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Liquid hydrogen is a promising energy carrier in the global hydrogen value chain with the advantages of high volumetric energy density/purity, low operating pressure, and high flexibility in delivery. Safe and high-efficiency storage and transportation are essential in the large-scale utilization of liquid hydrogen. Aiming at the two indicators of the hold time and normal evaporation rate (NER) required in standards, this paper focuses on the thermal behaviors of fluid during the no-vented storage of liquid hydrogen and thermal insulations applied for the liquid hydrogen tanks, respectively. After presenting an overview of experimental/theoretical investigations on thermal behaviors, as well as typical forms/testing methods of performance of thermal insulations for liquid hydrogen tanks, seven perspectives are proposed on the key challenges and recommendations for future work. This work can benefit the design and improvement of high-performance LH2 tanks. [ABSTRACT FROM AUTHOR]

Space heating and hot water supply usually have great energy consumption in terms of household, industry, and other services which could be a big issue especially for the cold region. From technical and economic aspect, the present work investigates a hybrid sorption heat transformer (HSHT), which also plays a role of energy storage and upgrade. A renewable source or off-grid electricity is used for electricity supply while solar heat or ambient heat is regarded as heat inputs for two different scenarios. Composite ammonium chloride is used for further analysis of HSHT. Results indicate that HSHT could be a good candidate for the domestic heating in the cold region. Compared with vapor compression heat pump (VCHP), payback period (PBP) of HSHT could be reduced by up to 40%. Under different scenarios, PBPs are in the range from 2.48 year to 4.1 year. Also the levelized costs of heating of HSHT ranges from 20 $·MWh−1 to 46 $·MWh−1 for scenario 1 while the values of 64–133 $·MWh−1 could be obtained for scenario 2 which is up to 35.6% lower than that of VCHP. Carbon emission of HSHT system only accounts for 18% and 11% of that of gas boiler and VCHP, respectively. [ABSTRACT FROM AUTHOR]

Liquid hydrogen (LH 2) is a promising and economical clean energy for achieving global carbon neutrality. Multi-layer insulation (MLI) with high performance is essential for the safe storage and operation of LH 2. To perform a better optimization of MLI, the second law of thermodynamics becomes a complement to the first law of thermodynamics. However, very few studies have carried out the optimization of MLI performance through the second law of thermodynamics. For the sake of achieving more efficient optimization of MLI as well as revealing the fundamental indicators limiting the performance of MLI, this paper analyzes the characteristics of entropy generation produced by the solid heat conduction, thermal radiation, and residual gas conduction distributed in the MLI schemes by a validated layer-by-layer model. For a 40-layer MLI arranged with a constant layer density of 20 layers/cm, the first 15 layers near the cold boundary occupy more than 98% of the total entropy generation, providing an effective range of layers for thermodynamic optimization. Besides, an optimization of variable-density MLI (VDMLI) separated into two segments based on the entropy generation minimization is conducted. The optimal VDMLI has substantially lowered the entropy generation from the solid heat conduction but at the cost of increasing the entropy generation from radiation and residual gas conduction. This study provides a reliable optimization method of MLI, which allows the safe storage of clean energy with a low boiling temperature. • A modified layer-by-layer model is built for entropy generation analysis. • Characteristics of entropy generation distributed in MLI are investigated. • Effect of layer density on components of entropy generation is detailed discussed. • Optimization of 2-segment VDMLI upon entropy generation minimization is conducted. [ABSTRACT FROM AUTHOR]

Clarification of thermal behaviors, involving self-pressurization, temperature rise of the fluid, temperature stratification, and free convective flows, is crucial to the safe storage and transportation of liquid hydrogen for large-scale applications. Given that the experiments have been carried out to observe the pressure build-up and temperature gradient in correlation with part of the thermal behaviors, the computational fluid dynamics method becomes a promising selection for investigating other thermal behaviors to complement the experiments. To comprehensively reveal the thermal behaviors of liquid hydrogen during the no-vented storage process, this paper reviews the progress in both experimental and computational investigations. The typical experimental facilities, conditions, and results of the self-pressurization and temperature stratification in liquid hydrogen tanks are presented. The basic formulations, state-of-the-art applications, as well as typical values of mass transfer coefficients of computational fluid dynamics models are also reviewed. Based on the status, the unclarified effects of vapor-liquid interfacial mass transfer, selection of flow models, and fluid sloshing on thermal behaviors of liquid hydrogen are outlined as the perspectives to benefit future research work. • Experimental investigations on thermal behaviors of LH 2 are summarized. • Progress in the development and applications of CFD studies on thermal behaviors. • Phase change coefficients and the selection of flow models remain unclarified. • Effects of phase change, flow models, and fluid sloshing need further research. [ABSTRACT FROM AUTHOR]

50–80 °C heat sources are abundant in renewable energy areas and industrial processes. However, they are difficult to be effectively used due to their ultralow grade. In order to solve this problem, this paper presents a high-efficient hybrid adsorption refrigeration system combing with desiccant coated heat exchangers. In this study, the performance of the hybrid system is experimentally investigated and parametric effects are fully discussed. Results indicate that the hybrid system operates efficiently across a wide heat source range of 50–80 °C. A high-temperature hot water facilitates the cooling production of the hybrid system, while a low-temperature hot water is more beneficial to the COP promotion. Also, a lower cooling water temperature, higher air temperature, higher relative humidity and longer switch time can enhance system performance. The optimal cooling capacity is quantified as 4579 W when powered by 80 °C hot water and the COP reaches its maximum of 0.673 under a heat source temperature of 50 °C. Comparison results show that compared with present systems, the hybrid system has greater adaptability as well as higher efficiency in utilizing 50–80 °C ultralow-grade heat sources, and can satisfy the simultaneous demand for cooling and dehumidification, which offers a promising way to high-efficient energy utilization and sustainable development. • A hybrid adsorption system using desiccant coated heat exchangers is presented. • The hybrid system operates efficiently across a wide heat source range of 50–80 °C. • The cooling capacity and COP reach 4579 W and 0.673, respectively. • The hybrid system provides a promising solution for efficient energy utilization. [ABSTRACT FROM AUTHOR]