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Introduction
My research focuses in the area of small-scale turbomachinery, oil-free bearing technology, integrated system simulation and optimization, and advanced energy conversion systems.
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Publications
Publications (22)
This paper presents the results of a theoretical and experimental investigation of the potential of enhanced groove geometries to increase the bearing clearance of a HGJB supported rotor. The theoretical study investigates various groove geometries of different complexity and their effect on the stability threshold of a particular rotor geometry. T...
The nonlinear behavior of a rigid rotor supported by herringbone grooved journal gas bearings (HGJBs) was investigated in this study. The two-dimensional narrow groove theory (2D-NGT) was adopted to model the HGJBs. A set of integrated rotor-bearing state equations were built by coupling the rotor motion equations and the bearing Reynolds equation....
A micro steam turbine with a tip diameter of 15 mm was designed and experimentally characterized. At the nominal mass flow rate and total-to-total pressure ratio of 2.3 kg/h and 2, respectively, the turbine yields a power of 34 W and a total-to-static isentropic efficiency of 37 %. The steam turbine is conceived as a radial-inflow, low-reaction (15...
A micro steam turbine with a tip diameter of 15 mm was designed and experimentally characterized. At the nominal mass flow rate and total-to-total pressure ratio of 2.3 kg h−1 and 2, respectively, the turbine yields a power of 34 W and a total-to-static isentropic efficiency of 37%. The steam turbine is conceived as a radial-inflow, low-reaction (1...
The blade tip clearance loss was studied experimentally and numerically for a micro radial fan with a tip diameter of 19.2mm. Its relative blade tip clearance, i.e., the clearance divided by the blade height of 1.82 mm, was adjusted with different shims. The fan characteristics were experimentally determined for an operation at the nominal rotation...
While the global fuel utilization of solid oxide fuel cells (SOFCs) is limited by the stack aging rate, the fuel excess is typically used in a burner, and thus limiting the system electrical efficiency. Further, natural-gas-fueled SOFCs require treated water for the steam reforming process, which increases operational cost. Here, we introduce a nov...
The Laboratory for Applied Mechanical Design (LAMD) designed, manufactured, and experimentally tested a novel recirculation fan for a 10 kWe solid oxide fuel cell (SOFC). The fan uses oil-free bearings, more specifically herringbone-grooved journal and spiral-grooved thrust gas bearings. The radial inducer-less fan with a tip diameter of 19.2 mm fe...
The Laboratory for Applied Mechanical Design (LAMD) designed, manufactured, and experimentally tested a novel recirculation fan for a 10 kWe solid oxide fuel cell (SOFC). The fan uses oil-free bearings, more specifically herringbone-grooved journal and spiral-grooved thrust gas bearings. The radial inducer-less fan with a tip diameter of 19.2 mm fe...
While the global fuel utilization of solid oxide fuel cells (SOFCs) is limited by the stack aging rate, the fuel excess is typically used in a burner, and thus limiting the system electrical efficiency. Further, natural-gas-fueled SOFCs require treated water for the steam reforming process, which increases operational cost.
Here, we introduce a no...
This thesis presents the results of the design and experimental investigation of a patented 10 kWel solid oxide fuel cell (SOFC) system with a thermally-driven anode off-gas recirculation (AOR) fan, the so-called fan-turbine unit (FTU). The system has the advantage of higher global fuel utilization, and thus higher efficiencies and/or lower local f...
To improve the industry benchmark of solid oxide fuel cell (SOFC) systems, we consider anode off-gas recirculation (AOR) using a small-scale fan. Evolutionary algorithms compare different system design alternatives with hot or cold recirculation. The system performance is evaluated through multi-objective optimization (MOO) criteria, i.e., maximiza...
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 e...
Use of intermediate temperature solid oxide fuel cells for power generation is attractive, due to the highest achievable electrical efficiencies in the low power generation range. Nonetheless, there still exists a potential to improve the industry benchmark SOFC systems, which use natural gas or biogas as fuel and consider steam methane reforming,...
One of the advantages of solar thermal power plants (STPPs) with molten salt as heat transfer fluid is the direct storage system. This means that the thermal energy collected by the solar field and the electric power generation can be fully decoupled. The plant operator must therefore make the daily decision when to start-up or to shut-down the pow...
One of the advantages of solar thermal power plants (STPPs) with molten salt as heat transfer fluid is the direct storage system. This means that the thermal energy collected by the solar field and the electric power generation can be fully decoupled. The plant operator must therefore make the daily decision when to start-up or to shut-down the pow...
The Gemasolar solar power tower plant uses molten salt as heat transfer fluid and is therefore the first commercial project to apply this technology. Current research and development in line focusing systems is concentrated on transferring this proved salt technology to solar thermal power stations with parabolic trough collectors. This thesis iden...
