In view of the problem that the stepless capacity control system of reciprocating compressor has a high failure rate and great impact on the operation of the unit,and the operation risk assessment methods of the existing system are difficult to complete the real-time and quantitative risk assessment,a risk dynamic analysis method for the safety of stepless capacity control system was proposed,which integrates Bayes network and variable weight AHP.The Bayesian network model,which includes fault type,fault mode and monitoring signal,was established to obtain the real-time probability of fault occurrence.Based on variable weight analytic hierarchy process(AHP),a semi-quantitative analysis model of fault hazard was established to calculate the influence index of fault mode.Further,the fault risk calculation formula of FMEA method was modified,the probability of fault occurrence was introduced,and the calculation method of historical fault and real-time operation risk was proposed.Test verification was carried out using the actual fault case data.The results show that the new method can quantify the real-time and historical operating risks of computer units,and the normalized real-time operating risk threshold is set at 0.5 to determine the need for maintenance.The research results can provide quantitative indexes for the development of inspection and maintenance plans for reciprocating compressors and gas volume regulation systems.
In view of the prominent and intractable problems of frequent high temperature alarms of the communication equipment and high energy consumption of air conditioners in Zhengzhou communication outdoor cabinets, a temperature control system with heat pipe as the main part and air conditioner as the auxiliary part is proposed in this paper. A prototype is developed and its applications are discussed. The annual field test shows the system works well, and it has a remarkable energy saving efficiency.
Transcritical CO2 system is eco-friendly for the application of refrigeration and cooling in supermarket. To evaluate the applicability of transcritical CO2 supermarket refrigeration system in China with different climate regions, this study focuses on the field tests of a transcritical CO2 two-stage throttling system in a supermarket in Suzhou, Jiangsu Province, China. Furthermore, based on the tested data, the system energy and emissions performance models of four system configurations are also developed and validated, including the system integrated with an internal heat exchanger, a parallel compression, and mechanically assisted subcooling. In order to improve the usability of the system in different climatic zones, 40 cities were selected for calculation in China. Five representative cities (Beijing, Harbin, Xiamen, Chongqing, and Kunming) located in different climate regions of China are selected, and the annual performance factor and life cycle climate performance (LCCP) are determined to evaluate the application potential of the CO2 refrigeration systems in different climate conditions. The tested results show the operation mode of transcritical and subcritical changes occurs at an ambient temperature of about 27°C, at which the coefficient of performance (COP), compressor discharge pressure and discharge temperature change dramatically. The simulation results demonstrate that the mechanical subcooling system shows the best performance. The annual performance factor can be improved by 18.69% when the mechanical subcooling is adopted. For the case of the system used in Xiamen by using mechanical subcooling, the carbon emissions can be reduced by 19.3%.
为了探究叶轮与蜗壳的上盖板间隙、下盖板间隙改变对风机性能的影响,分析风机性能改善的内部流场机理,获得静压效率更高的风机,将正交试验设计方法、CFD技术和试验验证等相结合,发展了一种基于正交试验设计方法和CFD技术的离心风机优化方法,并将该方法应用于某工业离心风机的优化设计;将叶轮与蜗壳的上盖板间隙、下盖板间隙和叶片前安装角作为3个独立因素,以静压效率为优化目标,基于该优化方法,对原风机进行多因素多水平的正交试验优化设计.结果表明,优化后风机的静压效率为77.29%,对比原风机静压效率提高了2.54%;叶轮与蜗壳上间隙对风机静压效率影响较大,优化后风机的湍流强度明显降低,二次流损失减小,风机气动性提高.
针对煤气化装置黑水阀的冲蚀磨损问题,分析了黑水阀冲蚀磨损失效机理、过程与条件,实现黑水阀的失效预测分析,获得关键部位的损伤速率;采用B/S架构方式搭建黑水闪蒸处理系统的智能防控体系,实现黑水阀流动参数的实时监测.结果表明:黑水阀内含固流体在流经节流区域时,固体颗粒以切削等方式高速冲击阀门壁面,导致阀芯以及阀座部位出现较严重损伤,且阀芯部位的冲蚀磨损率较阀座部位高出1个数量级,最高达到2×10-6 kg/(m2·s),但其磨损率会随着开度增加而减小.智能防控体系通过实时信号采集、二次信号采集和软测量建模等技术手段,实现装置的运行状态实时监测并提出针对性的工艺防护方案,使黑水闪蒸阀门使用寿命延长91%以上,有利于指导黑水闪蒸处理系统的安全稳定长周期运行,进而为煤气化系统的安全运行提供保障.
