A GEOMETRIC DESIGN METHOD OF RADIAL INFLOW TURBINE FROM 0D TO 3D FOR ORGANIC RANKINE CYCLE MICRO POWER GENERATION

Abstract

Radial turbine is an essential component of Organic Rankine Cycle system and requires a medium to high specific speed turbine. Radial turbine has a compact structure that can easily be made with current additive manufacturing technology if the 3D geometry of turbine components is known. Current researches only conduct 2D geometry design then import it into third-party software to construct the 3D geometry. This paper will explain design methodology to design radial inflow turbines from 0D until 3D using simple tools. The methods used to determine the geometry were based on Aungier, with modification in determining value of a, b, and c in nozzle design and A1 in Volute design to simplify the design process. The tools used in design were MS Excel and Autodesk Inventor. Rotor design starts with determining the two-dimensional parameters. All parameters are calculated based on the angle and velocities occurring in the velocity triangle at the inlet and outlet of the rotor using equations proposed by Aungier. Then, the straight, radial and quasi-normal lines of the blades are drawn based on governing equations. The transformation from 2D to 3D blade coordinates is done by using vector equations. The nozzle is designed by drawing the camber line profile and calculating the nozzle thickness to get the profile based on the governing equations given by Aungier. The volute dimensions are obtained by calculating the area of volute inlet passage and mean radius from mass and momentum conservation equations. A case study is shown in this paper with R134a as working fluid with the following range inlet conditions: mass flow rate at 1-2 kg/s, inlet pressure at 1.5 to 5 bar, inlet temperature at 80 to 130 °C, and power output target between 20 to 25 kW. The CFD results show that the designed turbine performs well with slight wake flow at the pressure side on the rotor inlet. A further study needs to be done in order to check the validity of this method by conducting analysis through experimental.