AUX air conditioner service manual
9
⑴The requirement for the thermodynamic character
The basic requirements the refrigerant shall meet are:
①Under the standard atmosphere pressure, the evaporation temperature must be low and generally
shall not higher than -10℃. The pressure value under the normal evaporation temperature shall be
higher or closed to the atmosphere pressure value in case of the air’s in leakage to the system.
②The condensing pressure of the refrigerant shall not be too high and generally shall not exceed
1.17-1.47 Mpa if within the range of the working temperatures. Otherwise it will add extra burden on
the intensity of the refrigerating devices and increase the power consumption subsequently.
③The capacity per unit refrigerant shall be large enough. It is the common understanding that the
refrigerant with the larger capacity per unit refrigerant can achieve larger quantity of refrigeration if at
the same cylinder diameter and same strolling stroke. However, as the exception, for the centrifugal or
mini type compressor, the preferable choice is the refrigerant with low capacity per unit refrigerant in
consideration of the convenience in machine design and manufacture.
④The critical temperature for the refrigerant shall be high enough in order to be liquidized at the
normal temperature or even the normal low temperature. The freezing temperature point shall be low
enough in order to be evaporated at a low evaporation temperature.
⑵The requirement for the physical and chemical character
①The adhesiveness and density of the refrigerant shall be low enough in order to have a free cycle
environment without too much resistance in the system.
②The refrigerant shall have the perfect performance in heat-exchanging in order to enhance the
efficiency of the complete refrigerator or air-conditioner.
③The refrigerant shall have a certain function of water-absorbing so as to maintain the normal
operation with no “ice block” when there is small water available in the system.
④The refrigerant shall be with a certain chemistry stability character for avoiding the chemolysis at
the high temperature, the corrosion to the material of the preparation, the inflammation and explosion
within a normal working pressure and temperature ranges; It also shall be with no much solubilization
or inflation impact applied to the hermetic material and with no chemical reaction to the lubricating
oil.
⑤The refrigerant shall be free of harm to the health of human beings and with no irritant.
3. The characters of the common refrigerant product:
There are many kinds of refrigerants available, the below are the typical types:
⑴Fluorine 22(CHF
2
Cl）
①Fluorine 22 with no character of inflammation and explosion. Its toxicity is deeper than R12’s, and
its solubility limit is higher than R12’s but also may form the phenomenon of “ice block”.
②Part of R22 can be solubilized by lubricating oil. The solubility limit is variable according to the
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