Development and optimization of efficient small-scale turbines for organic rankine cycle powered by low-temperature heat sources

Al Jubori, Ayad Mahmoud Salman (2017). Development and optimization of efficient small-scale turbines for organic rankine cycle powered by low-temperature heat sources. University of Birmingham. Ph.D.

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Abstract

In this this research, ORC systems using axial, radial-inflow and radial-outflow turbines are investigated for various low-power generation (1-15 kW) applications like domestic, rural and remote off-grid communities. This work presents a new integrated mathematical model for developing efficient axial, radial-inflow and radial-outflow (centrifugal) turbines with low mass flow rate (0.1-0.5 kg/s) using a range of organic working fluids (R14lb, R1234yf, R245fa, R365mfc, isobutene, n-butane and n-pentane). The new mathematical approach integrates mean-line design and 3D CFD analysis with ORC modelling. RANS equations for three-dimensional steady state and viscous flow were solved with k-ro SST turbulence model to predict 3D viscous turbulent flow and turbine performance. With the aim of enhancing the ORC performance by increasing its pressure ratio, novel small-scale two-stage axial and radial outflow turbines are modelled and compared with single-stage axial, radial-inflow and radial-outflow turbines. New performance maps in terms of isentropic efficiency and power output for each turbine configuration are developed in terms of expansion ratio, mass flow rate, rotational speed and turbine size.

Novel optimization technique using multi-objective genetic algorithm was applied to optimize small-scale single stage axial, radial-inflow and radial-outflow turbines with this flow rate. Experimental study of the ORC radial-inflow turbine was carried out.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):