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971.
《International Journal of Hydrogen Energy》2022,47(70):30234-30247
The dehydrogenation temperature of LiAlH4 was significantly reduced by the production of mixtures with ZrCl4. Stoichiometric 4:1, and 5 mol % mixtures of LiAlH4 and ZrCl4 were produced by ball milling at room temperature and ?196 °C, and tested for dehydrogenation at low temperature. Cryogenic ball-milling resulted in an effective way to produce reactive mixtures for hydrogen release; because of achieving small aggregates size (5–20 μm) in 10 min of cryomilling while preventing substantial decomposition during preparation. Dehydrogenation reaction in the mixtures LiAlH4/ZrCl4 started around 31–47 °C under different heating rates. Partial dehydrogenation was proved at 70 °C: 4.4 wt % for the 5 mol% ZrCl4–LiAlH4 mixture, and 3.4 wt % for the best 4:1 stoichiometric mixture. Complete dehydrogenation up to 250 °C released 6.4 wt% and 4.1 wt%, respectively. Dehydrogenation reactions are exothermic, and the LiAlH4/ZrCl4 mixtures are unstable and difficult to handle. The activation energy of the exothermic reactions was estimated as 113.5 ± 9.8 kJ/mol and 40.6 ± 6.6 kJ/mol for 4LiAlH4+ZrCl4 and 5%mol ZrCl4+LiAlH4 samples milled in cryogenic conditions, respectively. The dehydrogenation pathway was changed in the LiAlH4/ZrCl4 mixtures as compared to pure LiAlH4. Dehydrogenation reaction is proposed to form Al, LiCl, Zr, and H2 as main products. Modification of the dehydrogenation reaction of LiAlH4 was achieved at the cost of reducing the total hydrogen release capacity. 相似文献
972.
973.
Trevor Sweetnam Michael Fell Eleni Oikonomou Tadj Oreszczyn 《Building Research & Information》2019,47(4):344-361
ABSTRACTElectric heat pumps feature prominently in projected energy transitions in the UK and elsewhere. Owing to their high electricity consumption, heat pumps are viewed as important targets for demand-side response (DSR). Findings are presented from a field trial of a new control system that aims to optimize heat pump performance, including under time-varying tariff conditions. The trial involved monitoring 76 properties with heat pumps, but without dedicated heat storage; 31 of these received the control system. Interviews were conducted with a subsample of 12 participants. The controller successfully evened out electricity demand over the day (reducing the evening peak), but this was associated with increased late night and daytime temperatures. Interview participants reported some disturbance owing to overnight heating and noise, as well as usability issues with the controller interface and hardware. These issues present risks to the future acceptability of such systems. While the system delivered short-term demand reductions successfully, longer-term demand shifting risked causing unacceptable disturbance to occupants. Future control systems could overcome some of the issues identified in this pioneering trial through more effective zoning, using temperature caps or installing dedicated heat storage, but these may either limit the available flexibility or be challenging to achieve. 相似文献
974.
C. Mutungi F. G. Irungu J. Nduko F. Mutua H. Affognon D. Nakimbugwe 《Critical reviews in food science and nutrition》2019,59(2):276-298
In many African cultures, insects are part of the diet of humans and domesticated animals. Compared to conventional food and feed sources, insects have been associated with a low ecological foot print because fewer natural resources are required for their production. To this end, the Food and Agriculture Organization of the United Nations recognized the role that edible insects can play in improving global food and nutrition security; processing technologies, as well as packaging and storage techniques that improve shelf-life were identified as being crucial. However, knowledge of these aspects in light of nutritional value, safety, and functionality is fragmentary and needs to be consolidated. This review attempts to contribute to this effort by evaluating the available evidence on postharvest processes for edible insects in Africa, with the aim of identifying areas that need research impetus. It further draws attention to potential postharvest technology options for overcoming hurdles associated with utilization of insects for food and feed. A greater research thrust is needed in processing and this can build on traditional knowledge. The focus should be to establish optimal techniques that improve presentation, quality and safety of products, and open possibilities to diversify use of edible insects for other benefits. 相似文献
975.
《International Journal of Hydrogen Energy》2020,45(17):10353-10369
High temperature heat transfer and thermochemical storage performances of the solar driven bi-reforming of methane (SDSCB-RM) in a solar thermochemical micro-packed bed (ST-μPB) reactor are numerically investigated under different operating conditions along ST-μPB reactor length. A pseudo-homogeneous mathematical model is developed to simulate the heat and mass transfer processes coupled with thermochemical reaction kinetics in ST-μPB reactor with radiative heat loss. The effect of several parameters including the gas flow rate (Qg), effective thermal conductivity (λs,eff), operating time (ti) and operating temperature (Top.) were investigated. The simulated results shown that the pressure drop increases with the increase of Qg. When the Qg is increased, the temperature profiles at the surface of the solid phase as well as the temperature profiles of the gas phase are remarkably decreasing. The consumption of reactants (CH4, H2O and CO2) is increased when the λs,eff is gradually increased. On the other hand, the production of products (H2, and CO) is remarkably increasing with the increase of the λs,eff. According to simulated results, the overall conversions of reactants (CH4 and CO2) and the dimensionless flow rate (DFR) of H2 reach the maximum values of 98.18%, 75.61% and 1.6278 at the operating time of 2.50 h. The thermochemical energy storage efficiency (ηChem) remarkably increases with the operating temperature and the maximum value of the ηChem can be as high as 74.21% at 1123 K. The overall conversions of reactants (CH4 and CO2), DFR of H2 and the energy stored as chemical enthalpy (QChem) were also evaluated in relation to the operating temperature and their maximum values of 99.43%, 89.03%, 1.6383 and 1.3745 kJ/s are obtained at 1225 K. 相似文献
976.
Recently, earth observation system by using satellite network has attracted much attention due to its wide coverage and disaster resistance. Although the system is useful for collecting various data, which have an effect on a natural disaster, ecology and so forth, earth observation satellite hardly send the collected observation data to the ground station. This is because that the earth observation satellite needs to orbit near surface of the earth to get high-precision data, and it limited the time that can be used to send the observed data traffic to the ground station. Additionally, the amount of the observed data drastically increase in these days. Thus, we focus on the data relay satellite using optical communication in this network. By relaying observed data to traffic to the relay satellite, which has geostationary orbit, it is possible to increase the chance of sending data for the observation satellite due to the wide coverage of the relay satellite. In addition, laser light that is used in optical communication in satellite network has high frequency and it can deliver large data compared with radio wave. However, laser light is greatly influenced by atmosphere, and optical link capacity between satellite and ground station drastically changes according to weather condition. Therefore, we propose a new data traffic control method to use the network constructed by satellites which has mass storage device effectively according to the condition of optical downlink between satellite and optical ground station. The effectiveness of the proposed method is evaluated with numerical result. 相似文献
977.
Yong‐Ning Zhou Mahsa Sina Nathalie Pereira Xiqian Yu Glenn G. Amatucci Xiao‐Qing Yang Frederic Cosandey Kyung‐Wan Nam 《Advanced functional materials》2015,25(5):696-703
Searching high capacity cathode materials is one of the most important fields of the research and development of sodium‐ion batteries (SIBs). Here, we report a FeO0.7F1.3/C nanocomposite synthesized via a solution process as a new cathode material for SIBs. This material exhibits a high initial discharge capacity of 496 mAh g?1 in a sodium cell at 50 °C. From the 3rd to 50th cycle, the capacity fading is only 0.14% per cycle (from 388 mAh g?1 at 3rd the cycle to 360 mAh g?1 at the 50th cycle), demonstrating superior cyclability. A high energy density of 650 Wh kg?1 is obtained at the material level. The reaction mechanism studies of FeO0.7F1.3/C with sodium show a hybridized mechanism of both intercalation and conversion reaction. 相似文献
978.
In this brief note, a first assessment on the possibilities for thermal osmotic storage by harnessing the thermal dependence of the solubility of common salts as an alternative method to sensible heat storage is discussed. In a recent study it was found that such a dependence could be used to run a heat powered cycle (osmotic heat engine). The question raised then is whether that approach could be suitable for thermal energy storage as well. The attractiveness of such a possibility lies in the capability to store energy for an indefinite period of time without using expensive isolation systems if one considers that osmotic energy only is released when both streams with different salinities are brought together. Utilizing a simplified model, a comparative study with sensible heat storage was performed. It is shown that thermal osmotic storage via thermal precipitation of common salts could be an attractive option when long thermal storage (days) and compactness is desired. 相似文献
979.
In the current study, a solar tower–based energy system integrated with a thermal energy storage option is offered to supply both the electricity and freshwater through distillation and reverse osmosis technologies. A high‐temperature thermal energy storage subsystem using molten salt is considered for the effective and efficient operation of the integrated system. The molten salt is heated up to 565°C through passing the solar tower. The thermal energy storage tanks are designed to store heat up to 12 hours. The temperature variations in the storage tanks are studied and compared accordingly for evaluation. The effect of operating temperatures on the freshwater production and overall system efficiency is determined. About 24.46 MW electricity is generated in the steam turbine under sunny conditions. Furthermore, the storage subsystem stores heat during sunny hours to utilize later in cloudy hours and night time. The produced power decreases to 20.17 MW in discharging hours due to temperature decrease in the tank. The electricity generated by the system is then used to produce freshwater through the reverse osmosis units and also to supply electricity for the residential use. A total flowrate of 240.02 kg/s freshwater is obtained by distillation and reverse osmosis subsystems. 相似文献
980.
The gradual depletion of fossil fuels has greatly enhanced the necessity to look for alternative fuels for automobile engines. In response to this, biodiesel is being considered as a promising and potential alternative substitute to conventional petroleum diesel. However, long-term storage stability of biodiesel is poorer compared to conventional petroleum diesel. The aim of the project work is to study the long-term storage stability of biodiesel (B100) and its blend (B20) prepared from used frying oil in different conditions of storage. In this work, the effect of antioxidants and temperature on long storage stability of biodiesel obtained from with respect to storage period is analysed using response surface methodology (RSM). The long storage of biodiesel obtained from used frying oils were optimised by varying parameters such as antioxidant concentration, storage period by Box-Behnken RSM. The properties such as the acid value and the viscosity of biodiesel were initially measured. The results of the investigation showed that the addition of sufficient concentration of antioxidant (pyrogallol) significantly maintains the acid value and viscosity of biodiesel and helps to store for a longer storage period at the given storage temperature. 相似文献