Online Fault Detection Configuration on Equipment Side of a Variable-Air-Volume Air Handling Unit

With the development of the technology of the Internet of Things,more and more operational data can be collected from air conditioning systems.Unfortunately,the most of existing air conditioning controllers mainly provide controlling functions more than storing,processing or computing the measured data.This study develops an online fault detection configuration on the equipment side of air conditioning systems to realize these functions.Modbus communication is served to collect real-time operational data.The calculating programs are embedded to identify whether the measured signals exceed their limits or not,and to detect if sensor reading is frozen and other faults in relation to the operational performance are generated or not.The online fault detection configuration is tested on an actual variable-air-volume(VAV)air handling unit(AHU).The results show that the time ratio of fault detection exceeds 95.00%,which means that the configuration exhibits an acceptable fault detection effect.

DISPLACEMENT CONTROL AND KINETIC ANALYSIS OF A NOVEL VARIABLE DISPLACEMENT COMPRESSOR FOR AUTOMOTIVE AIR CONDITIONER

A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and instead of pneumatic valve the displacement is controlled by electronic control valve. In order to know the control mechanism well and get a good control effect, a mathematical model for the variable displacement mechanism is developed according to the geometrical and kinematical information of the compressor. Using the model, the effect of relevant parameters on variable displace control is estimated. It is helpful to make the optimum decision in the flow control of AAC. As the novel displacement control device, the structure and control rule of electronic control valve is introduced. It can get better effect than the conventional pneumatic valves. And by using this new electronic control device, the optimum systemic control of AAC is available.

Simulation of Variable Air Volume System with Different Duct Layout

The duct static pressure reset (DSPR) control method is a popular modern control method widely applied to variable air volume (VAV) systems of commercial buildings. In this paper, a VAV system simulation program was used to predict the system performance and zone air temperature of two kinds of layouts that were applied to a typical floor of an existing building office in Hong Kong. The position where the static pressure sensor was placed should affect the zones temperature and energy consumption. The comparison of predictions of the two kinds of layouts indicates that with the same DSPR control method the layout of the air duct might influence the fan control result and energy savings.

Impact of air pollution on urbanization:evidence at China’s city level

This paper investigates the effect and transmission mechanism of air pollution on urbanization based on data from China’s 107 cities during 2005–2018.In order to identify the impact of air pollution on China’s urbanization,we utilized night light data to represent the level of urbanization and used temperature inversion as an instrumental variable to mitigate endogeneity within the two-stage least squares framework.The results suggest that air pollution significantly slowed China’s urbanization process with economic growth acting as the transmission mechanism.The heterogeneity analyses revealed that air pollution had a greater negative impact on urbanization in northern regions than that in southern regions,and a greater negative impact in resource-oriented cities than that in non-resource-based cities.We also find that air pollution was to the detriment of urbanization in larger cities,which have more than 3 million residents,while it did not have a significant impact on Type II large cities,which have fewer than 3 million residents.

基于改进BSO算法的VAV空调系统GPC参数整定

针对变风量(variable air volume,VAV)空调系统具有大滞后、强耦合等控制难点,提出了一种基于改进天牛群优化(beetle swarm optimization,BSO)算法的VAV空调系统广义预测控制(generalized predictive control,GPC)参数整定方法。针对标准GPC整定算法只调节控制加权系数λ导致控制性能不佳的问题,首先,提出一种改进BSO算法,通过动态化选取权重参数与学习因子获得较佳的寻优性能。其次,提出一种基于改进BSO算法的新型GPC参数整定方法,可同时整定控制器的控制加权系数λ、控制时域Nu、预测时域Np及柔化系数α。最后,结合实际VAV空调系统,开展仿真与半实物实验。结果表明,采用改进BSO算法调优后GPC的控制效果得到显著提升,调节时间仅为7 s,超调量仅为0.28%。

Design of Control Scheme for Variable Air Volume Air- conditioning System

The air quantity of variable air volume system for the rooms and the total air quantity of the system changes with the change of room load. Combined with the system composition in the laboratory, the paper determines the control scheme of the variable air volume system, that is, indoor temperature-control, indoor positive pressure control, air distribution static pressure control, air-supply temperature control and new air volume control. The dotted lines with arrows mean the output signals from the control unit to actuator, and the solid lines with arrows represent the input signals from the actuator to the control unit.

VARIABLE STRUCTURE CONTROL OF AIRCRAFTFOR ATMOSPHERIC DISTURBANCE

Variable structure control (VSC) applied to atmospheric disturbance sup-pression is presented. The conditions are stipulated: the sliding mode existenee condi-tion, and invanance condition of atmospheric disturbanee in the variable structuresystem (VSS). A method of eigenstructure assignment technique for switching surfaeedesign is proposed. Based on different atmospheric disturbanee characteristics, such asrandom turbulence, discrete gust and wind shear, two kinds of control laws are derived that possess strong robustness. An example shows that this control approach isfeasible and effective.

VAV变风量空调系统施工技术

以某工程为例,对VAV变风量空调系统施工技术进行研究,通过采用BIM技术对风管的形状、构造及布置进行深化设计,优化了系统布置,降低了能耗;采用DDC数字控制的变风量空调系统,实现与计算机联网一体化智能控制,通过VAV末端,实施对空调房间的智能控制,消除了送风温度的变化对室内温度的影响,达到节能的目的。

Temperature Inversions,Meteorological Variables and Air Pollutants and Their Influence on Acute Respiratory Disease in the Guadalajara Metropolitan Zone,Jalisco,Mexico

The presence of temperature inversions (TI), concentration of air pollutants (AP) and meteorological variables (MV) affect the welfare of the population, creating public health problems (acute respiratory diseases ARDs, among others). The Guadalajara Metropolitan Zone (GMZ) experiences high levels of air pollution, which associated with the presence of temperature inversions and meteorological variations is conducive to the incidence of ARDs in children. The aim of this work is to evaluate the TI, MV, AP and their influence on the ARDs in children under five years in the GMZ from 2003 to 2007. In this period, the moderate and strong TI are the most frequent presenting from November to May. The AP shows a variable behavior during the year and between years, with the highest concentration of particles less than 10 microns (PM10), followed by ozone (O3), nitrogen dioxide (NO2), nitrogen oxides (NOX), carbon monoxide (CO) and sulfur dioxide (SO2), the most affected areas are the southeast of the GMZ. Annual arithmetic mean is 213,510 ± 41,209 ARDs consultations. The most important diseases are acute respiratory infections (98.0%), followed by pneumonia and bronchopneumonia (1.1%), asthma and status asthmaticus (0.5%) and streptococcal pharyngitis and tonsillitis (0.4%). Months with most inquiries were from October to March, mainly in the southeast, south and center of the city, coinciding with high levels of AP. Statistical analysis shows that the TI have significant correlation with ARDs in three years, temperature (Temp) in two, relative humidity (RH) in two, wind speed (WS) in three, wind direction (WD) in two, while that air pollutants NOX and NO2 showed significant correlation with ARDs throughout the period. CO and SO2 showed significance in two years, while the PM10 and O3 in one.

智能VAV通风柜PID控制系统的设计

针对传统的通风柜不能对面风速进行精准控制、无法保证实验的安全性等问题,提出了一种智能通风柜控制系统的设计方案,采用变风量控制(VAV)的方法保持通风管道静压恒定,通过PID控制算法自动调节风阀角度,实现通风柜的面风速保持恒定的要求。讨论了通风控制系统的滤波算法,并对PID控制算法进行了数值仿真,最后将仿真数据应用于通风系统的调试中,取得平稳的运行效果。

Genetic Optimization Algorithm of PID Decoupling Control for VAV Air-Conditioning System

Variable-air-volume (VAV) air-conditioning system is a multi-variable system and has multi coupling control loops. While all of the control loops are working together, they interfere and influence each other. A multivariable decoupling PID controller is designed for VAV air-conditioning system. Diagonal matrix decoupling method is employed to eliminate the coupling between the loop of supply air temperature and that of thermal-space air temperature. The PID controller parameters are optimized by means of an improved genetic algorithm in floating point representations to obtain better performance. The population in the improved genetic algorithm mutates before crossover, which is helpful for the convergence. Additionally the micro mutation algorithm is proposed and applied to improve the convergence during the later evolution. To search the best parameters, the optimized parameters ranges should be amplified 10 times the initial ideal parameters. The simulation and experiment results show that the decoupling control system is effective and feasible. The method can overcome the strong coupling feature of the system and has shorter governing time and less over-shoot than non-optimization PID control.

Variable structure guidance law for attacking surface maneuver targets

The characteristics of surface maneuver targets are analyzed and a 3-D relative motion model for missiles and targets is established. A variable structure guidance law is designed considering the characteristics of targets. In the guidance law, the distance between missiles and targets as well as the missile-target relative velocity are all substituted by estimation values. The estimation errors, the target＇s velocity, and the maneuver acceleration are all treated as bounded disturbance. The guidance law proposed can be implemented conveniently in engineering with little target information. The performance of the guidance system is analyzed theoretically and the numerical simulation result shows the effectiveness of the guidance law.

On the Relationship between Climatic Variables and Pressure Systems over Saudi Arabia in the Winter Season

The synoptic circulation over Saudi Arabia is complicated and frequently governed by the effect of large-scale pressure systems. In this work, we used NCEP–NCAR global data to illustrate the relationship between climatic variables and the main pressure systems that affect the weather and climate of Saudi Arabia, and also to investigate the influence of these pressure systems on surface air temperature（SAT） and rainfall over the region in the winter season. It was found that there are two primary patterns of pressure that influence the weather and climate of Saudi Arabia. The first occurs in cases of a strengthening Subtropical High（Sub H）, a weakening Siberian High（Sib H）, a deepening of the Icelandic Low（Ice L）, or a weakening of the Sudanese Low（Sud L）. During this pattern, the Sub H combines with the Sib H and an obvious increase of sea level pressure（SLP） occurs over southern European, the Mediterranean, North Africa, and the Middle East. This belt of high pressure prevents interaction between midlatitude and extratropical systems, which leads to a decrease in the SAT,relative humidity（RH） and rainfall over Saudi Arabia. The second pattern occurs in association with a weakening of the Sub H, a strengthening of the Sib H, a weakening of the Ice L, or a deepening of the Sud L. The pattern arising in this case leads to an interaction between two different air masses： the first（cold moist） air mass is associated with the Mediterranean depression travelling from west to east, while the second（warm moist） air mass is associated with the northward oscillation of the Sud L and its inverted V-shape trough. The interaction between these two air masses increases the SAT, RH and the probability of rainfall over Saudi Arabia, especially over the northwest and northeast regions.

水冷式集中空调冷源系统多变量耦合物理模型

水冷式集中空调系统是一个多变量耦合的非线性系统,运行数据稀疏程度大,导致基于数据驱动的机器学习模型泛化能力差,全面反映水力与传热机理的物理模型成为当前研究的关键。然而,系统变量耦合复杂,迭代嵌套导致整体计算量消耗巨大,设备启停又导致管路水力结构变化而不得不频繁重构模型等技术难点亟待解决。利用离散变量连续化及模式搜索法,以阻力系数关联支路开度与设备启停,以水泵运行频率关联水泵启停与运行状态,实现将离散变量整合至连续变量,减少迭代嵌套,可实现流量动态分配、水力热力全局耦合计算。该研究构建了冷负荷、冷冻水流量、冷冻水供水温度、冷冻水供回水压差及环境温湿度为外部约束的水冷式集中空调冷源系统多变量耦合物理模型,实现对冷水机组台数、冷冻水泵台数与频率、冷却水泵台数与频率、冷却塔台数与频率等多个独立变量的异步调节。通过综合实验平台验证模型的可靠性,探究了不同工况下的机塔泵运行特性与群控策略。研究表明,冷源系统物理模型仿真结果平均相对误差小于10%,少部分在15%内,单次迭代计算耗时约0.32 s,多变量组合调节可综合权衡各子系统的能效,系统全局优化可最大限度挖掘节能空间,解决传统主观经验控制难以维持稳定节能效果的缺陷,为智能诊断提供理论基础。

考虑变掺氧富氧燃烧与利用LNG冷能的LAES的综合能源系统低碳经济调度

为促进风电消纳,减少火电机组的碳排放,解决综合能源系统(Integrated Energy System,IES)低碳经济运行问题,文中引入变掺氧富氧燃烧技术对燃气机组进行改造,并结合利用液化天然气(Liquefied Natural Gas,LNG)冷能的液化空气储能(Liquid Air Energy Storage,LAES),提出了一种电热气冷IES低碳经济优化策略。首先,构建含变掺氧富氧燃烧燃气机组、利用LNG冷能的LAES、电转气(Power To Gas,P2G)设备、中央空调和溴化锂制冷机的IES架构,并建立各设备的数学模型;其次,引入阶梯式碳交易机制,建立了以系统运行成本最小为目标的电热气冷IES低碳经济调度模型;最后,采用MATLAB调用GUROBI求解器对多个场景进行求解,验证了文中提出的低碳经济优化调度策略可以提高系统的风电消纳、有效降低系统运行成本,实现碳减排。

超高层办公建筑暖通空调系统噪声控制分析

营造良好的室内声环境对人员身心健康至关重要。本文以某超高层办公楼为研究对象,分析了超高层办公建筑声学方面的特点、典型暖通空调系统的噪声传递途径;针对办公楼层剖析了声源降噪、隔绝机房噪声、办公区内空调末端及管道的噪声控制措施,并针对机电层的不同设备区域提出了相应的隔振、隔声、降噪做法。

某有机化学实验室项目通风空调系统设计

有机化学实验往往会产生对人体有害的气体,有效的通风空调系统可以避免有害物泄漏,以保证实验人员在工作环境里的安全和健康。不同的有机化学实验室要求不同,其通风空调系统设计也有相应的不同要求。合成实验室通风量大,但对房间温湿度要求不高;分析仪器实验室中仪器设备较多,发热量较大,且对环境温湿度有一定的要求。本文结合某实际工程,对不同功能化学实验室通风量的确定、新风送风温度及空调设置情况和通风系统控制进行了介绍。

融合改进NBEATSx和时间注意力机制的空气污染预测

针对现有空气污染预测存在结构复杂、对多元变量与不同时间步间依赖关系提取不充分和多步预测精度低的问题,引入了β分布和非线性动态控制函数改进星鸦优化算法(INOA),优化NBEATSx模型参数,提高收敛精度;并融合时间模式注意力机制(TPA)为不同时间尺度的多外生变量自适应分配权重,再结合预测因子获取时间模式关系.利用所提模型对北京地区的PM2.5进行预测,与传统模型相比精度提高超过18.45%,为空气污染预测提供了一种新方法.

地下大空间变工作区贴附送风空气分布特性

针对地下大空间环控系统能耗大以及实际中空调控制区改变的问题,在贴附送风的基础上提出适用地下大空间的变工作区贴附送风。采用数值模拟的方法,首先进行正交实验研究了等温工况下导流板与墙壁间的缝隙宽度、射流特征厚度、矩形柱跨度对流量比的影响程度大小,并通过量纲分析得出流量比q关于缝隙宽度与射流特征厚度之比x/δ_(0.5)间的关系式,即导流板的流量分配规律;其次将变工作区贴附送风与混合通风、柱壁贴附送风的空气分布特性进行了比较,研究结果显示,相比于另外两种送风方式,变工作区贴附送风可有效降低呼吸区的空气龄,并具有更好的节能效果。

面向变工况的车辆队列非线性控制策略

车辆队列间距控制策略能够影响车速稳定性和跟车间距,是降低队列能耗的关键,针对单一跟车间距策略无法满足间距控制问题,提出了一种双工况跟车间距控制策略。根据队列中每辆车空气动力特性,构建变空阻系数非线性车辆队列模型。将整个队列行驶工况分为匀速和变速工况,分别使用变时距和定时距跟车间距控制策略,变速时动态控制速度误差,匀速时控制每辆车最小能耗对应的跟车间距。在此基础上,设计兼容双工况跟车间距控制策略的非线性控制器,与单一定时距跟车策略进行仿真对比,仿真结果显示,非线性控制器速度误差平均降低25%,队列车辆油耗平均降低5.88%,验证了所提策略的有效性和可行性。