In the development and engineering application of advanced adiabatic compressed air energy storage (AACAES), system performance optimization is essential to get the best energy storage efficiency with the lowest cost. However, in general, thermal and economic performances cannot be simultaneously optimal. To solve this problem, a multi-objective optimization is adopted in this work. Energy and economic models of the AA-CAES system are established to obtain the system performances. On this basis, system performances under basic conditions and the effects of operation parameters are obtained. With the maximum round-trip efficiency (RTE) and the minimum total capital cost (TCC) as the optimization objectives, key system parameters, including pinch point temperature difference (PPTD), compressor outlet temperature and sliding pressure range, are optimized with the Non-Dominated Sorting Genetic Algorithm (NSGA-II). The results indicate that under basic conditions, RTE of the system is 67.64 % and TCC is $13.127 x 107. With the increase of PPTD, RTE decreases, while TCC first decreases and then increases. As the compressor outlet temperature increases, TCC gradually decreases, while RTE increases first and then decreases. Furthermore, every 1 MPa increase of sliding pressure range increases RTE by 0.16 %, and decreases TCC by $1.300 x 107. After multi-objective optimization, the optimal RTE is 67.96 %, and TCC is $11.672 x 107. Compared with the performances under basic conditions, RTE increases by 0.32 % and TCC decreases by $1.455 x 107.

Currently, advanced adiabatic compressed air energy storage (AA-CAES) has been widely used, but the quantitative study of its energy loss is still unresolved. Therefore, the ideal AA-CAES with a round-trip efficiency (RTE) of 100% is defined to quantify the energy losses in the AA-CAES from the aspects of factors and components, so as to clarify the loss mechanism of AA-CAES. First, eight energy loss factors affecting the performances of AA-CAES are identified. Then, based on component type, six components of AA-CAES are identified. After that, to obtain the system energy flow, the corresponding thermodynamic models are developed. Finally, based on the given operating conditions, the energy losses corresponding to each factor and component are obtained sequentially using univariate analysis, and parametric analysis is carried out. The results show that in terms of energy loss factors, the storage device has the greatest impact on system performance with a compression work increment dEcharge of 72.56 MWh and an RTE of 89.21%. In terms of components, the compressors and turbines have the greatest impact on system performance. Furthermore, there is a synergistic effect among the factors. The effect of different factors acting together is greater than the superposition of individual values.

To fully recover abundant waste heat and reduce the operation cost in liquid-cooled data centers, a Carnot battery consisting of a heat pump (HP) and organic Rankine cycle (ORC) is proposed. Due to the existence of different cycle states for HPs and ORCs, four different cycle combinations are considered. To evaluate and compare their performances, thermo-economic models are developed. Under the design conditions, the optimal working fluid combinations are first determined for each battery. On this basis, thermodynamic and economic performances of the four batteries are analyzed in detail. The results indicate that the system consisting of a subcritical HP/transcritical ORC achieves the highest round-trip efficiency at 76%. Notably, the round-trip efficiency of the system can exceed 100% at low ORC condensing temperatures. Additionally, the system cost is about 767–796 USD/kW∙h, depending on the cycle combinations. Furthermore, the effects of operating parameters on system performances are also investigated. Finally, with the objective of maximum round-trip efficiency, key parameters of four batteries are optimized. The results reveal that the system with a subcritical HP/subcritical ORC attains a maximum round-trip efficiency of 83% after optimization. These research results contribute to the development of green data centers and the reduction of power costs.

Currently, working fluids for adiabatic compressed energy storage primarily rely on CO2 and air. However, it remains an unresolved issue to which of these two systems performs better. Therefore, this paper compares the pros and cons of both systems in terms of thermodynamic and economic performances under the given boundary conditions. To accurately obtain the performance of energy storage systems, quasi-dynamic models are established for key components. On this foundation, corresponding thermal-economic models are developed. The results indicate that at thermal storage temperatures of 120°C, 140°C, and 160°C, a 100MW×5h compressed CO2 energy storage (CCES) system has a higher round-trip efficiency (RTE) than a compressed air energy storage (CAES) system. However, CCES also faces the difficulties of a higher cost and a longer payback period (PBP). Specifically, at a thermal storage temperature 140°C, RTEs of CAES and CCES systems are 59.48% and 65.16% respectively, with costs of $11.54×107 and $13.45×107, and PBPs of 11.86 years and 12.57 years respectively. Compared to CAES system, CCES system has a 9.55% higher RTE, 16.55% higher cost, and a 6% longer PBP. At other thermal storage temperatures, similar phenomenons can be observed for these two systems. After comprehensively considering the obtained thermal and economic performances, it can be concluded the overall performance of CAES system is superior to that of CCES system. In addition, in practical engineering, key components of CAES are more mature than those of CCES, and air has higher safety than CO2.

Currently, working fluids for adiabatic compressed energy storage primarily rely on carbon dioxide and air. However, it remains an unresolved issue to which of these two systems performs better. Therefore, this paper compares the advantages and disadvantages of both systems in terms of thermodynamic and economic performances under the given boundary conditions. To accurately obtain the performance of energy storage systems, quasi-dynamic models are established for key components. On this foundation, corresponding thermodynamic- economic models are developed. The results indicate that at thermal storage temperatures of 120 degrees C, 140 degrees C, and 160 degrees C, 100 MWx5h x5h compressed carbon dioxide energy storage systems have higher round-trip efficiencies than compressed air energy storage systems. However, the compressed carbon dioxide energy storage also faces the difficulties of higher cost and longer payback period. Specifically, at the thermal storage temperature of 140 degrees C, round-trip efficiencies of compressed air energy storage and compressed carbon dioxide energy storage are 59.48 % and 65.16 % respectively, with costs of $11.54 x 107and 7 and $13.45 x 107, 7 , and payback periods of 11.86 years and 12.57 years respectively. Compared to compressed air energy storage system, compressed carbon dioxide energy storage system has 9.55 % higher round-trip efficiency, 16.55 % higher cost, and 6 % longer payback period. At other thermal storage temperatures, similar phenomenons can be observed for these two systems. After comprehensively considering the obtained thermodynamic and economic performances, the overall performance of compressed air energy storage is superior to that of compressed carbon dioxide energy storage. In addition, in practical engineering, key components of compressed air energy storage are more mature than those of compressed carbon dioxide energy storage, and air has higher safety than carbon dioxide. In the future work, the comparison for performances between different types of compressed carbon dioxide energy storage and compressed air energy storage should be taken into account, and dynamic models of the systems should be developed. Additionally, the industry chain of compressed carbon dioxide energy storage should be accelerated to reduce equipment costs, enabling it to compete with compressed air energy storage.

Recently, supercritical CO2 (S-CO2) has been extensively applied for the recovery of waste heat from flue gas. Although various cycle configurations have been proposed, existing studies predominantly focus on the steady analysis and optimization of different S-CO2 structures under design conditions, and there is a noticeable deficiency in off-design research, especially for the innovative S-CO2 cycles. Thus, in this work aimed at the proposed novel S-CO2 power cycle, off-design characteristics and corresponding control strategies are investigated for the waste heat recovery. Based on the design parameters of the S-CO2 cycle, structural dimensions of printed circuit heat exchangers (PCHEs) and shell-and-tube heat exchangers are determined, and design values of turbines and compressors are specified. On this basis, off-design models for these key components are formulated. By manipulating variables such as cooling water inlet temperature, cooling water mass flow rate, flue gas inlet temperature and flue gas mass flow rate, cycle performances of the system are analyzed under off-design conditions. The simulation results show that when the inlet temperature and the mass flow rate of cooling water vary separately, the thermal efficiency both can reach the maximum value of 28.43% at the design point. For the changes in heat source parameters, the optimum point is slightly deviated from the design condition. Amidst the fluctuations in flue gas inlet temperature, the thermal efficiency optimizes to a peak of 28.56% at 530 °C. In the case of variation in the flue gas mass flow rate, the highest thermal efficiency 28.75% can be obtained. Furthermore, to maintain the efficient and stable operation of the S-CO2 power cycle, the corresponding control strategy of the cooling water mass flow rate is proposed for the cooling water inlet temperature variation. Generally, when the inlet temperature of cooling water increases from 23 °C to 27 °C, the cooling water mass flow should increase from 82.3% to 132.7% of the design value to keep the system running as much as possible at design conditions.

Compressed CO2 energy storage (CCES) technology has the advantages of high energy storage density, low economic cost, low carbon emission, which is suitable for the construction of large-scale and long-time energy storage system. Besides, as a scene with massive heat, the electricity consumption of servers in data center is mostly converted into heat. Thus, the purpose of this work is to integrate a trans-critical compressed CO2 energy storage system with the waste heat of data centers, so as to improve the system performance and reduce the operating cost of data center. Based on different operating principles of compressors, a single-stage compression system (System-CP) and a double-stage compression system (System-VP) are constructed. To analyze and compare the energy and exergy performance of these two systems under design conditions, a quasi-dynamic model is developed by considering the variations of pressure and temperature in the storage tank. On this basis, an economic model is developed to obtain the economy performance for the systems. The obtained results show that the round-trip efficiency (RTE) of System-CP and System-VP are 64.67 % and 67.41 %, respectively. For the energy storage capacity 15 MW x 5 h, volumes of high-pressure S-CO2 storage tank are 314,387.51 m3 and 287,982.91 m3 for System-CP and System-VP, respectively. Thereby, the energy storage density (ESD) of System-CP and System-VP are 0.24 kW & sdot;h/m3 and 0.26 kW & sdot;h/m3, respectively. Meanwhile, the total capital cost (TCC) is $477.84 x 106 for System-CP, and $437.41 x 106 for System-VP, and the corresponding payback period (PBP) are 14.76 years and 12.39 years respectively. Further, the effect of key parameters on systems performance is revealed. The results show that with the decrease of slip-pressure range decreases, RTE, TCC and the volume of storage tanks increase linearly.

压缩空气储能(CAES)是一种大规模物理储能技术,可广泛应用于电网削峰填谷和大规模新能源消纳.当前我国CAES正处于由示范项目向产业化发展的关键阶段,呈现出良好的发展态势.系统总结了国内外CAES工程现状,介绍了已投运的商业电站,并对其在新能源侧的应用前景进行了阐述.进一步,从装机规模、系统效率、应用场景、建设成本等多个方面对其发展趋势进行了介绍.针对CAES发展中遇到的挑战,从电站建设、核心装备、标准体系、价格机制4个角度进行阐述,给出了推动CAES发展的建议,推动其向多元化、规模化、产业化方向发展,成为支撑我国"双碳"目标的关键技术.

Bimetallic copper-steel composite could be an effective structural material to improve the performance of traditional nickel-aluminum bronze (NAB) ship propeller due to its high structural strength and corrosion resistance. In this work, the defect-free NAB coatings has been successfully fabricated by laser direct depositing technique on the 17-4PH stainless steel substrate. The phase constitution, microstructure characteristics and hardness properties were inves-tigated in details. The XRD results showed that the coatings mainly consisted of α-Cu, Fe and intermetallic κ phases despite the diffraction peaks shifted more than 0.5°, which may due to the influence of the Ni, Fe and Al atoms dis-solved into Cu-matrix. The microstructures of the coatings were affected significantly by laser energy density accord-ing to SEM and EDS results. The top region of the coating was more undercooled during solidification, therefore the grains at this region was much finer than that at the bottom region. The higher energy input would lead to coarser grains. Fe-rich dendrites and spherical particles were found in the Cu matrix, which could be a result of liquid separa-tion. The hardness of the coating is in the range of 204 -HV0.2–266 -HV0.2 which is higher than traditional as- cast NAB. The uneven distribution of Fe-rich phases as well as the hard κ phases could be the main reasons for the fluctuations of the hardness value. Tensile fracture occurred at bronze side, not at transition zone, which shows there is a good interfacial bonding between the two metals produced by laser cladding.

ARCH lattice structure is composed of arch microstrut units arranged in order, which has excellent energy absorption performance, good designability, and good predictability of failure mode. ARCH lattice structure is expected to be applied to a variety of energy absorption and anti‐impact components or devices. Herein, the quasistatic compression experiment is conducted on the ARCH lattice structure samples. The mechanical properties and energy absorption capability of ARCH lattice structures with different unit sizes and different relative densities are experimentally researched. The results show that, compared with other lattice structures, ARCH lattice structures have superior energy absorption capability. The relative density has a great influence on the mechanical properties and energy absorption capability of ARCH lattice structures. The Gibson−Ashby equation is established to estimate the mechanical properties and energy absorption capability of the lattice structures with different relative densities.

Purpose The purpose of this paper is to identify the energy absorption characteristics of arch micro-strut (ARCH) lattice structure (different from traditional straight micro-strut lattice structure) under high-speed impact, and promote the development of special-shaped micro-strut lattice structure. Design/methodology/approach The study serves to study the anti-impact and energy absorption characteristics of ARCH lattice structure under different strain rates and different unit layers of lattice structure. In this paper, quasi-static compression and Hopkinson compression bar experiments are used for comparative analysis. Findings The results show that the ARCH lattice structure has obvious strain rate effect. When the strain rate is low, the number of layers of lattice structure has a great influence on the mechanical properties. With the increase of strain rate, the influence of the number of layers on the mechanical properties gradually weakens. So the ARCH lattice structure with fewer layers (less than five layers) should be selected as the impact energy absorbing materials at lower impact rate, while at higher impact rate, the number of layers can be selected according to the actual requirements of components or devices space size. Originality/value This study shows that Arch lattice structure has excellent energy absorption performance, and provides a theoretical reference for the application of ARCH lattice structure in energy-absorbing materials. ARCH lattice structure is expected to be applied to a variety of energy absorption and anti-impact components or devices, such as aircraft black box fall buffer components, impact resistant layer of bulletproof and landing buffer device.

Nickel-aluminum bronze coatings were deposited on high strength stainless steel SUS630 by laser cladding. The microstructure of the multi-layer structures was investigated. The OM results showed that steel-bronze bimetallic materials were successfully fabricated without any defects. The dilution rate of substrate can be adjusted by controlling the laser parameters. The main phases of the coating are α-Cu, Fe-rich dendrites and κ phases. Tensile tests were carried out and it was found that the upper specimen with fewer Fe-rich related components had better tensile strength properties.

Lattice structure has a broad application in the fields of aerospace, automobile, bio‐medical treatment and energy. It is very suitable for the applications of secondary load‐bearing components, because of its characteristics of low density, high specific strength, and high specific stiffness. The flexural property is an important index of the material used in the secondary load‐bearing components. In this study, the flexural properties of ARCH lattice structure fabricated by selective laser melting (SLM) under different loading directions and with different relative densities are simulated and experimentally researched. The results show that ARCH lattice structure has better flexural properties under Y loading direction. The relative density has a great influence on the flexural properties of ARCH lattice structures. Moreover, the Gibson–Ashby equation is also established to estimate the flexural properties of the lattice structures with different relative densities, which can provide a theoretical basis and reference to the engineering application of ARCH lattice structures.

In recent years, selective laser melting (SLM) has been widely used in aerospace, automobile, biomedicine and other fields. However, there still remain many challenges to obtain consistent parts at the different positions on the base plate, which could be harmful to the industrial mass-production. In SLM process, the process by-products that flow with the shielding gas may influence the microstructure and tensile properties of the parts placed on different positions of the base plate. In this study, the velocity field of the shielding gas with different shielding gas volume flows was simulated. The tensile properties of the samples fabricated with different shielding gas volume flow were experimentally studied. The results show that the shielding gas volume flow has a strong influence on the sample consistency, and proper increase in shielding gas volume flows can be beneficial to consistency and tensile strength.

In this study, the main design parameters of the heat pump/heat pipe composite system were calculated. The operation characteristics of the heat pump/heat pipe composite system under low temperature were experimentally studied. The start-up character of the heat pipe radiator and heat pipe radiator surface temperature distribution were obtained. The variation of heating capacity and heating coefficient of performaance of the heat pump/heat pipe composite system with different working condition was obtained. Experimental results show that the heat pump/heat pipe composite system can operate efficiently and steadily when the outdoor temperature is ?20~5?C, and meet the winter heating demand in cold areas.

Abstract In this study, a new lattice structure ARCH is proposed, ARCH lattice structure and traditional lattice structures BCT were fabricated from 316 L stainless steel by SLM. Mechanical properties and deformation behavior of the lattice structures were experimentally investigated. The results show that the ARCH lattice structures have better mechanical property and energy absorption capability than BCT lattice structures. Under the same relative density, the compressive strength and elastic modulus of the ARCH lattice structure is 121.27% and 60.48% higher than the BCT lattice structure, and the ARCH lattice structures have better energy absorption properties than the BCT lattice structures.

航空发动机喷嘴是影响燃烧性能的关键部件,其组件众多、结构复杂,尤其内部流道加工困难,导致制造周期长、成本高.然而,作为非主承力件的喷嘴非常适用于激光选区熔化制造技术(SLM),这得益于激光选区熔化加工精度高,自由成形能力强,材料组织致密度高.基于SLM可实现自由制造的技术优势,首先对喷嘴的壳体组件进行了一体化设计,并进行了受力分析和拓扑优化,然后采用SLM打印了成形件,经过测量,可获得13.5％的轻量化效果,打印误差小于0.2mm,满足局部精加工的余量要求,随炉试件力学性能达到传统铸锻件水平.SLM简化了喷嘴的加工工序,缩短了制造周期,流道成形精度高,达到了减轻重量和改善性能的目的.

Sets up an experimental device for a scroll compressor.Under the condition of evaporating temperature from-25 ℃ to 0 ℃ and condensing temperature of 45 ℃,tests the performance of R22,R134a,R410A,R1234ze and R1234yf in single stage compression system and the vapor injection system respectively.The results show that R410A has the largest heating capacity,R1234yf has the lowest discharge temperature and R1234ze has the highest heating COP.Compared with the single stage compression system,though the compressor power of the vapor injection system increases slightly,it can significantly reduce the discharge temperature,increase the heating capacity and the maximum increase of heating COP is 29.3％.

In this study, the working principle of a heat pipe radiation heating device driven by heat pump was proposed. The prototype has been developed for testing based on a 1 HP compressor and the operating characteristics of the prototype under the working conditions of indoor temperature from 18 ℃ to 22 ℃, outdoor temperature from -15 ℃ to 0 ℃ are tested in the air enthalpy room. The experimental results showed that the heat pipe radiator can start rapidly and has a uniform temperature distribution. The optimal charge of heat pipe working fluid ratio is 0.1. The maximum heating coefficient of performance (COP) of the system can reach 4.1 under the condition of 22 ℃ indoors and﹣15-0 ℃ outdoors.

In this study, a concept of air-source heat pump using heat pipes as heat radiator system (ASHPP) for room heating was proposed. The heat pipes radiator was developed to replace the heating terminal equipment used in traditional heat pump plants. A tested room with artificial load was constructed and an experimental apparatus of ASHPP system was developed. Heat radiator performances with different kinds of refrigerant and different refrigerant mass filling ratio of heat pipe have been experimentally investigated. The variations of system heating performance under the condition of different indoor air temperature and outdoor air temperature were researched. The purpose of this study is to provide technique reference for developing new heat pump room heating system.