Predicting the optimum design of single stage axial expanders in ORC systems: Is there a single efficiency map for different working fluids?

Lio, Luca Da; Manente, Giovanni; Lazzaretto, Andrea

doi:10.1016/j.apenergy.2016.01.020

Cited by 77 publications

(22 citation statements)

References 21 publications

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“…Macchi and Perdichizzi [3] Axial flow Fixed recovery a Lozza et al [5] Axial flow Fixed recovery a Da Lio et al [6] Axial flow Fixed recovery b Astolfi and Macchi [7] Axial flow Fixed recovery b Da Lio et al [8] Axial flow Fixed recovery b Al Jubori et al [9] Axial flow Not considered Talluri and Lombardi [10] Axial flow Not considered Tournier and El-Genk [11] Axial flow Not considered Meroni et al [12] Axial flow Not considered Meroni et al [13] Axial flow Not considered Meroni et al [14] Axial flow Fixed recovery b Perdichizzi and Lozza [15] Radial inflow Fixed recovery a Uusitalo et al [16] Radial inflow Not considered Rahbar et al [17] Radial inflow Not considered Da Lio et al [18] Radial inflow Not considered Pini et al [19] Radial outflow Fixed recovery a Casati et al [20] Radial outflow Fixed recovery a Bahamonde et al [4] Axial flow Radial inflow Radial outflow Not considered a Fixed recovery of the total kinetic energy. b Fixed recovery of the meridional kinetic energy.…”

Section: Reference Turbine Type Diffuser Modelingmentioning

confidence: 99%

One-Dimensional Annular Diffuser Model for Preliminary Turbomachinery Design

Agromayor

Müller

Nord

2019

IJTPP

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Annular diffusers are frequently used in turbomachinery applications to recover the discharge kinetic energy and increase the total-to-static isentropic efficiency. Despite its strong influence on turbomachinery performance, the diffuser is often neglected during the preliminary design. In this context, a one-dimensional flow model for annular diffusers that accounts for the impact of this component on turbomachinery performance was developed. The model allows use of arbitrary equations of state and to account for the effects of area change, heat transfer, and friction. The mathematical problem is formulated as an implicit system of ordinary differential equations that can be solved when the Mach number in the meridional direction is different than one. The model was verified against a reference case to assess that: (1) the stagnation enthalpy is conserved and (2) the entropy computation is consistent and it was found that the error of the numerical solution was always smaller than the prescribed integration tolerance. In addition, the model was validated against experimental data from the literature, finding that deviation between the predicted and measured pressure recovery coefficients was less than 2% when the best-fit skin friction coefficient is used. Finally, a sensitivity analysis was performed to investigate the influence of several input parameters on diffuser performance, concluding that: (1) the area ratio is not a suitable optimization variable because the pressure recovery coefficient increases asymptotically when this variable tends to infinity, (2) the diffuser should be designed with a positive mean wall cant angle to recover the tangential fraction of kinetic energy, (3) the mean wall cant angle is a critical design variable when the maximum axial length of the diffuser is constrained, and (4) the performance of the diffuser declines when the outlet hub-to-tip ratio of axial turbomachines is increased because the channel height is reduced.

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Section: Reference Turbine Type Diffuser Modelingmentioning

confidence: 99%

One-Dimensional Annular Diffuser Model for Preliminary Turbomachinery Design

Agromayor

Müller

Nord

2019

IJTPP

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“…In case of high-temperature mini-ORC turbines, the use of such diagrams is questionable and may lead to erroneous choices, because they were developed for flow machines [15] operating with conventional gases and subsonic/transonic flows. Performance maps for ORC turbines have been recently presented by Da Lio et al [16,17]. However, these charts do not account for volumetric flow ratios higher than 15, a value which is largely exceeded in high temperature ORC applications where expansion ratios are in the order of 50-70.…”

Section: Radial-inflow Turbine Layoutmentioning

confidence: 99%

Design Method and Performance Prediction for Radial-Inflow Turbines of High-Temperature Mini-Organic Rankine Cycle Power Systems

Servi

Burigana

Pini

et al. 2019

Journal of Engineering for Gas Turbines and Power

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The realization of commercial mini organic Rankine cycle (ORC) power systems (tens of kW of power output) is currently pursued by means of various research and development activities. The application driving most of the efforts is the waste heat recovery from long-haul truck engines. Obtaining an efficient mini radial inflow turbine, arguably the most suitable type of expander for this application, is particularly challenging, given the small mass flow rate, and the occurrence of nonideal compressible fluid dynamic effects in the stator. Available design methods are currently based on guidelines and loss models developed mainly for turbochargers. The preliminary geometry is subsequently adapted by means of computational fluid-dynamic calculations with codes that are not validated in case of nonideal compressible flows of organic fluids. An experimental 10 kW mini-ORC radial inflow turbine will be realized and tested in the Propulsion and Power Laboratory of the Delft University of Technology, with the aim of providing measurement datasets for the validation of computational fluid dynamics (CFD) tools and the calibration of empirical loss models. The fluid dynamic design and characterization of this machine is reported here. Notably, the turbine is designed using a meanline model in which fluid-dynamic losses are estimated using semi-empirical correlations for conventional radial turbines. The resulting impeller geometry is then optimized using steady-state three-dimensional computational fluid dynamic models and surrogate-based optimization. Finally, a loss breakdown is performed and the results are compared against those obtained by three-dimensional unsteady fluid-dynamic calculations. The outcomes of the study indicate that the optimal layout of mini-ORC turbines significantly differs from that of radial-inflow turbines (RIT) utilized in more traditional applications, confirming the need for experimental campaigns to support the conception of new design practices.

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“…This implies that the thermodynamic parameters selected might affect negatively the design of the components. For this reason, some authors have proposed methods in which the selection of the thermodynamic parameters is bound by constraints that arise from practical limitations in the component design [78,79]. Furthermore, some works considered thermo-economic optimization models [80,81].…”

Section: R 143amentioning

confidence: 99%

Small Scale Organic Rankine Cycle (ORC): A Techno-Economic Review

et al. 2017

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Abstract:The Organic Rankine Cycle (ORC) is widely considered as a promising technology to produce electrical power output from low-grade thermal sources. In the last decade, several power plants have been installed worldwide in the MW range. However, despite its market potential, the commercialization of ORC power plants in the kW range did not reach a high level of maturity, for several reasons. Firstly, the specific price is still too high to offer an attractive payback period, and secondly, potential costumers for small-scale ORCs are typically SMEs (Small-Medium Enterprises), generally less aware of the potential savings this technology could lead to. When it comes to small-scale plants, additional design issues arise that still limit the widespread availability of the technology. This review paper presents the state of the art of the technology, from a technical and economic perspective. Working fluid selection and expander design are illustrated in detail, as they represent the bottleneck of the ORC technology for small-scale power production. In addition, a European market analysis is presented, which constitutes a useful instrument to understand the future evolution of the technology.

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Predicting the optimum design of single stage axial expanders in ORC systems: Is there a single efficiency map for different working fluids?

Cited by 77 publications

References 21 publications

One-Dimensional Annular Diffuser Model for Preliminary Turbomachinery Design

One-Dimensional Annular Diffuser Model for Preliminary Turbomachinery Design

Design Method and Performance Prediction for Radial-Inflow Turbines of High-Temperature Mini-Organic Rankine Cycle Power Systems

Small Scale Organic Rankine Cycle (ORC): A Techno-Economic Review

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