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  • 901.
    Woldemariam, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kullab, Alaa
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Khan, Ershad Ullah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Recovery of ethanol from scrubber-water by district heat-driven membrane distillation: Industrial-scale technoeconomic study2018In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 128, no SI, p. 484-494Article in journal (Refereed)
    Abstract [en]

    Membrane distillation (MD) integrated with a district heating network (DHN) to supply the heat demand has been investigated in a bioethanol production plant (BP). The specific application considered here is ethanol recovery from fermentation off-gas (CO2) scrubber water, where the main objective of this study was to develop an air gap MD system that is driven by heat from DHN, thereby offloading the steam-driven distillation column. Experiments conducted on an MD laboratory facility combined with data from the bioethanol industry were used to assess the technological and economic feasibility of this integrated MD-DHN-BP system. Comparisons were also made between the distillation column and MD units regarding heat demand and economic savings. Results of the study showed that MD could be a competitive technology for ethanol recovery given that low-grade heat such as from district heating network or waste heat is accessible.

  • 902.
    Woldemariam, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kullab, Alaa
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    District heat-driven water purification via membrane distillation: New possibilities for applications in Pharmaceutical Industries2017In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045Article in journal (Refereed)
    Abstract [en]

    Here, we presented a novel industrial application for membrane distillation (MD) in a pharmaceutical production facility’s wastewater treatment plant (WWTP). Two semi-commercial air gap MD module designs (Xzero and Elixir500) were studied for comparison, with experimental results of product yield and heat demand up-scaled for inclusion in system simulations. District heating was considered to drive the 3 m3/h capacity MD process, with heat recovery employed in various process streams and for heating purposes in offices. The selected configurations show a high degree of thermal integration with an increase of yearly district heating purchases of 2-13%. Economic assessments of the full-scale MD system indicate that unit costs of purification would be $1.3/m3 and $7/m3 for Elixier500 and Xzero MD modules respectively. Module heat losses should be considered in the future design of MD systems since the heat demand contributed to up to 77% of the specific costs.

  • 903.
    Woldemariam, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kullab, Alaa
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Membrane distillation pilot plant trials with pharmaceutical residues and energy demand analysis2016In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 306, p. 471-483Article in journal (Refereed)
    Abstract [en]

    In this study, an air gap membrane distillation (AGMD) system at pilot scale is applied for purification of effluent from a municipal wastewater treatment plant. A district heating network (DHN) is considered as a heat source for the membrane distillation system. Removal performance of pharmaceutical residuals, specific heat demand, and economic assessments were analyzed on the membrane distillation plant. Almost all targeted pharmaceutical compounds were removed to a very high degree, often below the method detection limit. The heat requirement for the MD process could be sufficiently supplied by the low-temperature district heating return line. Specific heat demands for the AGMD ranges from 692 to 875 kWh/m3 without heat recovery and as low as 105 kWh/m3 when heat recovery is possible. Different approaches to integrating the MD within the DHN system were analyzed; the advantages and shortcomings of each are discussed with emphasis on the MD system’s capacity requirement and annual heat demand. The thermoeconomic analyses from this study presented the potential for energy optimization regarding heat recovery and module design improvement of the current MD equipment.

  • 904.
    Woldemariam, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    District heating powered membrane distillation system for industrial applications2014Conference paper (Refereed)
    Abstract [en]

    In this study, membrane distillation pilot plant facility powered by district heating is considered for removal of drug residues from treated waste water and flue gas condensate treatment. The system consists of five pairs of air gap-MD modules. Three different cases were considered based on the configuration of the MD system in the district heating network. The test results showed that the MD process removes all except two from above thirty five drug residues tested, to below detection limits of the analytical method. The corresponding permeate rate, specific thermal energy consumption, and finally the membrane area required for an anticipated production capacity of 10m3/h were estimated and compared for the cases considered. Concentration tests were also done to get higher amounts of the compounds of interest, with up to 20 times concentrations. Treatment of flue gas condensates from a combined heat and power plant was also done to overcome problems (from previous study) of high permeate pH due to ammonia escape through membrane. Results showed that acidifying the feed sample made it possible to control ammonium slipping through the membrane in to permeate. Removal efficiency of other contaminants was also analysed. 

  • 905.
    Woldemariam, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Santarelli, Massimo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Exergy, thermo-Economic Analysis, and Optimization of Air-gap Membrane Distillation System2014Conference paper (Other academic)
    Abstract [en]

    Exergy and thermo-economic cost analysis are increasingly important tools for the evaluation of a desalination system’s performance and hence economic viability of the method for industrial or commercial applications. Membrane distillation (MD) is one important water desalination method that is still under development, not well established and not yet widely used in industries unlike reverse osmosis (RO). In this study, an exergetic and thermo-economic analysis for a large scale pilot plant air-gap membrane distillation system have been done. Experiments were carried out to get thermodynamic values of water streams. From the experimental data obtained and followed exergy analysis, it was found that the least exergetic efficiency (75%) was obtained for the feed. Maximum exergy efficiency was obtained for the hot side heat exchanger (98%) followed by the pumps. Thermo-economy of the MD water desalination under investigation was also analyzed and compared with other water desalination methods. Finally, the thermo-economic optimization for the MD system under consideration was investigated, and performance improvements were discussed.

  • 906.
    Woldemariam, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Santarelli, Massimo
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Exergy Analysis of Air-Gap Membrane Distillation Systems for Water Purification Applications2017In: Applied Sciences: APPS, ISSN 1454-5101, E-ISSN 1454-5101, Vol. 7, no 3, article id 301Article in journal (Refereed)
    Abstract [en]

    Exergy analyses are essential tools for the performance evaluation of water desalination and other separation systems, including those featuring membrane distillation (MD). One of the challenges in the commercialization of MD technologies is its substantial heat demand, especially for large scale applications. Identifying such heat flows in the system plays a crucial role in pinpointing the heat loss and thermal integration potential by the help of exergy analysis. This study presents an exergetic evaluation of air-gap membrane distillation (AGMD) systems at a laboratory and pilot scale. A series of experiments were conducted to obtain thermodynamic data for the water streams included in the calculations. Exergy efficiency and destruction for two different types of flat-plate AGMD were analyzed for a range of feed and coolant temperatures. The bench scale AGMD system incorporating condensation plate with more favorable heat conductivity contributed to improved performance parameters including permeate flux, specific heat demand, and exergy efficiency. For both types of AGMD systems, the contributions of the major components involved in exergy destruction were identified. The result suggested that the MD modules caused the highest fraction of destructions followed by re-concentrating tanks.

  • 907.
    Woldemariam, Daniel Minilu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    District Heating-driven Membrane Distillation for Water Purification in Industrial Applications2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Domestic and industrial water demands are growing globally due to population growth and rapid economic development, placing increasing strains on water resources. Wastewater effluents generated from these and other activities impact the environment and are thus subject to tightening regulation. The focus of research and development in water treatment processes aims at both pollutant removal efficiency and cost of purification.

    Membrane distillation (MD) is a developing thermally driven technology capable of achieving extremely high environmental performance utilizing renewable energy sources to a high degree. District heating networks, and in particular those driven by biomass, represent an ideal heat supply for MD systems.

    This thesis presents a technoeconomic assessment of district heating driven MD for water purification in selected industrial applications. The study covers analysis of MD separation performance and the related costs from different district heating integration scenarios. The analyses are based on three types of semi-commercial MD modules, with experiments conducted at laboratory and pilot scales. The case studies include pharmaceutical residue removal from effluents of municipal wastewater treatment plant, wastewater purification in pharmaceutical industry, and ethanol concentration in bioethanol production plant. Full-scale simulation studies were carried out for the identified case studies based on the experimental data obtained from MD module along with process information gathered from the industries. Results from the pharmaceutical residue removal pilot trials showed very good to excellent separation efficiency for 37 compounds at feed concentrations ranging from ng/L to mg/L. From alcohol-water feeds, ethanol concentrations were increased from 5% to nearly 90%. Simulation studies revealed that district heating integration of MD systems is feasible. Costs per unit volume of purified water are higher than competing technologies, however the configurations enable enhanced environmental performance that would be difficult to achieve otherwise.

  • 908. Wu, Junsheng
    et al.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mi, Youquan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Shih, Shao-Ju
    Wei, Jun
    Huang, Yizhong
    A novel core-shell nanocomposite electrolyte for low temperature fuel cells2012In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 201, p. 164-168Article in journal (Refereed)
    Abstract [en]

    We report a rapid and cost-effective method to coat SDC nano-particles with a thin LiZn-oxide nanocomposite layer. This composite is determined to have a structure with two phases consisting of Li2O and ZnO and examined to distribute over the surfaces of SDC nano-particles uniformly by using energy dispersive X-ray (EDX) and high-resolution TEM (HRTEM). The measurments of electrical property demonstrate that such a thin layer enables the ionic conductivity of SDC to be significantly increased (higher than 0.1 S cm(-1) at the temperature of 300 degrees C) equivalent to the conductivity of pure SDC at 800 degrees C or YSZ at 1000 degrees C. This superionic conductivity is caused by the two-phase interfaces formed between nano-particles.

  • 909. Wu, Renbing
    et al.
    Xue, Yanhong
    Qian, Xukun
    Liu, Hai
    Zhou, Kun
    Chan, Siew Hwa
    Tey, Ju Nie
    Wei, Jun
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Huang, Yizhong
    Pt nanodendrites anchored on bamboo-shaped carbon nanofiber arrays as highly efficient electrocatalyst for oxygen reduction reaction2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 36, p. 16677-16684Article in journal (Refereed)
    Abstract [en]

    In order to improve the Pt utilization and enhance their catalytic performance in fuel cells, a novel composite electrode composed of single-crystalline Pt nanodendrites and support constructed by bamboo-shaped carbon nanofiber arrays (CNFAs) on carbon paper, is reported. This electrode is designed by growing vertically CNFAs on carbon paper via plasma enhanced chemical vapor deposition, followed by the direct synthesis of Pt nanodendrites using a simple surfactant-free aqueous solution method. Electron microscopy studies reveal that the Pt nanodendrites are uniformly high dispersed and anchored on the surface of CNFAs. Electrochemical measurements demonstrate that the resultant electrode exhibits higher electrocatalytic activity and stability for oxygen reduction reaction than commercial Pt/C catalyst, suggesting its potential application in fuel cells.

  • 910.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development of Natural Mineral Composites for Low-Temperature Solid Oxide Fuel Cells2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Solid oxide fuel cells (SOFCs) have attracted growing attention worldwide because of their high conversion efficiency and low emissions when paired with clean fuel sources. Currently, reducing the temperature of SOFC to a low-temperature (LT) range is a mainstream trend of SOFC research. One effective way to reach this target is to explore alternative electrolytes that can maintain a desirable ionic conductivity at low temperatures. Meanwhile, it has been found that natural minerals hold great potential as functional materials for energy conversion technologies, especially ion-conducting hematite and rare-earth oxides. This thesis presents an experimental investigation of novel composite electrolytes based on two common natural minerals: hematite (LW) (α-Fe2O3) and La0.33Ce0.62Pr0.05O2-δ (LCP) for LT-SOFCs application. Initially, hematite (LW) and LCP are characterized and demonstrated as electrolytes in SOFCs. It is found the hematite ore is a mixture of α-Fe2O3, silica, and calcite, while the LCP mineral is a La/Pr co-doped CeO2. Both hematite (LW) and LCP cells exhibit encouraging performance with power densities of 150-225 and 295-401 mW cm-2 at 500-600 ℃, respectively.

    Following above findings, two mineral based nanocomposites – hematite-LCP and LCP/K2WO4 – are developed. Electrochemical and electrical studies reveal that the hematite-LCP gains a significantly enhanced conductivity (0.116 S cm-1 at 600 ℃) compared to individual hematite (LW) and LCP. The hematite-LCP based SOFC exhibits attractive power densities of 386-625 mW cm-2 at 450-600 ℃. Further investigation indicates that heterophasic interfacial conduction plays a crucial role in resulting in the good performance. Another composite LCP/K2WO4 is synthesized from LCP and tungstate through a wet-chemical route. The obtained composites exhibit enhanced grain boundary conduction compared to that of LCP. The composition dependence of the electrical conductivity has been studied, indicating that 90 wt% LCP/10 wt% K2WO4 is the optimum proportion with highest ionic conductivity and negligible electronic conductivity. The corresponding SOFC displays the highest power density of 500 mW cm-2 at 550 ℃. 

    Furthermore, by incorporating a semiconductor La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) into LCP and hematite-LCP, respectively, two semiconducting-ionic composites LCP-LSCF and hematite/LCP-LSCF are designed. Crystallographic and morphological characterizations are carried out to gain insight into the material features, and the two composites are applied as the intermediate membrane layer in LT electrolyte-layer free fuel cells (EFFCs). Investigations in terms of conductivity and fuel cell performance reveal that the two composites obtain improved ionic conductivities and cell power outputs compared with those of LCP and hematite-LCP. It is also found the two composites possess mixed ionic and electronic conductivities, which are balanced in the optimal composites. Additionally, stability and Schottky junction of the best-performance EFFC are studied to verify its reliability. 

  • 911.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Natural hematite for next-generation solid oxide fuel cells2015In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 6, p. 938-942Article in journal (Refereed)
    Abstract [en]

    Natural hematite ore is used as a novel electrolyte material for advanced solid oxide fuel cells (SOFCs). This hematite-based system exhibits a maximum power density of 225 mW cm −2 at 600 °C and reaches 467 mW cm −2 whenthe hematite is mixed with perovskite-structured La 0.6Sr0.4Co0.2Fe0.8O3–δ.These results demonstrate that natural materials for next-generation SOFCs can infl uence the multiutilization of natural resources, thereby affecting the environment and energy sustainability.

  • 912.
    Xia, Chen
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Cai, Yixiao
    Ma, Yue
    Wang, Baoyuan
    Zhang, Wei
    Karlsson, Mikael
    Wu, Yan
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Natural Mineral-Based Solid Oxide Fuel Cell with Heterogeneous Nanocomposite Derived from Hematite and Rare-Earth Minerals2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 32, p. 20748-20755Article in journal (Refereed)
    Abstract [en]

    Solid oxide fuel cells (SOFCs) have attracted much attention worldwide because of their potential for providing clean and reliable electric power. However, their commercialization is subject to the high operating temperatures and costs. To make SOFCs more competitive, here we report a novel and attractive nanocomposite hematite LaCePrOx (hematite LCP) synthesized from low-cost natural hematite and LaCePr-carbonate mineral as an electrolyte candidate. This heterogeneous composite exhibits a conductivity as high as 0.116 S cm(-1) at 600 degrees C with an activation energy of 0.50 eV at 400-600 degrees C. For the first time, a fuel cell using such a natural mineral-based composite demonstrates a maximum power density of 625 mW cm(-2) at 600 degrees C and notable power output of 386 mW cm(-2) at 450 degrees C. The extraordinary ionic conductivity and device performances are primarily attributed to the heterophasic interfacial conduction effect of the hematite-LCP composite. These superior properties, along with the merits of ultralow cost, abundant storage, and eco-friendliness, make the new composite a highly promising material for commercial SOFCs.

  • 913.
    Xia, Chen
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    Mi, Youquan
    Hubei Univ, Fac Phys & Elect Sci, Key Lab Ferro & Piezoelect Mat & Devices Hubei Pr, Wuhan 430062, Hubei, Peoples R China..
    Wang, Baoyuan
    Hubei Univ, Fac Phys & Elect Sci, Key Lab Ferro & Piezoelect Mat & Devices Hubei Pr, Wuhan 430062, Hubei, Peoples R China..
    Lin, Bin
    Univ Elect Sci & Technol China, Sch Mat & Energy, Chengdu 611731, Sichuan, Peoples R China..
    Chen, Gang
    Northeastern Univ, Liaoning Key Lab Met Sensor & Technol, Shenyang 110819, Liaoning, Peoples R China..
    Zhu, Bin
    Hubei Univ, Fac Phys & Elect Sci, Key Lab Ferro & Piezoelect Mat & Devices Hubei Pr, Wuhan 430062, Hubei, Peoples R China.;China Univ Geosci, Fac Mat Sci & Chem, Wuhan 430074, Hubei, Peoples R China.;Loughborough Univ, Dept Aeronaut & Automot Engn, Ashby Rd, Loughborough LE11 3TU, Leics, England..
    Shaping triple-conducting semiconductor BaCo0.4Fe0.4Zr0.1Y0.1O3-delta into an electrolyte for low-temperature solid oxide fuel cells2019In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 1707Article in journal (Refereed)
    Abstract [en]

    Interest in low-temperature operation of solid oxide fuel cells is growing. Recent advances in perovskite phases have resulted in an efficient H+/O2-/e(-) triple-conducting electrode BaCo0.4Fe0.4Zr0.1Y0.1O3-delta for low-temperature fuel cells. Here, we further develop BaCo0.4Fe0.4Zr0.1Y0.1O3-delta for electrolyte applications by taking advantage of its high ionic conduction while suppressing its electronic conduction through constructing a BaCo0.4Fe0.4Zr0.1Y0.1O3-delta-ZnO p-n heterostructure. With this approach, it has been demonstrated that BaCo0.4Fe0.4Zr0.1Y0.1O3-delta can be applied in a fuel cell with good electrolyte functionality, achieving attractive ionic conductivity and cell performance. Further investigation confirms the hybrid H+/O2- conducting capability of BaCo0.4Fe0.4Zr0.1Y0.1O3-delta-ZnO. An energy band alignment mechanism based on a p-n heterojunction is proposed to explain the suppression of electronic conductivity and promotion of ionic conductivity in the heterostructure. Our findings demonstrate that BaCo0.4Fe0.4Zr0.1Y0.1O3-delta is not only a good electrode but also a highly promising electrolyte. The approach reveals insight for developing advanced low-temperature solid oxide fuel cell electrolytes.

  • 914.
    Xia, Chen
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Qiao, Z.
    Feng, C.
    Kim, J. -S
    Wang, B.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei University, China.
    Study on zinc oxide-based electrolytes in low-temperature solid oxide fuel cells2017In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 11, no 1, article id 40Article in journal (Refereed)
    Abstract [en]

    Semiconducting-ionic conductors have been recently described as excellent electrolyte membranes for low-temperature operation solid oxide fuel cells (LT-SOFCs). In the present work, two new functional materials based on zinc oxide (ZnO)-a legacy material in semiconductors but exceptionally novel to solid state ionics-are developed as membranes in SOFCs for the first time. The proposed ZnO and ZnO-LCP (La/Pr doped CeO2) electrolytes are respectively sandwiched between two Ni0.8Co0.15Al0.05Li-oxide (NCAL) electrodes to construct fuel cell devices. The assembled ZnO fuel cell demonstrates encouraging power outputs of 158-482 mW cm-2 and high open circuit voltages (OCVs) of 1-1.06 V at 450-550 °C, while the ZnO-LCP cell delivers significantly enhanced performance with maximum power density of 864 mW cm-2 and OCV of 1.07 V at 550 °C. The conductive properties of the materials are investigated. As a consequence, the ZnO electrolyte and ZnO-LCP composite exhibit extraordinary ionic conductivities of 0.09 and 0.156 S cm-1 at 550 °C, respectively, and the proton conductive behavior of ZnO is verified. Furthermore, performance enhancement of the ZnO-LCP cell is studied by electrochemical impedance spectroscopy (EIS), which is found to be as a result of the significantly reduced grain boundary and electrode polarization resistances. These findings indicate that ZnO is a highly promising alternative semiconducting-ionic membrane to replace the electrolyte materials for advanced LT-SOFCs, which in turn provides a new strategic pathway for the future development of electrolytes.

  • 915.
    Xia, Chen
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Collaborative Innovation Center for Advanced Materials, Faculty of Physics and Electronic Technology, Hubei University, Wuhan, Hubei, China.
    Wang, Baoyuan
    Hubei Collaborative Innovation Center for Advanced Materials, Faculty of Physics and Electronic Technology, Hubei University, Wuhan, Hubei, China.
    Ma, Y.
    Department of Applied Physics, Aalto University, Aalto, Espoo, FI-00076, Finland.
    Cai, Y.
    Department of Engineering Sciences, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Liu, Y.
    Hubei Collaborative Innovation Center for Advanced Materials, Faculty of Physics and Electronic Technology, Hubei University, Wuhan, Hubei 430062, China.
    He, Yunjuan
    Hubei Collaborative Innovation Center for Advanced Materials, Faculty of Physics and Electronic Technology, Hubei University, Wuhan, Hubei 430062, China.
    Zhang, W.
    Hubei Collaborative Innovation Center for Advanced Materials, Faculty of Physics and Electronic Technology, Hubei University, Wuhan, Hubei 430062, China.
    Dong, W.
    Hubei Collaborative Innovation Center for Advanced Materials, Faculty of Physics and Electronic Technology, Hubei University, Wuhan, Hubei 430062, China.
    Li, J.
    Nanjing Yunna Nanotech Lth., Heyan Road 271, Nanjing, 210037, China.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Collaborative Innovation Center for Advanced Materials, Faculty of Physics and Electronic Technology, Hubei University, Wuhan, Hubei, China.
    Industrial-grade rare-earth and perovskite oxide for high-performance electrolyte layer-free fuel cell2016In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 307, p. 270-279Article in journal (Refereed)
    Abstract [en]

    In the present work, we report a composite of industrial-grade material LaCePr-oxide (LCP) and perovskite La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) for advanced electrolyte layer-free fuel cells (EFFCs). The microstructure, morphology, and electrical properties of the LCP, LSCF, and LCP-LSCF composite were investigated and characterized by XRD, SEM, EDS, TEM, and EIS. Various ratios of LCP to LSCF in the composite were modulated to achieve balanced ionic and electronic conductivities. Fuel cell with an optimum ratio of 60 wt% LCP to 40 wt% LSCF reached the highest open circuit voltage (OCV) at 1.01 V and a maximum power density of 745 mW cm-2 at 575°C, also displaying a good performance stability. The high performance is attributed to the interfacial mechanisms and electrode catalytic effects. The findings from the present study promote industrial-grade rare-earth oxide as a promising new material for innovative low temperature solid oxide fuel cell (LTSOFC) technology.

  • 916.
    Xu, Haoxin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical Study on the Thermal Performance of a Novel Impinging Type Solar Receiver for Solar Dish-Brayton System2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An impinging type solar receiver has been designed for potential applications in a future Brayton Solar Dish System. The EuroDish system is employed as the collector, and an externally fired micro gas turbine (EFMGT) has been chosen as the power conversion unit. In order to reduce the risks caused by the quartz glass window, which is widely used in traditional air receiver designs, a cylinder cavity absorber without a quartz window has been adopted. Additionally, an impinging design has been chosen as the heat exchange system due to its high heat transfer coefficient compared to other single-phase heat exchange mechanisms. This thesis work introduces the design of an solar air receiver without a glass window, which features jet impingement to maximize the heat transfer rate. A detailed study of the thermal performance of the designed solar receiver has been conducted using numerical tools from the ANSYS FLUENT package.

    Concerning receiver performance, an overall thermal efficiency of 72.9% is attained and an output air temperature of 1100 K can be achieved, according to the numerical results. The total thermal power output is 38.05 kW, enough to satisfy the input requirements of the targeted micro gas turbine. A preliminary design layout is presented and potential optimization approaches for future enhancement of the receiver are proposed, regarding local thermal stress and pressure loss reduction.

    This thesis project also introduces a ray-thermal coupled numerical design method, which combines ray tracing techniques (using FRED®), with thermal performance analysis (using ANSYS Workbench).

  • 917. Xu, Rong
    et al.
    Wu, Yan
    Wang, Xunying
    Zhang, Jing
    Yang, Xiang
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Enhanced ionic conductivity of yttria-stabilized ZrO2 with natural CuFe-oxide mineral heterogeneous composite for low temperature solid oxide fuel cells2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 27, p. 17495-17503Article in journal (Refereed)
    Abstract [en]

    We report for the first time that the commercial yttrium stabilized zirconia (YSZ) nano composite with a natural CuFe-oxide mineral (CF) exhibits a greatly enhanced ionic conductivity in the low temperature range (500-600 degrees C), e.g. 0.48 S/cm at 550 degrees C. The CF YSZ composite was prepared via a nanocomposite approach. Fuel cells were fabricated by using a CF YSZ electrolyte layer between the symmetric electrodes of the Ni0.8Co0.2Al0.5Li (NCAL) coated Ni foam. The maximum power output of 562 mW/cm(2) has been achieved at 550 degrees C. Even the CF alone to replace the electrolyte the device reached the maximum power of 281 mW/cm(2) at the same temperature. Different ion-conduction mechanisms for YSZ and CF YSZ are proposed. This work provides a new approach to develop natural mineral composites for advanced low temperature solid oxide fuel cells with a great marketability.

  • 918.
    Yang, Shu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    CFD Investigation of aeromechanic FORCING sensitivity for a generic transonic turbine2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Aeromechanic problems occur in various disciplines, the research here is focused on turbomachinery.  Advanced design criteria and accurate prediction methods for aeromechanic problems such as forced response and flutter become increasingly important with the present demand in turbomachine engine development towards lighter, cheaper, more efficient and reliable turbomachines. The aeromechanic analysis made at a late stage in the design process plays a crucial role to avoid failures. The present work aims at getting a better understanding of the aerodynamic mechanisms in transonic turbine stages and further development of numerical methods for stator-rotor interaction predictions.

     

    In this work standard industry tools are used for forced response computations for a one stage transonic high pressure turbine. Different configurations namely a tip shroud cavity, a hub cavity and external purge flow have been studied numerically to evaluate the influences on blade forcing predictions. CFD results are compared for all the cases with different features in both steady and unsteady state. Blade loading and integrated blade forcing are examined and physical interpretations of flow field features are given.

     

    The investigation shows that including detailing features has a significant influence on the aerodynamic forcing. Leakage flow going through the tip shroud cavity is approximately 4.0% of the main passage flow. The first harmonic of rotor circumferential forcing is reduced by 19.8% when including the hub cavity. The tip shroud cavity feature tends to increase the unsteady aerodynamic forcing for the rotor blade despite of the slightly different operating conditions. The external purge flow has been proven to have a relative difference of 1.1% on the rotor blade forcing. The change in forcing is considered to arise from the interaction between the cavity flow and the main passage flow. 

  • 919. Yasa, T.
    et al.
    Paniagua, G.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vogt, Damian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Performance of a nozzle guide vane in subsonic and transonic regimes tested in an annular sector2010In: Proceedings of the ASME Turbo Expo 2010: Power for Land, Sea, and Air, 2010, Vol. 7, no PARTS A, B, AND C, p. 1457-1467Conference paper (Refereed)
    Abstract [en]

    The understanding of shock interactions and mixing phenomena is crucial to design and analysis of advanced turbines. A nozzle guide vane (NGV) is experimentally investigated at subsonic and transonic off-design conditions (M2is of 0.6 and 0.95) in an annular sector at the Royal Institute of Technology (KTH). The effect of cooling ejection (3% of main stream mass flow rate) on the downstream flow field is also studied. The airfoil loading is monitored with pneumatic taps. The downstream pressure field is characterized at four different axial locations using a 5-hole probe and a total pressure probe that contains a single piezo-resistive transducer. The probe with a piezo resistive transducer is also used as a virtual 3-hole probe to measure the flow angle. The time-averaged yaw angle measured with the virtual 3-hole probe is in agreement with the 5-hole probe data. At subsonic conditions the wake causes a pressure loss of 7% of the upstream total pressure and covers 25% of the pitch whereas the pressure deficit is doubled in transonic operation. The coolant ejection results in an additional loss of 2% of the upstream total pressure. The flow speed does not have a significant effect on the wake width at 7% C ax. However, the low pressure region has different width at far downstream depending on the flow velocity. The fillet at the hub region has a significant effect on the secondary flow development. The frequency spectrums at the different conditions clearly reveal the shear layers. The results aim to help the characterization of mixing phenomena downstream of the NGV.

  • 920.
    Yissa Dawde, Oumer
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wind Resource Data Analysis: The case of MYDERHU project site, Tigray regional state, Ethiopia2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ethiopia is a developing country and its major primary energy consumption is largely covered by biomass and imported fossil fuels. Reliability of electricity supply varies widely across Ethiopia. Currently 65% of the population does not have access to electricity; 30 % of those without electricity live in village centers and 70% live in remote rural areas. However, the country is endowed with different renewable energy resources such as, hydro, wind, solar, geothermal and bioenergy. Wind energy is applicable for both power generation & water pumping applications for rural societies.

    The purpose of this study it to analyze the wind energy resource potential at Myderhu, to model the wind data with different statistical methods and software, selecting wind turbine class, forecast site wind energy & power density, develop site wind resource map, preliminary wind turbine micro siting, estimating farm annual energy production (AEP) and the expected cost of electricity. Based on the analysis and site survey, the site roughness and power exponent factors are classified as class I. Detailed wind resource data analysis is performed for the proposed site by using Excel, MatLab and WAsP software, based on a wind mast of 50m with an average wind speed of 7 m/s & mean power density of about 287 W/m2, this is categorized as a class-III wind resource (fair potential).

    Finally, wind resource mapping of 10km x 10km land area for a proposed wind farm is attempted at four different turbine hub heights of 30m, 50m, 80m and 100m. A supposed wind farm having 72 turbines with 82m rotor diameter at 80m hub height has been subjected to a simplified economy analysis by assuming investment costs of 1600 €/kW [38,400 birr/kW] and 1750 €/kW [42,000 birr/kW] and cost of energy estimated as 230.4 million € [5.53 billion birr], 0.028 €/kWhr [0.676 birr/kWhr] and 252 million € [6.05 billion birr], 0.031 €/kWhr [0.74 birr/kWhr] respectively. However, the Ethiopian FIT draft proclamation secure 0.073 €/kWhr [0.1 USD/kWhr] [1.75 birr/kWhr]. The calculation was done strictly by considering the power density at the site, and it didn’t address the issues of transportation and other installation related concerns and costs. Therefore, it is only applicable as a benchmark for future investigation work.

    As per this preliminary analysis the farm installed capacity is 144 MW, gross AEP is estimated about 593 GWhr, considering a wake loss of average 4.4% the net AEP is 567 GWhr and the average power density at the wind farm is estimated at 446 W/m2. The average capacity factor is estimated at 45%. The mean wind speed at hub height is 8.07 m/s. The Weibull shape factor (k) ranges from 2.8 to 3.3 with total average of 3.17.

  • 921. Yuan, K.
    et al.
    Yu, Y.
    Lu, X.
    Ji, X.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A new technology for spraying advanced low-temperature (300∼600 °C) Solid oxide fuel cells2017In: Proceedings of the International Thermal Spray Conference, ASM International , 2017, p. 132-137Conference paper (Refereed)
    Abstract [en]

    Solid oxide fuel cell (SOFC) has been developed for a hundred year and met a great challenge on material design and marketing. In recent years, new SOFC materials are dug up to achieve high energy-output performance at lower working temperature (300∼600 °C), namely low-temperature SOFC (LTSOFC). In this study, Ni-Co-Al-Li oxide (NCAL) was used for making dense, thin and uniform coatings on grooved bipolar electrode substrate for LTSOFC. Low-pressure plasma spray (LPPS) technology was applied to manufacture the NCAL coatings. The performance of a fuel cell package using the coated bipolars was tested between 350 and 600 °C, showing 6∼8 W power output with 4 single fuel cells (active area of 25 cm2). The LPPS technology is believed to be one of the ultimate ways for manufacturing the thin film/coatings for SOFC applications in future. 

  • 922.
    Yuwardi, Yuwardi
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Absorption cooling in district heating network: Temperature difference examination in hot water circuit2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Absorption cooling system driven by district heating network is relized as a smart strategy in Sweden. During summer time when the heating demand is low, the excessive hot water can be directly sold to drive absorption chillers instead of decreasing its production. In addition, this is also one answer to satisfy the cooling demand in more environmentally way since currently only around 26% of cooling demand in Sweden is satisfied by district cooling, the rest is fulfilled by individual air conditioning. Realizing this potential, the purpose of this study is to examine the returning hot water temperature in the district heating network with supply temperature of 70°C and also the effect to the absorption chiller’s COP. Through the simulation result, it is found out that the lowest possible returning water temperature is 55 °C at COP 0,69 with heat rejection (re-cooling) temperature water at 22 °C. This implies that the desired returning hot water temperature of 47 °C cannot be achieved. The lower returning hot water temperature is preferable since it gives the district heating network benefit in term of less distribution pump work, and energy recovery for the condensation process at central heating plant. 

  • 923.
    Zaytsev, Vitaly
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Photovoltaic panels application for energy savings in gas transportation system2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 924. Zhang, Liang
    et al.
    Yu, Zitao
    Fan, Liwu
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chen, Huan
    Hu, Yacai
    Fan, Jianren
    Ni, Mingjiang
    Cen, Kefa
    An experimental investigation of the heat losses of a U-type solar heat pipe receiver of a parabolic trough collector-based natural circulation steam generation system2013In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 57, p. 262-268Article in journal (Refereed)
    Abstract [en]

    The performance of a parabolic trough collector (PTC)-based steam generation system depends significantly on the heat losses of the solar receiver. This paper presents an experimental study of the heat losses of a double glazing vacuum U-type solar receiver mounted in a PTC natural circulation system for generating medium-temperature steam. Field experiments were performed to determine the overall heat losses of the receiver. Effects of wind, vacuum glass tube, radiation, and structural characteristics on the heat losses were analyzed. The thermal efficiency of the receiver was found to be 0.791 and 0.472 in calm and windy days, respectively, at a test temperature of about 100 degrees C, whereas the thermal efficiencies became 0.792 and 0.663, respectively, while taking the receiver element into consideration. The heat losses were increased from 0.183 to 0.255 kW per receiver for the two cases tested. It was shown that neither convection nor radiation heat losses may be negligible in the analysis of such U-type solar receivers.

  • 925.
    Zhang, Sherry
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Duke University.
    Seiya, Wolfgang
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Duke University.
    3D Printing as an Alternative ManufacturingMethod for the Micro gas Turbine Heat Exchanger2015Student paper other, 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    A variety of materials for high temperature applications were studied. Best materials forconstructing heat exchangers were selected using models based on preferential weights. Currentadditive manufacturing techniques and industries were also studied and rated to determine thebest materialprintingtechniquecombination. Although the rating models do not include everyimportant criterion, the results were expected to be the same if the state of the 3D manufacturingindustries and user preferences do not change. Design recommendations for a compact airtoairheat exchanger were made without considering manufacturing limitations. An economicalassessment of 3D manufacturing techniques was made to determine whether 3D manufacturingcould be a better alternative for heat exchangers. Although very promising, the choice to printheat exchangers with 3D techniques would not be economical at the moment. Future predictionsof the additive manufacturing industry were made having studied related industries.

  • 926.
    Zhang, Xiaoxiang
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical Study on Combustion Features of Gasified Biomass Gas2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is a great interest to develop biomass combustion systems for industrial and utility applications. Improved biomass energy conversion systems are designed to provide better combustion efficiencies and environmental friendly conditions, as well as the fuel flexibility options in various applications. The gas derived from the gasification process of biomass is considered as one of the potential candidates to substitute traditional fuels in a combustion process. However, the gascomposition from the gasification process may have a wide range of variation depending on the methods and fuel sources. The better understanding of the combustion features for the Gasified Biomass Gas(GBG) is essential for the development of combustion devices to be operated efficiently and safely at the user-end.

    The objective of the current study is therefore aiming to achieve data associated with the combustion features of GBG fuel for improving the efficiency and stability of combustion process. The numerical result is achieved from the kinetic models of premixed combustion with a wide range of operating ranges and variety of gas compositions. The numerical result is compared with experimental data to provide a better understanding of the combustion process for GBG fuel.

    In this thesis the laminar flame speed and ignition delay time of the GBG fuel are analyzed, using 1-D premixed flame model and constant volume model respectively. The result from different kinetics are evaluated and compared with experimental data. The influences of initial temperature, pressure and equivalence ratio are considered, as well as the variation of gas compositions. While the general agreement is reached between the numerical result and experimental data for laminarflame speed prediction, deviations are discovered at fuel-rich region and increased initial temperature. For the ignition delay time, deviations are found in the low-temperature and low pressure regime. The empirical equations considering the influence of initial temperature,pressure and equivalence ratio are developed for laminar flame speed and ignition delay times. The influence of major compositions such as CO, H2 and hydrocarbons are discussed in details in the thesis. Furthermore, a simplified kinetic model is developed and optimized based on the evaluation of existing kinetics for GBG fuel combustion. The simplified kinetic model is expected to be used for simulating the complexc ombustion process of GBG fuel in future studies.

  • 927.
    Zhang, Xiaoxiang
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fakhraie, Reza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Evaluation of reduced kinetics in simulation of gasified biomass gas combustion2013In: ASME Turbo Expo 2013: Turbine Technical Conference and Exposition: Volume 1B: Combustion, Fuels and Emissions, ASME Press, 2013, Vol. 1B, p. V01BT04A045-Conference paper (Refereed)
    Abstract [en]

    It is essentially important to use appropriate chemical kinetic models in the simulation process of gas turbine combustion. To integrate the detailed kinetics into complex combustion simulations has proven to be a computationally expensive task with tens to thousands of elementary reaction steps. It has been suggested that an appropriate simplified kinetics which are computationally efficient could be used instead. Therefore reduced kinetics are often used in CFD simulation of gas turbine combustion. At the same time, simplified kinetics for specific fuels and operation conditions need to be carefully selected to fulfill the accuracy requirements. The applicability of several simplified kinetics for premixed Gasified Biomass Gas (GBG) and air combustion are evaluated in this paper. The current work is motivated by the growing demand of gasified biomass gas (GBG) fueled combustion. Even though simplified kinetic schemes developed for hydrocarbon combustions are published by various researchers, there is little research has been found in literature to evaluate the ability of the simplified chemical kinetics for the GBG combustion. The numerical Simulation tool "CANTERA" is used in the current study for the comparison of both detailed and simplified chemical kinetics. A simulated gas mixture of CO/H2/CH4/CO2/N2 is used for the current evaluation, since the fluctuation of GBG components may have an unpredictable influence on the simulation results. The laminar flame speed has an important influence with flame stability, extinction limits and turbulent flame speed, here it is chosen as an indicator for validation. The simulation results are compared with the experimental data from the previous study [1] which is done by our colleagues. Water vapour which has shown a dilution effect in the experimental study are also put into concern for further validation. As the results indicate, the reduced kinetics which are developed for hydrocarbon or hydrogen combustion need to be highly optimized before using them for GBG combustion. Further optimization of the reduced kinetics is done for GBG and moderate results are achieved using the optimized kinetics compared with the detailed combustion kinetics.

  • 928.
    Zhang, Xiaoxiang
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kinetic Evaluation of the Laminar Flame Speed for Biomass Derived Gas CombustionManuscript (preprint) (Other academic)
    Abstract [en]

    The gas composition derived from gasification of biomass has been used in gasturbine combustion to achieve higher energy efficiency. However, there is an essential requirement to better understand the combustion characteristics of biomass derived gas before it can be used in the existing combustion facilities. A quantified study of the laminar flame speed of biomass derived gas combustionis presented in this paper. The study was carried out based on the kinetic model of the biomass derived gas flame and the results are compared with the experimental data from the our laboratory and various literatures. The laminarflame speed of the biomass derived gas was evaluated through a range of initial temperature (298 K - 398 K) and pressure (1 atm - 10 atm), as well as with various gas compositions. An empirical relationship for estimating the laminarflame speed has been derived for a composition of typical biomass derived gas. Furthermore, the evaluation of laminar flame speeds with various compositions have been carried out through numerical calculations and results were compared with experimental data from previous studies. The hydrogen concentration in gas composition has shown an essential importance for the laminarflame speed variation.

  • 929.
    Zhang, Xiaoxiang
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kinetic Study on Ignition Delay Time of Biomass Derived Gas CombustionManuscript (preprint) (Other academic)
    Abstract [en]

    The ignition delay time is one of the fundamental characteristics of a combustionprocess and has an essential effect on the performance of the combustion process. In the current study, a kinetic study on auto iginition delaytime is carried out for biomass derived gas combustion. A gas mixture of CO/H2/CO2/CH4/N2 is used to represent the typical composition from a biomass gasification process. The gas mixture is mixed with air under a certain range of operating conditions. A pressure range from 1 – 32 atm and an initial temperature range from 900 K to 1250 K were considered in the current study.The correlation between the ignition delay time and the operating conditions (pressures, initial temperatures and equivalence ratio) was derived for the biomass derived gas based on the kinetic calculations and published experimental data. The empirical correlation was obtained for the gas mixture ofCO/H2/CO2/CH4/N2/air and the gas mixture of CO/H2/O2/Ar. The influence of fuel compositions of the ignition delay time has also been discussed within this study. However, the influence of composition variation shown in the current study was not significant and was difficult to be cross-validated by various experimental data.

  • 930. Zhao, Y.
    et al.
    Xiong, D. -B
    Qin, Haiying
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Gao, F.
    Inui, H.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nanocomposite electrode materials for low temperature solid oxide fuel cells using the ceria-carbonate composite electrolytes2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 24, p. 19351-19356Article in journal (Refereed)
    Abstract [en]

    Low temperature solid oxide fuel cell (LTSOFC, 300-600 °C) is one of the hot areas in recent fuel cell developments. In order to develop high performance LTSOFCs, compatible electrodes are highly demanded. We used NANOCOFC (nanocomposites for advanced fuel cell technology) approach to develop nanocomposite electrodes based on metal oxides Ni-Cu-Zn-oxide and samarium doped ceria (SDC). It was found that the materials consist of individual metal oxide and SDC phase, indicating the material as a composite with a homogenous distribution for all constituent components. Highly homogenous distribution of the particles enhanced the catalyst function for electrode applications in LTSOFC devices. We constructed the devices using the SDC-carbonate nanocomposite (NSDC) as the electrolyte and above as prepared composite as electrodes in a symmetrical configuration. We found that the prepared composite electrodes had good catalytic function for both H2 and O2, to prove its anode and cathode functions. Based on the material properties, the LTSOFC devices have reached a power output more than 730 mW cm-2 at 550 °C.

  • 931. Zhao, Yicheng
    et al.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Lund, Peter
    Basile, Angelo
    Li, Yongdan
    Preface to the special issue section on "The 2nd International Symposium on Catalytic Science and Technology in Sustainable Energy and Environment (EECAT 2016), October 11-14th 2016, Tianjin, China"2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 27, p. 17339-17340Article in journal (Refereed)
  • 932. Zhao, Yufeng
    et al.
    He, Yunjuan
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China.
    He, Jing
    Xiong, Ding-Bang
    Gao, Faming
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China.
    Synthesis of hierarchically porous LiNiCuZn-oxide and its electrochemical performance for low-temperature fuel cells2014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 23, p. 12317-12322Article in journal (Refereed)
    Abstract [en]

    In this work, hierarchically porous composite metal oxide LiNiCuZn-oxide (LNCZO) was successfully synthesized through a sol-gel method with a bio-Artemia cyst shell (AS) as a hard template. The phase and morphology of the products were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM). The as-synthesized material was used as symmetrical electrodes, anode and cathode, for the SDC-LiNaCO3 (LNSDC) electrolyte based low temperature solid oxide fuel cell (LTSOFCs), achieving a maximum power density of 132 mW cm(-2) at 550 degrees C. Besides, a single-component fuel cell device was also demonstrated using a mixture of as-prepared LNCZO and ionic conductor LNSDC, and a corresponding peak power output of 155 mW cm(-2) was obtained, suggesting that the hierarchically porous product has high prospective in the single-component fuel cell.

  • 933.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nanocomposites for Advanced Fuel Cell Technology2011In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, Vol. 11, no 10, p. 8873-8879Article in journal (Refereed)
    Abstract [en]

    NANOCOFC (Nanocomposites for advanced fuel cell technology) is a research platform/network established based on the FP6 EC-China project www.nanocofc.org. This paper reviews major achievements on two-phase nanocomposites for advanced low temperature (300-600 degrees C) solid oxide fuel cells (SOFCs), where the ceria-salt and ceria-oxide composites are common. A typical functional nanocomposite structure is a core-shell type, in which the ceria forms a core and the salt or another oxide form the shell layer. Both of them are in the nano-scale and the functional components. The high resolution TEM analysis has proven a clear interface in the ceria-based two-phase nanocomposites. such interface and interfacial function has resulted in superionic conductivity, above 0.1 S/cm at around 300 degrees C, being comparable to that of conventional SOFC YSZ at 1000 degrees C. Against conventional material design from the structure the advanced nanocomposites are designed by non-structure factors, i.e., the interfaces, and by creating interfacial functionalities between the two constituent phases. These new functional materials show indeed a breakthrough in the SOFC materials with great potential.

  • 934.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Fan, L.
    Deng, H.
    He, Y.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dong, W.
    Yaqub, A.
    Janjua, N. K.
    LiNiFe-based layered structure oxide and composite for advanced single layer fuel cells2016In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 316, p. 37-43Article in journal (Refereed)
    Abstract [en]

    A layered structure metal oxide, LiNi0.1Fe0.90O2-δ (LNF), is explored for the advanced single layer fuel cells (SLFCs). The temperature dependent impedance profiles and concentration cells (hydrogen concentration, oxygen concentration, and H2/air atmospheres) tests prove LNF to be an intrinsically electronic conductor in air while mixed electronic and proton conductor in H2/air environment. SLFCs constructed by pure LNF materials show significant short circuiting reflected by a low device OCV and power output (175 mW cm-2 at 500°C) due to high intrinsic electronic conduction. The power output is improved up to 640 and 760 mW cm-2, respectively at 500 and 550°C by compositing LNF with ion conducting material, e.g., samarium doped ceria (SDC), to balance the electronic and ionic conductivity; both reached at 0.1 S cm-1 level. Such an SLFC gives super-performance and simplicity over the conventional 3-layer (anode, electrolyte and cathode) FCs, suggesting strong scientific and commercial impacts.

  • 935.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Lund, Peter
    Breakthrough fuel cell technology using ceria-based multi-functional nanocomposites2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 106, p. 163-175Article in journal (Refereed)
    Abstract [en]

    Recent scientific and technological advancements have provided a wealth of new information about solid oxide-molten salt composite materials and multifunctional ceria-based nano-composites for advanced fuel cells (NANOCOFC). NANOCOFC is a new approach for designing and developing of multi-functionalities for nanocomposite materials, especially at 300-600 degrees C. NANOCOFC and low temperature advanced ceramic fuel cells (LTACFCs) are growing as a new promising area of research which can be explored in various ways. The ceria-based composite materials have been developed as competitive electrolyte candidates for low temperature ceramic fuel cells (LTCFCs). In the latest developments, multifunctional materials have been developed by integrating semi- and ion conductors, which have resulted in an emerging insight knowledge concerned with their R&D on single-component electrolyte-free fuel cells (EFFCs) - a breakthrough fuel cell technology. A homogenous component/layer of the semi- and ion conducting materials can realize fuel cell all functions to avoid using three components: anode, electrolyte and cathode, i.e. "three in one" highlighted by Nature Nanotechnology (2011). This report gives a short review and advance knowledge on worldwide activities on the ceria-based composites, emphasizing on the latest semi-ion conductive nanocomposites and applications for new applied energy technologies. It gives an overview to help the audience to get a comprehensive understanding on this new field.

  • 936.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, China.
    Huang, Yizhong
    Fan, L.
    Ma, Y.
    Wang, Baoyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, China.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhang, B.
    Dong, W.
    Wang, H.
    Lund, P. D.
    Novel fuel cell with nanocomposite functional layer designed by perovskite solar cell principle2016In: Nano Energy, ISSN 2211-2855, Vol. 19, p. 156-164Article in journal (Refereed)
    Abstract [en]

    A novel fuel-to-electricity conversion technology resembling a fuel cell has been developed based on the perovskite solar cell principle using a perovskite, e.g. La0.6Sr0.4Co0.2Fe0.8O3-δ and an ionic nanocomposite material as a core functional layer, sandwiched between n- and p-conducting layers. The conversion process makes use of semiconductor energy bands and junctions properties. The physical properties of the junction and alignment of the semiconductor energy band allow for direct ion transport and prevent internal electronic short-circuiting, while at the same time avoiding losses at distinct electrolyte/electrode interfaces typical to conventional fuel cells. The new device achieved a stable power output of 1080mWcm-2 at 550°C in converting hydrogen fuel into electricity.

  • 937.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Goeta Technology Development International, Sweden .
    Liu, Xiangrong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Goeta Technology Development International, Sweden .
    Zhu, Z.
    Ljungberg, R.
    Development of low temperature solid oxide fuel cells2006In: Proceedings of 4th International ASME Conference on Fuel Cell Science, Engineering and Technology, 2006Conference paper (Refereed)
    Abstract [en]

    Based on innovative ceria-based composite (CBC) material advantages we have made strong efforts to make technical developments on scaling up material production, fabrication technologies on large cells and stack operated at low temperatures (300 to 600°C). Next generation materials for solid oxide fuel cells (SOFCs) have been developed based on abundant natural resources of the industrial grade mixed rare-earth carbonates named as LCP. Here we show the LCP-based materials used as functional electrolytes to achieve excellent fuel cell performances, 300-800 mWcm2 for low temperatures, exhibiting a great availability for industrialization and commercialization. Copyright

  • 938.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lund, Peter
    Aalto Univ, Dept Engn Phys, Sch Sci, FI-00076 Espoo, Finland..
    Advanced fuel cells: from materials and technologies to applications2011In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 35, no 12, p. 1023-1024Article in journal (Other academic)
  • 939.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lund, Peter
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Patakangas, Janne
    Huang, Qiu-An
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Singh, Manish
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    A new energy conversion technology based on nano-redox and nano-device processes2013In: Nano Energy, ISSN 2211-2855, Vol. 2, no 6, p. 1179-1185Article in journal (Refereed)
    Abstract [en]

    Electrolyte-separator-free fuel cell (EFFC) is a new emerging energy conversion technology. The EFFC consists of a single-component of nanocomposite material which works as a one-layer fuel cell device contrary to the traditional three-layer anode-electrolyte-cathode structure, in which an electrolyte layer plays a critical role. The nanocomposite of a single homogenous layer consists of a mixture of semiconducting and ionic materials that provides the necessary electrochemical reaction sites and charge transport paths for a fuel cell. These can be accomplished through tailoring ionic and electronic (n, p) conductivities and catalyst activities, which enable redox reactions to occur on nano-particles and finally accomplish a fuel cell function.

  • 940.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Ma, Ying
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wang, Xiaodi
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Qin, Haiying
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    A fuel cell with a single component functioning simultaneously as the electrodes and electrolyte2011In: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 13, no 3, p. 225-227Article in journal (Refereed)
    Abstract [en]

    A fuel cell device is realized by using a single component of lithium nickel oxide and gadolinium doped ceria (LiNiO2-GDC) composite material, a mixture of electronic and ionic conductors, when nickel foam and silver paste are attached to each surface of the single component pellet as current collectors. This simple fuel cell construction with only one component showed the same or even better performances compared to conventional three-component MEA (membrane electrolyte assembly) fuel cell using GDC as electrolyte. The maximum power density of 450 mW/cm(2) has been achieved at 550 degrees C for the single component fuel cell.

  • 941.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mat, Mahmut D.
    Studies on Dual Phase Ceria-based Composites in Electrochemistry2006In: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 1, no 8, p. 383-402Article, review/survey (Refereed)
    Abstract [en]

    The ceria-based dual-phase composites have been recently developed as functional electrolytes successful for intermediate and low temperature solid oxide fuel cell applications. These composite materials showed many unique advantages over the conventional single-phase electrolytes, such as superionic conduction in two-phase interfaces, dual proton and oxygen ion conduction resulting in extremely high ion conductivity and high current outputs in fuel cell and other applications, e. g. electrolysis. Interfacial superionic conduction is a characteristic for high conducting dual-phase composites. The composite approach can combine or integrate multi-ion functions, typically, dual H(+) and O(2-)conduction together to enhance the material conductivity and device performance. Dual or hybrid H+ and O(2-)conduction is based on a consideration that both proton (H+) and oxygen ion (O(2-)) are the fuel cell source ions. Proton conduction is important for LTSOFCs since it can be activated easier than oxygen ions in the low temperature (LT, 300-600 degrees C) region. The superionic conduction, dual phase proton and oxygen ion transport make significant conduction and electrical contributions for electrochemical devices. This paper makes a review on these recent studies.

  • 942.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Abbas, Ghazanfar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Singh, Manish
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    An Electrolyte-Free Fuel Cell Constructed from One Homogenous Layer with Mixed Conductivity2011In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 21, no 13, p. 2465-2469Article in journal (Refereed)
    Abstract [en]

    Rather than using three layers, including an electrolyte, a working fuel cell is created that employs only one homogenous layer with mixed conductivity. The layer is a composite made from a mixture of metal oxide, Li(0.15)Ni(0.45)Zn(0.4) oxide, and an ionic conductor; ion-doped ceria. The single-component layer has a total conductivity of 0.1-1 S cm(-1) and exhibits both ionic and semiconducting properties. This homogenous one-layer device has a power output of more than 600 mW cm(-2) at 550 degrees C operating with H(2) and air. Overall conversion is completed in a similar way to a traditional fuel cell, even though the device does not include the electrolyte layer critical for traditional fuel-cell technologies using the three-component anode-electrolyte-cathode structure.

  • 943.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Liu, Qinghua
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Qin, Haiying
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhu, Zhigang
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Singh, Manish
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Lund, Peter
    A new energy conversion technology joining electrochemical and physical principles2012In: RSC Advances, ISSN 2046-2069, Vol. 2, no 12, p. 5066-5070Article in journal (Refereed)
    Abstract [en]

    We report a new energy conversion technology joining electrochemical and physical principles. This technology can realize the fuel cell function but built on a different scientific principle. The device consists of a single component which is a homogenous mixture of ceria composite with semiconducting materials, e.g. LiNiCuZn-based oxides. The test devices with hydrogen and air operation delivered a power density of 760mWcm(-2) at 550 degrees C. The device has demonstrated a multi-fuel flexibility and direct alcohol and biogas operations have delivered 300-500 mW cm(-2) at the same temperature. Device physics reveal a key principle similar to solar cells realizing the function based on an effective separation of electronic and ionic conductions and phases within the single-component. The component material multi-functionalities: ion and semi-conductions and bi-catalysis to H-2 or alcohol (methanol and ethanol) and air (O-2) enable this device realized as a fuel cell.

  • 944.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Qin, Haiying
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Liu, Qinghua
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fuel cells based on electrolyte and non-electrolyte separators2011In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 4, no 8, p. 2986-2992Article in journal (Refereed)
    Abstract [en]

    In the long-history of fuel cell R&D, the electrolyte is an essential part in a three-component configuration because it separates the anode and cathode to realize the fuel cell's functions. We report here non-electrolyte separator fuel cells (NEFCs) compared with electrolyte based fuel cells (EBFCs). The NEFC consists of single- or dual-components based on mixed ionic and semi-conductors but with no electrolyte separator. A maximum power density of 680 mW cm(-2) has been achieved by the NEFC at 550 degrees C. The NEFCs exhibit performances comparable to, and in some cases even better than, those of conventional EBFCs. The design of NEFCs, new material functionalities and device performances may contribute to new fuel cell R&D.

  • 945.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Institute of Materials and Technology, Dalian Maritime University, China .
    Sun, J.
    Sun, X.
    Li, S.
    Gao, W.
    Liu, Xiangrong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Goeta Technology Development International, Sweden .
    Zhu, Z.
    Compatible cathode materials for high performance low temperature (300-600°C) solid oxide fuel cells2006In: Proceedings of 4th International ASME Conference on Fuel Cell Science, Engineering and Technology, FUELCELL2006, 2006Conference paper (Refereed)
    Abstract [en]

    We have made extensive efforts to develop various compatible electrode materials for the ceria-based composite (CBC) electrolytes, which have been, reported as most advanced LTSOFC electrolyte materials (Zhu, 2003). The electrode materials we have investigated can be classified as four categories: i) LSCCF (LaSrCoCaFeO) and BSCF perovskite oxides applied for our CBC electrolyte LTSOFCs; ii) LFN (LaFeO-based oxides, e.g. LaFe0.8Ni 0.2O3) perovskite oxides; iii) lithiated oxides: e.g. LiNiOx, LiVOx or LiCuOx are typical cathode examples for the CBC LTSOFCs; iv) other mixed oxide systems, most common in a mixture of two-oxide phases, such CuOx-NiOx, CuO-ZnO etc. systems with or without lithiation are developed for the CBC systems, especially for direct alcohol LTSOFCs. These cathode materials used for the CBC electrolyte LTSOFCs have demonstrated excellent performances at 300-600°C, e.g. 1000 mWcm-2 was achieved at 580°C. The LTSOFCs can be operated with a wide range of fuels, e.g. hydrogen, methanol, ethanol etc with great potential for applications. Copyright

  • 946.
    Zhu, Bin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Wang, Baoyuan
    Wang, Yi
    Raza, Rizwan
    Tan, Wenyi
    Kim, Jung-Sik
    van Aken, Peter A.
    Lund, Peter
    Charge separation and transport in La0.6Sr0.4Co0.2Fe0.8O3-delta and ion-doping ceria heterostructure material for new generation fuel cell2017In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 37, p. 195-202Article in journal (Refereed)
    Abstract [en]

    Functionalities in heterostructure oxide material interfaces are an emerging subject resulting in extraordinary material properties such as great enhancement in the ionic conductivity in a heterostructure between a semiconductor SrTiO3 and an ionic conductor YSZ (yttrium stabilized zirconia), which can be expected to have a profound effect in oxygen ion conductors and solid oxide fuel cells [1-4]. Hereby we report a semiconductorionic heterostructure La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) and Sm-Ca co-doped ceria (SCDC) material possessing unique properties for new generation fuel cells using semiconductor-ionic heterostructure composite materials. The LSCF-SCDC system contains both ionic and electronic conductivities, above 0.1 S/cm, but used as the electrolyte for the fuel cell it has displayed promising performance in terms of OCV (above 1.0 V) and enhanced power density (ca. 1000 mW/cm(2) at 550 degrees C). Such high electronic conduction in the electrolyte membrane does not cause any short-circuiting problem in the device, instead delivering enhanced power output. Thus, the study of the charge separation/transport and electron blocking mechanism is crucial and can play a vital role in understanding the resulting physical properties and physics of the materials and device. With atomic level resolution ARM 200CF microscope equipped with the electron energy-loss spectroscopy (EELS) analysis, we can characterize more accurately the buried interface between the LSCF and SCDC further reveal the properties and distribution of charge carriers in the heterostructures. This phenomenon constrains the carrier mobility and determines the charge separation and devices' fundamental working mechanism; continued exploration of this frontier can fulfill a next generation fuel cell based on the new concept of semiconductor-ionic fuel cells (SIFCs).

  • 947.
    Zhuang, Qingyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Parametric Study on the Aeroelastic Stability of Rotor Seals2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Labyrinth seals are widely used in rotating machinery and have been shown to experience aeroelastic instabilities. The rapid development of computational fluid dynamics now provides a high fidelity approach for predicting the aeroelastic behavior of labyrinth seals in three dimension and exhibits great potential within industrial application, especially during the detailed design stages. In the current publication a time-marching unsteady Reynolds- averaged Navier-Stokes solver was employed to study the various historically identified parameters that have essential influence on the stability of labyrinth seals. Advances in understanding of the related aeroelastic (flutter) phenomenon were achieved based on extensive yet economical numerical analysis of a simplified seal model. Further, application of the same methodology to several realistic gas turbine labyrinth seal designs confirmed the perceived knowledge and received agreements from experimental indications. Abbott’s criteria in describing the labyrinth seal aeroelastic behaviors were reaffirmed and further developed. 

  • 948.
    Åkerberg, Andreas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    CFD analyses of the gas flow inside the vessel of a hot isostatic press2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Hot isostatic pressing (HIP) is a thermal treatment method that is used to consolidate, densify or bondcomponents and materials. Argon gas is commonly used as the pressure medium and is isostaticallyapplied to the material with an excess pressure of 500-2000 bar and a temperature of 500-2200oC. WithHIP treatment being a well-established technology for the last decades, one is now striving to obtain anincreased understanding of local details in the internal gas flow and heat flux inside the HIP apparatus.The main objective of this work is to assess the potential of using computational fluid dynamics (CFD) asa reliable tool for future HIP development. Two simulations are being performed of which the first one isa steady-state analysis of a phase in the HIP-cycle called sustained state. The second simulation is atransient analysis, aiming to describe the cooling phase in the HIP-cycle. The most suitable modelingapproaches are determined through testing and evaluation of methods, models, discretization schemes andother solver parameters. To validate the sustained state simulation, the solution is compared tomeasurements of operating pressure, heat dissipation rate out through the HIP vessel and localtemperature by the vessel wall. However, no validation of the cooling simulations has been conducted. Asensitivity analysis was also performed, from which it could be established that a mesh refinement ofstrong temperature gradients resulted in an increase of wall heat dissipation rate by 1.8%. Both of thesimulation models have shown to yield satisfactory solutions that are consistent with the reality. With theachieved results, CFD has now been introduced into the HIP field and the presented modeling methodsmay serve as guidelines for future simulations.

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