Chouhan, Ashish2021-05-182021-05-182021https://udspace.udel.edu/handle/19716/28986Hydrogen offers the potential to decarbonize the automotive and stationary power sectors and is therefore expected to play an increasingly significant role in meeting global energy demand. Despite its high gravimetric energy density, hydrogen possesses very low volumetric energy density, and hence, it is important to find methods to efficiently store hydrogen in order to grow the hydrogen economy. Storing hydrogen as a compressed gas could be achieved by electrochemical compression (ECC), which is a membrane-based alternative to conventional mechanical compressors. ECC can be superior to mechanical compressors because of its higher efficiency, lack of moving parts, and noiseless operation. ☐ First, we investigate the performance of a single hydrogen electrochemical compressor cell in this study. In particular, detailed experiments have been conducted to study the detrimental effect of back-diffusion. These results have allowed us to propose a theoretical formulation for the ECC process incorporating back-diffusion and validate it by experiments. A robust definition for ECC efficiency that properly accounts for back diffusion is also proposed. Next, we turn our attention to practical systems that employ multiple cells in a stack configuration to achieve higher flowrates and gas pressures. Here, we analyze two different stack configurations - electrically in series/flow in parallel (ESFP) and electrically in series/flow in series (ESFS) - in order to understand their influence on gas throughput and exit pressure in the presence of back-diffusion. A theoretical performance analysis has been conducted for both configurations to gain insights into the compressed gas flux, pressure rise, back diffusion, and efficiency. Furthermore, a novel hybrid configuration that combines the features of both configurations is proposed that can optimize both flow and pressure for a given application. ☐ Finally, we study the application of ECC to environmentally friendly refrigerants like ammonia. We explore the ECC of ammonia using hydrogen as a carrier gas. Experimental results on the performance of an ECC operated on ammonia-hydrogen blends indicate that the back-diffusion of ammonia through the perfluorosulfonic acid membrane poses an even greater challenge, and we provide recommendations to facilitate the ECC of ammonia-hydrogen blends.AmmoniaElectrochemical CompressionElectrolysisFuel cellsHydrogenBack-diffusionThesis1251517840https://doi.org/10.58088/wyn8-jf222021-03-19en