Rotor-blades’ profile influence on a gas-turbine’s compressor effectiveness

The relationship between changes in the incident rotor-blade angle due to compressor blade profile distortions and the required compressor power is investigated. This was achieved by measuring certain performance characteristics of an operational gas-turbine. Corresponding theoretical predictions were obtained from computer simulations. Graphs plotted from both the measurements and theoretical predictions were compared, and showed significant similarities. Compressor blade profile distortions from the design profile, results in significant increases in the power required by the compressor.     

核电站应急柴油发电机组调速系统对电气指标的影响

针对某核电站应急柴油发电机组在进行BASS55试验时机组频率恢复时间超差的问题开展相关试验研究.试验表明:发电机组在应急启动时突加较大感性负载,容易造成低频及稳态恢复时间超差等问题;通过优化匹配电子调速器的PID控制参数,可使机组的电气指标满足技术要求;柴油机以及调试系统、发电机以及励磁系统等是影响应急柴油发电机组电气...     

湿蒸汽两相压缩过程工作特性理论研究

为了抑制高温进汽水蒸气压缩过程的温度升高,可以采用湿压缩方式,利用水滴升温显热和汽化潜热来降低压缩终了的排汽温度,改善压缩机工作性能。本文通过对两相湿压缩过程的分析,建立水蒸气基元容积两相湿压缩过程数学模型。根据所建立的模型,采用数值模拟的方法对螺杆压缩机压缩水蒸气过程进行了计算,并分析了湿蒸汽进汽千度及水滴微粒直径对排汽温度和压缩功率的影响。     

Fuzzy Online Auto-Tuning for an Industrial PID Controller

This paper presents a fuzzy tuning system for real-time industrial PID （proportional-integral-derivative） controllers. The algorithm set the proportional gain, integral time and derivative time of a classical PID structure according to the set point, error and error derivative of the process, respectively. The tuning of the PID controller is based on a fuzzy inference machine. The set of rules of the fuzzy inference machine was obtained by experts engineering. The system is tested in an austempering process but can be applied in any industrial plant. Besides, an analysis between the response of the process with a PID controller and the system of fuzzy auto-tuning for P1D proposed was made.     

Design,development, construction and operation of a novel metal hydride compressor

Metal Hydride Compressors (MHC) is a promising technology for thermal compression of hydrogen. Besides the absence of a necessity for significant mechanical or electrical energy input, this type of compressor has the advantage that no moving parts are involved. A brief review on the reported experimental set ups of metal hydride compressors is carried out and compared to the metal hydride compressor developed and constructed by HYSTORE Technologies Ltd in Cyprus. The compressor built by HYSTORE consists of 6 stages using AB₂ and AB₅ – type metal hydride alloys. The MHC is operated between 10 C and 80 °C, which is a temperature range that can be supplied by solar thermal collectors. Furthermore, the experimental results showed, that even lower temperatures of 17 C are sufficient thus reducing the demand for cooling capacity. During the operation, the compressor achieved stable compression of hydrogen from 7 bar more than 220 bar. The specific productivity of the compressor achieved values up to 67.2 l_H2 kg^?1 h^?1.     

船用汽轮发电机组甩负荷工况控制系统研究

以某船用汽轮机发电机组为研究对象,对其控制原理进行理论分析与推导,建立其控制系统的数学模型,并在SIMULINK平台上完成了常规法甩负荷50％与100％仿真实验,得到两组响应曲线.分析结果表明:该控制系统能够实现机组的甩负荷工况转速控制,在负荷骤降的情况下可以保证机组安全稳定运行.     

Some fundamental aspects in electrochemical hydrogen purification/compression

The electrochemical concentration of hydrogen from a poor hydrogen–inert gas mixture has been investigated by means of an electrochemical cell similar in construction to a hydrogen–air fuel cell, hydrogen being transported as hydrated protons, thorough a Nafion membrane, from the inlet (anode) to the outlet (cathode) compartments of the cell. Galvanostatic and tensiostatic mode of operation have been investigated: in the first case and erratic behaviour of the cell has been observed, mainly because of the non-controllable variations of the membrane water content. Under tensiostatic condition the role of the applied voltage, feed flow rate, water vapour content in the feed mixture and temperature has been studied, with two different designs of the gas feed distribution plates. From the analysis of experimental data it is possible to evaluate the current efficiency, the hydrogen recovery, the hydrogen purity, the exergy gain and the coefficient of performance of the cell.     

Fuzzy logic controller implementation for a solar air-conditioning system

The implementation of a variable structure fuzzy logic controller for a solar powered air conditioning system and its advantages are investigated in this paper. Two DC motors are used to drive the generator pump and the feed pump of the solar air-conditioner. Two different control schemes for the DC motors rotational speed adjustment are implemented and tested: the first one is a pure fuzzy controller, its output being the control signal for the DC motor driver. A 7 × 7 fuzzy matrix assigns the controller output with respect to the error value and the derivative of the error. The second scheme is a two-level controller. The lower level is a conventional PID controller, and the higher level is a fuzzy controller acting over the parameters of the low level controller. Step response of the two control loops are presented as experimental results. The contribution of this design is that in the control system, the fuzzy logic is implemented through software in a common, inexpensive, 16-bit microcontroller, which does not have special abilities for fuzzy control.     

Hydrogen compression characteristics of a dual stage thermal compressor system utilizing LaNi5 and Ca0.6Mm0.4Ni5 as the working metal hydrides

The research performed herein consisted of the design, construction, and testing of a dual stage metal hydride hydrogen compression system intended to be used with lower grade geothermal or waste energy sources. The metal hydrides used in this study were LaNi₅ and Ca_0.6Mm_0.4Ni₅. A Finite Time Thermodynamics (FTT) model was also developed and the model proved useful in determining how the compression results and energy requirements for the system change with variations in the system parameters. Dual stage system results showed a final compression ratio of approximately 12 when using cooling and heating temperatures of 10 °C and 90 °C, respectively. The final output pressures and compression ratios were found to follow an upward trend when increasing the heating bath temperatures. It can be concluded from the experimental results, that though the dual stage hydrogen compression system has room for improvement, it is an effective way of compressing the hydrogen from low initial pressures while using low grade energy sources.     

基于模糊PID的风电系统转速控制仿真研究

由于风速具有随机性、不确定性、变化范围大等特点,风力发电机转速若采用传统PID控制,仅一组固定的参数难以在不同风速下均有好的控制效果。分析了风力发电系统各参数之间的关系,结合PID控制和模糊控制各自的特点,设计了模糊自适应PID控制器。在额定风速以下,该控制器用于改变发电机定子电压,从而改变发电机反力矩,调节转速,使得输出功率快速跟随风速变化。MATLAB/Simulink仿真结果证实其稳定性、动态速度响应均优于传统的PID控制,取得了较为理想的控制效果。     

Dynamic behaviour of non-isothermal compressible natural gases mixed with hydrogen in pipelines

This paper focuses on non-isothermal transient flow in mixed hydrogen–natural gas pipelines. The effect of hydrogen injection into natural gas pipelines has been investigated in particular the pressure and temperature conditions, Joule–Thomson effect, linepack and energy consumption of the compressor station. The gas flow is described by a set of partial differential equations resulting from the conservation of mass, momentum and energy. Real gas effects are determined by the predictive Soave–Redlich–Kwong group contribution method. The Yamal-Europe gas pipeline on Polish territory has been selected as case study.     

Dynamic neural network controller model of PEM fuel cell system

This paper presents the artificial intelligence techniques to control a proton exchange membrane fuel cell system process, using particularly a methodology of dynamic neural network. In this work a dynamic neural network control model is obtained by introducing a delay line in the input of the neural network. A static production system including a PEMFC is subjected to variations of active and reactive power. Therefore the goal is to make the system follow these imposed variations. The simulation requires the modelling of the principal element (PEMFC) in dynamic mode. The simulation results demonstrate that the model-based dynamic neural network control scheme is appropriate for controlling, the stability of the identification and the tracking error were analyzed, and some reasons for the usefulness of this methodology are given.     

基于模型的发动机空燃比控制策略研究与仿真

空燃比的精确控制是现代车用汽油机控制最为关键的技术。发动机平均值模型由于其模型简单、计算时间短、使用方便,且能满足控制设计的要求而被广泛应用。基于模型的空燃比控制技术是当前国内外研究的热点。在建立某型汽油发动机空燃比平均值数学模型的基础上设计了稳态工况下模糊自适应PID控制器,并与传统的PID控制器空燃比控制效果进行了对比。设计了瞬态工况下燃油前馈补偿控制器并进行仿真。仿真结果表明在稳态工况下模糊自适应PID控制策略不仅能够满足实际控制需要,而且比传统的PID控制策略控制效果更好。前馈补偿控制策略能满足瞬态工况下空燃比的控制要求。