Performance and energy efficiency of single and multi-coolant pre-cooling strategies in liquid hydrogen pipeline cooling systems

Pre-cooling of hydrogen (H2) in its liquid form, liquid hydrogen (LH2), is a critical and energy-intensive stage in the liquefaction and transportation of H2, and improving its efficiency is essential for achieving global decarbonization goals. To address this, this study systematically proposes an innovative pre-cooling strategy involving single-coolant and multi-coolant cooperation, using numerical simulations to reveal the differences in cooling performance and energy efficiency of liquid nitrogen (LN2), liquid helium (LHe), LH2, and methane (CH4) during the pre-cooling process. Results show that within the temperature range of 298 K–20.3 K, the single-coolant strategy (constant flow scheme) achieves uniform temperature distribution but exhibits relatively high unit energy consumption (1450.45 J/K). The LHe strategy, under rapid and efficient cooling conditions, demonstrates lower unit energy consumption (571.57 J/K) and higher cooling efficiency (57.34 K/s2·J), although its temperature control uniformity is limited. Notably, the multi-coolant cooperative strategy (LN2-LHe-LH2) achieves a unit energy consumption of 794.06 J/K and a cooling efficiency of 2.37 K/s2·J, combining temperature stability with energy efficiency advantages, making it suitable for long-term stable operation under complex demands. The study indicates that this cooperative pre-cooling strategy can significantly reduce energy consumption, enhance cooling efficiency, and reduce dependence on high-pressure systems, providing theoretical references for H2 liquefaction and transportation, supporting the construction of low-carbon H2 infrastructure, and advancing the transition towards a global clean energy system.