Thermal Energy Storage Systems： Power-to-Heat Concepts in Solid Media Storage for High Storage Densities

The German Aerospace Center has merged a wide range of technological research and development for future cars in a project called ＂Next Generation Car＂. Within this large research project, three vehicle concepts for different applications （urban, regional and interurban） and with different powertrains （fuel-cell, battery and hybrid） will be developed. Research questions on different levels from conceptual question about vehicle modularity down to detailed technological aspects like combining hydrogen storage with cabin climatization and a systematic investigation of different thermal energy storage systems for electric vehicles concepts are covered by this project. To the latter, the contribution shows an overview about three thermal storage technologies--sensible solid media, metallic latent and thermochemical thermal energy storage systems--and details about the development of an electrically heated （power-to-heat） solid media storage system to achieve high storage densities and to allow flexible thermal discharging values. Central works target the identification of suitable thermal management solutions in future electric vehicle concepts to increase range, efficiency and flexibility.

Overlooked risk of microplastics from municipal solid waste-storage site

Municipal solid waste(MSW)storage sites are potential and overlooked contributors to microplastic(MP)pollution.Herein,the distribution and dispersion characteristics of MPs at MSW storage sites were investigated through modeling,sampling analysis,and prediction methodologies.The results indicated a notable adsorption phenomenon of MPs on smooth surfaces within such sites,achieving high saturation levels and making MPs prone to re-release by airflow disturbance.Quantitative analysis revealed that the MP concentrations on these surfaces varied from 4.48×10^(5) to 1.90×10^(6) n/m^(2) and that MPs predominantly accumulated in the corner areas.Notably,MP accumulation on wall surfaces can be reduced by 76.4%using washing procedures.The majority of MPs were under 50μm in size and were primarily in fragment form.Operational activities such as ventilation and waste handling were identified to amplify the airborne spread of MPs.The atmospheric concentrations of MPs peaked seasonally,with concentrations of 28.25 n/m3 in summer and 3.90 n/m^(3) in winter,and the spatial dispersion ranged from 14.98 to 124.08 km^(2) per station.This study highlights that MSW storage sites are substantial yet overlooked sources of MP pollution,where wall surfaces play a critical role in MP adsorption and dispersal.The implementation of robust management and cleaning protocols is essential to mitigate the environmental footprint of MPs emanating from these locations.This study also provides a typical case for the precise prevention and control of MPs in the environment.

Improved hydrogen storage properties of MgH_2 catalyzed with K_2NiF_6

In this study, the hydrogen storage properties of MgH-X wt% KNiF（X = 5, 10, 15, 20, and 50） were investigated for the first time. From the analysis of the onset desorption temperature and isothermal de/absorption kinetics, it was shown that MgH+ 5 wt% KNiFsample has the best performance. The 5wt% doped sample started to release hydrogen at about 260 °C, which was a reduction of about 95 °C and 157 oC compared with the as-milled and as-received MgH. In addition, the de/absorption kinetics of the MgH+ 5 wt% KNiFwere also improved significantly compared to the un-doped MgH. The apparent activation energy for hydrogen desorption exhibited the decrement from 167.0 k J/mol for as-milled MgHto 111.0 k J/mol with the addition of 5 wt% KNiF. Moreover, the X-ray diffraction spectra displayed the formation of new phases of KF, KH, MgNi and MgNiHby doping the KNiFwith MgHafter the dehydrogenation and rehydrogenation processes. The scanning electron microscope results revealed that MgHdoped with 5 wt% KNiFdemonstrated the smallest particle size compared to the as-received and as-milled MgH. It is believed that the formation of in situ active species of KF, KH, and MgNi could provide a synergetic catalytic effect in enhancing the hydrogen sorption properties of MgH.

Operational Robustness Studies of Solid Oxide Electrolysis Stacks

Stacks of solid oxide cells which can be run as both electrolysers and fuel cells have been tested for robustness towards simulations of stress conditions which are likely to occur during operation of solid oxide electrolysis systems, for which the energy supply comes from renewable sources, such as wind mills and solar cells. Such conditions are thermo mechanical stress conditions as well as loss of fuel and air supply. The cells have Ni/YSZ （yttria stabilized zirconia） fuel electrodes, YSZ electrolytes, and LSCF （lanthanum strontium cobalt ferrite） oxygen electrodes with a CGO （cerium gadolinium oxide） barrier layer. In the stacks, the cells are separated by chromium rich steel interconnects. The robustness tests of stacks are one step in the development of a SOEC （solid oxide electrolysis cell） core; the core component in a SOEC system, including one or more SOEC stacks, heaters, heat exchangers, insulation, and feed troughs.

Storage life of silicone rubber sealing ring used in solid rocket motor

It is urgent to carry out detailed research on storage performance of rubber sealing ring to get the criterion for its storage life. This paper acquires material ageing regularity by theoretical analysis and experimental confirmation. On this condition, failure mode and failure criterion of typical sealing structure is studied, and the failure mechanism is found. Thus by analyzing the stress distribution, the relationship between ageing state and sealing condition is established. Rationalization proposal is put forward and storage life of sealing ring is evaluated. The research mentionedabove has special reference to the design of sealing structures and can provide reference for prolonging their service life.

Application of Liquid Nitrogen Cold Trap for Purification of Hydrogen Gas Stream Generated from NaBH4

The feasibility of using liquid nitrogen cold trap （LNCT） for the removal of water vapour and alkaline mist from the hydrogen gas stream which is generated from the catalytic and acidic decomposition of sodium borohydride is investigated. Practically, the target application is mobile fuel cells based on hydrogen production from storage in chemical hydrides. The LNCT would be used as a one step purification method with less cost and space requirements instead of applying the conventional purification techniques. Two catalysts were investigated for the production of hydrogen from the aqueous solution of NaBH4 in a small scale packed bed reaction column. The hydrogen generated from the catalytic decomposition of NaBH4 was accompanied by limited quantity of water vapour and alkaline mist. Nonetheless, higher quantities were generated when applying the acidic decomposition of NaBH4 and consequently the utilization of LNCT for H2 purification has proved useful and lead to a reduction in the content of these impurities; thereby the concentration of hydrogen in the outlet stream has increased.