البحث الثامن بحث منفرد منشور فى مؤتمر دولى متخصص ( منشور التحكيم علي البحث الكامل ) Adel A. Elbaset 14 th International Middle East Power Systems Conference (MEPCON'10), Cairo University, Egypt, December 19-21,

Modeling and Analysis of a PEM Fuel cell for Electrical Applications نموذج محاكاة وتحليل خلية الوقود الكهروكيميائية للتطبيقات الكهربائية Adel A. El-Baset Mohammed Dept. of Electrical Engineering, Minia University, Minia, Egypt,

ملخص البحث باللغة العربية يقدم هذا البحث دراسة نموذج ثلاثي الأبعاد لأداء وتقييم خلية الوقود الكهروكيميائية. يستخدم النموذج المقترح للتنبؤ بالجهد والكفاءة، والهيدروجين المطلوب ودراسة الاستجابة العابرة لخلية الوقود الكهروكيميائية عندما تتعرض لحمل متغير. بالإضافة إلى ذلك ، دراسة تأثيرالحرارة وكثافة التيار. تم التحقق من فعالية النموذج المقترح من خلال عمل محاكاة واسعة النطاق باستخدام برنامج ماتلاب لتقييم مدى متغيرات التشغيل الرئيسية التي تؤثر على الأداء الناتج. وأوضحت النتائج إلى أن النموذج المقترح يوفر تمثيلا دقيقا لخلية الوقود لكهروكيميائية ،ويمكن استخدامه في دراسة وتصميم خلايا والوقود للتطبيقات الكهربائية تحت شروط تحميل مختلفة ودرجات الحرارة. هذا البحث غير مأخوذ من رسالة علمية. 3

This paper presents a proposed three-Dimensional (3D) computational electrochemical simulation model for simulation and evaluation performance of Polymer Electrolyte Membrane (PEM) fuel cell. The proposed model is used to predict the output voltage, efficiency, hydrogen supply and study the transient response of PEM power plant when subjected to variable load connected to it. Additionally, the effects of temperature and current density have been studied. 4

5 The results have indicated that the model provides an accurate representation of the dynamic and static behaviors of the fuel cell power module and guarantee a better analytical performance. On the other hand, the results show that the model can be used to study and design of fuel cell for electrical applications under different load conditions and temperatures.

Background - PEMFC Fuel cells are electrochemical devices that convert the chemical energy of a reaction directly into electrical energy. Unlike batteries, which store the energy, fuel cells operate continuously as long as they are provided with reactant gases. Zero Emission FC are considered as “Zero Emission” Technology. This is one of the reasons why FC are attractive High Efficiency FC are produced electrical energy at a very high efficeincy than combustion generator These features make FCs as a power generation systems both for stationary and transport applications. 6

7 Fig. 1: Basic PEM Fuel Cell Operation The electro-chemical reactions in the PEMFC are shown below:- H 2(g)  2 H + (aq) +2e - +waste heat 2H 2(aq) +2e - +1/2O 2(g)  H 2 O (L)

PEM Fuel Cell Operation

9 PEMFC Mathematical Model Fig. 2 Simplified circuit diagram of the PEMFC

10 The output voltage of a single cell can be obtained as the result of the following expression [1], [9,10]:

11 The power output for the fuel cell system can then be calculated by the equation: The power system model presented as shown in Fig. 3 consists of four major subsystems:

12 Fig. 3. PEMFC stack block diagram the PEMFC stack module, the air compression subsystem, the hydrogen supply subsystem, and the cooling subsystem.

13 Results and Discussion First, the paper discuss the influence of operating cell temperature on the behaviour of a single fuel cell as well as a stack, which include the typical polarization curves and efficiency at different working temperatures moreover transient responses of the stack on a current.

14 Parameters In this work, the parameters of a Mark V cell, manufactured by the Canadian Company Ballard, are used, whose operation and data are well known in the literature as shown in Table I Param.ValueParam.Value T20:100 °C 1 AaAa 50.6 cm 2 2 Ln(A a ) Ln(cH 2 ) L178µm 33 7.6x10 -5 PH 2 3 atm 4 PO 2 3 atm  23 B0.016 VJ max 1.5 A/cm 2 RC  jnjn 1.2 mA/cm 2 Table I – Parameters of the Ballard Mark V fuel cell.

15 Effect of operating temperatures Fig. 4. Temperature effect on the cell voltage of a PEM

16 Fig. 5. Temperature effect on the activation loss of a PEMFC.

17 Fig. 6. Temperature effect on ohmic voltage loss of a PEMFC

18 Fig. 7. Temperature effect on the performance surface of a PEMFC.

19 Fig. 8. Potential cell and power density effect on the efficiency of a PEMFC

20 Fig. 9. Temperature and power density effect on the efficiency of a PEMFC.

21 Fig. 10. Temperature and current density effect on the efficiency of a PEMFC.

22 Transient response Fig. 10. Stack current for partial load insertion Fig. 12. Stack Power for load variation Fig. 11. Stack Voltage for load variation Fig. 14. Stack Efficiency for load variation

23 Fig. 13. Hydrogen input for load variation

24 Conclusions The paper presents a 3D computational electrochemical simulation model for PEMFC, on the other hand, it presents analysis of a PEMFC stack. From the results obtained above, the following salient conclusions can be drawn: Voltage, power, hydrogen supply and efficiency affect by load demand and temperature The potential and efficiency are higher values for low current densities and power densities.

Higher values of the power, the efficiency and the voltage are smaller values. Therefore, the control system for PEMFC needs to find the optimum operation point for the cell. 25 If temperature increases from 60°C to 100 °C for the same current density at A/cm 2, the operating voltage increase from to V and Power output decrease from to W resulting in high efficiency of 60.44%.

Thanks for your attention 26