Practice and analysis of recycling non-drinking water from air-condition and reverse-osmosis system into rainwater collection system

This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilization, and precipitation adjustment.The rainwater collection system in this program also adds the condensation water from the heating, ventilation and air conditioning （ HVAC） system and the concentration from the reverse-osmosis system used for watering greens and supplying waterscapes.By calculating, the quantity of the HVAC condensation water in summer is 3.48 m3/d, and the quantity of the reverse-osmosis concentrated water is 198 to 396 L/d.This method solves the water shortage caused by high evaporation in summer and low precipitation in winter.Supported by empirical monitoring data, the proposed method significantly increases the economic efficiency of the system during the summer period.

Study on the Elman Neural Network Operation Control Strategy of the Central Air Conditioning Chilled Water System

The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.

Orientation and Motion of Water Molecules at Air/Water Interface

Here we report a quantitative study of the orientational structure and motion of water molecule at the air/water interface. Analysis of Sum Frequency Generation （SFG） vibrational peak of the free O-H stretching band at 3700 cm^-1 in four experimental configurations showed that orientational motion of water molecule at air/water interface is libratory within a limited angular range. The free OH bond of the interracial water molecule is tilted around 33°from the interface normal and the orientational distribution or motion width is less than 15°. This picture is significantly different from the previous conclusion that the interracial water molecule orientation varies over a broad range within the ultrafast vibrational relaxation time, the only direct experimental study concluded for ultrafast and broad orient, ational motion of a liquid interface by Wei et al. （Phys. Rev. Lett. 86, 4799, （2001）） using single SFG experimental configuration.

Research on characteristics of water motion and influencing factors for the flexible air chamber jig body

The air bag deformation data were obtained by high-speed dynamic videos experiments. Based on gas–liquid flow VOF model, dynamic mesh technique and deformation data, numerical simulations for different structure models were achieved, and the law of water motion and influencing factors were analyzed.The results show that the flow in the length direction of the jig is smooth, and second pulsation appears in the separation time and forms the secondary separation. The installation position of screen and the number of air bags have a great influence on the uniformity of flow and velocity. The screen height cannot be too low to avoid forming the unstable flow. At the same time, the screen height cannot be too high, otherwise water velocity will be too small and was unable to provide enough power. At the height of 1.4m,velocity unevenness is minimum and the best uniform flow can be obtained. Compared with double air bags, there are the following features of single air bag: water flow is not smooth, the time achieving the maximum velocity is too long, maximum velocity is smaller, and overall effect is worse than double air bags.

Simulation of Air-Water Interface Effects for High-speed Planing Hull

High-speed planing crafts have successfully evolved through developments in the last several decades.Classical approaches such as inviscid potential flow–based methods and the empirically based Savitsky method provide general understanding for practical design.However,sometimes such analyses suffer inaccuracies since the air–water interface effects,especially in the transition phase,are not fully accounted for.Hence,understanding the behaviour at the transition speed is of fundamental importance for the designer.The fluid forces in planing hulls are dominated by phenomena such as flow separation at various discontinuities viz.,knuckles,chines and transom,with resultant spray generation.In such cases,the application of potential theory at high speeds introduces limitations.This paper investigates the simulation of modelling of the pre-planing behaviour with a view to capturing the air–water interface effects,with validations through experiments to compare the drag,dynamic trim and wetted surface area.The paper also brings out the merits of gridding strategies to obtain reliable results especially with regard to spray generation due to the air–water interface effects.The verification and validation studies serve to authenticate the use of the multi-gridding strategies on the basis of comparisons with simulations using model tests.It emerges from the study that overset/chimera grids give better results compared with single unstructured hexahedral grids.Two overset methods are investigated to obtain reliable estimation of the dynamic trim and drag,and their ability to capture the spray resulting from the air–water interaction.The results demonstrate very close simulation of the actual flow kinematics at steady-speed conditions in terms of spray at the air–water interface,drag at the pre-planing and full planing range and dynamic trim angles.

Dynamic Study of Gemini Surfactant and Single-chain Surfactant at Air/Water Interface

Molecular dynamics (MD) simulation are used to study the properties of gemini surfactant of ethyl-α,ω-bis(dodecyldimethylammonium bromide) (C12C2C12) and dodecyl- trimethylammonium bromide (DTAB) at the air/water interface, respectively. In the two systems, the surfactant concentrations are both 28 wt. %, and other conditions are also the same. After reaching the thermodynamic equilibrium, the concentration profiles, the radial distributions functions (RDF) and the mean squared displacement (MSD) are investigated. The results reveal that the surface activity of C12C2C12 surfactant is higher than DTAB surfactant.

Absolute Orientation of Molecules with Competing Hydrophilic Head Groups at the Air/Water Interface Probed with Sum Frequency Generation Vibrational Spectroscopy

The constructive or destructive spectral interference between the molecular groups oriented up and down at the interface in the sum-frequency generation （SFG） spectra provides a direct measurement of the absolute orientation of these molecular groups. This simple approach can be employed to interrogate absolute molecular orientations other than using the complex absolute phase measurement in the SFG studies. We used the -CN group in the p-cyanophenol （PCP） molecule as the internal phase standard, and we measured the phases of the SFG fields of the -CN groups in the 3,5-dimethyl-4-hydroxy-benzonitrile （35DMHBN） and 2,6-dimethyl-4-hydroxy-benzonitrile （26DMHBN） at the air/water interface by measuring the SFG spectra of the aqueous surfaces of the mixtures of the PCP, 35DMHBN, and 26DMHBN solutions. The results showed that the 35DMHBN had its -CN group pointing into the aqueous phase; while the 26DMHBN, similar to the PCP, had its -CN group pointing away from the aqueous phase. The tilt angles of the -CN group for both the 35DMHBN and 26DMHBN molecules at the air/water interface were around 25°-45° from the interface normal. These results provided insights on the understanding of the detailed balance of the competing factors, such as solvation of the polar head groups, hydrogen bonding and hydrophobic effects, etc., on influencing the absolute molecular orientation at the air/water interface.

Influence of water content on the inactivation of P. digitatum spores using an air–water plasma jet

In order to investigate whether an air–water plasma jet is beneficial to improve the efficiency of inactivation, a series of experiments were done using a ring-needle plasma jet. The water content in the working gas（air） was accurately measured based on the Karl Fischer method. The effects of water on the production of OH（A;Σ;–X;Π;） and O（3p;P–3s;S） were also studied by optical emission spectroscopy. The results show that the water content is in the range of 2.53–9.58 mg l;, depending on the gas/water mixture ratio. The production of OH（A;Σ;–X;Π;） rises with the increase of water content, whereas the O（3p;P–3s;S） shows a declining tendency with higher water content. The sterilization experiments indicate that this air–water plasma jet inactivates the P. digitatum spores very effectively and its efficiency rises with the increase of the water content. It is possible that OH（A;Σ;–X;Π;） is a more effective species in inactivation than O（3p;P–3s;S） and the water content benefit the spore germination inhibition through rising the OH（A;Σ;–X;Π;） production. The maximum of the inactivation efficacy is up to 93% when the applied voltage is -6.75 kV and the water content is 9.58 mg l;.

CURIOUS TO SAY——Air2Water Dolphin 2 饮水机

新加坡的Air2Water公司有一项非常非常“Inconceivable”的专利——就是把空气变成可以直接饮用的水。基于此技术专门研发生产的Dolphin 2是该公司继Dolphin之后推出的第二代产品。在70%湿度的环境中，Dolphin——天最多可以“变”出24公升纯净水。这种引水机把空气变成净水的过程大致为：空气→特殊抗菌过滤器→送到储水箱进行第一次紫外消毒→超过滤并颗粒化活性碳→再次紫外消毒抽水储水箱备用。

PIV Studies on Turbulence Structure in Air/Water Interface with Wind-Induced Water Waves

When wind appears over the free surface, water waves and turbulence are generated by an interfacial shear stress. In particular, turbulent diffusion promotes significantly mass and momentum transport beneath the interface between the water and air significantly in ocean and lakes, and thus it is very important for global environment problems to reveal such turbulence property and coherent structure. Simultaneous measurements of velocities and free-surface elevation allow us to conduct reasonably the phase analysis of the coherent structure in interfacial shear layer. Furthermore, multi-point measurements such as PIV are very powerful to detect the space-time structure of coherent motions. Therefore, in the present study, we developed a specially designed PIV system which can measure the velocity components and surface-elevation fluctuation simultaneously by using two sets of high-speed cameras to reveal the coherent structure in the interfacial shear layer.

Experimental Study of Energy-Saving Air-Conditioner with Hot Water

Energy-saving air-conditioner with hot water is an air source heat pump air-conditioner,which can also supply hot water.The hot water is heated by a double pipe condenser connected with an air-cooled condenser in series in the system.This experiment of the energy-saving air-conditioner was carried out in the enthalpy-difference air-conditioner laboratory.The hot water temperature and the compressor's discharge and suction pressure were recorded in the working condition,where the ambient temperature was at 43 ℃,35 ℃,21 ℃,7 ℃,and 2 ℃ separately.The results showed that the system operated stably and reliably.This system can supply 240 L hot water at 50 ℃ in the whole year,and its coefficience of performance(COP)is much higher than the conventional air source heat pump system.Its energy conservation was proved by comparing the thermal efficiency with other sourece water heaters.

地铁站空调水系统节能控制研究

为了降低空调水系统的能耗,研究广州某地铁站的空调水系统节能控制策略。使用设备厂商提供的样本数据进行参数拟合,建立较为准确的设备模型,利用Trnsys软件搭建地铁站空调水系统模型。针对“大流量、小温差”现象,提出定温差控制策略,以降低水系统的能源消耗。结果显示:与定流量水系统相比,定温差控制策略下地铁站空调水系统节能率达到25.86%;在整个供冷季,相对于常规7℃的供水温度定温差控制策略,变冷冻水供水温度定温差控制策略的空调水系统节能约3.40%。

空调二次泵系统在地铁车站中的应用

杭州地铁机场轨道快线工程杭州西站为地铁四线换乘车站,地铁车站体量大、空调系统末端多、运营要求高。针对本工程特点,经过比较分析水系统采用二次泵变流量系统,根据不同区域负荷特点和运营需求进行分区划分,可有效的降低空调水系统输送能耗,为运营后的稳定运行和场所管理创造了了良好条件。同时,文中给出了二次泵系统分区划分、设备选型及运行控制方案,并对选用条件进行了验证,可为类似工程提供参考。

某超高层建筑空调冷源系统技术经济性分析

对于超高层建筑,其常用的空调系统为传统的空调水系统形式,以位于深圳的某超高层建筑为研究对象,基于超高层建筑的空调水系统需要竖向分区的特点,以常规集中式系统和竖向分布式系统为研究对象,探讨了这两种系统形式空调冷源的设备配置、初投资、运行费用、土建需求和竖向运输等方面的内容,得到了该超高层建筑适宜采用竖向分布式系统的空调冷源方案。

数据中心冷却系统研究及应用进展

为加速实现数据中心节能降耗的目标,在合理、高效、最大化地利用自然冷源的同时,更不能忽视机械制冷系统本身能效的提升。加强自然冷却与机械制冷的协同,降低数据中心PUE,充分发挥安全稳定、高效运行的数据中心冷却系统自身能效至关重要。本文通过对气流组织、供/回水温度和冷却系统部件及形式3个方面的研究梳理,总结分析数据中心冷却系统节能提效有关技术研究与应用进展,从而为绿色、高效数据中心冷却系统的研发提供参考和借鉴。

太阳能-空气源热泵热水系统新型组合优化设计

太阳能-空气源热泵热水系统(solar-air source heat pump hot water system, SAHWS)常用于宿舍楼宇供暖,通过对系统参数的优化设计可显著提高系统能效性能与环境友好性。为得到一种综合考虑SAHWS经济、能源、环保与节能的优化方法,提出了一种新型组合优化设计策略,并利用TRNSYS软件搭建系统仿真模型,以西安、西宁、拉萨这3座不同太阳能资源等级城市为例,对SAHWS运行工况对比分析。结果表明:与常用生命周期成本设计相比,所提出的组合优化设计不仅降低了系统成本,还有着较低的系统能耗;组合优化设计的热泵能耗与工作小时数最短,且有最低的热损,在投资成本、系统季节性能因子、太阳能保证率以及碳粉尘、二氧化碳排放量均有较好表现。

联合收获机发动机风冷系统优化设计

为了减少联合收获机收获过程中水箱“开锅”现象的发生,延长收获机的无故障工作时长,对4LXZ-8F型联合收获机的发动机风冷系统散热量进行了计算,并基于计算结果对防尘罩、散热器进行了优化设计,对冷却风扇进行了匹配选型。利用SolidWorks对优化前后风冷系统进行了三维建模,利用Fluent软件对发动机风冷系统优化前和优化后散热器散热性能分别进行仿真分析。仿真结果表明:优化前的冷却水入口温度为90℃,出口温度为72.3℃,进出口温差为17.7℃;优化后的冷却水入口温度为90℃,出口温度为71.1℃,进出口温差为18.9℃,表明优化后散热器散热性能提升了6.78%。研究成果可为提高发动机风冷系统的散热性能,延长无故障收获时长提供理论指导。

汽车焊装车间循环冷却水运行问题分析与研究

汽车焊装车间采用闭式循环水系统对焊接等主要设备进行冷却。研究分析了其循环水系统工艺流程及运行过程中存在的问题,针对问题实施了提升循环水系统水质、增加主管排气阀、使用自主设计优化的气控阀并定期巡检等措施。结果表明,采用的措施有效降低了循环水中悬浮物量,季度沉积物由最高720 g减少至32 g;稳定了水流量,降低水气互窜的影响,减少了为排除杂质和空气而排放的循环水,日均补水量由最高15.8 t减少至最低0.5 t,且稳定在2 t以内;降低了由循环水系统故障引起的设备损坏率,保证了自动焊装生产线的设备开动率,累计停线时间由2019年的2 514 min降低到2022年的73 min。

基于GWO-BP神经网络的空调水系统泵阀联调优化控制方法

空调水系统的节能潜力较大,但管网中却通常存在动态水力不平衡的问题,这不仅影响了空调房间的室内舒适度,还会造成运行能耗的浪费。根据实验实测数据,建立了基于GWO-BP神经网络的水系统管网末端阀门开度预测模型,并根据最小阻力控制的原理,建立了基于神经网络的水系统泵阀联调优化控制方法。实验结果验证了该优化控制方法在优化计算后显著提升了末端阀门的开度,降低了水泵频率,可以有效降低水系统管网阻力并精确调节末端支路流量,对于水泵运行实现了27.63%至65.19%的节能率,具有明显的节能效果,且在水系统流量需求越小时,节能效果越好。

空冷岛喷嘴预冷模拟研究

直接空冷岛的换热效果受气温影响严重,为提高夏季高温工况下空冷岛的冷却效果,常采用喷水减温技术。以西北地区某空冷机组为例,采用数值模拟计算分析了喷嘴喷水角度、喷水量和喷水压力对冷却效果的影响。为更好地分析喷嘴喷出的液滴在空间上的发展并量化冷却效果,采用了新的冷却效率。研究结果表明:在本文研究参数内,随着流动距离的增加,冷却效率逐渐提高。喷水量对冷却效率影响最大,喷水量分别为0.48kg/s和1.58kg/s时的冷却效率分别为24.472%和48.071%,冷却效率几乎翻倍,而喷嘴喷水压力的影响稍弱,喷嘴喷水角度影响最小。在调整喷嘴参数时可以着重考虑喷嘴喷水量和喷水压力。