Doğrudan metanollü yakıt pillerinin sistem-düzeyi modellemesi ve simülasyonu

In this thesis, a thermodynamic model of an active direct methanol fuel cell (DMFC) system, which couples in-house experimental data for the DMFC with the equations of the mass, energy and exergy balances for the system components, is developed. For this purpose, the thermodynamic analysis is developed by following; firstly, a semi-empirical mathematical DMFC system model which is less costly than fully experimental methods and more accurate than fully theoretical methods, is formed. Secondly, the empirical data which are obtained with experiments on DMFC for some operating conditions (e.g. methanol concentration, current density and air flow rate) are integrated to the model equations (mass, energy and exergy balances) through curve fitting method. Thus, this model gives the mass and exergy flow rates at the inlet and exit of the anode and cathode sides as well as power density of DMFC. The basic thermodynamic equations are then applied around control volume enclosing system components of DMFC to find mass flow rates and exergy flows at the inlet and exit of these components. Solving these equations in Engineering Equation Solver (EES), the effect of operating conditions on the condenser outlet temperature, exergy destruction of each component, the required power of system components, electrical and exergetic efficiency of DMFC system is calculated. Moreover, water autonomy for this system is examined through a novel two-phase condenser model developed. The comprehensive results (e.g. relative humidity and mole fraction) as well as condensate mass flux in the condenser are obtained through this model for water autonomy.