Numerical performance analysis of liquid hydrogen centrifugal pumps: A focus on the effectiveness of water as a substitute test fluid

Green hydrogen is considered a viable means of decarbonizing heavy-duty transport. Liquid hydrogen (LH2) outperforms compressed hydrogen due to its higher density, particularly for long-distance, massive transport. Transferring high LH2 mass flow rates may require switching to cryogenic centrifugal pumps. The necessary experimental tests with LH2 are complex to handle; hence, water is commonly used as a substitute test fluid. This study considers five different centrifugal pump impellers for LH2 with specific speeds from 10 to 90. The aim is to analyze the effectiveness of water as a substitute test fluid. Loss analyses show that the impeller is less efficient with water (up to a 6% drop) due to higher dynamic viscosity, which leads to lower Reynolds numbers and higher skin friction. Finally, we propose a correlation for the hydraulic efficiency factor between LH2 and water, based on the specific speed number.