14th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

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Main Topic:

Axial Turbines



Konstantinos Mpollas - Aristotle University of Thessaloniki
Theofilos Efstathiadis - Aristotle University of Thessaloniki
Anestis I. Kalfas - Aristotle University of Thessaloniki


The present study focuses on the design of a high-efficient Organic Rankine Cycle (ORC) power production system utilizing waste heat from heavy industrial exhaust gases before guided to the rejection chimney. The thermodynamics of an ORC is similar to a Rankine steam cycle; however, instead of steam as a working fluid, ORC employs denser organic media. Dense gases are defined as single phase vapors, characterized by complex molecules and moderate to large molecular weights, giving the opportunity to exploit low – temperature sources.In recent years, there is a global need for emissions reduction in transport and industrial sector. The new environmental regulations have forced industries in search of feasible waste heat recovery systems. In this context, there is a growing interesting for effective ORC systems. During the design process of these systems priorities are given to the turbine, where the optimization aims at the maximization of the power output, with respect of the operating costs. This target can be achieved easily by considering supersonic turbines. Towards to this direction, an innovative single-stage turbine was designed by means of the Method of Characteristics and the resulting geometry was extruded in 3D domain by implementing the Radial Equilibrium Equation. Plenty of working media were examined for the purposes of the present study and the working fluid MDM presented the most promising results in power production with annually energy saving of 208MWhth¬. The final geometry is compared with the ideal respective turbine geometry, where it is shown that the errors, introduced by ideal gas assumption, can lead to deviations in the turbine design parameters, from 3% to 20% as we approach the critical point. This can lead to a maximum annual energy loss of 4.5 MWh, which indicates the need to use more precise real gas models.


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