Tuesday, 1 September 2015

Refrigerants



Refrigerants
The regular refrigerants are halo carbon mixes (chlorofluorocarbons - CFCs), inorganic mixes and hydrocarbons. Some of these in like manner utilization are:
Smelling salts
Carbon dioxide
Air (in flying machine cooling)
Freon-1 or Refrigerant-1 (C Cl3 F3) = (aerating and cooling)
Freon-2 (residential plants)
Freon-22 (low temperature applications)
(Two-digit numbers are for methane based mixes and three-digit numbers for ethane based mixes.)
Some alluring properties of a refrigerant are
1.       High dormant warmth lessens the amount needed.
2.       Low breaking point at barometrically weight for low temperature in evaporator without spillage.
3.       Low consolidating weight with temperature of 40oC for cooling water or air at 25o to 30oC.
4.       High discriminating weight and temperature and low the point of solidification for a wide working extent.
5.       Inertness and substance steadiness.
6.       Non-combustible and non-dangerous.
7.       Low expense and simple accessibility.

8.       Possibility of high COP.
It was acknowledged in the 1970s that the CFCs not just permit more ultra-violet radiation into the world's air, additionally keep the infra-red radiation from getting away from the earth to space, which adds to the nursery impact and subsequently, a dangerous atmospheric devotion. Thus the utilization of some CFCs is banned and eliminated in numerous nations. Completely hydrogenated CFCs like R11, R12 and R115 do the most harm to the ozone layer. The halfway hydrogenated refrigerants, for example, R22 have around 5% of the ozone draining potential (ODP) of R12.
CFCs, well disposed to the ozone layer that shields the earth from ultra violet beams and which don't add to the nursery impact are being created. Teh without chlorine R134 an, a late finding, is in a matter of seconds supplanting R12, the most broadly utilized refrigerant, especially in household fridges and car aeration and cooling systems.
Aerating and cooling 

PSYCHOMETRIY:
Dry air is a mechanical blend of the gasses: nitrogen, oxygen, carbon dioxide, hydrogen, argon, neon, krypton, helium, and so forth. For commonsense purposes dry air is considered to comprise of 79% by volume (77% by mass) nitrogen and 21% by volume (23% by mass) oxygen. Totally dry air does not exist in nature. Water vapor in fluctuating sums is constantly present in air. The investigation of moist (air-water vapor blend) is known as psychrometry.
The wellspring of water vapor in air is principally the vanishing of water from substantial water bodies like lakes and ocean. The measure of water vapor fluctuates broadly in air with region and climate conditions and is regularly 1% to 3% by mass of the blend.
By Daltons law of halfway weights, the climatic weight, P = Pa + Pw, where Pa is the incomplete weight of dry air and Pw fractional weight of water vapor. Since Pw is little, the immersion temperature of water at Pw is much lower than environmental temperature. In this manner 
Psychrometric properties
The accompanying are the essential terms utilized as a part of psychrometry, or psychrometric properties.
Dry globule temperature (DBT) is the temperature of air recorded by a normal thermometer (with a dry knob).
Wet globule temperature (WBT) is the temperature recorded by a thermometer having its knob secured by a cotton wick immersed with water. The distinction between the DBT and WBT is known as the wet knob sorrow.
Dew point temperature (DPT). At the point when the climatic temperature is the same as the immersion temperature the air is in a soaked condition any further bringing down of temperature causes the water vapor to consolidate. The temperature at which the water vapor in air is immersed is known as the dew point temperature.
At the point when the air is unsaturated the wet knob temperature lies between the dry globule temperature and the dew point temperature. At the point when the air is immersed, the wet knob, dry globule and dew point temperatures are same. water vapor in air exists as superheated steam and such air is said to be unsaturated.

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