مدل‌سازي عددي و مقايسه روش‌هاي مديريت حرارت فعال، غيرفعال و تركيبي در پيل سوختي غشاي پليمري

Numerical Modeling an‎d Comparison of Active, Passive, an‎d Hybrid Thermal Management Methods in Proton Exchange Membrane Fuel Cells

مهندسي مكانيك

Proton Exchange Membrane Fuel Cells (PEMFCs), characterized by prominent features such as high efficiency, high power density, low operating temperatures (60 to 90 °C), near-zero emissions, fast dynamic response, an‎d instantaneous startup, play a key role in the future of power generation systems. However, the performance an‎d lifespan of these devices strictly depend on thermal management; an unintended temperature rise leads to membrane drying, mechanical stress, an‎d structural degradation, while an excessive temperature dro‎p results in reduced electrochemical reaction rates an‎d performance degradation. In the present study, to manage the thermal behavior of a PEMFC, four cooling configurations, including parallel air channels (Design 1), liquid water serpentine channels (Design 2), a heat pipe array (Design 3), an‎d a hybrid system combining parallel air channels with a heat pipe array (Design 4), are proposed an‎d numerically eva‎luated under non-uniform heat flux patterns. Investigating various heat flux patterns is crucial because the generated heat flux directly correlates with the fuel cellʹs current density an‎d Current density is a function of variable internal conditions of the cell, such as gas saturation, inlet gas humidity, an‎d reactant concentration distribution. Applying non-uniform heat fluxes enables a more realistic assessment of the cooling systemsʹ performance under actual operating conditions. A comparison among these methods is conducted based on key indicators such as maximum an‎d minimum plate temperature difference, index of uniform temperature, average plate temperature, thermal resistance, pressure dro‎p, parasitic power, performance eva‎luation criterion (PEC), an‎d advantage ratio (AR). The results indicate that in terms of temperature uniformity, Design 2, due to laminar flow with a temperature difference exceeding 7.0 °C, an‎d Design 1, with a temperature difference ranging from 3.3 to 5.9 °C an‎d a uniformity index of 1.65, exhibit the weakest performance. Conversely, Design 3 (by stabilizing the temperature difference within 1.7 to 2.0 °C) an‎d Design 4 (by controlling it within 2.6 to 3.8 °C) both achieved a stable uniformity index of 0.34. Regarding thermal resistance, Design 3 provided the lowest thermal resistance among all cooling methods, while Design 4 ranked second by recording a stable thermal resistance of 0.045 to 0.064 °C/W. In the power consumption analysis, Design 1 imposed a constant parasitic power of 56 W, whereas Design 3 experienced a spike in power consumption up to 275 W an‎d a negative AR down to -2.0 under descending heat fluxes due to high convective heat transfer coefficients applied at the condenser section. In contrast, Design 4 offered the best balance between heat removal an‎d parasitic power, featuring power consumption fluctuations between 12 an‎d 26 W, the highest PEC between 7.4 an‎d 9.4, an‎d an AR exceeding +4.5. Overall, despite reducing the stack volumetric power density due to double the plate thickness an‎d manufacturing complexity, Design 4 stan‎ds out an‎d good option for industrial applications an‎d stationary power plants owing to its thermal-hydraulic superiority among the studied configurations.

5

171817