HİDROJEN-OKSİJEN YAKIT HÜCRELERİNDE ÇALIŞMA PARAMETRELERİNİN NERNST VOLTAJINA ETKİSİNİN İNCELENMESİ

Öz

Hidrojen-oksijen yakıt hücrelerinde çalışma parametrelerinin beklenen maksimum açık devre (Nernst) voltajı üzerinde etkisi vardır. Yakıt hücreleri birçok araştırmaya konu olmasına rağmen hiçbiri, özellikle Nernst voltajı ve maksimum termodinamik verimlilikle ilgili çeşitli çalışma parametrelerinin etkisini teorik olarak incelememiştir. Bu çalışmada, hidrojen-oksijen yakıt hücrelerinde çeşitli çalışma parametrelerinin Nernst voltajına etkisini teorik olarak belirlemek için bir bilgisayar programı geliştirilmiştir. Bu bilgisayar programı, hidrojen ve oksijen mol oranlarının, anot ve katot basınçlarının ve çalışma sıcaklıklarının beklenen maksimum açık devre voltajı üzerindeki etkilerini matematiksel olarak incelemek için MATLAB'da geliştirilmiştir. Yan ürün olarak su içeren yakıt hücresi reaksiyonları için Nernst voltajları ve maksimum termodinamik verim hesaplanırken, çözümlerde üst ısıl değeri (HHV) ve alt ısıl değerinin (LHV) etkileri de dikkate alınmaktadır. Sonuç olarak sıcaklık artışının yakıt hücresi Nernst voltajını ve maksimum termodinamik verimi azalttığı sonucuna varılmıştır. Dolayısıyla Nernst voltajı için en iyi koşulların HHV kabulünde, sıcaklığın 353 K, hidrojen ve oksijenin mol oranlarının 1,0, anot ve katot basınçlarının sırasıyla 5 atm ve 6 atm olduğu durumlarda oluştuğu, grafiklerden gözlemlenmiştir. Termodinamik verim açısından diğer çalışma parametrelerinin sabit tutulması koşuluyla 1000 K sıcaklıkta LHV varsayımında HHV varsayımına göre maksimum %92,2 oranında bir artış olduğu tespit edilmiştir.

Anahtar Kelimeler

• Nernst voltajı
• Yakıt hücresi
• Termodinamik verim
• Hidrojen-oksijen

INVESTIGATION OF THE EFFECT OF OPERATING PARAMETERS ON NERNST VOLTAGE IN HYDROGEN-OXYGEN FUEL CELLS

Öz

In hydrogen-oxygen fuel cells, operating parameters have an influence on the maximum expected open circuit (Nernst) voltage. Even though fuel cells have been the subject of many research, none of them have theoretically investigated the impact of various operating parameters, particularly concerning Nernst voltage and maximum thermodynamic efficiency. In this study, a computer program was developed to theoretically determine the effect of various operating parameters on the Nernst voltage in hydrogen-oxygen fuel cells. This computer program was developed in MATLAB to mathematically examine the effects of hydrogen and oxygen mole ratios, anode and cathode pressures, and operating temperatures on the maximum expected open circuit voltage. When calculating Nernst voltages and maximum thermodynamic efficiency for fuel cell reactions containing water as a by-product, the effects of higher heating value (HHV) and lower heating value (LHV) are also considered in the solutions. As a result, it was also concluded that temperature increase reduces the fuel cell Nernst voltage and maximum thermodynamic efficiency. Therefore, it was observed from the figures that the best conditions for the Nernst voltage occur when HHV is assumed, the temperature is 353 K, the mole ratios of hydrogen and oxygen are 1.0, the anode and cathode pressures are 5 atm and 6 atm, respectively. In terms of thermodynamic efficiency, it was determined that there was a maximum increase of 92.2% in the LHV assumption compared to the HHV assumption at the temperature of 1000 K, provided that other operating parameters were kept constant.

Anahtar Kelimeler

• Nernst voltage
• Fuel cell
• Thermodynamic efficiency
• Hydrogen-oxygen

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