US Patent 7775783 Refrigeration system including a scroll expander

A scroll expander that is efficient in a wide range of operating conditions by suppressing leakage loss and decreasing in recovered power using a simple construction includes: an expansion mechanism, including an orbiting scroll and a first fixed scroll, recovers power by expanding a refrigerant; and an auxiliary compression mechanism, including an orbiting scroll and a second fixed scroll, compresses a refrigerant using power recovered by the expansion mechanism. A tip seal is mounted only on a spiral tooth of an orbiting scroll and a fixed scroll of one of the expansion mechanism or the auxiliary compression mechanism.