Numerical Simulation Of Electro Chemical Refrigeration And Heat Ing System And Mixed Convection Heat Transfer Of Fuel Cells

Fuel cell is considered as a new energy supply system which has high energy conversion efficiency and reliability, and it is environmental friendly, modular, quiet. What's more, the installation time is short, and the fuel is added convenience. So, in this paper, the complete electrochemical refrigeration and heating system based on fuel cells is established by a self-developed simulation code. The electrochemical refrigeration and heating is based on exothermic reaction and endothermic reaction in the electrochemical reaction process.The electrochemical refrigeration and heating cycle in this paper is made up of four parts which are proton exchange membrane (PEM) fuel cell stack, alkaline electrolytic cell stack, heat exchangers and solar photovoltaic cells. The steady state and dynamic electrochemical modeling and thermal modeling of proton exchange membrane fuel cell and alkaline electrolytic cell are established respectively. The steady state and dynamic thermal modeling of heat exchanger is also established. And the models of system components above are combined into a complete model of electrochemical refrigeration and heating system.The coefficient of performance (COP) of refrigeration and heating of the system in this paper is analyzed. The research of steady state performance contains: the influence on the system components and the system COP of refrigeration and heating with the system load current change and the operating temperature of proton exchange membrane fuel cell stack and alkaline electrolytic cell stack. The research of dynamic performance contains: the influence on the system components and the system COP of refrigeration and heating with the system load current sudden change. And the time of response is also considered.The simulation results show that the electrochemical refrigeration and heating system based on fuel cell stack, alkaline electrolytic cell stack and heat exchanger is reasonable. And it can be used as a way to instead the traditional way of cooling. The system COP of refrigeration and heating will stay a high level with the low system load current. And the response is fast with the system load current sudden change. The energy efficiency of the system is improved by the use of heat exchangers. Meanwhile, the hot water can be obtained from the system.Besides, an important way to improve the performance of the fuel cell is to find out the fuel cell internal temperature distribution and the heat transfer law, because the heat transfer is one of the most important factors of the performance of the fuel cell. In this paper, the two dimensional, non-isothermal model is established by a self-developed simulation code for anode membrane electrode assembly (MEA) of passive direct methanol fuel cell (DMFC). The model is applied to simulate the heat transfer caused by the natural convection and mixed convection.With the numerical simulation, the distribution of fluid flow and temperature within MEA are researched. And it provides a theoretical basis for improving the performance of the fuel cell.