The refrigerant migration during the operation switching of a parallel cycle frost-free refrigerator-freezer was experimentally studied. The refrigerator-freezer mainly consists of a compressor

two evaporators

two capillary tubes and a condenser. The refrigeration zone and the freezing zone have separate evaporators

fans

wind tunnels

and temperature wraps. The results show that the process of the freezing operation switching to the refrigeration operation can be divided into three stages according to the temperature of two evaporators

i.e.

pressure equilibrium

refrigerant emigrating from the F-evaporator

and refrigerant immigrating to the R-evaporator. In the first stage

the pressure of the low side begins to rise from the freezing evaporating pressure to the refrigeration evaporating pressure. In the second stage

the two-phase state of the refrigerant occurs slightly in the R-evaporator most of the time and the capacity is very small. In the third stage

the refrigerant in the R-evaporator begins to keep the stable two-phase state and the capacity increases with the extending of the two-phase. The switching from the freezing operation to the refrigeration operation possesses 23% of the whole refrigeration operation time while the energy consumption and the capacity in this process are 20% and 3.4% of the total

respectively

indicating that the process has great migrating loss. In addition

the effect of the refrigerant migration switching from the refrigeration operation to the freezing operation on the system performance can be ignored.