Underground Hydrogen Storage (UHS) is a promising technology for large-scale energy storage. Geological formations, in which buoyant hydrocarbons have been retained for a long term, provide vast capacity for hydrogen storage in a safe manner. Different types of formations have been considered, such as salt caverns, saline aquifers, and depleted gas reservoirs. In this study we focus on saline aquifers. Although lessons were learnt from similar studies such as carbon capture and sequestration and underground gas storage, the unique thermodynamic and physical properties of hydrogen make UHS distinguished from the other subsurface storage projects. To this end, we developed a two-phase, three-component reservoir simulator, which incorporated essential physics based on the fully-coupled multi-physics framework of the DARSim simulator. Particularly, properties of fluid mixtures were computed using the thermodynamic model of GERG-2008. In the simulation, different types of cushion gases (CO2, CH4, and N2) were saturated at the top of the aquifer. Hydrogen was then injected into and produced from the aquifer periodically. Results showed that most of the injected hydrogen stayed at the top of the aquifer due to its light density, which led to a high extraction purity. The low solubility of hydrogen was favorable in UHS because dissolution trapping had a negligible impact. Our study confirmed the feasibility of large-scale underground hydrogen storage and showed the impact of different types of cushion gases on UHS.@en

In this work, an experimental study on the aluminum plate fin evaporator based on a compact two-phase cooling system for high heat flux electronic packages is presented. Single-chip and multi-chip wire-bonded thermal test vehicles (TTVs) were fabricated and assembled in the PCB grooves designed to emulate high heat flux sources. The issue of heat dissipation was addressed by applying the evaporator to the TTVs, respectively, to evaluate their thermal characteristics. It is found that, the evaporator system could dissipate over 380 W/cm² for the TTV1 while maintaining its temperature at about 90 °C. As the effective heat source area and thermal design power (TDP) increased, the maximum heat flux that the system could dissipate decreased given the same chip temperature rise. Furthermore, the addition of a second evaporator and heat source following the main evaporator, increased the dissipation of the system. As a result, an increase of 48 W/cm² in heat removal capacity was observed in our test system. Finally, the effect of the differential pressure between the condenser and the evaporator was investigated. The increase in the differential pressure could improve the heat dissipation capacity of the two-phase cooling system. The temperature of the TTV2 dropped by 19 °C when the differential pressure increased by 2.7 bar. It can be concluded that the compact two-phase cooling system is a promising solution for removing heat from high heat flux electric packages.

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