微生物燃料电池在污水处理中的研究进展

微生物燃料电池（Microbial Fuelcell,MFC）是一种以微生物为催化剂,将有机物中的化学能转化为电能的装置。本文介绍了微生物燃料电池的原理和特点,阐述了反应器结构、底物种类、电极等方面的研究进展,分析了微生物燃料电池未来的发展方向,并对今后的研究提出建议。     

Simulation Study of a PEM Fuel Cell System with Steam Reforming

Abstract

This article summarizes the results of a study for a 100 kWe DC electrical power PEM fuel cell system. The system consists of a pre-steam reformer, a steam reformer, high and low temperature shift reactors, a preferential oxidation reactor, a PEM fuel cell, a combustor, and an expander. Acceptable net electrical efficiency levels can be achieved via intensive heat integration within the PEM fuel cell system. The calculations take into account the auxiliary equipment such as pumps, com pressors, heaters, coolers, heat exchangers and pipes. The process simulation package “Aspen-HYSYS 3.1’’ has been used. The operation parameters of the reactors have been determined considering all the technical limitations involved. A gasoline type hydrocarbon fuel has been studied as hydrogen rich gas source. Thermal efficiencies have been calculated for all of the major system components for selected operation conditions. The fuel cell stack efficiency has been calculated as a function of cell numbers (500, 750, 1000, and 1250 cells). Efficiencies of all of the major system components along with auxiliary unit efficiencies determine the net electrical efficiency of the PEM fuel cell system. The obtained net electrical efficiency levels are between 34 (500 cells) to 41% (1250 cells).     

Thermal and Electrical Analysis in a Solid Oxide Fuel Cell Stack Using a Curved Profile for the Inlet Flow Rate Along the Stacking Direction

This study analyzes the cell temperature and current density fields of a solid oxide fuel cell stack, in which the inlet flow rate along the stacking direction of the fuel is either a curved profile derived through hydraulics or a progressively decreasing profile. The results show that the temperature field was neglibibly affected by the non-uniform inlet profile of the fuel, but the current density distribution was apparently affected. The difference in current density distribution between the curved profile and the progressively decreasing profile was small in the case of an solid oxide fuel cell (SOFC) with 10 stacks, but became larger in an SOFC with 20 stacks. In the 10-stack SOFC, the difference of current density between the uniform inlet flow and the curved inlet flow was less than 3%, whereas the deviation in the curved profile was less than 12%. However, in a 20-stack SOFC, the difference of current density was over 20%, whereas the deviation in the curved profile was more than 50%. Comparing the results between the curved and the progressively decreasing inlet profile indicates that the current density difference was over 20% in the 20-stack SOFC, but below 1% in the 10-stack SOFC. Therefore, a progressively decreasing inlet profile can replace a curved profile for analyzing an SOFC stack when the number of stacks is less than 10.     

Numerical Analysis of Heat Transfer and Gas Flow in PEM Fuel Cell Ducts by a Generalized Extended Darcy Model

Abstract

In this work, gas flow and heat transfer have been numerically investigated and analyzed for both cathode/anode ducts of proton exchange membrane (PEM) fuel cells. The simulation is conducted by solving a set of conservation equations for the whole domain consisting of a porous medium, solid structure, and flow duct. A generalized extended Darcy model is employed to investigate the flow inside the porous layer. This model accounts for the boundary-layer development, shear stress, and microscopic inertial force as well. Effects of inertial coefficient, together with permeability, effective thermal conductivity, and thickness of the porous layer on gas flow and heat transfer are investigated.