Oscillation of water droplets for enhanced water removal from the gas flow channels of fuel cells  This invention includes a means for providing cyclic force to a water drop on the surface of a fuel cell component at or near the drops natural frequency of the water drop. The droplet is caused to oscillate at a frequency that the liquid inertial forces produced by the oscillation are sufficient to overcome the force of contact line pinning at the solid/liquid/gas interface.
The function of this invention is to assist with the removal of product water from the gas flow channels of a fuel cell. Product water forms on surface of the gas diffusion layer of a fuel cell as a result of fuel cell operation. The product water migrates through the gas diffusion layer into the gas flow channel. The water drops are moved through the channel to the exit via the gas flow. The movement of the water drops is inhibited by pinning of the three-phase region commonly referred to as the contact line region; that is, the line of contact where the gas, liquid, and solid coincide. Efficient removal of this product water is currently a technical challenge and is an important step in fuel cell operation and effective product water removal is a barrier to increased commercial utilization of fuel cells.
A balance between keeping the membrane from becoming too dry or too wet must be maintained for efficient and reliable operation. At high current densities, the production of liquid water may exceed the capacity of the gas streams to evaporate the water out of the fuel cell stack and drops of water will appear within the gas flow channels. If the water accumulation becomes too great, then the gas flow channel may become completely blocked by water and the fuel cell will "flood". The water drops must be removed from the gas flow channels for reliable operation. |
Fuel Cell Group This group is a multi-disciplined team focused on fuel cell heat recovery and fuel cell conversion efficiency improvement. These thrust areas are linked to a set of topics within which the group possesses expertise including heat recovery, initial start issues of high temperature fuel cells, high thermal and/or electrical conductivity materials, energy density, weight, and space related issues, high temperature membranes. low cost high energy cathode/anode, hydrogen generation, storage, transportation, and safety, fuel reforming, low CO emission, long life high power density battery development and hybrid battery. |
Examining Biomass Substrates in Ethanol Production as Source of Alternative Fuel  Bio-fuel ethanol as an alternative fuel is gaining interests for environmental and economical reasons. To reach ethanol goals needed in the United States, it will be essential to take advantage of various biomass substrates for ethanol production (e.g. agricultural and industrial waste products). Recent work includes study of the growth inhibitor, furfural, which induces cellular stress signals in Saccharomyces cerevisiae. Using various fluorescent indicators and transmission electron microscopy techniques, it was determined that furfural causes an increase in reactive oxygen species accumulation, cellular membrane damage (vacuole and mitochondrial membranes), chromatin damage, and cytoskeletal damage in wild-type S. cerevisiae. Whether or not overexpressing any of the previously identified genes will reduce oxidative damage is being investigated. |
The Least-Squares Meshfree Particle Finite Element Method  Although the finite element method has been astonishingly successful in solving various problems in engineering and science, it has significant drawbacks: mesh generation and remeshing are very difficult and time-consuming. Meshfree methods may avoid these difficulties by constructing approximation functions entirely in terms of a set of nodes. Most meshfree methods are based on the Galerkin principle and employ moving least-squares approximation for the construction of shape functions. Although there is no need for an explicit mesh in the construction of moving least-squares shape functions, a separate background mesh is required to integrate the weak form, so they are not truly meshfree methods. Due to the non-interpolative character of the moving least-squares approximation, the enforcement of essential boundary conditions in the Galerkin formulation is quite awkward. Moreover, the moving least-squares approximation is more expensive computationally than the finite element interpolation. In the proposed research, we will develop a least-squares meshfree particle finite element method which combines the features of the least-squares finite element method and the meshfree particle method. The least-squares finite element method (LSFEM), based on minimization of the L2 norm of the residuals of a first-order system of differential equations, is a simple, efficient and robust technique, and can solve almost any kind of partial differential equation with the same mathematical/computational formulation. Since the least-squares method doesn't make use of the integration by parts for converting domain integration into boundary integration, and the meshfree particle method employs the usual finite element interpolations based on particles, all troubles that plague the Garlerkin-based meshfree methods disappear. The least-squares meshfree particle finite element method always leads to a symmetric positive definite system of linear algebraic equations. The matrix-free particle-by-particle conjugate gradient method can be used to solve very large problems on parallel computers, and the implementation is straightforward..
The purpose of this project is to develop a new computer method to simulate complicated engineering designs and sophisticated multi-physical processes with much greater accuracy and efficiency. Achievements of this project would enable numerical simulations beyond current capabilities in many important applications of national interest, including car crash safety analysis, noise reduction of cars, energy efficiency in full cells, heat reduction in semiconductor devices, etc. |
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