Recovery　of　the　energy　loss　caused　by　throttling　plays　an　important　role　in　improv-ing　the　performance　of　a　cycle.　Based　on　the　original　Kalina　cycle　system　34g,　two　redesigned　cycles,　which　have　different　placement　of　single-screw　expanders　used　to　replace　the　throttle　valve,　are　proposed　in　this　paper.　The　thermodynamic　performance　of　two　redesigned　cycles　is　analyzed　and　compared　with　the　original　Kalina　cycle　system　34g.　The　results　show　that　the　thermodynamic　performance　of　each　redesigned　cycle　is　better　than　that　of　the　original　Kalina　cycle　system　34g　and　the　II-redesigned　cycle　performs　best.　At　a　low　and　moderate　evapora-tion　pressure,　there　is　an　optimal　ammonia-water　concentration　and　it　increas-es　with　the　increase　of　evaporation　pressure.　With　the　concentration　increases　of　ammonia-water,　the　performance　advantage　of　the　redesigned　cycle　system　over　the　original　Kalina　cycle　system　34g　gradually　decreases.　When　the　ammonia　-wa-ter　concentration　is　much　lower　than　the　optimal　concentration,　the　single-screw　expander　produces　much　work　and　plays　a　positive　role　in　net　work　output　of　cycle　system.　The　highest　cycle　exergy　efficiency　of　54.14%　can　be　obtained　in　the　II-redesigned　cycle　when　the　evaporation　pressure　is　3.0　MPa　and　ammonia-water　concentration　is　0.85.