To provide an air refrigerant type freezing apparatus that enables an efficient defrosting-energy-saving operation, shortens the defrosting process time, and improves its operability.
A defrosting device of the air refrigerant type freezing apparatus includes: a first bypass passage 38 that bypasses a compartment 32 to supply an air refrigerant on an outlet side of an expander to an inlet side of a frosting trap 34; a second bypass passage 36 that bypasses the compartment 32 to supply an air refrigerant on an outlet side of a primary cooler 22 to an inlet side of an expander 18; a pressure sensor 50 which detects an inlet pressure of a compressor 12; a temperature sensor 51 that detects a refrigerant temperature T1 on an inlet side of the compressor; temperature sensors 52 and 53 that detect the air refrigerant temperature T2 and air refrigerant passage wall temperature T3 in an inlet area on a low temperature side of a heat recovery unit 30; and a temperature sensor 54 that detects a refrigerant temperature T4 on an outlet side of the compressor. The defrosting process finishes when the air refrigerant passage wall temperature T3 reaches the melting completion temperature Tg of 2-7°C while maintaining the air refrigerant temperature T1 on the inlet side of the compressor at the set value Tcs during the defrosting operation.
SABUZAWA TOSHIKAZU
TSUBATA KOICHI
ISHIZUKA SHINYA
KUDO MIZUO
UEDA SHOTA
