The organic Rankine cycle (ORC), which generates electric energy using low temperature heat sources, is a promising technology in energy production sector. The ORC, which uses an organic fluid with its lower boiling point and higher vapor pressure than water steam as a working fluid. The thermal efficiency of an ORC showes the performance of system, depend s on system compenents, working fluid and operating conditions. This paper presents an thermodynamics examination of basic ORC and regenerative ORC for waste heat recovery applications using dry organic fluids. R113, R114, R227ea, R245fa and R600a with the boiling points from 16o C to 48 o C are selected in the analyses. The relationships between the ORC's performance parameters for basic and regenerative technologies and the properties of working fluids are evaluated based on various turbine inlet
pressure values. Results show that regenerative ORC has higher thermal efficiency compared with basic ORC.
Also, the thermal efficiency increases with the increment of the turbine inlet pressure for both basic ORC and regenerative ORC.