Jürg Alexander Schiffmann

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The current paper presents the thermo-economic optimization and comparison, through a multi-objective algorithm, between HP-ORC and the competing single effect absorption heat pump (SEAHP), with the aim to find the best trade-off between investment cost an ...

The organic Rankine cycle (ORC) system is considered a promising technology to exploit thermodynamic potential of waste heat. The weight and size of standard pumps can penalize the benefits of installing an ORC system on vehicles. Small-scale ORC applicati ...

The Laboratory for Applied Mechanical Design (LAMD) designed, manufactured, and experimentally tested a novel steam-driven anode off-gas recirculation (AOR) fan for 10 kWel solid oxide fuel cell (SOFC) systems. Due to the dynamic steam-lubricated bearings, the AOR unit is expected to have a high lifetime, even at elevated rotational speeds and temperatures. Additional, the unit is oil-free, explosion-proof, very compact, and cheap to manufacture. The AOR fan diameter is at 19.2 mm and the nominal rotational

Designing turbocompressors is a complex and challenging task, as it involves balancing conflicting objectives such as efficiency, stability, and robustness against manufacturing deviations. This paper proposes an integrated design methodology for turbocomp ...

The present invention concerns an SOFC system comprising an anode off-gas recirculation arrangement in which anode off-gas is pumped by a fan or pump of a coaxial turbine-fan assembly, the system comprising a condenser for condensing water contained in sai ...

The presence of oil in domestic heat pumps is an obstacle toward higher efﬁciency, particularly for enhanced surface evaporators and for advanced concepts based on two- stage cycles. Very compact direct driven radial compressors supported on oil-free beari ...

Exploiting the recent advancements in artificial intelligence, showcased by ChatGPT and DALL-E, in real-world applications necessitates vast, domain-specific, and publicly accessible datasets. Unfortunately, the scarcity of such datasets poses a significan ...

Self-acting gas bearings are a popular solution for small scale turbomachinery. Many designs have been studied, and among those, the following three are very diffused and promising: foil bearings (FBs), herringbone-grooved bearings (HGBs), and tilting pad bearings (TPBs). Despite the many studies investigating these architectures individually, a direct benchmark between them is still absent. This paper proposes a side-by-side comparison of the three concepts specialized to one common application: a 14 mm ro

To improve the industry benchmark of solid oxide fuel cell systems (SOFC), we consider anode off-gas recirculation using a blower as an add-on to our next-generation SOFC system. Evolutionary algorithms compare the different design alternatives, i.e. co-flow or counter-flow stack operation with hot or cold recirculation. The system performance is evaluated through multiobjective optimization criteria, i.e. maximization of electrical efficiency and cogeneration efficiency. The results obtained suggest that i

Domestic scale heat pumps and air conditioners are mainly driven by volumetric com-pressors. Yet the use of reduced scale centrifugal compressors is reconsidered due to their high efficiency and power density. The design procedure of centrifugal compressor ...

Increasing the capability of automated driving vehicles is motivated by environmental, productivity, and traffic safety benefits. But over-reliance on the automation system is known to cause accidents. The role of the driver cannot be underestimated as it ...

This paper offers an extensive review of publications dealing with the modeling, the design and the experimental investigation of grooved dynamic gas lubricated bearings. Recent years have witnessed a rise in small-scale and high-speed turbomachinery appli ...

In the domain of engineering design, where efficiency in simulation and precision in modeling are paramount, this study introduces DARTS-NETGAB, a pioneering platform uniquely designed for real-time simulation and automated design. Specifically tailored fo ...

In compressor design, a convenient way to save time is to scale an existing geometry to required specifications, rather than developing a new design. The approach works well when scaling compressors of similar size at high Reynolds numbers but becomes more ...

Potential geometrical deviations in bump foil bearings due to manufacturing uncertainty can have significant effects on both the local stiffness and clearance, and hence, affecting the overall bearing performance. The manufacturing uncertainty of bump type ...

Heating and cooling will more and more rely on heat pumping in order to enable a more rational use of energy. The further development of domestic and small industrial multi-stage heat pumps with enhanced performance is impaired by the presence of oil mixed ...

This work presents the influence of splitters on the performance of small-scale turbopumps for organic Rankine cycle applications numerically. Different design parameters, such as impeller diameter at the outlet, number of blades, blade angle at the traili ...

This paper presents measurements of the motion amplitudes from flexibly supported Herringbone Grooved Journal Bearing bushings. Measurements taken in four locations on the flexibly supported bearing bushing enable the distinction between the radial and the ...

DARTS-NETGAB is a unified framework for real-time simulation and automated design of gas-bearing supported turbocompressors, facilitating efficient transition from optimization to manufacturable designs. The framework integrates ensemble artificial neural ...

Foil bearings are strong candidates to support oil-free turbomachinery. Although foil bearings are a widely used technology, models describing their behavior are not validated using the film pressure, which is the fundamental variable of any fluid film bea ...

Jürg Alexander Schiffmann

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Thermo-economic optimization of an ORC driven heat pump based on small scale turbomachinery and comparison with absorption heat pumps

Small-scale turbopumps for waste heat recovery applications based on an organic Rankine cycle, modeling, analytical and experimental investigations

Design and Experimental Realization of a Steam-Driven Micro Recirculation Fan for Solid Oxide Fuel Cell Systems

An Integrated Approach to Designing Robust Turbocompressors on Gas Bearings Through Surrogate Modeling and Constrained Multi-Objective Optimization

Sofc system with anode off-gas recirculation

Experimental investigation of a direct driven radial compressor for domestic heat pumps

Dated: Guidelines for Creating Synthetic Datasets for Engineering Design Applications

A Comparison Between Foil, Herringbone-Grooved, and Tilting Pad Gas Journal Bearings

Towards the Next-Generation of Solid Oxide Fuel Cell Systems

Data-Driven Predesign Tool for Small-Scale Centrifugal Compressor in Refrigeration

Haptics based multi-level collaborative steering control for automated driving

A Review of Grooved Dynamic Gas Bearings

DARTS-NETGAB: DESIGN AUTOMATION AND REAL-TIME SIMULATION USING NEURAL NETWORKS ENSEMBLES FOR TURBOCOMPRESSORS ON GAS-BEARINGS

The Role of Reynolds Number Effect and Tip Leakage in Compressor Geometry Scaling at Low Turbulent Reynolds Numbers

Comparative Evaluation of Foil Bearings with Different Compliant Structures for Improved Manufacturability

Integrated design, optimization and experimental investigation of a direct driven turbocompressor for domestic heat pumps

The influence of splitter blades and meridional profiles on the performance of small-scale turbopumps for ORC applications; analysis, neural network modeling and optimization

Unstable tilting motion of flexibly supported gas bearing bushings

DARTS-NETGAB: Design Automation and Real-Time Simulation Using Neural Network Ensembles for Turbocompressors on Gas-Bearings

Pressure Profile Measurements within The Gas Film of Journal Foil Bearings Using An Instrumented Rotor with Telemetry