A refrigeration circuit (3) for household appliances comprises a compressor (4) suitable for compressing a predetermined cooling fluid and for allowing circulation thereof within said circuit (3), a first heat exchanger (5) or condenser in fluid communication with the compressor (4) for allowing cooling and the consequent condensation of the cooling fluid going therethrough, and a second heat exchanger (7) or evaporator in fluid communication with the first exchanger (5) through a circuit with a special device (6) suitable for decreasing the pressure of the cooling fluid and acting at a space (2) to be cooled (normally inside the refrigerator). The second exchanger (7) allows the cooling fluid to evaporate, by heat absorption, thus cooling the space (2) and returning through the tubing (17) to the compressor (4). The cooling fluid circulates from the compressor (4) towards the first exchanger (5), from the latter towards the second exchanger (7), then returning to the compressor (4) for a subsequent cycle. At least one of the heat exchangers (5, 7) comprises a plastic tubing (9), at least one portion whereof exhibits such a corrugated profile as to impart flexibility thereto and/or increase the thermal exchange surface. The tubing in section exhibits a structural layer (100) of plastic material and a layer (101) comprising a film of metal material adapted to constitute a barrier against humidity and gases in general, such shaped as to maintain the tube flexibility.