NOVELTY - The system has a pump that circulates working fluid containing carbon dioxide throughout working fluid circuit (110) separated from the pump. A heat exchanger (102) is fluidly coupled to pump and in thermal communication with heat source (106), for receiving mass flow (m1) and transferring heat from heat source to mass flow. A turbine (112) is fluidly coupled to heat exchanger, to expand mass flow. A recuperator (116) is fluidly coupled to turbine, to transfer residual thermal energy from mass flow discharged from turbine to mass flow directed to heat exchanger.    USE - System for converting thermal energy to work energy e.g. electricity. Uses include but are not limited to gas turbine, stationary diesel engine, genset, industrial waste heat recovery application, refineries, compression stations and internal combustion engine.    ADVANTAGE - The power from waste heat and from wide range of thermal sources Waste heat energy conversion cycles can be produced efficiently and effectively. Multiple waste heat exchangers are arranged in series in waste heat stream and multiple thermodynamic cycles run in parallel with the waste heat exchangers, so that the thermal energy extraction from waste heat stream by working fluid can be maximized. The combined mass flow is enabled by arrangement of the recuperators, so that the thermal efficiency of the working fluid circuit can be increased. The power generation from a given heat source can be increased. By addition of lower temperature heat exchanging cycles through heat exchangers, recovery of higher fraction of available energy from heat source can be enabled. The pressure ratios for each individual heat exchanging cycle can be optimized, so that thermal efficiency is improved.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for converting thermal energy to work.    DESCRIPTION OF DRAWING(S) - The drawing shows a circuit diagram of the system for converting thermal energy to work.    Heat exchangers (102,104)    Heat source (106)    Turbine (112)    Recuperator (116)    Mass flows (M1,M2)