Energies 2022, 15, 8110. https://doi.org/10.3390/en15218110 www.mdpi.com/journal/energies Article Proton-Exchange Membrane Fuel Cell Balance of Plant and Performance Simulation for Vehicle Applications Tino Vidović, Ivan Tolj *, Gojmir Radica and Natalia Bodrožić Ćoko Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, R. Boškovića 32, 21000 Split, Croatia * Correspondence: itolj@fesb.hr Abstract: In this study, a newly developed zero-dimensional electrochemical model was used for modeling and controlling proton-exchange membrane fuel cell (PEMFC) performance. Calibration of the model was performed with measurements from the fuel cell stack. Subsequently, a compres- sor and a humidifier on the cathode side were sized and added to the existing model. The aim of this work was to model the PEMFC stack and balance of plant (BoP) components in detail to show the influence of operating parameters such as cathode pressure, stack temperature and cathode stoi- chiometric ratio on the performance and efficiency of the overall system compared to the original model using a newly developed real-time model. The model managed to predict the profile of es- sential parameters, such as temperature, pressure, power, voltage, etc. The most important conclu- sions from this particular case are: the cell power output is only slightly changed with the variations in stoichiometric ratio of the cathode side and adding an external compressor is valid only for high current applications, but in those cases, there is 10–22% power gain. Stack temperature is a very influential parameter. Optimal temperatures were determined through design of experiments (DoE) and for this case are in the 40–60 °C range, where for low current applications lower temperatures are better due lower activation loss (8% difference between 80 °C and 40 °C at 20 A current). For high current applications, due to lower ohmic losses, higher temperatures are desirable. Keywords: proton-exchange membrane fuel cells; system modeling; balance of plant component sizing 1. Introduction One of the most important topics being studied today is climate change and its effects [1,2]. World energy consumption increased by 2.9% in 2019. That is almost a 100% increase in comparison to the constant average of 1.5% per year over the last decade. Carbon emis- sions from energy production also increased by 2% compared to the year before, which is alarming growth, with total emissions approaching 0.6 GT [3]. Unfortunately, fossil fuels continue to be the largest contributor to global energy demand. This creates problems as most fossil reserves are rapidly depleting and their prices are constantly fluctuating and volatile [4]. The research community has explored various ways to address this problem, such as improving the efficiency of fuel usage [5] and/or using various renewable energy sources. Additionally, many governments around the world have recognized the serious- ness of finding a permanent solution for climate change [6]. This has led to the signing of numerous climate agreements between these countries to address this problem [7]. In par- ticular, the Paris Agreement [8] and the Kyoto Protocol [9] are most influential. As a result, renewable sources of energy are considered as the only and inevitable substitute for fossil fuels. However, the irregularity of renewable energy sources is another demanding issue that prevents its full commercialization. One of the sources which does not produce any Citation: Vidović, T.; Tolj, I.; Radica, G.; Bodrožić Ćoko, N. Proton-Exchange Membrane Fuel Cell Balance of Plant and Performance Simulation for Vehicle Applications. Energies 2022, 15, 8110. https://doi.org/10.3390/en15218110 Academic Editor: Tek Tjing Lie Received: 30 September 2022 Accepted: 26 October 2022 Published: 31 October 2022 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional claims in published maps and institu- tional affiliations. Copyright: © 2022 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https://cre- ativecommons.org/licenses/by/4.0/).