Finite element method modeling and optimization of the mechanical behavior of a low-temperature PEM fuel cell

Abstract

Proton exchange membrane fuel cells (PEMFCs) consist of six main components: current collectors (CC), end plates (EP), bipolar plates (BPP), gas diffusion layers (GDL), gaskets, and membrane electrode assembly (MEA). PEMFC assembly or design parameters are critical for maximum performance, strength, and reliability. The cell's mechanical behavior should be known for optimum fuel cell assembly and design. Therefore, a three-dimensional finite element model of PEMFC with an active area of 100 cm² was developed, and the stress and deformation values in the cell components were calculated with Ansys Mechanical software. The response surface method (RSM) was applied to obtain optimum levels and analyze the effect of design parameters. For statistical analysis, bolt number, bolt hole diameter, and clamping torque were defined as three different independent design variables, and their individual-combined effects on stress and deformation, which were determined as response parameters, were analyzed. Therefore, the number of bolts, bolt hole diameter, and clamping torque ranges are 12- 20, 4-6 mm, and 9-15 Nm, respectively. When the number of bolts is 12, the bolt hole diameter is 6 mm, the clamping torque is 9 Nm, the total minimum deformation is 0.063 mm, and the minimum stress on the membrane is 12.846 MPa. As a result of reducing the bolt hole diameter from 6 mm to 4 mm, the total deformation has increased by approximately 60.4%. With the increasing number of bolts, more homogeneous stress distributions were achieved, and the end plate's maximum stress increased by about 83.3%. The increase in clamping torque has caused a pressure increase of roughly 21 MPa on the membrane. The numerical and statistical findings of the study can be an important guide in evaluating the performance, durability and reliability of the PEMFC.

Keywords

• 3D PEMFC
• Finite element method
• Response surface method
• Optimization
• Mechanical analysis

Düşük sıcaklıklı bir PEM yakıt hücresinin mekanik davranışının sonlu elemanlar yöntemiyle modellenmesi ve optimizasyonu

Öz

Proton değişim membranlı yakıt pilleri (PEMYP) altı esas bileşenden oluşmaktadır: akım toplayıcılar (AT), uç plakalar (UP), bipolar plakalar (BP), gaz difüzyon tabakaları (GDT), contalar ve membran elektrot ünitesi (MEÜ)’dir. Maksimum performans, yüksek dayanım ve güvenilirlik için PEMYP montaj veya tasarım parametreleri kritik bir öneme sahiptir. Optimum yakıt pil montaj ve tasarımı için hücrenin mekanik davranışlarının bilinmesi gerekmektedir. Yakıt pilinin mekanik montaj sürecinin deneysel tekniklerle gerçek zamanlı olarak yapılması oldukça maliyetli ve zaman alıcıdır. Bu nedenle, 100 cm² aktif alana sahip PEMYP’nin üç boyutlu sonlu eleman modeli geliştirilmiş, hücre bileşenlerindeki gerilme ve deformasyon değerleri Ansys Mechanical yazılımı ile hesaplanmıştır. Optimum seviyeleri elde etmek ve tasarım parametrelerinin etkisini analiz etmek için cevap yüzeyi yöntemi (CYY) uygulanmıştır. İstatistiksel analiz için cıvata sayısı, cıvata delik çapı ve sıkıştırma torkları üç farklı bağımsız tasarım değişkeni olarak tanımlanmış, bunların yanıt parametreleri olarak belirlenen gerilme ve deformasyon üzerindeki bireysel-birleşik etkileri analiz edilmiştir. Bu nedenle çalışılan cıvata sayısı, cıvata delik çapı ve sıkıştırma torku aralıkları sırasıyla 12-20, 4-6 mm ve 9-15 Nm’dir. Cıvata deliği çapının 6 mm'den 4 mm'ye düşürülmesi sonucunda, toplam deformasyon yaklaşık olarak %60.4 oranında artmıştır. Artan cıvata sayısıyla birlikte daha homojen gerilme dağılımları sağlanmış ve uç plakadaki maksimum gerilme yaklaşık olarak %83.3 oranında artmıştır. Sıkıştırma torkundaki yükselme ise membran üzerinde yaklaşık olarak 21 MPa'lık bir basınç artışına neden olmuştur. Çalışmanın sayısal ve istatistiksel bulguları, PEMYP performansının, dayanıklılığının ve güvenilirliğinin değerlendirilmesinde önemli bir rehber olabilir.

Anahtar Kelimeler

• 3B PEMYP
• Sonlu elemanlar yöntemi
• Cevap yüzeyi yöntemi
• Optimizasyon
• Mekanik analiz

Kaynakça

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