Kjeld Bøhm Andersen
Technical University of Denmark
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Publication
Featured researches published by Kjeld Bøhm Andersen.
Applied Physics Letters | 2012
Christian Robert Haffenden Bahl; David Velázquez; Kaspar Kirstein Nielsen; Kurt Engelbrecht; Kjeld Bøhm Andersen; Regina Bulatova; Nini Pryds
We have applied mixed valance manganite perovskites as magnetocaloric materials in a magnetic refrigeration device. Relying on exact control of the composition and a technique to process the materials into single adjoined pieces, we have observed temperature spans above 9 K with two materials. Reasonable correspondence is found between experiments and a 2D numerical model, using the measured magnetocaloric properties of the two materials as input.
Journal of Materials Chemistry | 2012
Marie Lund Traulsen; Kjeld Bøhm Andersen; Kent Kammer Hansen
The electrochemical conversion of NOx on non-impregnated and BaO-impregnated LSM15-CGO10 (La0.85Sr0.15MnO3–Ce0.9Gd0.1O1.95) porous cell stacks has been investigated, and extensive impedance analysis have been performed to identify the effect of the BaO on the electrode processes. The investigation was conducted in the temperature range 300–500 °C, a polarisation range from 3 V to 9 V and in atmospheres containing 1000 ppm NO, 1000 ppm NO + 10% O2 and 10% O2. On the non-impregnated cell stacks no NOx conversion was observed under any of the investigated conditions. However, BaO impregnation greatly enhanced the NOx conversion and at 400 °C and 9 V polarisation a BaO-impregnated cell stack showed 60% NOx conversion into N2 with 8% current efficiency in 1000 ppm NO + 10% O2. This demonstrates high NOx conversion can be achieved on an entirely ceramic cell without expensive noble metals. Furthermore the NOx conversion and current efficiency was shown to be strongly dependent on temperature and polarisation. The impedance analysis revealed that the BaO-impregnation increased the overall activity of the cell stacks, but also changed the adsorption state of NOx on the electrodes; whether the increased activity or the changed adsorption state is mainly responsible for the improved NOx conversion remains unknown.
Journal of The European Ceramic Society | 2014
Rasmus Bjørk; Vincenzo Esposito; E.M. Lauridsen; Peter Stanley Jørgensen; Julie L. Fife; Kjeld Bøhm Andersen; Søren Preben Vagn Foghmoes; Nini Pryds
The densification, delamination and crack growth behavior in a Ce0:9Gd0:1O1:95 (CGO) and (La0:85Sr0:15)0:9MnO3 (LSM) multi-layer ceramic sample was studied using in situ X-ray tomographic microscopy (microtomography), to investigate the critical dynamics of crack propagation and delamination in a multilayered sample. Naturally occurring defects, caused by the sample preparation process, are shown not to be critical in sample degradation. Instead defects are nucleated during the debinding step. Crack growth is significantly faster along the material layers than perpendicular to them, and crack growth and delamination only accelerates when sintering occurs.
Heliyon | 2017
Kjeld Bøhm Andersen; Benoit Charlas; Eugen Stamate; Kent Kammer Hansen
An electrochemical reactor can be used to purify flue gasses. Such a reactor can be a multilayer structure consisting of alternating layers of porous electrodes and electrolytes (a porous cell stack). In this work optimization of such a unit has been done by changing the pore former composition and the electrode powder pre-treatment. The effect on permeability, mechanical strength and electrochemical behavior was studied in this work. The effects were evaluated by measuring the pressure difference over the samples in relation to the flow through the sample, by the ball on ring method and by electrochemical impedance spectroscopy in air at temperatures between 300 and 450 °C. The resulting structures were also evaluated with scanning electron microscopy. The work showed a dependence on the pore former composition and electrode powder pre-treatment resulting in variations in porosity, strength and flow resistance. A higher porosity gives a lower backpressure. The electrochemical performance shows that both thickness and amount of pore former in the electrolyte is important, but almost no dependence of electrode composition on the polarization resistances within the tested compositions.
Journal of The European Ceramic Society | 2013
De Wei Ni; Cristine Grings Schmidt; Francesca Teocoli; Andreas Kaiser; Kjeld Bøhm Andersen; Severine Ramousse; Vincenzo Esposito
Journal of the American Ceramic Society | 2013
De Wei Ni; Vincenzo Esposito; Cristine Grings Schmidt; Tesfaye Tadesse Molla; Kjeld Bøhm Andersen; Andreas Kaiser; Severine Ramousse; Nini Pryds
Ionics | 2009
Zeming He; Kjeld Bøhm Andersen; Li Keel; Frederik Berg Nygaard; Mohan Menon; Kent Kammer Hansen
Journal of The European Ceramic Society | 2016
Cristine Grings Schmidt; Kent Kammer Hansen; Kjeld Bøhm Andersen; Zongwen Fu; Andreas Roosen; Andreas Kaiser
Journal of The European Ceramic Society | 2014
De Wei Ni; Kjeld Bøhm Andersen; Vincenzo Esposito
Ceramics International | 2012
M. Skovgaard; Kjeld Bøhm Andersen; Kent Kammer Hansen