Heat transfer methods, systems and compositions

A method of cooling in a heat transfer system comprising an evaporator, a condenser and a compressor, the process comprising:

• i) condensing a refrigerant comprising:
• from about 40% by weight to about 49% by weight difluoromethane (HFC-32),
• from about 6% by weight to about 12% by weight pentafluoroethane (HFC-125),
• from about 33% by weight to about 40% by weight trifluoroiodomethane (CF3I);
• and
• from about 2% by weight to about 12% by weight of trans 1,3,3,3-tetrafluoropropene (trans HFO-1234ze), provided that together said HFC-32, said HFC-125, said CF3I and said transHFO-1234ze comprise at least about 97% by weight of said refrigerant, and
• ii) evaporating the refrigerant in the vicinity of the body or article to be cooled;
• wherein the evaporator temperature of the heat transfer system is in the range of from about −40° C. to about −10° C.

A method of heating in a heat transfer system comprising an evaporator, a condenser and a compressor, the process comprising:

• i) condensing in the vicinity of a body or article to be heated a refrigerant comprising:
• from about 40% by weight to about 49% by weight difluoromethane (HFC-32),
• from about 6% by weight to about 12% by weight pentafluoroethane (HFC-125),
• from about 33% by weight to about 40% by weight trifluoroiodomethane (CF3I);
• and
• from about 2% by weight to about 12% by weight of trans 1,3,3,3-tetrafluoropropene (trans HFO-1234ze), provided that together said HFC-32, said HFC-125, said CF3I and said transHFO-1234ze comprise at least about 97% by weight of said refrigerant, and
• ii) evaporating the refrigerant;
• wherein the evaporator temperature of the heat transfer system is in the range of about −20° C. to about 3° C.

A method of replacing an existing refrigerant contained in a heat transfer system comprising removing at least a portion of said existing refrigerant from said system, said existing refrigerant being R-410A and replacing at least a portion of said existing refrigerant by introducing into said system a refrigerant comprising:

• from about 40% by weight to about 49% by weight difluoromethane (HFC-32),
• from about 6% by weight to about 12% by weight pentafluoroethane (HFC-125),
• from about 33% by weight to about 40% by weight trifluoroiodomethane (CF3I);
• and
• from about 2% by weight to about 12% by weight of trans 1,3,3,3-tetrafluoropropene (trans HFO-1234ze), provided that together said HFC-32, said HFC-125, said CF3I and said transHFO-1234ze comprise at least about 97% by weight of said refrigerant.