REFRIGERATING CYCLE

PURPOSE:To reduce the extent of temperature increase inside the chamber at the time of a defrosting operation by providing a switching means which selectively routes the gas refrigerant from a bypass pipe either to a first evaporator or to a second evaporator. CONSTITUTION:In order to perform a defrosting operation of an evaporator 13, a shutoff valve 19, a bypass valve 23 and an expansion valve 15 are opened and another expansion valve 14 is closed so that the flow passage may become as shown by a solid line within a four-way valve 17. When a compressor 11 is operated, the high temperature, high pressure gas refrigerant discharged flows through the chamber interior side (b) without being condensed via a bypass pipe 22. Since the expansion valve 14 is being closed, it flows into the evaporator 13 from a connecting pipe 18 through the four-way valve 17 and a flow passage switching pipe 21. Because of this, front is removed, and, upon exchanging heat, the high temperature, high pressure gas refrigerant is condensed to be liquified. It then is expanded in the expansion valve 15 to flow into another evaporator 16 to become a low pressure gas, which then returns to the compressor 11 through the four-way valve 17. As a result, the temperature inside the chamber (b) is prevented from rising remarkably.