Many types of refrigerant, the actual application should be based on the type of compressor, evaporation temperature and pressure, condensation temperature and pressure and other thermodynamic conditions and the use of the location of the appropriate choice of refrigeration equipment.
Ammonia (NH3)
Ammonia has long ago applied to refrigeration, is still widely used as one of the refrigerant. The ammonia evaporation temperature range is +5 ~ -70, and the working pressure in the condenser is generally controlled at no more than CMZ / 15.85kgf. Advantage of ammonia refrigerant is the standard boiling temperature for -33.4 DEG C, the appropriate pressure in condenser and evaporator; water chiller system with leakage can easily be found, even a slight leakage is also very easy to find; cooling capacity per unit volume, small throttling loss, can be dissolved in water; low prices, abundant supply. Its shortcoming is toxic, with a strong pungent smell; when the containing water, of copper and copper alloy (phosphorus bronze) corrosion; mixed with air (content accounted for air 16 to 25%) of explosion danger; high temperature easily decomposed.
Freon
Freon refrigerant is a colorless and transparent liquid, has a fragrance. It has more varieties, most of them are non-toxic, and have no pungent smell, no burning, no explosion danger. In Freon molecules, the fewer number of hydrogen atoms, combustible worse; the number of fluorine atoms, adverse effects on the human body more light, chemical effect of metal is smaller, at the same time, water solubility in the is also lower. The standard of Freon boiling temperature increased with the increase of the number of chlorine atoms, the unit volume refrigeration capacity with the standard boiling temperature increase and reduce. Therefore, the thermodynamic properties of the various kinds of freon refrigerant will be different.
Is the advantage of freon refrigeration system using refrigerant and large molecular weight for centrifugal compressor; adiabatic index, compression end temperature and solidification temperature low; good wettability of metal for in low-temperature refrigeration system. The drawback is, less volume refrigeration capacity per unit, than the major, throttling loss, and the heat transfer coefficient is low; in case of fire can be decomposed into toxic gases (phosgene); is easy to leak and not easily found; the price is more expensive.
Hydrocarbon
Hydrocarbon refrigerant is commonly used in petrochemical sector, in the separation of gas, oil cracking, often used as a refrigerant in the use of hydrocarbons. The advantage of hydrocarbon refrigerant is that the freezing point is low; the pure hydrocarbon and water do not function, and the metal is not corroded; the price is low. The disadvantage is that it is easy to burn, there is a risk of explosion after mixing with air. The critical temperature is low and the molecular weight is small. Hydrocarbon refrigerant mainly methane, ethane, propane, propylene, ethylene, propylene, etc..