Design And Simulation On The Cooling Flow Channel Of Proton Exchange Membrane Fuel Cell

Fuel cells have emerged as a potential replacement for the internal combustion engine in vehicles because the advantages of fuel cell are both environmental and economic. The proton exchange membrane (PEM) fuel cell is the focus of current development efforts because it is capable of higher power density and faster start-up than other fuel cells. Most (PEM) fuel cell systems produce electrical energy at high efficiency that may range from 40% to 60%, at the same time there are 40%to 60% energy being transferred into heat. Improper thermal management causes electrolyte drying (global or local) or electrode flooding which both lower the fuel cell performance. In the present study, the cooling performance of several serpentine and parallel channel designs was evaluated in through a numerical simulation of fluid flow and heat transfer within the cooling plates. Z-type and U-type coolant manifold are simulated and optimized.Firstly of all, heat sources/sinks distribution and the way of heat dissipation was discussed in the cell. A steady-state mathematical model of PEMFC was developed with the characteristics of mass transfer and electrochemical. In the model, mass transportation and charge balance, as well as chemical reaction in the catalyst layers are considered. The voltage was calculated under different current densities, and results of simulation are compared with the experimental results. Heat flux and cooling water flow rate were predicted, when the current density is 1A/cm2.Four cooling plates were designed with different channel configurations. Models A and B had typical parallel configurations and Models C and D had typical serpentine configurations. The performance of cooling plates with different coolant channel designs was evaluated by simulating the fluid flow and heat transfer using CFD. In addition, the effects of computational mesh of the results, and each model have 370000 cells. And then the following indices were calculated and compared, all of which are dependent on temperature distribution uniformity:the maximum temperature Tmax, the average temperature Tav, the temperature uniformity index, Ut and Pressure drop. The results are as following:(1) a higher coolant flow rate in the cooling plates leads to better cooling performance in terms of temperature uniformity; but, this also requires higher power consumption to pump the cooling fluid through the cooling plates more quickly. (2) Cooling performance of Models A and B was lower than that of Model C and D due to non-uniform temperature distributions when there was the same the coolant flow rate in the coolant plant.Three-dimensional computational fluid dynamics stack model composed of 40 coolant plate is constructed to evaluate the flow distribution caused by channel flow resistance. In order to simplify this mode, the straight channels which are filled with porous media take the place of the real coolant channels. The results are as following: (1) Increasing or decreasing the cooling water flow affects the flow distribution in the manifold. (2) The flow distribution is more uniform in the U-type coolant manifold. (3) While manifold widths increase, a more uniform flow distribution will be achieved.