Method for defrosting an external heat exchanger, operated as an air heat pump, of a refrigeration system for a motor vehicle, refrigeration system and motor vehicle with such a refrigeration system

摘要

A method (500) is described for defrosting an external heat exchanger (18), operated as an air heat pump evaporator, of a refrigeration system (10) for a motor vehicle, the refrigeration system (10) having: a refrigerant compressor (12) which is connected to a primary line (14) and a secondary branch (16) is connectable or connected; an external heat exchanger (18) which is arranged in the primary branch (14); an evaporator (22) which is arranged in the primary branch (14); a heating register (26) which is located in the Secondary line (16) is arranged; a primary line valve (A4) arranged between the refrigerant compressor (12) and the external heat exchanger (18), which is closed in air heat pump operation; a secondary line valve (A3) arranged between the refrigerant compressor (12) and the heating register (26) ), which is open in air heat pump operation; the method comprising the following steps: closing (S502) the secondary branch valve (A3); opening (S503) the primary branch valve (A4), see above that refrigerant flows directly from the refrigerant compressor (12) to the external heat exchanger (18); setting (S504) an inlet-side pressure level of the refrigerant at the external heat exchanger (18) to a target pressure that corresponds to a condensation temperature (Tcond) of the refrigerant in the following range: 2 ° C.≤Tkond≤20 ° C., Especially 4 ° C.≤Tkond≤10 ° C.