The heat integration of existing single-effect ammonia-water absorption system is studied. A set of possible heat modifications involving with absorption heat or rectification heat recovery are identified on energy transfer diagram, the performance of each heat modification is studied and compared, and the interaction of heat transfer in generator, absorber, rectifier and solution heat exchanger is investigated through different combinations of heat modifications. There are two approaches of increasing thermal performance, one is aimed to increase the feed temperature of the distillation column by isolating heat exchanger components. The purpose of the other approach is to reduce heat consumption through heat integration by using bridge analysis. The two approaches can both boost the thermal performance effectively. The results demonstrate 22% increases in Coefficient of Performance (COP) compared with traditional single-effect cycle under certain working conditions. In general, obtaining the maximum heat saving capacity in advance under different working conditions is necessary either for retrofit or in preliminary design stage. In this paper, the selection guidance of suitable cycle under different working conditions is provided. (C) 2017 Elsevier Ltd. All rights reserved.