Burheim O.,Institute Kjemi |
Vie P.J.S.,Institute for Energy Technology of Norway |
Pharoah J.G.,Institute Kjemi |
Pharoah J.G.,Queens RMC Fuel Cell Research Center |
Kjelstrup S.,Institute Kjemi
Journal of Power Sources | Year: 2010
In this paper thermal properties for materials typically used in the proton exchange membrane fuel cell (PEMFC) are reported. Thermal conductivities of Nafion membranes were measured ex situ at 20 °C to be 0.177 ± 0.008 and 0.254 ± 0.016 W K-1 m-1 for dry and maximally wetted membranes respectively. This paper also presents a methodology to determine the thermal conductivity of compressible materials as a function of applied load. This technique was used to measure the thermal conductivity of an uncoated SolviCore porous transport layer (PTL) at various compaction pressures. For the dry PTL at 4.6, 9.3 and 13.9 bar compaction pressures, the thermal conductivity was found to be 0.27, 0.36 and 0.40 W K-1 m-1 respectively and the thermal contact resistivity to the apparatus was determined to be 2.1, 1.8 and 1.1 × 10-4 m2 K W-1, respectively. It was shown that the thermal contact resistance between two PTLs is negligible compared to the apparatus' thermal contact resistivity. For a humidified PTL, the thermal conductivity increases by up to 70% due to a residual liquid saturation of 25%. © 2009 Elsevier B.V. All rights reserved.
Dean D.,Queens University |
Davis B.,Queens RMC Fuel Cell Research Center |
Jessop P.G.,Queens RMC Fuel Cell Research Center
New Journal of Chemistry | Year: 2011
Efficient hydrogen storage is one of the critical requirements for the use of hydrogen fuel cells in light-duty vehicles. Our investigation of reversible chemical hydrogen storage systems has led to the development of a mixed endothermic-exothermic carrier system. Herein we further investigate the factors affecting the dehydrogenation rate of these carriers. A range of heterogeneous catalysts was synthesized via sol-gel methodology and their activity for indoline dehydrogenation was assessed. Metals used included Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir and Pt. SiO 2, Al 2O 3, TiO 2 and ZrO 2 were used as supports and Pd/SiO 2 gave the highest conversion over a fixed time. A marked increase in the rate of indoline dehydrogenation was observed when the temperature was increased between 100 and 180 °C, with measured first order rate constants of 1.8 × 10 -4 s -1 at 100 °C and 5.9 × 10 -4 at 120 °C. Although piperidines dehydrogenate more slowly than indolines, steric hindrance around the nitrogen atom in piperidine increases its dehydrogenation rate significantly. © 2011 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Saha M.S.,Queens RMC Fuel Cell Research Center |
Kundu A.,Queens RMC Fuel Cell Research Center
Journal of Power Sources | Year: 2010
In recent years, carbon nanotubes (CNTs) have been increasingly considered as an advanced metal catalyst support for proton exchange membrane fuel cells (PEMFCs), owing to their outstanding physical and mechanical characteristics. However, the effective attachment of metal catalysts, uniformly dispersed onto the CNT surface, remains a formidable challenge because of the inertness of the CNT walls. Therefore, the surface functionalization of CNTs seems necessary in most cases in order to enable a homogeneous metal deposition. This review presents the different surface functionalization approaches that provide efficient avenues for the deposition of metal nanoparticles on CNTs, for the application of catalyst supports in PEMFCs with improved reactivity. © 2010 Elsevier B.V. All rights reserved.
Dhingra H.,Queens RMC Fuel Cell Research Center |
Peppley B.A.,Queens RMC Fuel Cell Research Center
Journal of Power Sources | Year: 2013
Off-grid electricity generation creates a number of environmental, social and economic concerns for remote communities. This represents an opportunity for deployment of SOFC systems in remote areas for distributed power generation. In this paper, a simulation of a 1 kW diesel-fed SOFC system using an auto-thermal reformer is developed and studied using a sensitivity analysis. The influence of key design and operating variables on system performance, where system performance is characterized by the net system efficiency, gross stack efficiency and the final system exhaust temperature is examined. Selected paired variable sensitivities are also examined based on the ranking of individual sensitivities, where two variables at a time are adjusted simultaneously. Of the variables studied, it is observed that variability in the air utilization, fuel utilization and the steam to carbon ratio have the greatest impact on system performance. Overall, an insight is provided into the nature of operating variable interactions as well as those operating variables that require more rigorous process control. The work presented in this study is to be used as a tool by the SOFC Canada NSERC Strategic Network for the design and development of a demonstration small-scale diesel-fed SOFC system. © 2013 Elsevier B.V. All rights reserved.
Monder D.S.,Queens RMC Fuel Cell Research Center |
Monder D.S.,Queens University |
Karan K.,Queens RMC Fuel Cell Research Center |
Karan K.,Queens University
Journal of Physical Chemistry C | Year: 2010
The presence of trace amounts of H2S in H2-rich fuel poisons Ni-based solid oxide fuel cell anodes, adversely affecting the electrochemical performance. This study uses density functional theory (DFT) to describe the competitive adsorption thermodynamics of H2S and H 2 on Ni(111). Unlike previous DFT-based studies on the H 2S-H2-Ni system, a vibrational analysis of the adsorbates is performed to calculate the thermal corrections to the enthalpy and entropy of the surface species. Parallel adsorption reactions of H2 on Ni explicitly accounting for coverage effects of the S and H adatoms on the Ni(111) surface are included in the analysis. The resulting equilibrium equations for the multiple adsorption/desorption reactions are then solved to calculate the S and H coverage over a wide range of T, PH2S, and PH2.This study illustrates the errors introduced in the predicted S coverage if H 2 adsorption in parallel with H2S adsorption is neglected or if the thermal corrections to the enthalpy and entropy of reaction are not handled properly. © 2010 American Chemical Society.