Name: combustion characterization and model fuel development for micro-tubular flame-assisted fuel cells
Uploaded: 2016-10-02T15:00:00
Description: Watch this Scientific Journal Video about Combustion Characterization and Model Fuel Development for Micro-tubular Flame-assisted Fuel Cells at JoVE.com

This work is supported by an agreement with Syracuse University awarded by the Syracuse Center of Excellence in Energy and Environmental Systems with funding under prime award number DE-EE0006031 from the US Department of Energy and matching funding under award number 53367 from the New York State Energy Research and Development Authority (NYSERDA), contract 61736 from NYSERDA, and an award from Empire State Development's Division of Science, Technology and Innovation (NYSTAR) through the Syracuse Center of Excellence, under award number #C120183. This work is supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. 1247399.

1. Combustion Calculations
<ol>
	<li>Select fuel for analysis. Here, choose methane as the reference fuel, but the principles are transferable to other hydrocarbon fuels.</li>
	<li>With 1 mole of methane as the fuel, balance equation (1) for stoichiometric combustion to get equation (2). 
	<img alt="Equation 1" src="/files/ftp_upload/54638/54638eq1.jpg" /> 
	<img alt="Equation 2" src="/files/ftp_upload/54638/54638eq2.jpg" /></li>
	<li>Calculate the fuel-air ratio for stoichiometric (F/Astoich.) as ...

<ol>
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Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integration+of+solid+oxide+fuel+cells+with+multi-element+diffusion+flame+burners.">Integration of solid oxide fuel cells with multi-element diffusion flame burners.</a> J. Electochem. Soc. 160 (11), F1241-F1244 (2013).</li><li>Horiuchi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+of+a+solid+oxide+fuel+cell+couple+operated+via+in+situ+catalytic+partial+oxidation+of+n-butane.">Performance of a solid oxide fuel cell couple operated via in situ catalytic partial oxidation of n-butane.</a> J. 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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> An Introduction to Combustion: Concepts and Applications. , (2000).</li><li>Glassman, I., Yetter, R. A., Glumac, N. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Combustion. , (2015).</li></ol>

The protocol discussed here is an important bridge between previous combustion characterization research and fuel cell testing. The use of combustion for fuel reforming and fuel cell testing has been applied for several years in DFFC setups10-15. However, the characterization of the combustion process in DFFCs is primarily concerned with in-situ characterization of the flame composition16 and uses a MS8. As the DFFC is open to the ambient, the exhaust composition consists mostly ...

Solid oxide fuel cell (SOFC) innovations have been reported in recent years as the technology continues to develop. Among the many advantages, SOFCs have become known for high fuel efficiency, low emissions and moderate fuel flexibility compared to other combustion based power generation techniques1. Furthermore, SOFCs are scalable allowing for high fuel efficiency even at small scales. Unfortunately, limitations in current hydrogen infrastructure have created a need for fuel reforming systems that are often inefficient. A recent development is the micro-tubular flame-assisted fuel cell (mT-FFC) reported in the author&#39;s previous work2. The mT-FFC is the first example of a flame-assisted fuel cell (FFC) that builds on the benefits of the original direct flame fuel cell (DFFC), which provides heat generation and fuel reforming via combustion3. The DFFC setup places a SOFC in direct contact with a flame open to the ambient environment. The flame partially oxidizes heavier hydrocarbon fuels to create H2 and CO, which can be used directly in the SOFC with less potential for carbon coking compared to pure methane or other heavier hydrocarbons. In addition, the flame provides the thermal energy needed to bring the SOFC to its operating temperature. A recent change to the original DFFC occurred by moving the SOFC out of the flame region and channeling the combustion exhaust to the SOFC to create the FFC2. Unlike the DFFC, the combustion occurs in a partially enclosed chamber (instead of the ambient) so that the fuel to air ratio can be controlled and the exhaust can be directly fed to the fuel cell without complete combustion occurring. FFCs have additional advantages including high fuel utilization and high electrical efficiency compared to DFFCs2.
As an emerging area of research, experimental techniques are needed that can assess the potential of mT-FFCs for future power generation applications. These techniques require analysis of partial oxidation, or fuel-rich combustion, and the exhaust which has been identified as a way of generating H2 and CO, also known as syngas, along with CO2 and H2O. The syngas can be used directly in the fuel cells for power generation. The analysis of fuel-rich combustion exhaust has been well established in recent years and has been carried out theoretically4, computationally5,6 and experimentally7 for many different purposes. Many of the theoretical and computational studies have relied on chemical equilibrium analysis (CEA) to assess the combustion product species that are energetically favorable, and chemical kinetic models for reaction mechanisms. While these methods have been very useful, many emerging technologies have relied upon experimental techniques during research and development. Experimental techniques typically rely on analysis of the combustion exhaust using either a gas chromatograph (GC)7 or a mass spectrometer (MS)8. Either the GC line/syringe or the MS probe is inserted into the combustion exhaust and measurements are taken to assess the species concentration. Application of the experimental techniques has been common in the area of small scale power generation. Some examples include micro combustors that have been developed to operate with single chamber SOFCs7,9 and DFFCs10-15. The analysis of the combustion exhaust occurs under a wide range of operating conditions including different temperatures, flow rates and equivalence ratios.
In the area of DFFC research, fuel and oxidant can be partially premixed or non-premixed, with the burner open to the ambient which ensures complete combustion. With a need to analyze the flame composition, a MS has been used in many instances for DFFC research and combustion analysis16. The more recent development of the FFC differs by relying on premixed combustion with the burner in a partially enclosed environment to prevent complete oxidation of the fuel. As a result, analysis of the combustion exhaust in a controlled environment free from air leakage is needed. Experimental techniques developed for this purpose rely on the earlier techniques used for micro combustor research with GC analysis of the combustion exhaust at varying equivalence ratios. The GC analysis leads to characterization of the combustion exhaust composition (i.e., the volume percent of each exhaust constituent including CO2, H2O, N2, etc.) This analysis allows for mixing of separate gases according to the ratios measured by the GC to create a model fuel-rich combustion exhaust for future FFC research.
The protocols for analyzing fuel-rich combustion exhaust, developing a model fuel-rich combustion exhaust and applying the exhaust for SOFC testing are established in this paper. Common challenges and limitations are discussed for these techniques.

<table border="0" cellpadding="0" cellspacing="0" width="758">
	<tbody>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Gas chromotograph</td>
			<td style="width:111px;">SRI Instruments, Inc.</td>
			<td style="width:129px;">SRI 8610C</td>
			<td style="width:303px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">K type thermocouples</td>
			<td style="width:111px;">Omega</td>
			<td style="width:129px;">KQXL-116G-6</td>
			<td>Custom length</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">K type thermocouple extension wire</td>
			<td style="width:111px;">Omega</td>
			<td style="width:129px;">EXTT-K-20-SLE-100</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Mass flow controller</td>
			<td style="width:111px;">Omega</td>
			<td style="width:129px;">FMA5427</td>
			<td style="width:303px;">0-40 L/min (N2) 
			Used for methane</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Mass flow controller</td>
			<td style="width:111px;">Omega</td>
			<td style="width:129px;">FMA5443</td>
			<td style="width:303px;">0-200 L/min (N2) 
			Used for air</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Mass flow controller</td>
			<td style="width:111px;">Omega</td>
			<td style="width:129px;">FMA5402A</td>
			<td style="width:303px;">0-10 mL/min (N2) 
			Used for CO</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Mass flow controller</td>
			<td style="width:111px;">Brooks Instrument</td>
			<td style="width:129px;">SLA5850</td>
			<td style="width:303px;">200 SCCM (Propane) 
			Used for CO2</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Mass flow controller</td>
			<td style="width:111px;">Brooks Instrument</td>
			<td style="width:129px;">SLA5850</td>
			<td style="width:303px;">5 L/min (Air) 
			Used for N2</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Mass flow controller</td>
			<td style="width:111px;">Brooks Instrument</td>
			<td style="width:129px;">SLA5850</td>
			<td style="width:303px;">500 SCCM (N2) 
			Used for H2</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Regulator</td>
			<td style="width:111px;">Harris Products Group</td>
			<td style="width:129px;">HP721-125-350-F</td>
			<td style="width:303px;">Methane tank</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Regulator</td>
			<td style="width:111px;">Harris Products Group</td>
			<td style="width:129px;">HP702-050-590-E</td>
			<td>Air tank</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Regulator</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:129px;">Y11-SR145B</td>
			<td>CO tank</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Regulator</td>
			<td style="width:111px;">Harris Products Group</td>
			<td style="width:129px;">HP702-050-320-E</td>
			<td>CO2 tank</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Regulator</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:129px;">Y12-215B</td>
			<td>N2 tank</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Regulator</td>
			<td style="width:111px;">Harris Products Group</td>
			<td style="width:129px;">HP702-015-350-D</td>
			<td>H2 tank</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Methane, Compressed , 
			Ultra high purity</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:129px;">UN1971</td>
			<td style="width:303px;">Extremely Flammable</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Air, Compressed, 
			Ultra pure</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:129px;">UN1002</td>
			<td style="width:303px;">Not classified as hazardous to health.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">CO, Compressed, 
			Ultra high purity</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:129px;">UN1016</td>
			<td style="width:303px;">Toxic by inhalation, Extremely flammable</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">CO2, Compressed, 
			Research grade</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:129px;">UN1013</td>
			<td style="width:303px;">Asphyxiant in high 
			concentrations</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">&#160;N2, Compressed, 
			Ultra high purity</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:129px;">UN1066</td>
			<td style="width:303px;">Not classified as hazardous to health.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">H2, Compressed, 
			Ultra high purity</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:129px;">UN1049</td>
			<td style="width:303px;">Extremely flammable, 
			burns with invisible flame</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Source meter</td>
			<td style="width:111px;">Tektronix, Inc.</td>
			<td style="width:129px;">Keithley 2420</td>
			<td style="width:303px;">Connects to computer 
			via USB</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Horizontal split tube furnace</td>
			<td style="width:111px;">MTI Corportation</td>
			<td style="width:129px;">OTF-1200X</td>
			<td style="width:303px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Data acquisition</td>
			<td style="width:111px;">National Instruments</td>
			<td style="width:129px;">NI cDAQ-9172</td>
			<td style="width:303px;">Connects to computer 
			via USB</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Thermocouple input</td>
			<td style="width:111px;">National Instruments</td>
			<td style="width:129px;">NI 9211</td>
			<td>Connects to cDAQ-9172</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Computer control for Mass Flow Controllers</td>
			<td style="width:111px;">National Instruments</td>
			<td style="width:129px;">NI 9263</td>
			<td style="width:303px;">Connects to cDAQ-9172 
			Computer control for Mass Flow Controllers</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Testing software</td>
			<td style="width:111px;">National Instruments</td>
			<td style="width:129px;">LabVIEW 8.6</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Ceramabond</td>
			<td style="width:111px;">Aremco</td>
			<td>552-VFG</td>
			<td>1 Pint</td>
		</tr>
	</tbody>
</table>

combustion characterization and model fuel development for micro-tubular flame-assisted fuel cells

Combustion based power generation has been accomplished for many years through a number of heat engine systems. Recently, a move towards small scale power generation and micro combustion as well as development in fuel cell research has created new means of power generation that combine solid oxide fuel cells with open flames and combustion exhaust. Instead of relying upon the heat of combustion, these solid oxide fuel cell systems rely on reforming of the fuel via combustion to generate syngas for electrochemical power generation. Procedures were developed to assess the combustion by-products under a wide range of conditions. While theoretical and computational procedures have been developed for assessing fuel-rich combustion exhaust in these applications, experimental techniques have also emerged. The experimental procedures often rely upon a gas chromatograph or mass spectrometer analysis of the flame and exhaust to assess the combustion process as a fuel reformer and means of heat generation. The experimental techniques developed in these areas have been applied anew for the development of the micro-tubular flame-assisted fuel cell. The protocol discussed in this work builds on past techniques to specify a procedure for characterizing fuel-rich combustion exhaust and developing a model fuel-rich combustion exhaust for use in flame-assisted fuel cell testing. The development of the procedure and its applications and limitations are discussed.

The combustion characterization chamber should be checked prior to testing at the desired equivalence ratios for back-flow of air into the chamber or other air leakage during testing. Combustion processes in open chambers are known to be nearly isobaric. As a result, pressure within the combustion chamber may not be enough to ensure that no air from the external environment is back-flowing into the combustion chamber from the chamber exhaust port or other leakage points. There are several...

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Combustion Characterization and Model Fuel Development for Micro-tubular Flame-assisted Fuel Cells

A protocol for creating a model fuel-rich combustion exhaust is developed through combustion characterization and is applied for micro-tubular flame-assisted fuel cell testing and research.

Combustion based power generation has been accomplished for many years through a number of heat engine systems. Recently, a move towards small scale power ...

The overall goal of this combustion characterization experiment is to develop a model combustion exhaust by mixing the exhaust species of interest in order to test a solid oxide fuel cell in the mixture. This maxsold can help answer key questions in solid oxide fuel cell fields, such as whether fewer rich combustion is forming instead of endothermic fuel reformer. The main advantage of this technique is that we can develop a model combustion exhaust for fuel cell testing without actually developing an entire burner and fuel cell prototype.Visual demonstration of this method is critical, as the experimental setup procedure, safety precautions and troubleshooting can be difficult to understand by reading a manuscript alone. Construct the characterization apparatus using a prepared combustion chamber at a bench with sources of air and the methane fuel. Select the mass flow controllers based on previously determined flow rates.For this experiment, use a 40 liter per minute controller for methane. Use a 200 liter per minute controller for air. Next, get copper tubing and connect it to the outlet of the methane source.From there, connect the tubing to the fuel mass flow controller. Similarly, connect the air mass flow controller to its source. For safety, add a one way valve after the methane flow controller.Orient the valve to only allow flow away from the controller and connect it to the controller output. Next, use copper tubing to merge the flows from the air and the fuel flow controllers. Have the flows from the controllers enter a T connector.As added safety measures, place a flame arrestor and another one way valve after the T connector. In this setup, the one way valve is connected first to the T connector, oriented to allow flow away from the T connector. The flame arrestor is next.At the source tanks for the gases, set the regulators to the appropriate pressures. For this experiment, that is 138 kilopascal. Back at the bench, obtain leak detection solution to test all the tubing for leaks.With the flow controllers on, apply the leak detection solution with a brush onto the copper tubing. Make sure there are no bubbles which would indicate a leak. At this point, turn attention to the combustion chamber and it's attached burner.This chamber has K type thermocouples already in place, with their tips at the center of the chamber. Ports along the chamber length accommodate both combustion exhaust analysis and the thermocouples. Mount the thermocouples using compression fittings matched to their diameter.To add a thermocouple, begin with the stem of the compression fitting that is already in the chamber wall. Place an appropriate high temperature metal feral into the stem. Next, lower the compression nut with a thermocouple probe threaded through it onto the stem.Push the thermocouple probe through until its end is at the center of the chamber. Then tighten the compression nut to seal the chamber against leaks from this opening. Connect the thermocouples to the computer setup for data acquisition and control.Return to connect the output of the mass flow controllers to the combustion chamber burner. For this, use copper tubing to send the flow from the one way valve to the combustion chamber. The final addition is the hardware for testing the exhaust, which has already been assembled here.For this, an exhaust port in the chamber allows gases to flow into the copper tubing. This tubing goes into a three way valve. One output of the valve is tubing leading to a gas chromatograph.The other output is tubing that goes to a 25 milliliter syringe used for drawing and redirecting exhaust. The setup can now be used for characterization. Before testing, prepare the syringe and three way valve.First, push the syringe plunger in fully. Then ensure the three way valve is open on the exhaust port side. Move to the computer to start the fuel and air flowing and start data collection.Initiate the air flow and the methane flow using a rich mixture for ease of ignition. Get a butane lighter and move to the end of the combustion chamber. When it is safe to do so, ignite the mixture.Before proceeding, perform a visual check to make sure the flame has stabilize at the burner front. This flame is changing as the air flow is slowly adjusted to the desired value to avoid quenching the flame. Meanwhile, monitor the thermocouple temperatures and record the temperature data when the temperatures stabilize.Now, go to the syringe connected to the three way valve. Pull the plunger back to extract residual gas and exhaust from the exhaust port. Use the three way valve to open the gas chromatograph side and close the exhaust port side.Continue by pushing the plunger until all of the exhaust has been sent to the gas chromatograph. Return the valve to allow the syringe to extract more residual gas and exhaust. Continue extracting gas and injecting it into the gas chromatograph until all residual gases are removed.When all the residual gases have bee removed, extract a final exhaust sample for analysis. Turn the three way valve and push the exhaust gas into the gas chromatograph. Perform the gas chromatograph analysis and record the data.Continue by choosing another air flow rate and repeating the analysis for the new equivalents ratio. These results for chemical equilibrium analysis of methane and air combustion give the thermodynamic equilibrium predictions of the exhaust gas composition at different equivalents ratios. The left vertical axis is for the volume percentage of Nitrogen gas, plotted in black.The right vertical axis gives the volume percentage scale for the exhaust products and other molecules. This analysis will not necessarily match the experiment data perfectly, but should indicate expected trends and magnitude of the results. Initial experiment data for the combustion chamber did not follow the trends expected from chemical equilibrium analysis.For example, the molecular oxygen data in red, suggests a high concentration at high equivalence ratios compared to low equivalence ratios. This is a possible indication of incomplete mixing or back flow in the combustion chamber, which other data corroborated. When back flow is identified and prevented, the data were more consistent with the trends expected from chemical equilibrium analysis.After watching this video, you should have a good understanding of how to characterize a combustion exhaust and to build a model combustion exhauster for fuel cell testing. Don't forget that working with combustion can be extremely hazardous and precautions such as flame arrestor, one way valves and other personal protective equipment should always be used while performing this procedure. Following this procedure, other methods, like integrating a fuel cell and a burner together can help answer additional questions about long term performance stability, Carbon deposition, and total system efficiency of the flame assisted fuel cell.

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Research

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JoVE Journal

JoVE Core

Organic Chemistry

Engineering

Unit 1

Alkanes and Cycloalkanes

SCIENTISTS IN ACTION

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

Preparation and Evaluation of Hybrid Composites of Chemical Fuel and Multi-walled Carbon Nanotubes in the Study of Thermopower Waves

When a chemical fuel at a certain position in a hybrid composite of the fuel and a micro/nanostructured material is ignited, chemical combustion occurs along the interface between the fuel and core materials. Simultaneously, dynamic changes in thermal and chemical potentials across the micro/nanostructured materials result in concomitant electrical energy generation induced by charge transfer in the form of a high-output voltage pulse. We demonstrate the entire procedure of a thermopower wave experiment, from synthesis to evaluation. Thermal chemical vapor deposition and the wet impregnation process are respectively employed for the synthesis of a multi-walled carbon nanotube array and a hybrid composite of picric acid/sodium azide/multi-walled carbon nanotubes. The prepared hybrid composites are used to fabricate a thermopower wave generator with connecting electrodes. The combustion of the hybrid composite is initiated by laser heating or Joule-heating, and the corresponding combustion propagation, direct electrical energy generation, and real-time temperature changes are measured using a high-speed microscopy system, an oscilloscope, and an optical pyrometer, respectively. Furthermore, the crucial strategies to be adopted in the synthesis of hybrid composite and initiation of their combustion that enhance the overall thermopower wave energy transfer are proposed.

A protocol for conducting thermopower wave experiments is presented. The synthesis of hybrid composites of a chemical fuel and micro/nanostructured material, manufacturing of a thermopower wave generator, and methods for measuring the corresponding physical phenomena are described.

When a chemical fuel at a certain position in a hybrid composite of the fuel and a micro/nanostructured material is ignited, chemical combustion occurs ...

Characterization of Nanocrystal Size Distribution using Raman Spectroscopy with a Multi-particle Phonon Confinement Model

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The common techniques used for the size analysis are transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). These techniques, however, are not suitable for analyzing the nanocrystal size distribution in a fast, non-destructive and a reliable manner at the same time. Our aim in this work is to demonstrate that size distribution of semiconductor nanocrystals that are subject to size-dependent phonon confinement effects, can be quantitatively estimated in a non-destructive, fast and reliable manner using Raman spectroscopy. Moreover, mixed size distributions can be separately probed, and their respective volumetric ratios can be estimated using this technique. In order to analyze the size distribution, we have formulized an analytical expression of one-particle PCM and projected it onto a generic distribution function that will represent the size distribution of analyzed nanocrystal. As a model experiment, we have analyzed the size distribution of free-standing silicon nanocrystals (Si-NCs) with multi-modal size distributions. The estimated size distributions are in excellent agreement with TEM and PL results, revealing the reliability of our model.

We demonstrate how to determine the size distribution of semiconductor nanocrystals in a quantitative manner using Raman spectroscopy employing an analytically defined multi-particle phonon confinement model. Results obtained are in excellent agreement with the other size analysis techniques like transmission electron microscopy and photoluminescence spectroscopy.

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The ...

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Reaction Kinetics and Combustion Dynamics of I4O9 and Aluminum Mixtures

Tetraiodine nonoxide (I4O9) has been synthesized using a dry approach that combines elemental oxygen and iodine without the introduction of hydrated species. The synthesis approach inhibits the topochemical effect promoting rapid hydration when exposed to the relative humidity of ambient air. This stable, amorphous, nano-particle material was analyzed using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) and showed an exothermic energy release at low temperature (i.e., 180 &#176;C) for the transformation of I4O9 into I2O5. This additional exothermic energy release contributes to an increase in overall reactivity of I4O9 when dry mixed with nano-aluminum (Al) powder, resulting in a minimum of 150% increase in flame speed compared to Al + I2O5. This study shows that as an oxidizer, I4O9 has more reactive potential than other forms of iodine(V) oxide when combined with Al, especially if I4O9 can be passivated to inhibit absorption of water from its surrounding environment.

Reaction Kinetics and Combustion Dynamics of I4O9 and Aluminum Mixtures

A protocol for measuring flame speeds of a reactive mixture composed of tetraiodine nonoxide (I4O9) and aluminum (Al) is presented. A method for resolving reaction kinetics using differential scanning calorimetry (DSC) is also presented. It was found that I4O9 is 150% more reactive than other iodine(V) oxides.

Tetraiodine nonoxide (I4O9) has been synthesized using a dry approach that combines elemental oxygen and iodine without the introduction of hydrated ...

Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent

The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with sufficient heavy metal adsorption capacity. To this end, blast furnace slag, a residue from iron-making, is utilized as the starting material. Calcium is selectively extracted from the slag by leaching with acetic acid (2 M CH3COOH) as the extraction agent. The filtered leachate is subsequently physico-chemically purified and then carbonated to form precipitated calcium carbonate (PCC) of high purity (&lt;2 wt% non-calcium impurities, according to ICP-MS analysis). Sodium hydroxide is added to neutralize the regenerated acetate. The morphological properties of the resulting calcitic PCC are tuned for its potential application as a filler in papermaking. In parallel, the residual solids from the extraction stage are subjected to hydrothermal conversion in a caustic solution (2 M NaOH) that leads to the predominant formation of a particular zeolitic mineral phase (detected by XRD), namely analcime (NaAlSi2O6&#8729;H2O). Based on its ability to adsorb Ni2+, as reported from batch adsorption experiments and ICP-OES analysis, this product can potentially be used in wastewater treatment or for environmental remediation applications.

A protocol for the parallel production of precipitated calcium carbonate and zeolitic material from blast furnace slag via mineral carbonation and alkaline hydrothermal conversion, respectively, is presented. The performance of the zeolitic material towards nickel adsorption is tested.

The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with ...

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing

We present a protocol for performing gas spectroscopy using infrared degenerated four-wave mixing (IR-DFWM), for the quantitative detection of gas species in the ppm-to-single-percent range. The main purpose of the method is the spatially resolved detection of low-concentration species, which have no transitions in the visible or near-IR spectral range that could be used for detection. IR-DFWM is a nonintrusive method, which is a great advantage in combustion research, as inserting a probe into a flame can change it drastically. The IR-DFWM is combined with upconversion detection. This detection scheme uses sum-frequency generation to move the IR-DFWM signal from the mid-IR to the near-IR region, to take advantage of the superior noise characteristics of silicon-based detectors. This process also rejects most of the thermal background radiation. The focus of the protocol presented here is on the proper alignment of the IR-DFWM optics and on how to align an intracavity upconversion detection system.

Here, we present a protocol to perform sensitive, spatially resolved gas spectroscopy in the mid-infrared region, using degenerate four-wave mixing combined with upconversion detection.

We present a protocol for performing gas spectroscopy using infrared degenerated four-wave mixing (IR-DFWM), for the quantitative detection of gas species ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...

Measuring Sub-23 Nanometer Real Driving Particle Number Emissions Using the Portable DownToTen Sampling System

The current particle size threshold of the European Particle Number (PN) emission standards is 23 nm. This threshold could change because future combustion engine vehicle technology may emit large amounts of sub-23 nm particles. The Horizon 2020 funded project DownToTen (DTT) developed a sampling and measurement method to characterize particle emissions in this currently unregulated size range. A PN measurement system was developed based on an extensive review of the literature and laboratory experiments testing a variety of PN measurement and sampling approaches. The measurement system developed is characterized by high particle penetration and versatility, which enables the assessment of primary particles, delayed primary particles, and secondary aerosols, starting from a few nanometers in diameter. This paper provides instruction on how to install and operate this Portable Emission Measurement System (PEMS) for Real Drive Emissions (RDE) measurements and assess particle number emissions below the current legislative limit of 23 nm.

Presented here is the DownToTen (DTT) portable emission measurement system to assess real driving automotive emissions of sub-23 nm particles.

The current particle size threshold of the European Particle Number (PN) emission standards is 23 nm. This threshold could change because future ...

Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure

A technique to improve the combustion performance of a hybrid rocket engine using a novel fuel grain structure is presented. This technique utilizes the different regression rates of acrylonitrile butadiene styrene and paraffin-based fuels, which increase the exchanges of both matter and energy by swirl flow and recirculation zones formed at the grooves between the adjacent vanes. The centrifugal casting technique is used to cast the paraffin-based fuel into an acrylonitrile butadiene styrene substrate made by three-dimensional printing. Using oxygen as the oxidizer, a series of tests were conducted to investigate the combustion performance of the novel fuel grain. In comparison to paraffin-based fuel grains, the fuel grain with a nested helical structure, which can be maintained throughout the combustion process, showed significant improvement in the regression rate and great potential in improvement of combustion efficiency.

A technique utilizing a solid fuel grain with a novel nested helical structure to improve the combustion performance of a hybrid rocket engine is presented.

A technique to improve the combustion performance of a hybrid rocket engine using a novel fuel grain structure is presented. This technique utilizes the ...