Energy, Exergy, and Economic (3E) Analysis of Transcritical Carbon Dioxide Refrigeration System Based on ORC System

This paper used the energy, exergy, and economic analysis of a carbon dioxide (CO2) transcritical two-stage compression system based on organic Rankine cycle (ORC) waste heat recovery technology. When the intermediate pressure and high-pressure compressor outlet pressure were changed, respectively, this study simulated the change in system energy efficiency by adding the ORC for waste heat recovery, calculated the ratio of exergy loss of each component, and performed an economic analysis of the coupled system. The results show that adding waste heat recovery can effectively increase the energy efficiency of the system, and among all components, the heat exchanger had the largest exergy loss, while the evaporator had the highest capital investment and maintenance costs

Low-Cost Halide Electrolytes Li_2+<i>x</i>Hf_1–<i>x</i>Fe_<i>x</i>Cl₆ with Superior Ionic Conductivities for All-Solid-State Lithium–Metal Based Batteries

All-solid-state batteries (ASSBs) employing inorganic solid electrolytes have been considered as promising candidates for next generation energy storage owing to their intrinsic safety performance and high energy density. Designing highly ionically conductive and (electro)chemically stable inorganic solid electrolytes utilizing cost-effective materials is of vital importance for the development of practical ASSBs. Herein, we report a series of new lithium-conducting superionic halides Li2+xHf1–xFexCl6 that are free of rare-earth elements with high ionic conductivities up to 0.91 mS cm–1 at 30 °C by aliovalent substitution with low-cost and earth-abundant Fe elements. By means of complementary characterization techniques and bond-valence site energy (BVSE) calculations, we gain insights into the influence of aliovalent doping engineering on the local structural environment and the underlying lithium-ion transport properties of Fe3+-substituted Li2HfCl6. Importantly, it is demonstrated that the prevalently existent distortion of octahedral structure and redistribution of the lithium ion induced by the aliovalent substitution strongly benefits the transport properties. Notably, the formation of infinitely 3D connected lithium-ion migration pathways comprised of a directly connected face-sharing octahedron along the c direction is revealed by structural analysis and theoretical calculations. Additionally, owing to the intrinsic oxidation tolerance of Fe3+-substituted Li2HfCl6, the fabricated bulk-type ASSBs with uncoated LiCoO2 deliver an outstanding electrochemical performance

Heat transfer rate prediction and performance optimization of CO2 air cooler in refrigeration system

In order to determine the heat transfer rate of CO2, heat transfer criterion equations were selected and validated using experiment data. The impacts of various operating conditions and structural parameters on CO2 air coolers were numerical simulation investigated. The results show that the inlet dryness and mass flow rate are proportional to heat transfer coefficient (HTC) and pressure drop (PD). When the mass flow reaches 240 kg/h, CO2 reaches the critical state, and further increasing the mass flow rate has little effect on the HTC. The HTC reaches its maximum value at a dryness of 0.2, after which, it decreases due to the flow pattern changing from wavy/intermittent flow to annular flow. Moreover, the tube spacing, tube diameter, and fin spacing affect the HTC, heat exchange area, and heat exchange capacity differently. Hence, a thoroughly consideration of the structural parameter design is crucial during the actual design process

Lignin Redistribution for Enhancing Barrier Properties of Cellulose-Based Materials

Renewable cellulose-based materials have gained increasing interest in food packaging because of its favorable biodegradability and biocompatibility, whereas the barrier properties of hydrophilic and porous fibers are inadequate for most applications. Exploration of lignin redistribution for enhancing barrier properties of paper packaging material was carried out in this work. The redistribution of nanolized alkali lignin on paper surface showed excellent water, grease, and water vapor barrier. It provided persisted water (contact angle decrease rate at 0.05&deg;/s) and grease (stained area undetectable at 72 h) resistance under long-term moisture or oil direct contact conditions, which also inhibited the bacterial growth to certain degree. Tough water vapor transmission rate can be lowered 82% from 528 to 97 g/m2/d by lignin redistribution. The result suggests that alkali lignin, with multiple barrier properties, has great potential in bio-based application considering the biodegradability, biocompatibility, and recyclability

Self-Host Blue Dendrimer Comprised of Thermally Activated Delayed Fluorescence Core and Bipolar Dendrons for Efficient Solution-Processable Nondoped Electroluminescence

A self-host thermally activated delayed fluorescence (TADF) dendrimer POCz-DPS for solution-processed nondoped blue organic light-emitting diodes (OLEDs) was designed and synthesized, in which the bipolar phosphine oxide carbazole moiety was introduced by alkyl chain to ensure balanced charge transfer. The investigation of physical properties showed that the bipolar dendrons not only improve the morphological stability but also restrain the concentration quenching effect of the TADF emissive core. The spin-coated OLEDs featuring POCz-DPS as the host-free blue emitter achieved the highest external quantum efficiency (7.3%) and color purity compared with those of doped or nondoped devices based on the parent molecule DMOC-DPS, which indicates that incorporating the merits of encapsulation and bipolar dendron is an effective way to improve the electroluminescent performance of the TADF emitter used for a solution-processed nondoped device

Enhanced Electron Affinity and Exciton Confinement in Exciplex-Type Host: Power Efficient Solution-Processed Blue Phosphorescent OLEDs with Low Turn-on Voltage

A benzimidazole/phosphine oxide hybrid 1,3,5-tris­(1-(4-(diphenylphosphoryl)­phenyl)-1H-benzo­[d]­imidazol-2-yl)­benzene (TPOB) was newly designed and synthesized as the electron-transporting component to form an exciplex-type host with the conventional hole-transporting material tris­(4-carbazoyl-9-ylphenyl)­amine (TCTA). Because of the enhanced triplet energy and electron affinity of TPOB, the energy leakage from exciplex-state to the constituting molecule was eliminated. Using energy transfer from exciplex-state, solution-processed blue phosphorescent organic light-emitting diodes (PHOLEDs) achieved an extremely low turn-on voltage of 2.8 V and impressively high power efficiency of 22 lm W^–1. In addition, the efficiency roll-off was very small even at luminance up to 10 000 cd m^–2, which suggested the balanced charge transfer in the emission layer. This study demonstrated that molecular modulation was an effective way to develop efficient exciplex-type host for high performanced PHOLEDs

New superionic halide solid electrolytes enabled by aliovalent substitution in Li3−xY1−xHfxCl6 for all-solid-state lithium metal based batteries

Rechargeable all-solid-state batteries (ASSBs) are considered as promising candidates for next-generation energy storage due to their high energy density and excellent safety performance. However, the low ionic conductivity of the solid-state electrolytes (SSEs) and interfacial issues are still challenging. Herein, we report a series of new mixed-metal halide superionic conductors Li3−xY1−xHfxCl6 (0 ≤ x < 1) with high ionic conductivity up to 1.49 mS cm−1 at room temperature. Using various experimental characterization techniques and bond-valence energy landscape (BVEL) calculations, we gain insights into the aliovalent substitution of Hf for Y in halide Li3YCl6 that influences the local structural environment and the underlying lithium-ion transport. Importantly, it is found that the existence of prevalent cation site disorder and defect structure as well as the synthetically optimized (Y/Hf)Cl6 framework with a more covalent feature in Hf4+-substituted Li3YCl6 strongly benefits the transport properties. In particular, the formation of an infinitely 3D connected Li+ ion diffusion pathway consisting of face-sharing octahedra within the lattice of Hf4+-substituted Li3YCl6 is revealed by structural elucidation and theoretical calculations. Additionally, owing to the exceptional interfacial stability of the as-milled SSEs against high-voltage cathode materials, all-solid-state lithium-ion batteries with a LiCoO2 cathode and Li–In anode exhibit outstanding electrochemical performance.Fil: Tuo, Kaiyong. School Of Chemical & Environmental Engineering; ChinaFil: Sun, Chunwen. School Of Chemical & Environmental Engineering; ChinaFil: Lopez, Carlos Alberto. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Área Química General e Inorgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Fernández Díaz, María Teresa. Institut Laue Langevin; FranciaFil: Alonso, José Antonio. Instituto de Ciencia de Materiales de Madrid; Españ

Hygrothermal and energy performance assessment of a passive building wall integrating PCM and bio-based hygroscopic material

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