Next Energy最新文献

On battery electric vehicles a precise control of heat flows is required for passenger comfort and for both performance and safety of battery packs. This is typically achieved with a thermal management system which employs some type of liquid coolant to transfer heat. Coolant distributor valves are used to regulate coolant flows through the exchangers, for example to recover heat from hot sources, thus to increase vehicle energy efficiency. The development of this type of component is high-priced and the design is generally complex since several operating functions and manufacturing constraints should be satisfied. Despite this complexity and the positive impact such valves have on the thermal management of electric vehicles, a few works are currently available in the literature on design procedures for this component, where only a partial overview of the topic is provided and a comprehensive design methodology considering the effective operating conditions is still missing. In this work we construct a physical model of the valve for torque, internal leakage and pressure drop, and we build an optimization procedure to improve the global performance of the valve. We compare the obtained designs with a simpler approach that optimizes performance parameters independently and we show that designs which severely under-perform with respect to the uncontrolled performance parameters can be produced if an over-simplified design approach is followed. We then show with a global vehicle thermal model that the impact of valve design on global vehicle performance crucially depends on the thermal exchanges at vehicle level and, thus, on its operating conditions. In particular, the impact is considerable when mixing of cold and hot flows through the valve occurs. For a specific example vehicle evaluated in a type-3a cycle of the Worldwide Harmonized Light Vehicle Test Procedure, a valve determined with the proposed optimization procedure allows us to obtain in this condition an increase of about 1 km in the vehicle driving range with respect to a valve defined with the simpler approach.

This paper describes a complete cycle of designing, developing, and characterising a Pulsed Power System (PPS) and generating microwaves using the relativistic source. For low impedance relativistic High Power Microwave (HPM) sources, Blumlein Pulse Forming Line (BPFL) based high voltage pulsed power systems are the most suited. An HPM source such as a virtual cathode oscillator (VIRCATOR) operating in nanosecond durations consists of a primary voltage source that charges a Marx pulse generator’s capacitor bank over a long time. The requirements of a diode load are met by compressing the output pulse width of a Marx generator by a BPFL. This article describes the novel design, construction and characterization of a circulating De-Ionized (DI) water insulated BPFL pulsed power system. A novel approach of insulating gas filled Marx generator of this class/rating is attempted. A pulse power system consisting of high pressure gas insulated Marx generator and circulating DI water-based BPFL was developed and experimented with the resistive load as well as HPM source. The PSPICE simulation of the Blumlein circuit for various load conditions is described. Criticalities in the design of end bushings are elaborated along with the development and testing of a compact BPFL-based pulsed power system.

Anion exchange ionomers employed as electrode catalyst binders and anion exchange membranes are central components for anion exchange membrane fuel cells. Fast oxygen transport in the catalyst binder and high ion conductivity of the ionomer and membrane are essential while designing their molecular structure. Here, we tailor a fluorinated ionomer and elucidate the effect of fluorination on the properties of catalyst binder and membrane. The extraordinary oxygen-dissolving capacity of the fluorinated ionomer improves the local oxygen transport at the catalyst layer triple-phase boundary. Moreover, fluorination enhances the mechanical stability and chemical inertness of the ionomer membrane and promotes its self-assembly to construct well-defined microphase separated morphology by increasing chain thermodynamic immiscibility. The resulting fluorinated membrane shows 1.4–1.8-fold improvements in hydroxide conductivity and mechanical properties compared to the fluorine-free counterpart, as well as exceptional alkaline stability (over 90% hydroxide conductivity retention under 2 M aq. NaOH at 80 °C for 2000 h). Such synergistic improvements in ionomer binder and membrane significantly improve the single-cell performance (1.7 vs. 1.0 W cm⁻² peak power density) and durability (1.8 vs. 2.4 mV h⁻¹ voltage decline rate for 100 h).

Transverse thermoelectricity (TTE) based on the Nernst effect has proven to be an alternative solution for the energy harvesting from environments, in contract to the classic longitudinal thermoelectric materials based on the Seebeck effect. The past years have witnessed significant progress both in exploring materials and adaption performance boosting strategies. Most of the reported TTE materials belong to the category of topological semimetal with high carrier mobility, which is very different from the classic thermoelectric semiconductors. This review presents the recent advances in the new TTE materials and performance enhancement strategies. The state-of-the-art TTE materials were classified into the Dirac-type, Weyl-type, and Nodal-line type according to their unique topological characters. The strategies for boosting the TTE performance, including defect engineering and topological phase transition, are systematically reviewed. Besides, the architectures of the TTE power generation devices are discussed, with a special attention on the challenge to achieve high energy conversion efficiency. Finally, the related challenges for further development both in TTE materials and devices are discussed, shining a light on the understanding of various emergent physical mechanisms.

Electrochemistry has enabled a wide range of important energy technologies such as fuel cells and batteries, emerging as a powerful tool to achieve active materials and devices with novel applications. In this Perspective, we highlight the great potential of electrochemistry in propelling the next generation of dynamic thermal metamaterials with a focus on thermal radiation applications. After a brief introduction of the mechanisms of electrochemistry to change material properties, we discuss the possibilities of achieving highly tunable thermal radiation features by electrochemically manipulating the carrier densities of plasmonic materials. Recent studies in the intersections between electrochemistry, metamaterials, and thermal radiation applications are reviewed, indicating an emerging research direction incorporating these three fields — electrochemically dynamic thermal metamaterials. Towards this direction, we anticipate a promising pathway of employing conducting polymers and point out its remarkable opportunities and potential challenges. We hope this perspective could encourage more researchers to contribute to the development of this interdisciplinary field targeting the next energy technologies and applications.

Nowadays the interest in deep space exploration is very strong; however, powering devices where sunlight is unavailable is a challenging task. Conventional radioisotope thermoelectric generators are difficult to miniaturize, while low-energy particle voltaic devices lack sufficient power density. In this study, we experimentally investigated the use of state-of-the-art 5 × 5 mm² silicon pad radiation detectors operated at cryogenic temperatures as high-energy particle voltaic devices. Our results show that operating the detectors at 80 K with ²⁴¹Am (0.1 mCi) and ⁹⁰Sr- ⁹⁰Y (0.8 mCi) radioactive sources results in a maximum electrical power of 100 nW/cm² and 165 nW/cm², respectively. These values correspond to 11% and 12% efficiency, which is unprecedented for silicon voltaic devices. Additionally, we found that the device’s radiation hardness significantly increases at cryogenic temperatures, consistent with the Lazarus effect. After more than 270 h of continuous irradiation with the ⁹⁰Sr- ⁹⁰Y source at 80 K, the device’s residual efficiency is as high as 1.8% and remains stable. This efficiency value could be increased by stacking multiple devices together, while passive radiative cooling in space allows reaching cryogenic temperatures without extra power.

The experimental investigation on using R452A in refrigeration system operating with R404A is conducted in this study. A tube-in tube internal heat exchanger is also utilized to retrofit the system for improving its energy performance. The evaporation temperatures are adjusted as − 3, 0 and + 3 °C while the condenser temperatures are studied for the cases of 25, 40 and 55 °C. The coefficient of performance, discharge temperature as well as volumetric efficiency of the compressor and total equivalent warming impact values are determined and compared in the investigation for the covered cases. Generally, the coefficient of performance of R404A is detected to be greater for condenser temperature of 25 °C while that of R452A is better for 40 and 55 °C cases. Hence, R452A may be suggested to use in R404A refrigeration systems for hot climate regions. Additionally, the energy performance of the system further enhanced for both tested refrigerants when the system is retrofitted with the internal heat exchanger. The environmental warming impact amounts of the refrigerants are also considered in the study. According to the computations, R452A has been determined to be more environmental-friendly compared to R404A. Hence, R452A can be suggested to be a suitable candidate as an alternative to R404A in a refrigeration system in the medium term considering its better energetic performance as well as lower environmental impact. Additionally, utilizing a tube-in-tube type internal heat exchanger should provide further both improvement on energy efficiency of the system and reduced carbon dioxide emissions to the environment.

Typical air conditioning terminals mainly focus on room temperature control, often neglecting adequate satisfactory room humidity management, resulting in poor thermal comfort. In addition, the direct heat exchange between refrigerant and air in these terminals cannot facilitate free-cooling using natural or waste cooling capacities. This study proposes a low-grade energy bus system that connects three-fluid heat exchange terminals, allowing for simultaneous control of room temperature and humidity. Furthermore, it enables the direct circulation of anti-icing fluid to each terminal for free cooling. Considering an office building in Nanjing, China, as an example, the annual operational performance of the proposed system is numerically studied and compared with two typical systems. The results reveal the following. 1) The three-fluid heat exchange terminals used can accurately regulate the room temperature and humidity, even when there are significant differences in the indoor cooling and dehumidification loads. 2) The annual system coefficient of performance (COP) of the proposed system increases from 3.3 to 3.9, leading to an annual energy saving rate of 14.4% compared to a typical water loop heat pump system in a typical office building in Nanjing, China. 3) Compared to commonly used room air conditioners, the proposed system is more energy-efficient.

Among the inorganic-organic hybrid complexes the zinc phenyl phosphinate (PhPZn) represent high char yield to the benefit of electron transfer of its derivatives. Herein, a γ/α-Zn₂P₂O₇/C composite derived from PhPZn during pyrolysis exhibits surface porous framework supported by thin nanosheet shells and the internal mesoporous structure. Based on the conversion/alloy reaction mechanism, the γ/α-Zn₂P₂O₇/C anode for sodium storage shows the impressive reversible capacity of 277 mA h g⁻¹ at 0.1 A g⁻¹, rate capability of 107 mA h g⁻¹ at 5 A g⁻¹ and cyclic stability of 115 mA h g⁻¹ after 1000 cycles at 1 A g⁻¹ with a capacity retention rate of 73.0%. This work is of great significance in broadening the anode material systems of sodium-ion batteries.

In the search for cutting-edge energy storage technologies, alkali ion batteries (AIBs) development has accelerated significantly. Due to its outstanding qualities, indium sulfide (In₂S₃) has emerged as a potential contender among the many anode materials for lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and potassium-ion batteries (PIBs). This review paper thoroughly examines In₂S₃-based materials for AIBs, placing particular emphasis on their importance in the context of environmentally friendly energy storage technologies. We explore In₂S₃'s distinctive characteristics, such as its high theoretical capacity, improved rate capability, cyclability, adjustable bandgap features, and environmental friendliness, which make it suited for AIBs. The development in material engineering, nanostructuring, composite materials, and novel electrode topologies is also highlighted as we discuss current developments in In₂S₃-based electrodes. In₂S₃-based materials provide a compelling path towards a cleaner and greener energy future, opening the way for scalable and sustainable energy storage systems thanks to their outstanding features and continuous advances. Further material engineering, improved knowledge of degradation mechanisms, exploring synergistic composite materials, and cutting-edge characterization techniques are all part of the future outlook for In₂S₃-based materials in AIBs. Due to their large theoretical capacity and advantageous electrochemical characteristics, materials based on In₂S₃ have demonstrated promise as anodes in AIBs. Researchers can maximize the performance of In₂S₃ in AIBs by concentrating on these factors, which will progress the development of effective and environmentally friendly energy storage technologies.