Refrigerating device formed by a main compressor (190), a condenser (140) downstream of and in fluid communication with the main compressor (190), main expansion means (170) downstream of the condenser (140) and an evaporator (180) downstream of and in fluid communication with the main expansion means (170), which also comprises a turbocompressor unit (160) in fluid communication between the evaporator (180) and the main compressor (190) and a heat exchanger (150, 152) having a hot branch (150c) connected upstream, via an inlet line (145), to the condenser (140) and downstream, via an outlet line (149), to the main expansion means (170) and a cold branch (15Of) connected, upstream, to an expansion means (142, 144) mounted on a branch (146) of the line (145) and, downstream, to a turbine portion (162) of the turbocompressor unit (160). The invention also relates to a method for circulating a refrigerating fluid inside the abovementioned device.