Rising concerns over carbon emissions from fossil fuels have fueled interest in renewable energies. Hydrogen, as a clean energy source, stands out for its free of pollution and high calorific value. However, challenges in safely storing and transporting hydrogen, such as embrittlement, fire and explosion risks, are critical. This study reviews hydrogen storage and transportation safety research through a bibliometric approach, analyzing 948 relevant publications obtained from the Web of Science Core Collection, SCOPUS, and Science Direct literature databases since 2007. Then, a bibliometric analysis is conducted to obtain the publication's distribution, organization, source, and cooperation networks. Besides, the research hotspots in different periods are identified, and the evolution trend of hot topics is analyzed. Moreover, this paper proposes the possible future research needs in this field. The main hot topics in the field of hydrogen storage and transportation safety research include microstructure, crack, susceptibility, and hydrogen embrittlement and they change over time. In the future, research topics such as hydrogen damage in materials, compatibility of hydrogen in natural gas pipelines, and risk assessment should obtain more attention.

China will launch the “Tianwen-IV” mission around 2030, focusing on the orbiting exploration of Jupiter and Callisto, a moon of Jupiter. As part of this ambitious mission, a main satellite will carry another satellite that will be released in the Jupiter system to continue its journey toward Uranus. Considering the current mission planning, we propose an inter-satellite radio-observation mode that differs from the conventional observation mode of tracking from Earth to precisely determine the orbit of the satellites. Given the significance of the Callisto gravity field model in both science objectives and satellite navigation, we have conducted a series of simulation experiments to evaluate the potential of this inter-satellite range-rate data for accurately estimating the Callisto gravity field. The results obtained from the analysis demonstrate that by utilizing 40 days of ground station observations, it is possible to estimate the gravity field model of Callisto up to a degree of 70. Remarkably, when combining these ground station observations with inter-satellite observations, a comparable level of accuracy can be achieved with just 10 days of observations. Furthermore, with reduced inter-satellite observation noise, accuracy improves, enabling estimation up to 80 degrees or higher. Initial inter-satellite distance selection impacts estimation accuracy. These findings serve as a valuable test bed for the future “Tianwen-IV” mission to perform precise orbit determination and gravity field model estimation to reduce reliance on deep space stations.

High concentration NH₃/H₂O is suitable for Kalina cycles used for the recovery of low grade heat. Plate heat exchangers (PHEs) are compact and reduce the charge of working fluid. This paper investigates the condensation of NH₃/H₂O with NH₃ mass concentrations of 80%-96%. The vapor and liquid concentrations are close to equilibrium state, which are different from normal absorbers. The apparent heat transfer coefficients (HTCs) and frictional pressure drop are presented, covering the mass fluxes of 32–86 kgm⁻²s⁻¹, the averaged vapor qualities of 0.08–0.65 and the saturated pressure of 610 to 780 kPa. Larger mass fluxes noticeably increase the apparent HTCs and frictional pressure drop. At the mass concentrations of 96%, 91% and 88%, higher vapor qualities increase the apparent HTCs for large mass fluxes. The apparent HTCs decrease slightly with vapor qualities for 80% mass concentration. The experimental results are compared with those of pure NH₃. The flow patterns of high concentration NH₃/H₂O are considered as full film flow and partial film flow, which are the same as for NH₃. The mass transfer resistance deteriorates the heat transfer especially for partial film flow, which happens at small liquid mass fluxes. The mass transfer resistance has negligible influences on frictional pressure drop.

Gas separation performance of mixed matrix membrane heavily depends on the pore structure of the nanofillers. Metal-organic frameworks (MOFs) are promising platform materials for constructing molecular-selective pores for specific applications. In this work, deliberately-selected polymers with CO₂ affinity (PVAm, Pebax and PEI) are employed as pore regulators to manipulate the pore chemistry and size of MOF UiO-66 nanoparticles and consequently control gas transport rate of CO₂ and N₂ molecules. The branched polymer (polyethyleneimine (PEI)) grafted UiO-66, denoted as UKI, is beneficial to enhancing the membrane selectivity. The UKI doped Pebax/mPSf membranes exhibit CO₂/N₂ selectivity up to 278, 6.5 times of the bare Pebax/mPSf membranes. Meanwhile, the CO₂ permeance is boosted from around 690 to 1120 GPU (1 GPU = 10⁻⁶ cm³ (STP)·cm⁻²·s⁻¹·cmHg⁻¹ = 3.35 × 10⁻¹⁰ mol m⁻² s⁻¹·Pa⁻¹). The block copolymer (poly(ether block amide) (Pebax)) grafted UiO-66, denoted as UKX, is conducive to increasing the membrane permeance. The UKX doped Pebax/mPSf membranes exhibited CO₂ permeance up to 1683 GPU, 2.45 times of the bare Pebax/mPSf membranes. Meanwhile, CO₂/N₂ selectivity increased from around 42 to 146. Additionally, excellent pressure-resistant property and outstanding stability are observed under simulated flue gas.

Recently, the Sulfate reduction Autotrophic denitrification Nitrification Integrated (SANI^®) process was developed for the removal of organics and nitrogen with sludge minimization in the treatment of saline sewage (with a Sulfate-to-COD ratio > 0.5 mg SO₄ ^2--S/mg COD) generated from seawater used for toilet flushing or salt water intrusion. Previously investigated in lab- and pilot-scale, this process has now been scaled up to a 800-1000 m³/d full-scale demonstration plant. In this paper, the design and operating parameters of the SANI demo plant built in Hong Kong are analyzed. After a 4-month start-up period, a stable sulfur cycle-based biological nitrogen removal system having a hydraulic retention time (HRT) of 12.5 h was developed, thereby reducing the amount of space needed by 30-40% compared with conventional activated sludge (CAS) plants in Hong Kong. The demo plant satisfactorily met the local effluent discharge limits during both the summer and winter periods. In winter (sewage temperature of 21 ± 1 °C), the maximum volumetric loading rates for organic conversion, nitrification, and denitrification were 2 kg COD/(m³·d), 0.39 kg N/(m³·d), and 0.35 kg N/(m³·d), respectively. The biological sludge production rate of SANI process was 0.35 ± 0.08 g TSS_produced/g BOD₅ (or 0.19 ± 0.05 g TSS/g COD), which is 60-70% lower than that of the CAS process in Hong Kong. While further process optimization is possible, this study demonstrates the SANI process can be potentially implemented for the treatment of saline sewage.