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R134a
From;    Author:Stand originally
Formal name 1, 1, 1, 2 - 4 fluorine ethane, weigh HFC-134a again.
One, R134a winner wants a characteristic:
1) have connect to get heating power quality nearly with R12.
2) security is good, colorless, without smelly, do not burn, do not explode, do not have noxiousness basically, chemistry is stable, without caustic.
3) do not contain chloric atom, ozonosphere destroys coefficient (ODP) for 0, atmosphere life is very brief (it is 18 years about, r12 is 120 years) , do not destroy atmosphere ozonosphere. Greenhouse effect is very little also, GWP value has 0.26 only.
4) saturated vapour pressure and R12 are adjacent, in 18 ℃ or so both has same saturated pressure value. Inside the temperature area under 18 ℃ , the saturated pressure of R134a slightly under R12; In prep above inside the temperature area of 18 ℃ , the R12 of saturated pressure prep above of R134a. Be in compressor entry point consequently, the pressure of R134a is inferior, inspiratory quantity is little; And be in in vent, the saturated pressure of R134a is higher, make compress mechanic to make a requirement slightly abominable, compress result add slightly.
5) evaporate latent heat is high, heat of calm pressure ratio is big, have better refrigeration capacity, but mass flow is little, so from integrated respect for, the refrigeration coefficient of R134a and R12 identical or slightly small.
6) coefficient of thermal conductivity is taller, it is good that heat conducts the result.
7) viscosity is inferior, liquidity is good.
8) molecular diameter compares R12 slightly small (the molecular diameter of R134a is 4.2×10-10m, r12 is 4.4×10-10m) , pass balata more easily so outward leak, be sifted more easily also to absorb by the element.
9) with mineral oil not Xiang Rong.
10) water imbibition and water dissolvability are taller than R12.
11) as antipathic as fluorine balata, with the Xiang Rong of fourth nitrile balata the gender also compares R12 to differ.
2, the hot content sex of R134a and refrigeration loop character:
1, of R134a unit quality evaporate latent heat and R22 are identical, bigger than R12. But R134a gets an element to measure (102.03) than R12 (120.03) small, consequently of unit volume evaporate what latent heat changes however is as identical as R12. Add fall in identical temperature operating mode, the flow of R134a is little (inspiratory amount is small) , consequently the refrigeration coefficient of R134a (CDP) as identical as R12 or slightly small. By some company the experiment makes clear: In car air conditioning, the energy efficiency of R134a is lower than R12 6 % left and right sides, refrigeration capacity is smaller than R12 12 % left and right sides. But refrigeration unit is different, this is numeric somewhat difference.
2, in same refrigeration dose mass flow falls [(125 ~ 400) G/(cm2*s) ] , of the R134a when evaporating conduct heat of coefficient comparing R12 rise (35 ~ 50) % [evaporate) of temperature T0=(5~15 ℃ , the entrance is spent with exit doing it is respectively 10% with 90 % ] ; When condensation, what the radiative coefficient of R134a compares R12 is tall (25 ~ 35) % [℃ of condensing temperature Tk=30~50, the entrance is spent with exit doing it is respectively 90 % and 10 % ] .
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