In　order　to　recover　the　energy　loss　due　to　the　throttling　in　the　path　of　ammonia-lean　solution　in　the　Kalina　Cycle　System　(KCS)　34,　two　redesigned　cycles,　in　which　single-screw　expanders　that　can　perform　two-phase　expansion　are　used　to　replace　the　throttle　valve,　are　proposed　in　this　paper.　The　results　show　that　the　thermal　efficiency　and　net　work　of　two　redesigned　cycles　are　higher　than　those　of　the　original　KCS　34.　With　the　concentration　increase　of　ammonia-water　mixture,　the　work　produced　by　the　single-screw　expander　B　in　two　redesigned　cycles　gradually　decreases,　and　the　difference　between　the　work　produced　in　two　redesigned　cycles　also　gradually　decreases.　The　original　KCS　34　and　two　redesigned　cycles　have　high　exergy　efficiency.　The　highest　cycle　exergy　efficiency　of　56.59%　can　be　obtained　in　the　II-redesigned　cycle　when　the　evaporation　pressure　is　3.0　MPa　and　ammonia-water　concentration　is　0.75.