Smart Hybrids of Zn2GeO4 Nanoparticles and Ultrathin g‐C3N4 Layers: Synergistic Lithium Storage and Excellent Electrochemical Performance

Smart hybrids of Zn₂GeO₄ nanoparticles and ultrathin g‐C₃N₄ layers (Zn₂GeO₄/g‐C₃N₄ hybrids) are realized by a facile solution approach, where g‐C₃N₄ layers act as an effective substrate for the nucleation and subsequent in situ growth of Zn₂GeO₄ nanoparticles. A synergistic effect is demonstrated on the two building blocks of Zn₂GeO₄/g‐C₃N₄ hybrids for lithium storage: Zn₂GeO₄ nanoparticles contribute high capacity and serve as spacers to isolate the ultrathin g‐C₃N₄ layers from restacking, resulting in expanded interlayer and exposed vacancies with doubly bonded nitrogen for extra Li‐ion storage and diffusion pathway; 2D g‐C₃N₄ layers, in turn, minimize the strain of particles expansion and prevent the formation of unstable solid electrolyte interphase, leading to highly reversible lithium storage. Benefiting from the remarkable synergy, the Zn₂GeO₄/g‐C₃N₄ hybrids exhibit highly reversible capacity of 1370 mA h g^?1 at 200 mA g^?1 after 140 cycles and excellent rate capability of 950 mA h g^?1 at 2000 mA g^?1. The synergistic effect originating from the hybrids brings out excellent electrochemical performance, and thus casts new light on the development of high‐energy and high‐power anode materials.     

精准冰温对鲜牛肉贮藏品质的影响

在-2.5℃的冰温和0℃、4℃三种温度条件下贮藏排酸后的鲜牛肉,定期测定牛肉出汁率、TPA指标、色泽、p H、挥发性盐基氮(TVB-N)、微生物菌落总数等品质指标,为鲜牛肉的精准冰温保鲜提供参考。结果表明:冰温库库温稳定,在4℃、0℃和-2.5℃条件下贮藏的牛肉,有效保鲜期分别为8 d、15 d和24 d。在-2.5℃条件下贮藏24 d时,鲜牛肉p H值为5.59,TVBN含量为15.39 mg/100 g,微生物菌落总数为2.2×106CFU/g,色泽鲜红,无腐败异味出现。与4℃和0℃相比,-2.5℃冰温能够有效保持牛肉的颜色,减少出汁率,减缓p H值和TVB-N含量增大,抑制微生物的生长繁殖,有效延长生鲜牛肉的贮藏保鲜时间。     

填充相变材料的复合搁架的传热与蓄冷特性研究

为改善冷藏陈列柜性能,降低柜内食品温度,抑制融霜期间食品温度的回升,利用热管的高导热性和相变材料的蓄冷特性,将冷藏陈列柜的搁架设计成由热管和相变材料构成的复合式搁架。通过实验研究填充三种相变材料(RT3、RT4、RT5)的搁架的传热和蓄冷特性以及对冷藏陈列柜中食品包温度的影响。实验结果显示：相比未改进的搁架,填充RT3的复合搁架上食品包温度降低13.7%~80%,温升减小53.3%~70%;填充RT4的复合搁架上食品包温度降低20%~83.3%,温升减小83.3%~87.5%;填充RT5的复合搁架上食品包温度回升减小66.7%~75%。三种复合搁架相比较,填充RT4的复合搁架上各层、各排食品包平均温度最低,均在5 ℃以内,因此RT4相变材料蓄冷效果最好。     

不同贮藏温度对草莓呼吸强度及品质的影响

本文研究了不同贮藏温度(0℃、5℃、10℃、15℃、20℃、25℃、30℃)对草莓呼吸强度、感官评价、失重率、硬度、相对电导率、糖酸比、维生素C和色差的影响。研究表明:贮藏温度越高,草莓呼吸越旺盛,货架寿命越短,草莓30℃条件下的呼吸强度是0℃条件下的13.97倍;草莓在0℃、5℃、10℃、15℃、20℃、25℃、30℃条件下贮藏的商品寿命分别为9 d、7 d、6 d、5 d、3d、2 d、8 h。随着贮藏温度的升高,草莓的失重率、相对电导率和呼吸强度迅速升高,而草莓的感官评价、硬度、糖酸比、维生素C含量、L*、hue值逐渐降低;贮藏在0℃的草莓品质保持最好,贮藏9 d后的感官评价、失重率、硬度、相对电导率、糖酸比、Vc含量、L*和hue值分别为5.4、3.18%、11.13 N、39.05%、12.48、22.01 mg/100 g、37.84、32.81。     

应用精细积分法的结构MBC状态方程求解

基于市场机制控制(Market-Based Control,MBC)属于分散控制,以往求解状态方程都采用差分类的近似,有时由于计算存在较大误差,不能得到结构真实状态的精确响应。精细积分法以其高精度、无条件稳定等优点被广泛的应用。文中引入两种精细积分方法,将精细积分的思想运用到基于市场机制(MBC)控制算法的求解中,推导了两种基于MBC控制状态方程的精细递推格式,大大提高了计算的精度及算法的稳定性,并且比较了两种精细积分方法的优缺点。最后通过算例,说明了采用精细积分方法计算MBC控制的必要性及有效性。     

Effect of Sm on hydrogen storage performance of La–Sm–Mg–Ni alloys

In this study, Sm was adopted in order to completely replace the expensive Pr/Nd elements in the A2B7 type alloy. The results indicate that Sm is a favourable element for forming Ce2Ni7 type and Ce5Co19 type phases. With the increasing amount of Sm, the discharge capacity of the alloy retains a value of 283·3 mAh g^?1 at the current density of 1200 mA g^?1. The maximum discharge capacity of the alloys increases with the increasing Sm content when Mg content is relatively low. By optimising the composition and processing technology, the cycle life the alloy enhances from 74 cycles to more than 540 cycles, and the maximum discharge capacity also increases from 300 to 355 mAh g^?1.     

相变蓄热系统放热过程性能实验研究

本文通过对热泵空调系统的相变蓄热冷凝热回收装置进行放热实验,分别测试了不同冷水进水温度和不同水流量下蓄热箱中石蜡及蓄热箱热水出口温度的变化情况。实验结果表明:水流量对石蜡凝固过程的影响较小,提高水流量或者冷水温度可以在一定程度上缩短获取热水时间,但会相应增加能耗;石蜡初始温度提高,石蜡释放显热的速率加快,可以缩短获取热水时间;提高系统的蓄热效率对冷凝热的回收和利用有较大意义。     

Performance Evaluation of Compressed Air Energy Storage Using TRNSYS

The appreciable economic growth in some of the developing countries like India in the recent years, towards providing energy security causes large environmental impact. Renewable Energy (RE) is being seen as one of the important means to meet the growing power needs of the economy while enhancing energy security and providing opportunities for mitigating greenhouse gas emissions. However, RE sources are highly intermittent in nature. The variability of these sources has led to concerns regarding the reliability of an electric grid that derives a large fraction of its energy from these sources as well as the cost of reliably integrating large amounts of variable generation into the electric grid. Hence at this juncture, it is necessary to explore the benefits of suitable Energy storage technologies. Compressed air energy storage (CAES) is a commercial, utility-scale technology that provides long-duration energy storage with fast ramp rates and good part-load operation. It is a promising storage technology for balancing the large-scale penetration of renewable energies, such as wind and solar power, into electric grids. Considering the potential of CAES storage, the present work, a thermodynamic model is developed with suitable assumptions and the simulation analysis is performed using transient system simulation (TRNSYS) v17 software. The system performance is compared by considering the recovery during the heat of compression using a thermal storage system and without considering the heat recovery. The overall turnaround efficiency of the system without considering the thermal energy storage (TES) system is 57% and with TES system the efficiency is increased to 70%.     

水溶液法制备硝酸盐/膨胀石墨粉复合相变材料的实验研究

在制备(KNO3-LiNO3-Ca(NO3)2)/膨胀石墨粉(Expanded graphite,EG)复合相变材料过程中,硝酸共晶盐与EG的混匀程度直接影响着复合相变材料的蓄放热性能。KNO3、LiNO3、Ca(NO3)2按一定比例熔融混合制备得到共晶盐,然后再加入不同质量的水使共晶盐溶解,最后再将设定质量比的EG加入并搅拌混匀,加热将水分蒸发完全后得到复合相变材料。利用电子扫描显微镜(SEM)观察EG的微观形貌,用综合热分析仪(DSC Q600)测定所制备的复合相变材料的相变潜热值并用导热仪测量其导热系数。实验结果表明,对于EG质量分数为5%的复合相变材料,当溶解水量大于200g时,热物性较为理想。另外,EG含量越多,复合相变材料的导热系数越大。