Yanyan Zhang

Biography

Yanyan Zhang received the B.S. and M.S. degrees in Mechanical Engineering from Shanghai Jiao Tong University in 1999 and 2002, respectively, and worked for the Daimler Chrysler Corporation in China prior to starting her doctoral work in the Advanced Materials and Technologies Laboratory in Fall 2003.

Research Projects

Graded Porosity and Catalyst Distribution for Uniformity of Current Density Distribution in (PEM) Fuel Cells

In the fuel cell, the variation of the current density increases the possibility of the damages due to sharp temperature and stress gradients on certain points. This project investigated the effects of the operating conditions on the uniformity of the current density distribution and identified the optimum operating conditions which led to the uniform current density distribution while maximizing the power density and minimizing anode stoichiometry. To this end, a two-dimensional PEM fuel cell modeling was developed. Systematic parametric studies were implemented to investigate the effects the operating conditions and the design windows were constructed to determine the optimum operating conditions.

To improve the uniformity in local current density distribution and enhance the catalyst utilization, this research further presents a novel concept of functionally graded porosity of the gas diffusion layers and graded catalyst loading in the cathode along the gas channel. A two-dimensional isothermal numerical model for PEM fuel cells combined with an optimization model was developed to determine the optimum porosity and cathode catalyst loadings and the associated local current density distributions for different operating conditions. Experiments were conducted to measure the local current density distribution for the graded designs, using a segmented current collector. The results show that an optimized graded porosity and catalyst loading significantly reduce the current density variation along the length of the channel and enhances catalyst utilization.

Analysis and Design of Passive Air Breathing PEM Fuel Cell

Passive air-breathing fuel cell is promising portable energy source as an alternative to dry-cell battery. The objective of this research is to investigate the performance of the passive PEM fuel cell and its stack under different operating conditions and different orientations with different geometry parameters. A two dimensional nonisothermal multi-components modeling with natural convection air supply was developed. The investigation of the performance of single passive fuel cell was completed by implementing parametric studies for the effects of operating conditions and studying temperature and species distributions across the cell under different orientations. The performance of the passive fuel cell stack is decided by a few factors including the geometry parameters and operating parameters. The effect of geometry parameters including the gap between the cells, the height between the stack and the bottom board and the length of the cell were investigated and the design window were created to determine the optimum design parameters under certain requirements for the stack.

Publications

1. Y. Zhang, A. Verma and R. Pitchumani, “Studies on Graded Porosity Distributions of Gas Diffusion Layer in Proton Exchange Membrane (PEM) Fuel Cells,” International Journal of Hydrogen Energy, 41, 8412–8426, 2016.
2. Y. Zhang, A. Smirnova, A. Verma and R. Pitchumani, “Design of a Proton Exchange Membrane (PEM) Fuel Cell with Variable Catalyst Loading,” Journal of Power Sources, 291, 46–57, 2015.
3. Y. Zhang and R. Pitchumani, “Numerical Studies on an Air-breathing Proton Exchange Membrane (PEM) Fuel Cell,” International Journal of Heat and Mass Transfer, 50(23–24), 4698–4712, 2007.
4. Y. Zhang, A. Mawardi, and R. Pitchumani, “Numerical Studies on an Air-breathing Proton Exchange Membrane (PEM) Fuel Cell Stack,” Journal of Power Sources, 173, 264–276, 2007.
5. Y. Zhang, A. Mawardi, and R. Pitchumani, “Effects of Operating Parameters on the Uniformity of Current Density Distribution in Polymer Electrolyte Membrane Fuel Cells,” ASME Journal of Fuel Cell Science and Technology, 3(4), 464–476, 2006.
6. Y. Zhang, A. Mawardi and R. Pitchumani, “Analysis and Design of Proton Exchange Membrane Fuel Cells for Maximum Power Density and Uniform Current Density Distribution,” First European Fuel Cell Technology & Applications Conference, Dec 2005, Rome, Italy. 

Sponsor