Results 1 - 10 of 556
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[en] A mathematical model of the operation of the pneumatic subsystem of the compressed air energy storage device and the computer program developed on its basis are presented, which made it possible to investigate the influence of the geometric and thermophysical parameters of the pneumatic system elements on the efficiency of energy storage and heat losses. (paper)
[en] Analytical solutions of the linearized governing equation are presented for periodic gas flow around a well in porous media. Two cases are considered: a fully penetrating well and a partially penetrating well. For the first case, a closed form solution is obtained, whereas for the second case the solution is in the form of eigenfunctions expansions. The results have practical application in compressed air energy storage. (authors)
[en] Highlights: •A concise analytical solution for SC-CAES system was presented for the first time. •The analytical solution is universal for SC-CAES and other similar CAES systems. •A method of sectional treatment and Taylor expansion was carried out. •Exergy analysis for SC-CAES system with its analytical model was conducted. -- Abstract: An analytical solution for a novel Compressed Air Energy Storage (CAES) system, Supercritical Compressed Air Energy Storage (SC-CAES) system, was conducted in this paper. The analytical solution can explore the evolution and its reason of roundtrip efficiency varying with system key parameters in depth, while it can also reveal the coupling mechanism of different sections of the system. On that basis, the model of exergy destruction for each part was obtained, and the exergy destruction can be easily calculated. Furthermore, the analytical solution has the character of universality due to the deduced method of sectional treatment, hence it can be extended to other similar CAES systems. Lastly, a sensitivity analysis and an exergy analysis were conducted for SC-CAES system. It is found and proved that the system efficiency varies linearly with isentropic efficiencies of compressor and expander, temperature difference of intercooler and reheater, pressure loss of intercooler and reheater. Meanwhile, the main factors of the varying tendency of total exergy destruction with different parameters are revealed.
[en] The paper study on the process of rockfall falling, consider the air below the rockfall will be compressed, calculate the force of the compressed air to the rockfall; Set up theory mode and divide the process into n parts, using the theory of Aerodynamics, Conservation of energy theorem and Air moving theory to derive the method of calculate the rockfall impacts; The results have certain reference, it can be used in the theory study of disaster reduction and technical of rockfall. (paper)
[en] Highlights: • The paper presents an A-CAES system thermodynamic model with low temperature thermal energy storage integration. • The initial parameter value ranges for A-CAES system simulation are identified from the study of a CAES plant in operation. • The strategies of system efficiency improvement are investigated via a parametric study with a sensitivity analysis. • Various system configurations are discussed for analysing the efficiency improvement potentials. - Abstract: The key feature of Adiabatic Compressed Air Energy Storage (A-CAES) is the reuse of the heat generated from the air compression process at the stage of air expansion. This increases the complexity of the whole system since the heat exchange and thermal storage units must have the capacities and performance to match the air compression/expansion units. Thus it raises a strong demand in the whole system modelling and simulation tool for A-CAES system optimisation. The paper presents a new whole system mathematical model for A-CAES with simulation implementation and the model is developed with consideration of lowing capital cost of the system. The paper then focuses on the study of system efficiency improvement strategies via parametric analysis and system structure optimisation. The paper investigates how the system efficiency is affected by the system component performance and parameters. From the study, the key parameters are identified, which give dominant influences in improving the system efficiency. The study is extended onto optimal system configuration and the recommendations are made for achieving higher efficiency, which provides a useful guidance for A-CAES system design.
[en] The technology of ISO Solenoid Valves is now considered as a core technology in the fields of the production line of semi-conductor chips and the ISO fluid chips for medical applications. And ISO Solenoid Valves, which operate by compressed air, are characterized by high speed response, great repeatability and that the pressure on the cross sectional area of poppet is kept constant regardless of the fluctuation of the pressure exerted on the ports. The primary objective of this study is to compare the optimally designed Solenoid Valve with the actually produced one and to design a power saving circuit which can highly improve the efficiency by providing optimal current according to mechanical load.
[en] Highlights: •A new configuration of compressed air energy storage system is proposed and analyzed. •This system, so-called subcooled-CAES, offers cogeneration of electricity, heat and cooling. •A pseudo-dynamic energy, exergy and economic analysis of the system for an entire year is presented. •The annual power, cooling and heat efficiencies of the system are around 31%, 32% and 92%. •The overall energy and exergy performance coefficients of the system are 1.55 and 0.48, respectively. -- Abstract: Various configurations of compressed air energy storage technology have received attention over the last years due to the advantages that this technology offers relative to other power storage technologies. This work proposes a new configuration of this technology aiming at cogeneration of electricity, heat and cooling. The new system may be very advantageous for locations with high penetration of renewable energy in the electricity grid as well as high heating and cooling demands. The latter would typically be locations with district heating and cooling networks. A thorough design, sizing and thermodynamic analysis of the system for a typical wind farm with 300 MW capacity in Denmark is presented. The results show a great potential of the system to support the local district heating and cooling networks and reserve services in electricity market. The values of power-to-power, power-to-cooling and power-to-heat efficiencies of this system are 30.6%, 32.3% and 92.4%, respectively. The exergy efficiency values are 30.6%, 2.5% and 14.4% for power, cooling and heat productions. A techno-economic comparison of this system with two of the most efficient previous designs of compressed air energy storage system proves the firm superiority of the new concept.
[en] This report describes the modification of a Self Contained Compressed Air Breathing Apparatus to provide extended respiratory protection to grossly contaminated personnel during a decontamination period which may exceed the duration of the Breathing Apparatus air supply. (author)