotive ACs and other refrigeration and freezing applications. But due to its damaging effect on ozone, it has been banned in phases starting from 1994. Freon (Freon-11, Freon-12, Freon-13, Freon-21, Freon-22, Freon-113, etc.)Įarlier, the R-12 (also sold under the brand name Freon-12) was used as the main refrigerant in automobiles and household refrigeration.Based on these and several other properties, some of the popular and industry approved refrigerants are: There are many other properties that a refrigerant must have (there are some requirements even at the molecular level). It should be easy to liquify or vaporize and also moderate its pressure and temperature.It should have a large latent heat value.It shouldn’t be hazardous and must be safe and non-toxic.It should be non-corrosive to metals and must mix well with oils.It should not be explosive or flammable.It is important for the refrigerant to have certain properties such as: To expel all the heat absorbed by the refrigerant, it is condensed from gas to liquid at high temperature and pressure. During this phase, the refrigerant is converted from liquid to gas. At a low temperature and pressure, the refrigerant absorbs heat. It is clear that the main component that helps in cooling your cabin is the refrigerant. During this process, it absorbs heat and humidity from the car’s cabin and provides with cool and dry air.Īll the components i.e., the compressor, condenser, accumulator (or receiver drier) and evaporator work in harmony to give you with cool air. Refrigerators and Air Conditioners are the perfect examples of this system.Ī special fluid called Refrigerant is used in refrigerators and air conditioners that helps in transfer of heat by continuously cycling between high high-pressure liquid state and a low-pressure gas state. The unwanted heat is mechanically transferred to an external area where the heat is unobjectionable. The process of removing heat from an area or location is called as Refrigeration. Let us first see a very basic overview of how the air conditioning system in your car works. Low Side Pressure and High Side Pressure.Meteorologists and weather reporters worldwide often use this unit for convenience, since working in pascals would result in much larger values.ġ5 psi = 15 × 0.0689475729 bar = 1. Millibars (symbol: mb) are also commonly used when referencing atmospheric air pressure, where atmospheric pressure equals 1013.25 mbar (101.325 kPa). The International Bureau of Weights and Measures has specified the bar as a unit that authors should have the freedom to use but has chosen not to include the bar in the list of non-SI units accepted for use with SI. The term "bar" comes from the Greek word "baros," which means weight.Ĭurrent use: Although the bar is a metric unit of pressure, it is not accepted within the International System of Units (SI) and is even deprecated within certain fields. History/origin: The unit, bar, was introduced by Vilhelm Bjerknes, a Norwegian meteorologist who founded modern weather forecasting. It is equal to 0.987 atmospheres (101,325 Pa), the unit often used as a reference of standard pressure. Barĭefinition: A bar (symbol: bar) is a metric unit of pressure that is defined as exactly 100,000 pascals (symbol: Pa). Although the pascal is more widely used in scientific contexts, psi is more often used in everyday contexts, particularly in countries like the United States as well as others under the US customary or imperial systems of units. As such, the prototype pound at the time was known as the avoirdupois wool pound.Ĭurrent use: The psi is fairly widely used to measure numerous pressures, such as tire pressure, scuba tank pressure, natural gas pipeline pressure, among others. The system is believed to have come into use in England around 1300 and was used in the international wool trade. It is based on the avoirdupois system, a system that uses weights in terms of the avoirdupois pound, which was standardized in 1959. History/origin: Pound-force per square inch is a unit that originated in the imperial and US customary systems of units. One psi is approximately 6,895 pascals (N/m 2). It is defined as the pressure that results when a force of one pound-force is applied to a one-square-inch area. Definition: A pound-force per square inch (symbol: psi) is an imperial and US customary unit of pressure based on avoirdupois units.
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