地铁车辆定频空调系统节能方案分析

空调系统是地铁车辆的重要组成部分,承担着为地铁车辆提供良好车内温湿环境的作用,是满足车内乘客舒适性要求的主要设备。由于地铁车辆空调系统能耗占总运行能耗的30%以上,因此有必要对空调系统节能方案进行研究,以减少其能耗。基于北京地铁某线路车辆的空调系统,对空调系统热负荷组成及影响进行分析,并计算了该空调系统的制冷量,通过与常规空调机组的比较、试验的验证以及数值的估算,得出了新型定频空调系统的节能率。分析结果表明:对定频空调机组进行节能设计可以大大提高节能率。     

冰蓄冷空调系统的多目标优化控制策略研究

为了减少制冷机组的能耗和降低冰蓄冷空调系统的运行费用,提出了基于非线性多目标模型的优化控制策略。首先建立了多台制冷机组总能耗最少的目标函数;其次根据系统设备能耗和当地电价结构,得到了系统总运行费用最小的目标函数;最后使用MATLAB软件编程求得最优解。通过工程实例仿真对比在不同冷负荷时的优化控制策略和制冷机组优先策略下的制冷机组能耗和系统运行费用,结果表明非线性多目标优化控制能够发挥系统潜力,减少制冷机组能耗,降低系统运行费用。     

冷源方式选择对CEC影响的分析

以空调系统能耗系数CEC(Coefficient of Energy Consumption)即空调设备全年总能量消耗量与假想空调负荷累计值之比作为空调系统能耗性能评价指标,对天津地区某典型办公大楼建筑空调系统选用水源热泵和溴化锂冷热水机组条件下的能耗状况进行计算与分析。并证明了与采用水源热泵的空调系统相比较,采用溴化锂冷水机组的空调系统节电不节能。     

不同地下水流速对土壤源热泵系统运行的影响研究

利用Fluent建立土壤源热泵空调系统仿真模型,通过模拟结果与热响应测试所得结果的比较验证了模型的准确性。该模型耦合了土壤源热泵空调系统三大组成部分:负荷末端、热泵机组以及地埋管换热器。在此前提下,研究土壤源热泵空调系统中不同地下水流速工况下热泵机组COP的变化情况。结果表明,在常见的地下水流速0m/a至300m/a范围内,地下水流速越大,热泵机组COP越大,其中夏季制冷期间,当地下水流速从0分别增加到60m/a,100m/a,150m/a,200m/a,250m/a,300m/a时,机组COP分别增加11.54%,16.04%,19.91%,23.17%,25.50%,27.14%,从而减小了机组运行能耗。     

基于PSO-LM-BP算法的空调系统节能预测控制研究

针对夏季建筑空调系统能耗高、碳排放量大的问题,提出一种改进后的LM-BP神经网络,并结合粒子群优化算法,建立基于建筑历史数据的空调系统冷负荷神经网络预测模型,通过粒子群算法寻优得到不同负荷率下冷源系统各设备的最优运行参数。以青岛某一公建项目为例,采用TRNSYS仿真模拟空调运行能耗。结果表明,与传统控制策略相比,所采用的空调系统负荷预测控制策略节能9.9%。     

数据中心空调系统节能降耗研究进展

介绍了数据中心空调系统负荷特性和能耗现状,分析了包括风冷直接膨胀式、水冷直接膨胀式、冷冻水型机房空调等常规机房空调机组的适用情况,论述了目前重点的研究方向即气流组织优化、局部热点消除与液体冷却以及自然冷量利用三方面的研究进展。进一步,综述了热管式机房空调、分离式热管型空调系统(SHP)、分离式热管结合分体式空调系统的研究进展和最新的研究成果。     

办公楼地源热泵空调系统夏季运行特性

以泰安市某办公楼地源热泵系统为研究对象,通过对夏季运行工况的实时监测,得到地源侧出水温度、负荷侧回水温度、机组COP和机组制冷量随室外气温的变化特性。研究结果表明,地源侧出水温度波峰较室外气温波峰滞后22h;机组COP和机组制冷量不仅与室外气温有关,还与空调末端供冷需求有关,在供冷需求相同的情况下,室外气温每升高1℃,机组COP、制冷量升高2.5%;在室外温度相同的情况下,地源侧出水温度每升高1℃,机组COP降低5%。该研究结论为地源热泵空调系统的设计、节能运行提供了必要的参考。     

热负荷分开配置机组的冷库制冷系统设计

冷库制冷机组配置存在的最大问题是设计冷量与热负荷不相匹配,制冷机组长期处于小于设计负荷运行状态下,造成冷库能耗增加。针对这一问题,提出热负荷分开配置机组的冷库制冷系统设计方案,以含有8个同温冷间的装配式冷库为例,设计制冷系统和控制系统。冷库各冷间采用分时进货方式,进货时间间隔取3小时,总共配置两套压缩冷凝机组,对于不进货、无操作人员工作的冷间使用一套压缩冷凝机组维持冷间温度,压缩冷凝机组按冷库总降温概率进行配置;对于正在进货、有操作人员工作的的冷间,使用另一套压缩冷凝机组快速降温,压缩冷凝机组按一个冷间所有的热负荷进行配置。结果表明:两套压缩冷凝机组配置的总制冷量比最大负荷法配置的制冷量减少1/4左右,同时缩短货物热量和开门热量冷却时间,提高了冷藏食品品质。     

热负荷分开配置机组的冷库制冷系统设计北大核心

冷库制冷机组配置存在的最大问题是设计冷量与热负荷不相匹配,制冷机组长期处于小于设计负荷运行状态下,造成冷库能耗增加。针对这一问题,提出热负荷分开配置机组的冷库制冷系统设计方案,以含有8个同温冷间的装配式冷库为例,设计制冷系统和控制系统。冷库各冷间采用分时进货方式,进货时间间隔取3小时,总共配置两套压缩冷凝机组,对于不进货、无操作人员工作的冷间使用一套压缩冷凝机组维持冷间温度,压缩冷凝机组按冷库总降温概率进行配置;对于正在进货、有操作人员工作的的冷间,使用另一套压缩冷凝机组快速降温,压缩冷凝机组按一个冷间所有的热负荷进行配置。结果表明:两套压缩冷凝机组配置的总制冷量比最大负荷法配置的制冷量减少1/4左右,同时缩短货物热量和开门热量冷却时间,提高了冷藏食品品质。     

纺织厂空调节能探析

分析了纺织厂空调能耗过高的主要原因,并从车间温湿度基数确定、冷负荷计算、气流组织、新风预处理设备及旁通风道使用和冷冻水管路系统设计等方面介绍了减少空调能耗的系统设计;对喷淋室、挡水板等空调设备进行了节能改造,分析了管式间接蒸发冷却器使用的节能效果。在空调运行方面采用智能调节实现自动控制、合理选择冷水机组台数等措施实现节能目的。测试表明,通过挡水板、喷淋室及管式间接蒸发冷却器节能改造,空调室节能1.91%,10.52%和5.07%;制冷机组由三台在80%制冷量减少为一台在90%制冷量下工作,耗电减少653kW/h,减少率为64.33%;采用自动控制系统空调室能耗日减少477kW.h,与人工调节方式比减少45.60%。     

Reducing Power Consumption in Core Wavelength Division Multiplexing Optical Networks

Abstract

This work proposes some heuristic criteria aiming at saving energy by efficiently switching off optical fibers in generalized multi-protocol label switching-controlled optical networks during low traffic load periods and by taking into account network equipment power consumption. Simulations show that up to 80% of energy can be saved when the traffic is reduced by 20% with respect to its maximum. The impact of network design parameters is also investigated.     

适用于字符串加密的全同态加密方案

面对轨道交通能耗逐年递增的现状,我国大力提倡轨道交通节能,并提出绿色轨道交通的概念。针对传统轨道交通空调系统所存在的冷水机组制冷量过剩、冷冻和冷却水流量无法自动调节等问题,本文设计一种新型节能控制系统,对车站冷负荷变化规律进行分析,对系统进行集中监控。利用变频技术和闭环控制系统,计算所需冷负荷,智能控制电机转速,自动调节冷水机组的制冷量与空调末端冷量,使冷却系统处于最节能的工作点。轨道交通空调水系统应用该节能系统后耗电量大幅度降低,从而节约大量能源。     

能量异构的无线传感器网络加权无标度拓扑研究

针对无线传感器网络节点能耗不均和如何高效获得节点和边的负载问题,提出一种局域范围内能量异构的加权无标度拓扑演化模型.通过对节点能量与负载、能耗的关系建模,建立节点能量与点权和边权的联系,进而结合点权和加权模型给出网络的演化方式,推出点权、度和边权的幂率分布规律,最终根据网络获得的点权和边权来分析负载和能耗.仿真结果表明,提出的模型不仅能够准确计算点边的负载,而且缓解了无标度网络的节点能耗不均衡问题.     

电子膨胀阀应用于低温陈列柜制冷系统的节能研究

与热力膨胀阀相比,电子膨胀阀应用于陈列柜制冷系统,可以更为精确地控制其柜温及过热度。为进一步减小低温陈列柜制冷系统能耗,文中提出通过改变电子膨胀阀脉冲信号的控制策略以达到节能的目的。通过试验证明:与热力膨胀阀相比,可节能25%;同时可减小系统过热度,提高低温陈列柜制冷系统温度特性。为电子膨胀阀在低温制冷陈列柜中的应用提供参考依据。     

Building resilient power grids from integrated risk governance perspective: A lesson learned from china's 2008 Ice-Snow Storm disaster

In the past three decades, the electric energy industry made great contribution to support rapid social and economic development in China, and meanwhile has been grown at the highest rate in the human history owing to the economic reform. In its new national development plan, more investment has been put into installation of both electricity generating capacity and transmitting capacity in order to meet fast growing demand of electric energy. However, energy resources, both fossil fuel and renewable types, and energy consumption and load centers in China are not evenly distributed in both spatial and temporal dimensions. Moreover, dominated by coal as its primary energy source, the whole eastern China is now entering an environmental crisis in which pollutants emitted by coal power plants contribute a large part. To balance the regional differences in energy sources and energy consumption while meeting the steadily increasing demands for electric energy for the whole country, in addition to increase electric generating capacity, building large-scale, long-distance ultra high voltage power grids is the top priority for next five years. China is a country prone to almost all kinds of natural disasters due to its vast, complex geographical and climatic conditions. In recent years, frequent natural disasters, especially extreme weather and climate events, have threatened the safety, reliability and stability of electric energy system in China. Unfortunately, with fast growth rate but lacking of risk assessing and prevention mechanism, many infrastructure constructions, including national power grids, are facing integrated and complex economic, social, institutional and ecological risks. In this paper, based on a case analysis of the Great Ice Storm in southern China in January 2008, risks of building a resilient power grid to deal with increasing threats from extreme weathers are discussed. The paper recommends that a systematic approach based on the social-ecological system framework should be applied to assess the risk factors associated with the power grid, and the tools to deal with complex dynamic systems need to be applied to deal with constant changes in the whole social-ecological system.     

Matching of an extended high-current Z-discharge to a pulsed power system

Conditions for matching an extended high-current Z-discharge to a pulsed power system are numerically investigated. The power system consists of a pulsed voltage generator and a long transmission line. Experiments are aimed at generating a highly ionized dense plasma as an active medium for an extreme ultraviolet laser on hydrogen-like ions of nitrogen (λ = 13.4 nm). Emphasis is on the distribution of the energy transmitted from a storage ring to a load among its components and on the reduction of the energy that remains in the electrical circuit by the end of the pump pulse and will inevitably dissipate in the discharge tube. The solution of this problem will make it possible to diminish the load on the walls of the discharge chamber and extend its service life. It is shown that energy deposition into the load is effective when the timeaveraged sum of the ohmic and dynamic components of the discharge resistance is roughly equal to the wave impedance of the transmission line. In this case, the wave reflected from the load carries away a minimal energy, which allows for optimization of the energy deposited into the load. The input and output energy balances for different matching conditions are calculated with an eye to designing an efficient short-wavelength extreme ultraviolet laser with a long service life of the discharge tube.     

CFQS装置准环对称测试用磁体电源系统设计

CFQS装置是中国西南交通大学(SWJTU)和日本国家核融合科学研究所(NIFS)联合设计制造的中国首台准环对称仿星器,为满足装置0.1 T稳态运行的实验要求,需要为其磁体线圈设计相应的电源系统。本设计方案考虑工程实际估算线路阻抗,考虑工程裕度、电源以负载参数的1.2倍进行计算,并建立电源系统的Simulink仿真模型,分析负载电流纹波大小及网侧谐波含量。根据仿真结果优化设计方案,通过在直流侧增加无源滤波器,减小输出电流纹波,分析直流侧电压代数形式,计算滤波器参数,并仿真调节得到更加符合实际需求的滤波器参数,满足装置准环对称位形的分布磁场精度对磁体线圈电流纹波的要求。     

Monochromatic X-ray-induced thermal effect on four-reflection“nested” me V-monochromators: dynamical diffraction theory and finite-element analysis

The high energy resolution monochromator(HRM) is widely used in inelastic scattering programs to detect phonons with energy resolution, down to the me V level. Although the large amount of heat from insertion devices can be reduced by a high heat-load monochromator, the unbalanced heat load on the inner pair of crystals in a nested HRM can affect its overall performance. Here, a theoretical analysis of the unbalanced heat load using dynamical diffraction theory and finite element analysis is presented. By utilizing the ray-tracing method, the performance of different HRM nesting configurations is simulated. It is suggested that the heat balance ratio, energy resolution, and overall spectral transmission efficiency are the figures of merit for evaluating the performance of nested HRMs. Although the present study is mainly focused on nested HRMs working at57 Fe nuclear resonant energy at14.4 ke V, it is feasible to extend this to other nested HRMs working at different energies.