Jacob LaManna

Through-Plane Water Transport Visualization in a PEMFC by Visible and Infrared Imaging

In this study, water transport and thermal profile in the through-plane direction of a proton exchange membrane fuel cell (PEMFC) gas diffusion layer (GDL) are reported. Direct optical and infrared access to both cathode and anode GDLs are provided in a typical 50 cm test section. Dynamic visualization (pixel resolution of 0.6 lm at 28 Hz) of liquid water transport and emergence in the gas distribution channels and diffusion layers are reported and the underlying transport processes are discussed. The temperature distributions across the anode and cathode GDL are also measured with a high resolution infrared camera with a pixel resolution of 5 lm at 30 Hz. VC 2011 The Electrochemical Society. [DOI: 10.1149/1.3560163] All rights reserved.

A CRITICAL REVIEW OF WATER TRANSPORT MODELS IN GAS DIFFUSION MEDIA OF PEM FUEL CELL

Proton Exchange Membrane (PEM) fuel cells are gaining popularity as a replacement to the internal combustion engine in automobiles. This application will deman d high levels of performance from the fuel cell making it critical that proper water management is maintained. One of the areas of interest in water management is the transport of wa ter through the Gas Diffusion Medium (GDM) on the cathode side of the cell. Research is currently being conducted to und erstand how water moves through the porous structure of the GDM. Due to the small scale of the GDM, most work done is analytical modeling. This paper will focus on reviewing curre nt models for water transport within the GDM of a PEM fuel cell to address state of the art and provide recommendation s for future work to extend current models.

Through-Plane Water Transport Visualization in an Operating PEM Fuel Cell by Visible and Infrared Imaging

In this study, the liquid water emergence and transport within anode and cathode gas diffusion layers in an operating fuel cell was observed from the cross-section with a digital microscope and a high resolution infrared camera. In the cathode, water droplets were found to be formed on the channel side of the GDL cross-section, while little water was detected in the vicinity of the microporous layer. This finding suggested that water was condensing inside the GDL and may imply the existence of a condensation front, which has been predicted by numerical simulation but previously has not been verified experimentally. The anode results indicate that water was transported through anode GDL dominantly in the vapor form. The temperature distributions across the anode and cathode GDL were also measured with a high resolution infrared camera. These visualizations provided critical information on the water transport across a fuel cell.

Feasibility of Thermoelectric Waste Heat Recovery in Large Scale Systems

With the growing emphasis on energy efficiency because of environmental, political, and economic reasons and the fact there has been significant advances in thermoelectric materials, there is a renewed interest in using thermoelectrics for waste heat recovery. A mathematical model of a thermoelectric power system is developed from a heat transfer analysis of a waste heat recovery system. The model is validated by altering design parameters of a small prototype thermoelectric system that converts heat into electricity. A heated air stream is produced using an exhaust simulation test stand and provides the waste heat source for the prototype. The prototype is designed to be able to change several system parameters such as different heat sinks, thermoelectric module counts, and module configurations to better validate the developed model. The model does predict the electrical performance with typical accuracy of 30% error from the prototype over a range of configurations and operating conditions. A feasibility study using the validated model was used to determine under what conditions this technology will become economically viable, such as remote power generation with 20 year payback.Copyright

Investigation of Water Vapor Diffusivity Through GDL of a PEMFC

Water transport through the gas diffusion layer (G DL) of a proton exchange membrane (PEM) fuel cell is of critical importance in the operation of the fuel cell. In th is study, the transport of water vapor through the GDL is investi gated. A one-dimensional, single-phase heat and mass transfe r model is developed to investigate the diffusivity of water v apor through the GDL of a PEMFC. An experimental apparatus is developed to induce water vapor gradients across the GDL whil e varying humidity levels and flow rates comparable to actual fuel cell operational conditions. Experimental data is then used to extract an effective water vapor diffusivity from t he numerical model. Effective diffusivity was found to be 0.104 x10 -4 m 2 /s and the overall mass transfer coefficient was found to be 0.019 m/s at a temperature of 40°C.