## 1 Introduction
Centrifugal compressors exhibit the advantage of high efficiency over a wide range of operating conditions, resulting in minimized energy consumption during oxygen supply to the fuel cell stack. This efficiency contributes to the overall energy optimization of the vehicle, potentially extending the driving range per unit of stored hydrogen. Moreover, centrifugal compressors can offer a favorable power-to-weight ratio due to their compact and streamlined design, aligning with the imperative lightweight components in FCHEVs to enhance overall energy efficiency and vehicle performance. In terms of cost feasibility, advancements in manufacturing techniques and materials can contribute to reducing production costs, making centrifugal compressors economically viable for integration into FC systems [20; 21; 22]. Additionally, their relatively compact dimensions address volume constraints, and they are especially pertinent in vehicle applications with limited available space [23; 24; 25; 26]. One of the main purposes of this study is to design a pressurized air compressor system for OCFC. A new, air-pressurized cabin system will be developed for using the pressured air in the OCFC [27; 28; 29; 30]. The OCFC will be enclosed within a novel cabin geometry. The parameters encompassing air cabin design play a critical role in influencing the overall effectiveness of the fuel cell stack. A crucial factor is the uniformity index of the pressurized air distribution within the cabin. Achieving a high uniformity index is imperative as it ensures a consistent oxygen supply across the entire active area of the fuel cell stack [31; 32]. A uniform air distribution mitigates the risk of localized oxygen depletion and subsequently promotes balanced electrochemical reactions, preventing performance disparities among individual cells. Furthermore, maintaining uniform air distribution assists in enhancing the durability of fuel cell stacks by reducing the likelihood of uneven wear and tear, which can lead to accelerated degradation and a decreased operational lifespan [33; 34; 35]. Additionally, meticulous attention to pressure distribution within the air cabin is of the utmost importance. Optimal pressure distribution ensures that each cell within the fuel cell stack receives an appropriate amount of oxygen for efficient electrochemical reactions [35]. The related paper [36] presents a numerical model for an automobile fuel cell system using a two-stage turbo-compressor for air supply, incorporating mass and energy balances and pressure losses across various components. The study highlights the design and analysis of a highly efficient two-stage turbo compressor with an expander, demonstrating significant improvements in power output and efficiency compared to a single-stage compressor. The model predicts and optimizes the performance of PEM fuel cell systems, with and without the expander. Another study [37] has proposed a multi-objective optimization scheme for an electric turbo compressor (ETC) to minimize axial thrust and power consumption, addressing key reliability and efficiency challenges in fuel cell air management systems. By integrating MATLAB-based modeling, CFD simulations, and experimental validation, and optimizing eight geometric parameters using the NSGA-II algorithm, the results demonstrate a 7.80% reduction in motor power consumption, an 18.83% decrease in axial thrust, and efficiency improvements of 6.39% and 2.75% for the compressor and turbine, respectively. In this study, a novel pressurized cabin is developed to enhance the performance of the open-cathode fuel cell (OCFC) system. The paper delves into the intricacies of the issue through three comprehensive sections, namely, the theoretical background, control algorithm, and experimental setup. Within the theoretical background section, the proposed 3D geometry of the pressurized cabin will be introduced, followed by the definition of design parameters utilizing the Taguchi approach.