Patent ID: 8555703

Claim:
A leakage diagnosis apparatus for diagnosing presence/absence of refrigerant leakage in a refrigerant circuit including a compressor, a radiator, a depressurization mechanism and an evaporator provided as circuit components thereof and performing a refrigeration cycle by circulating refrigerant therethrough, comprising: an index value calculator for calculating for calculating a radiator-side index value which changes in accordance with an amount of refrigerant leaking out of the refrigerant circuit based on an amount of refrigerant exergy loss in the radiator; and a leakage determinator for determining whether there is refrigerant leakage in the refrigerant circuit based on the radiator-side index value calculated by the index value calculator, wherein the index value calculator calculates, as the radiator-side index value, a ratio of one of an amount of exergy loss during a process in which the refrigerant is in a two-phase gas/liquid state in the radiator and an amount of exergy loss during a process in which the refrigerant is in a single-phase liquid state in the radiator with respect to the other.