Oil flooded compression has been found to be able to improve the energy efficiency of vapor injection cycle significantly by reducing the specific compression work. In order to optimize the coupling and study the thermodynamic characteristics, six coupled cycles were proposed and studied in heating conditions. A detailed analysis on each cycle using R32 working fluid was conducted. COP and heating capacity at various conditions were obtained and compared to the respective values of the vapor injection cycle. The respective COP improvement of oil flooded compression in the coupled cycles were investigated and compared to that of oil flooded compression in the single stage vapor compression cycle. The effects of oil temperature and regenerator efficiency on the cycles were also investigated and revealed. The results can provide theoretical guide to the design of a coupled cycle system. (C) 2018 Elsevier Ltd. All rights reserved.