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[en] Experience in optimal synthesis of individual vehicle components and mechanisms on the basis of additive technology is analyzed. A list of basic additive technologies is presented. The benefits of additive technology in combination with three-dimensional computer simulation are noted. The possibility of visualizing CAE calculations by means of additive technology is considered. In addition, the role of additive technology in the manufacture of individual vehicle components and mechanisms is discussed.
[en] Highlights: • Four performance indexes of constant-sliding mode are the best. • Cooling capacity of constant-sliding mode is the strongest. • The exergy destruction of air storage chamber is the largest. • Three modes have similar variation tendencies of parameters of air storage chamber. - Abstract: The tri-generative system based on advanced adiabatic compressed air energy storage can simultaneously provide cooling energy, heating energy and mechanical energy. In order to study the discharge characteristics, three operation modes of expanders, which contain constant pressure, constant-sliding and sliding pressure, are proposed in this paper. By utilizing the numerical simulation method, the performance difference of three modes is compared with each other. The results show that four performance indexes of constant-sliding mode are all the biggest, which are respectively cycle efficiency 40.55%, thermal efficiency 80.06%, exergy efficiency 48.45% and exergy density 4.071 × 106 J·m−3, and cooling capacity of it is also the strongest, 8.386 × 109 J, among the three operation modes. Air storage chamber has the largest exergy destruction. Operation process of air storage chamber is similar for three operation modes. Meanwhile, the effects of heat exchanger effectiveness, ambient pressure and air storage chamber model on system performance are also investigated.
[en] Over the last two decades, Pakistan’s energy demand has grown exponentially with very diminutive measures taken by the government to fulfill the needs. The large power plant projects are cumbersome, take years to be completed and require plenty of time to get fully operational. The idea of distributed generation works well in this case. Renewable energy comes well into play when we talk about distributed generation but the dependability of renewable energy resources on back-up such as batteries makes them unappealing. The objective of this paper is to practically implement a backup for the renewable energy resources using a mechanical storage such as CAES (Compressed Air Energy System). The proposed model is a composite technology, which comprises of EES (Electrical Energy Storage) and electrical power supply system. Solar energy driven compressor is used to compress the air in a storage tank, which is used on demand to drive the generator coupled air turbine. The fact that the developed system is solar powered, no other fuel is used with air and it uses mechanical storage instead of conventional storage like batteries, which makes the developed prototype system efficient, economical and durable as compared to the existing CAES. This paper focuses on the thermodynamic investigation, design and finally implementing a prototype CAES for a small load as an un-interrupted power supply system. (author)
[en] The fight against climate change requires harnessing novel technologies to decrease CO2 emissions. Renewable energy must be among the main strategies for complying with the COP-21 agreements. Energy storage technologies will play a crucial role in increasing the efficiency and availability of this kind of energy source. Moreover, energy storage technologies will help reduce the supply risk of the electric power system, by overcoming the uncertainty of renewable energy generation. Compressed air energy storage (CAES) enables large amounts of energy to be accumulated reliably. Although there are different structures in the subsurface that may be considered for this purpose, the development of CAES in a salt dome offers several technical and economic advantages. Furthermore, currently this kind of structure is the only one used for this purpose on an industrial scale. In order to reduce the inherent risk associated with the definition and selection of subsurface structures, this study proposes a multi-criteria algorithm based on the Analytic Hierarchy Process methodology. In this scenario, the algorithm focuses on the process to rank salt domes for CAES development. The study applies this methodology in the Basque–Cantabrian basin, where as many as eleven structures have been examined.
[en] Highlights: • a-Cr-PO4-typed NaV3(PO4)3 is explored as anode materials for Na-ion battery for the first time. • The introduce of carbon to obtain NaV3(PO4)3/C nanocomposite is effectively way to enhance the cycling stability of battery. • Na-ion full battery based on NaV3(PO4)3/C anode and Na3V2(PO4)3/C cathode shows excellent cycling performance, retaining 80% of initial capacity after 1000 cycles at charging/discharging rate of 5 C. Anode materials with long cycling life and rate capability have remained a great challenge for sodium-ion batteries. Herein, a vanadium-based orthophosphate, NaV3(PO4)3/C nanocomposite has been investigated as a novel anode material for Na-ion batteries. The electrochemical performance of NaV3(PO4)3/C nanocomposite is evaluated in Na-half cell, which delivers a reversible capacity of 146 mA h g−1 at the charging/discharging rate of 1 C, and remarkable rate capability. EIS, XPS and in-situ XRD are performed to give the insight into interfacial property of electrode and structural evolution of material during cycling. The excellent cycling stability could be attributed to stable interface at higher cutoff voltage and slight change of structure with intercalation/deintercalation of Na+. Moreover, we achieve a Na-ion full battery with long term cycle life based on NaV3(PO4)3/C anode and Na3V2(PO4)3/C cathode, retaining 80% of initial capacity after 1000 cycles at charging/discharging rate of 5 C, suggesting the feasibility of the as-obtained materials applied as a promising candidate for anode of Na-ion batteries.
[en] This report documents findings from the Hybrid Systems Task Force of the U.S. Department of Energy's (DOE) Geothermal Technologies Office (GTO) Geothermal Vision Study (GeoVision Study). The GeoVision Study projects and quantifies the future electric and nonelectric deployment potentials of geothermal technologies within a range of scenarios in addition to their impacts on U.S. jobs, the economy, and environment. The Hybrid Systems Task Force is one of seven task forces within the GeoVision Study with the others being Exploration and Confirmation, Potential to Penetration, Thermal Applications, Reservoir Maintenance and Development, Institutional Market Barriers, and Social and Environmental Impacts. A summary of the study is captured in DOE’s report, GeoVision: Harnessing the Heat Beneath Our Feet. The Hybrid Systems Task Force investigated geothermal hybrid systems that have potential to increase the utilization of geothermal resources and/or decrease the costs of geothermal power generation. Applications evaluated include: hybrid thermal power generation in which geothermal energy is coupled with solar or fossil heat sources; use of geothermal energy to provide process heat for thermal desalination or CO2 capture from fossil power plants; analysis of compressed air energy storage augmented with geothermal energy; as well as an assessment of potential mineral recovery from geothermal brines. This report additionally discusses areas of research and development that should be pursued to enhance the ability of geothermal hybrid systems to provide valuable benefits in operational flexibility, reduction of project risks, increased energy security, and the ability to recover critical and strategic materials.
[en] Highlights: • A “quasi dynamic iterative searching” is proposed in turbine dynamic modelling. • A simulation platform is built to synchronise multiple time scale dynamic responses. • Low-temperature system dynamic characteristics is extensively investigated. • Effects of heat exchangers’ thermal inertias on system dynamics are analysed. - Abstract: It is challenging to gain insight of a Compressed Air Energy Storage (CAES) system dynamic behaviour under various operation conditions due to its complexity with mixed mechanical, thermal, chemical and electrical processes in one. Although a number of studies are reported on CAES steady state and dynamic modelling to reveal its characteristics, few studies have been reported in whole CAES system dynamic modelling involving a radial turbine. This paper explores a new method to analyse the transient performance of the radial turbine while it is integrated with whole low temperature Adiabatic-CAES system. The proposed modelling method approximates the average air flow within single stator/rotor stage. By applying the principle of energy and torque balance on the transmission shaft, the dynamic speed-torque characteristics of the turbine is obtained with a “quasi dynamic iterative searching” process. The model is then integrated to a simulation platform, which is created to synchronise the wide range of time scale dynamic responses including heat transfer, mechanical and electrical energy conversion processes. As every component of the low temperature adiabatic CAES system is built on its fundamental physical and engineering principles, the model is capable of revealing the system transient characteristics. Based on the model, various simulation studies are conducted and the results are compared with the operation data from the literature. It provides a valuable tool for preliminary design of a radial turbine to test its suitability in full and partial load operation conditions, and analyse its transient behaviours.
[en] Highlights: • Mode 4 has the highest exergy efficiency. • Mode 2 has the largest exergy density. • Second heat exchanger has the largest exergy destruction. - Abstract: Advanced adiabatic compressed air energy storage system plays an important role in smoothing out the fluctuated power from renewable energy. Under different operation modes of charge-discharge process, thermodynamic behavior of system will vary. In order to optimize system performance, four operation modes of charge-discharge process are proposed in this paper. The performance difference of four modes is compared with each other based on energy analysis and exergy analysis. The results show that exergy efficiency of mode 4 is the highest, 55.71%, and exergy density of mode 2 is the largest, 8.09 × 106 J m−3, when design parameters of system are identical. The second heat exchanger has the most improvement potential in elevating system performance. In addition, a parametric analysis and multi-objective optimization are also carried out to assess the effects of several key parameters on system performance.
[en] Highlights: • A grid-connected CCHP system with CAES and hybrid refrigeration is proposed. • A multi-objective assessment and optimization is presented. • Each component capacity of the CCHP system is determined by optimization. • A sensitivity analysis is conducted by the key parameters of the system. • Performance comparison with conventional CCHP system has been done. - Abstract: As one of attractive technology of energy conservation, combined cooling, heating and power (CCHP) system has brought about widespread attention. However, the variability of users demand has limited the application of CCHP system. To ensure stable and efficient operation, the compressed air energy storage is considered to be integrated with CCHP system. A grid-connected CCHP system with compressed air energy storage (CAES) and hybrid refrigeration is proposed in this paper. The power from grid is stored in CAES at off-peak time and released at on-peak time. The hybrid refrigeration system including LiBr absorption chiller and electric compression refrigerator provides cooling load to users. A multi-objective assessment and optimization synthetically considering energy, economy and environment are presented. The multi-objective indicator used as objective function to optimize each component capacity of the proposed CCHP system. A sensitive analysis of key parameters and performance comparison with conventional CCHP system have been carried out. The results shows that when the capacity of gas turbine is 691 kW, the comprehensive performance of the proposed CCHP system is the optimal performance. The power price, natural gas price, compression ratio and turbine inlet temperature of CAES have great influence on the performance of the proposed CCHP system. Meanwhile, the multi-objective indicator’s value of the proposed CCHP system is more than conventional CCHP system 4.85%.