Scale limitations of gas bearing supported turbocompressors for vapor compression cycles

Schiffmann, Jürg; Kontomaris, K.; Arpagaus, Cordin; Bless, Frédéric; Bertsch, Stefan S.

doi:10.1016/j.ijrefrig.2019.09.019

Cited by 12 publications

(5 citation statements)

References 31 publications

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“…Progress in research makes it possible to use gas-lubricated bearings in such turbomachines for applications in the power range of P = [0.5 − 250 kW], see [14]. As the lubrication is provided by the working fluid, they are inherently oil-free, thus eliminating concerns of contamination of the working fluid by lubricants or vice versa.…”

Section: Design Challenges For Small-scale Turbinesmentioning

confidence: 99%

“…• the impeller • seal • rotor with permanent magnets • thrust and journal bearings • the electrical stator as shown in Figure 4. A comprehensive discussion about the design of single components is given by Schiffmann et al [14]. In the steam conditioning process, the turbine operates close to the vapor saturation pressure; therefore, special care must be taken to avoid condensation in the bearings to avoid a reduction in load capacity and rotor dynamic stability [13].…”

Section: Design Challenges For Small-scale Turbinesmentioning

confidence: 99%

“…Hence, the vapor temperature surrounding the bearings has be high enough that the maximum bearing pressure is lower than the saturation vapor pressure to prevent condensation. Furthermore, with a low pressure of the steam in the motor, the windage loss between rotor and stator is reduced [14].…”

Section: Design Challenges For Small-scale Turbinesmentioning

confidence: 99%

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On the Application of Small-Scale Turbines in Industrial Steam Networks

et al. 2021

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This study investigates the technical and economic feasibility of replacing throttling valves with smale-scale, oil-free turbomachinery in industrial steam networks. This is done from the perspective of the turbomachine, which has to be integrated into a new or existing process. The considered machines have a power range of P=[0.5,…,250 kW] and have been designed using real industrial data from existing processes. Design guidelines are developed, which take into account the thermodynamic process as well as engineering aspects of such a turbomachine. The results suggest that steam conditioning prior to heat exchange could be completed by small expanders to produce mechanical work, reducing exergy destruction and improving site-wide energy efficiency compared to throttling valves. Cost estimates for such machines are presented, which serve as a basis for case-specific investment calculations. The resulting payback times of less than 18 months highlight the economic potential such solutions.

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Section: Design Challenges For Small-scale Turbinesmentioning

confidence: 99%

Section: Design Challenges For Small-scale Turbinesmentioning

confidence: 99%

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On the Application of Small-Scale Turbines in Industrial Steam Networks

et al. 2021

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“…The level of industrialization is improving continually, and rotating machinery is also developing in a more excellent direction. In recent years, the emergence of electromagnetic bearings and gas bearings has made rotating machinery more and more efficient, and various advantages of these two bearings have made their applications more and more widespread [1][2][3]. Electromagnetic bearing is easy to be controlled, but there are many limitations for its application.…”

Section: Introductionmentioning

confidence: 99%

Control of hybrid electromagnetic bearing and elastic foil gas bearing under deep learning

Sun

2020

PLoS ONE

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The hybrid electromagnetic and elastic foil gas bearing is explored based on the radial basis function (RBF) neural network in this study so as to improve its stabilization in work. The related principles and structure of hybrid electromagnetic and elastic foil gas bearings is introduced firstly. Then, the proportional, integral, and derivative (PID) bearing controller is introduced and improved into two controllers: IPD and CPID. The controllers and hybrid bearing system are controlled based on the RBF neural network based on deep learning. The characteristics of the hybrid bearing system are explored at the end of this study, and the control simulation research is developed based on the Simulink simulation platform. The effects of the PID, IPD, and CIPD controllers based on the RBF neural network are compared, and they are also compared based on the traditional particle swarm optimization (PSO). The results show that the thickness, spread angle, and rotation speed of the elastic foil have great impacts on the bearing system. The proposed CIPD bearing control method based on RBF neural network has the shortest response time and the best control effect. The controller parameter tuning optimization starts to converge after one generation, which is the fastest iteration. It proves that RBF neural network control based on deep learning has high feasibility in hybrid bearing system. Therefore, the results provide an important reference for the application of deep learning in rotating machinery.

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“…Due to their ability to achieve high rotational speeds and to operate without petroleum-based lubricant, gas-lubricated bearings are a convenient solution to support high-speed rotating machinery, while avoiding process fluid contamination. They are particularly suited for small-scale turbomachinery applications such as fuel cell air compressors [1], fuel cell anode off-gas recirculation fans [2,3], vapor compression cycle compressors [4,5], or organic Rankine cycle turbines [6]. Such bearings are subjected to viscous friction losses in the narrow clearance between the rotating and the stationary parts.…”

Section: Introductionmentioning

confidence: 99%

Extended Windage Loss Models for Gas Bearing Supported Spindles Operated in Dense Gases

Rosset

Schiffmann

2020

Journal of Engineering for Gas Turbines and Power

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Generic models are proposed to evaluate the skin friction coefficient acting on enclosed rotating disks and cylinders under various flow regimes. In particular, a model taking into account the inner radius of the disk is developed. The models are compared with experimental data obtained from coast-down tests of a high-speed spindle supported on gas lubricated bearings, operated in air and in halocarbon R245fa at various pressures. The windage losses are first computed considering state-of-the-art laminar flow loss models in the gas bearings and an experimentally validated laminar-turbulent flow loss model in the air gap. This reference approach predicts the air data with a good accuracy (deviation less than 5%) but underestimates the organic fluid data by up to 36%. This deviation is considerably reduced (max 6.8%) when applying the proposed multiflow regime loss model for enclosed rotating disks to the thrust bearing. Finally, the proposed laminar-turbulent flow loss model for enclosed rotating cylinders is simultaneously applied to the journal bearings and the air gap. A peak deviation of 6.5% is maintained among all test cases when setting the critical Taylor number to an artificial value (67) instead of the theoretical value (41.1) characterizing the onset of growth of Taylor vortices. Taking into account the uncertainties on the bearing clearances, as well as on the operating pressure and temperature, a ±10% agreement with the experimental data is obtained.

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Scale limitations of gas bearing supported turbocompressors for vapor compression cycles

Cited by 12 publications

References 31 publications

On the Application of Small-Scale Turbines in Industrial Steam Networks

On the Application of Small-Scale Turbines in Industrial Steam Networks

Control of hybrid electromagnetic bearing and elastic foil gas bearing under deep learning

Extended Windage Loss Models for Gas Bearing Supported Spindles Operated in Dense Gases

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