Christoph Hochenauer

The use of a high temperature wind tunnel for MT-SOFC testing—Part I: detailed experimental temperature measurement of an MT-SOFC using an avant-garde high temperature wind tunnel and various measurement techniques

The purpose of the first part of this study was to compare four different temperature measuring methods. The application of these tools for possible temperature monitoring or calibration of monitors of microtubular solid oxide fuel cells (MT-SOFCs) is explored. It was found that a thermographic camera is very useful to visualize the temperature gradient on the outside of a cell, while an electrochemical impedance spectroscopy method was useful for estimating the core temperature of a test cell. A standard thermocouple was also used in combination with the previous two methods. Furthermore, an inexpensive laser guided thermometer was also tested for MT-SOFC temperature measurement. This initial study has opened up a range of questions not only about the effect of the experimental apparatus on the measurement results but also about the radial temperature distribution through a MT-SOFC in a working mode. Both these topics will be further investigated in part II of this study through a computational fluid dynamics study. This should provide additional interesting information about any differences between testing single cells and those within a bundle of cells. The discussed results are expected to be mainly temperature related, which should have direct consequences on power output and optimized gas inlet temperatures.

Prediction and Validation of Short Fiber Orientation in a Complex Injection Molded Part with Chunky Geometry

Abstract The paper shows the capability of state-of-the-art models and software to predict the fiber orientation distribution (FOD) on injection molded parts with a complex and thick-walled geometry. Predictions by the standard Folgar-Tucker model and the Reduced Strain Closure model were compared to measurements of the fiber orientation distribution obtained by X-ray Computed Tomography. Measurements and simulations were performed under different processing conditions to investigate the influence of injection velocity and packing pressure on the FOD. It was found that the predicted fiber orientation is in good qualitative agreement with the measurements. The measured orientation shows a distinct shell-core structure with high alignment of the fibers in flow direction in the shell layer and a orientation perpendicular to the flow direction in the core layer. While the orientation in the shell layer is predicted fairly well, a significant deviation is found in the prediction of the orientation in the core layer.

Experimental and Numerical Study of Various MT-SOFC Flow Manifold Techniques: Single MT-SOFC Analysis

Standard anode supported micro tubular-solid oxide fuel cell (MT-SOFC) stacks may provide the oxidant, in relation to the fuel, in three different manifold regimes. Firstly, “co-flow” involves oxidant outside the MT-SOFC flowing co-linearly in relation to the fuel inside. Secondly, “counter flow” involves oxidant outside the MT-SOFC flowing counter-linearly in relation to the fuel inside the MT-SOFC. Finally, “cross-flow” involves the oxidant outside the MT-SOFC flowing perpendicular to the fuel flow inside the MT-SOFC. In order to examine the effect of manifold technique on MT-SOFC performance, a combination of numerical simulation and experimental measurements was performed. Furthermore, the cathode current tap location, in relation to the fuel flow, was also studied. It was found that the oxidant manifold and the location of the cathode current collection point on the MT-SOFC tested and modeled had negligible effect on the MT-SOFC’s electrical and thermal performance. In this study, a single MT-SOFC was studied in order to establish the measurement technique and numerical simulation implementation as a prerequisite before further test involving a 7 cell MT-SOFC stack. [DOI: 10.1115/1.4023216]

Low-temperature H2S removal for solid oxide fuel cell application with metal oxide adsorbents:

The desulfurization of biogas is essential for the successful operation of solid oxide fuel cells. H2S is one of the main components in biogas. In order to feed a solid oxide fuel cell, the contaminated gas has to be reduced to a certain degree. In this work, different parameters onto the desulfurization performance of commercially available desulfurization adsorbents were investigated. The experiments were carried out using a custom made lab-scale unit. Synthetic biogas was passed through the sorbent bed and the outlet H2S concentration was measured. Experimental runs in a fixed bed reactor were conducted to monitor H2S removal efficiency of a zinc oxide adsorbent, an adsorbent based on a mixture of manganese and copper oxide and a zeolite adsorbent. H2S removal efficiency was monitored under various operating conditions such as different temperatures, space velocities and inlet concentrations. This work provides useful data for adsorption tower design and process optimization.

Scrutiny of MT-SOFC Stack Manifolding Design Using CFD

In this work we investigated the use of Computational Fluid Dynamics (CFD) in order to describe the behav- iour of a single Micro Tubular Solid Oxide Fuel Cell (MT-SOFC) and a bundle thereof. It is the first step before building a rather necessarily complicated experimental apparatus in order to compare the predictions with experimental measure- ment. The first goal of this study was to test the suitability of commercially available CFD & SOFC modelling software, with some modified features. The second goal was to predict the effects of various fuel and oxidant manifolding tech- niques regarding temperature, species and current density distributions. A result of this paper showed that CFD is a very useful tool, when a SOFC module is incorporated for MT-SOFC stack modelling. A second result showed that the oxidant flow regime was much more important than the fuel regime in order to manipulate a single MT-SOFCs temperature pro- file. The cases investigated had a radiation model included and the differences in temperature profiles, when radiation was included and neglected, especially for MT-SOFCs with view factors to the reactor housing, was shown to be important. The CFD predictions clearly showed the benefits and advantages associated with the different forms of fuel and oxidant manifoldings. A future experimental analysis is currently being designed.

Measurement and Numerical Simulation of Void and Warpage in Glass Fiber Reinforced Molded Chunky Parts

Abstract The aim of this paper is to determine the reason for the large warpage of an injection molded chunky part made of glass fiber reinforced polyamide 6. State of the art commercial 3D injection molding simulation software was used to predict the warpage of the part. While the simulation predicted a product virtually free of warpage the molded parts showed a large deformation. Several molding experiments and X-ray computed tomography (μCT) scans of the moldings have been performed to figure out the reason for this. The μCT scans revealed voids in the thick walls of the part. It was found that these defects were the main cause of the unreliable simulation results. Therefore it is concluded that voids can have a major influence on the reliability of numerical warpage predictions. This paper shows a simplified method to determine the zones were voids will appear and shows the comparison with μCT-data.

Adsorptive hydrogen chloride and combined hydrogen chloride–hydrogen sulphide removal from biogas for solid oxide fuel cell application

In order to reduce the toxic effect on solid oxide fuel cells performance caused by biogas contaminated with hydrogen chloride and hydrogen sulphide, the purification of biogas is essential. Adsorptive gas purification is a highly auspicious technology to provide pollution-free biogas for solid oxide fuel cell-based power units. In this work the authors examined the influence of different parameters onto the adsorption capacity of three commercially available sorbents. Experimental runs in a laboratory glass downflow fixed-bed reactor were carried out to analyse the adsorption capacity of a potassium carbonate impregnated activated carbon and two sorbents based on a mixture of aluminium oxide and silicon dioxide. Hydrogen chloride removal was accomplished with the impregnated activated carbon and metal oxide-based sorbents. Hydrogen chloride adsorption capacity was analysed under space velocities 8000 and 16,000 h−1. In addition, the effect of a hydrogen chloride inlet concentration of 100 and 1000 ppmv was investigated. Furthermore, pellets in the size of 3–4 mm in diameter were crushed into a fraction between 500 and 1000 µm to investigate the influence of particle size on hydrogen chloride adsorption capacity. Additionally, the combined adsorption of hydrogen chloride and hydrogen sulphide was realized using the impregnated activated carbon. The experimental runs and the results obtained in this work provide useful data for designing an adsorption reactor to clean up biogas and optimizing the process.

Experimental and Numerical Investigation of Shrinkage and Warpage of a U-Shaped Injection Molded Part

Abstract Prediction of shrinkage and warpage of injection molded plastic parts is a key issue of injection molding simulation. In the present work a U-shaped part is investigated experimentally and by means of state of the art injection molding simulation software. The part has thick walls in the corner where inner defects such as voids and porous zones may appear. Experiments and simulations were performed with POM and glass fiber reinforced polyamide. Measurements of pressure in the cavities and temperature profiles around the cavities were used to validate the numerical model. In case of POM it was found that warpage predictions are way off when the void volume is high and in good agreement when the void volume is minimized. No such correlation was observed in case of fiber reinforced materials. Here, shrinkage and warpage are dominated by the fiber orientation state with minor influence of the processing conditions. Predicted warpage was found to be extremely dependent on the used closure approximation.