Abstract
The organic Rankine cycle (ORC) is a thermodynamic cycle in which electrical power is generated using an organic refrigerant as a working fluid at low temperatures with low-grade enthalpy. We propose a turbine embedded in a generator (TEG), wherein the turbine rotor is embedded inside the generator rotor, thus simplifying turbine generator structure using only one bearing. The absence of tip clearance between the turbine rotor blade and casing wall in the TEG eliminates tip clearance loss, enhancing turbine efficiency. A single-stage axial-flow turbine was designed using mean-line analysis based on physical properties, and we conducted a parametric study of turbine performance, and predicted turbine efficiency and power using the tip clearance loss coefficient. When the tip clearance loss coefficient was applied, turbine isentropic efficiency and power were 0.89 and 20.42 kW, respectively, and ORC thermal efficiency was 4.81%. Conversely, the isentropic efficiency and power of the turbine without the tip clearance loss coefficient were 0.94 and 22.03 kW, respectively, and the thermal efficiency of the ORC was 5.08%. Therefore, applying the proposed TEG to the ORC system simplifies the turbine generator, while improving ORC thermal efficiency. A 3D turbine generator assembly with proposed TEG structure was also proposed.
Highlights
Applications that are able generate electricity by recovering waste heat without additional energy resources, such as oil and coal, have been increasingly investigated in the past decade
The organic Rankine cycle (ORC) is a thermodynamic cycle that is widely used for converting various low-grade heat sources into electrical power [1,2]
An increase in ORC thermal efficiency means an increase in electrical power that may be generated under a given heat source condition, which leads to decrease the levelized cost of energy (LCOE) [3]
Summary
Applications that are able generate electricity by recovering waste heat without additional energy resources, such as oil and coal, have been increasingly investigated in the past decade. Lazzaretto and Manente [9] suggested an optimization procedure for the design parameters of an ORC with respect to the correlation of turbine efficiency in terms of volumetric expansion ratio (VR) and size parameter (VH) Their results showed that turbine efficiency and optimum cycle parameters are influenced by the turbine VH and VR values. Al Jubori et al [11] designed an innovative small-scale axial turbine for ORC driven by low-temperature heat sources. The results revealed that the two-stage turbine had higher turbine performance with overall isentropic efficiency of 83.94%, power output of 16.037 kW and ORC thermal efficiency of 14.19%, compared to those of the single-stage turbine with 78.30%, 11.06 kW, and 10.5%, respectively. A three-dimensional (3D) assembly with the proposed TEG structure was presented
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
