Gypsum-based Silica Gel Humidity-controlling Composite Materials:Preparation,Characterization,and Performance

Gypsum was used as substrate,and silica gel was mixed into substrate at a certain mass ratio to prepare humidity-controlling composites;moreover,the moisture absorption and desorption properties of gypsum-based composites were compared with adding different silica gel particle size and proportion.The morphological characteristics,the isothermal equilibrium moisture content curve,moisture absorption and desorption rate,moisture absorption and desorption stability,and humidity-conditioning performance were tested and analyzed.The experimental results show that,compared with pure-gypsum,the surface structure of the gypsum-based composites is relatively loose,the quantity,density and aperture of the pores in the structure increase.The absorption and desorption capacity increase along with the increase of silica gel particle size and silica gel proportion.When 3 mm silica gel particle size is added with a mass ratio of 40%,the maximum equilibrium moisture content of humidity-controlling composites is 0.161 g/g at 98% relative humidity(RH),3.22 times that of pure-gypsum.The moisture absorption and desorption rates are increased,the equilibrium moisture absorption and desorption rates are 2.68 times and 1.61 times that of pure-gypsum at 58.5% RH,respectively.The gypsum-based composites have a good stability,which has better timely response to dynamic humidity changes and can effectively regulate indoor humidity under natural conditions.

Hydration Characteristics and Humidity Control Performance of Calcium Silicate Board Prepared from Mine Tailing and Diatomite

The feasibility of utilizing molybdenum tailing and diatomite as siliceous materials to prepare calcium silicate board was explored.The influences of molybdenum tailing/diatomite proportion on hydration characteristics,thermal conductivity,water absorption,flexural strength and moisture adsorption-desorption property of calcium silicate board were investigated in detail.The experimental results reveal that molybdenum tailing is environmentally friendly to prepare building materials.The main hydration products in calcium silicate board under autoclaved condition are C-S-H with low crystallinity and tobermorite.Molybdenum tailing is favorable to the formation of tobermorite.The flexural strength and bulk density of the calcium silicate board gradually increase when the content of molybdenum tailing increases.Netlike C-S-H is formed with the increase of diatomite content during autoclaved curing process,resulting in the enhancement of moisture adsorptiondesorption performance and the reduction of thermal conductivity.The optimal content of molybdenum tailing is 20%,furthermore,the flexual strength and thermal conductivity of calcium silicate board at this content meet the Chinese standard JC/T564.1-2008.

Synthesis and analysis of new humidity-controlling composite materials

Gypsum is a traditional building material. To improve the humidity-controlling properties of gypsum, we prepared a new type of humidity-controlling composite using the sol-gel method. Methods to determine the maximum equilibrium moisture content and speed of adsorption/desorption were subsequently applied to analyze the performance of the samples. The appearance and structural properties of the samples were characterized by scanning electronic microscopy (SEM). The experimental results show that the humidity-controlling gel with added LiCl exhibits high moisture storage and that the equilibrium maximum moisture content is 5.652 g/g at a 75.29% relative humidity (RH). A mass ratio of LiCl/sol = 0.15 is demonstrated to be appropriate for the preparation of the new humidity-controlling composites. A coarse network with tiny pores is observed on the surface of the new humidity-controlling composites, and this pore network provides sufficient space for moisture adsorption.

Preparation and Absorption/Desorption Performance of Gypsum-based Humidity Controlling Materials

Absorption/desorption properties of some humidity controlling materials which contain gypsum as basic cement materials and activated Sepiolite powder as humidity controlling media were tested. The kinetics curve of moisture adsorption/desorption were drawn and humidity controlling performance in nature environment was verified. The experimental results show that moisture absorption/desorption rates are increased, and the speed is also accelerated. These materials, which can adjust environmental humidity effectively, are new ones with good humidity controlling performance.

Development of Temperature-Humidity Independent Control Air-Conditioning Unit for Residential Buildings

Cooling panels are increasingly used in domestic residential buildings.To provide medium temperature cold water for the cooling panel,and dehumidify the indoor air simultaneously,a new kind of temperature-humidity independent control air-conditioning unit was developed for single residential house by utilizing multi-variable technology.First,the supply air temperature was studied to determine the proper supply air flow rate for the humidity control.Then,the energy consumption of different temperature-humidity independent control systems was studied.The analysis indicates that unity evaporating temperature can be used to handle the moisture load and sensible heat load in two evaporators.So the unit scheme was put forward.Two evaporators were used to produce medium temperature water and dry air separately,and electric expansion valves were used to control the refrigerant distribution between the two evaporators.Then,experimental work was carried out to investigate the influence of compressor frequency,refrigerant distribution on the dehumidification capacity,energy efficiency and refrigeration capacity.In the end,the paper concludes that both compressor frequency and refrigerant distribution can control the dehumidification capacity,but the former influences the EER more than the latter,while the latter influences the refrigeration capacity more than the former.We can find a proper running point at certain sensible and latent cooling load by adjusting both compressor frequency and electric expansion valve.The energy consumption of this kind of unit was estimated and compared with present room air conditioners,which shows that it can save about 41% cooling energy consumption.

Indoor biology pollution control based on system-based humidity priority control strategy

Indoor biological contamination and HVAC system secondary contamination problems caused wide public concerns. Biological contamination control will be the next step to achieve better IAQ. The most efficient and safe way to control biological contamination was to limit relative humidity in HVAC system and conditioned environment in the range that is more unsuitable for microorganism to survive. In this paper,by referring to bio-clean project experiences,a system-based humidity priority control manner came into being by lowering outdoor air humidity ratio to eliminate all indoor latent load and using self recirculation units to bear indoor sensible load. Based on the whole-course residue humidity contaminant control concept,dynamic step models for coil and conditioned zone were developed to describe mass and energy conservation and transformation processes. Then,HVAC system and conditioned zone dynamic models were established on LabVIEW+Matlab platform to investigate optimized regulation types,input signatures and control logics. Decoupling between cooling and dehumidification processes can be achieved and a more simplified and stable control system can be acquired by the system-based humidity priority control strategy. Therefore,it was a promising way for controlling biological pollution in buildings in order to achieve better IAQ.

COMPUTER DECOUPLE CONTROL OF TEMPERATURE AND HUMIDITY IN PREPROCESSING CHAMBER OF AIR-CONDITIONING TEST EQUIPMENT

This paper deals with the application of decouple Control theory to temperature and humidi-ty control in air-conditioning system. The decouple control algorithm for bivariable systems isderived applicablly for air-conditioning system. The algorithm is used to design a temperatureand humidity computer control system for the preprocessing chamber of air-conditioning testequipment. The results of the real-time control experiments indicate that the decouple controlalgorithm is feasible, the control quality is improved and high control precision is achieved.

Temperature and Humidity Control in Greenhouses in Desert Areas

Water consumption can be reduced by using a greenhouse for agriculture in desert areas. We analyzed the effect of control of ventilation, sprinkler water, and solar radiation?shielding on changes of temperature and humidity in a greenhouse under various desert area conditions. We calculated the changes in temperature and humidity in a greenhouse for a whole day in four seasons, and the calculation results of water consumption with and without a greenhouse were compared. When ventilation, shielding, and sprinkler water were controlled under suitable conditions to grow orchids in a desert area, water consumption in July was only 7% of that without a greenhouse.

Visco-elastic-plastic model of deep underground rock affected by temperature and humidity

As the depth of exploitation increases,studies on constitutive models of rock affected by temperature and humidity become very important.Based on the Nishihara model,a visco-elastic-plastic rock model was established by using the coefficients of thermal and humidity expansion,thermal viscosity attenuation,humid viscosity attenuation and acceleration rheology components.We used the definition of a controlled heat circle to explain the model.The results show that the behavior of rock,affected by temperature and humidity,is stable as a function of time when the stress is lower than the first yield stress σS1;the creep rate will increase due to the effect of temperature and humidity when the stress is greater than or equal to σS1;the creep rate will accelerate at an increasing rate when the stress is greater than or equal to the second yield stress σS2,which results in a failure of the roadway.The model derived in this study can completely describe visco-elastic-plastic characteristics and reflects the three stages of rock creep.

Analysis of the Effect and Solution of Geomagnetic Room Humidity on Geomagnetic Observation

It is not easy to control humidity in a geomagnetic room. If humidity is too high or the change is too fast it will lead to an abnormal change on data. The intelligent real-time humidity analysis and monitoring system of a geomagnetic room and probe can not only monitor and display the change of humidity in the geomagnetic room and send an alarm signal when it exceeds the pre-set range, but also dehumidify intelligently. One can arbitrarily control the sensor to monitor the ambient humidity of the probe in order to ensure that the data is stable and true. The design idea and main functions of the system are introduced in the paper.

Occurrence and Epidemic Dynamics and Control Countermeasures of Important Sugarcane Diseases in Rainy and Humid Season

The rainy and humid season from July to September is the crucial period for elongation and jointing and yield performance of sugarcane,and also a peak occurrence and damage period of many important sugarcane diseases. In order to prevent large-area outbreak of sugarcane diseases and ensure safe growth in late stage,the occurrence dynamics of important sugarcane diseases in the rainy and humid season was analyzed and discussed from the aspects of three epidemic outbreak elements of plant diseases: host plant,pathogen and environmental condition. Moreover,the corresponding control ideas and technical countermeasures were put forward according to the epidemic characteristic of sugarcane diseases and the actual sugarcane production.

Feasibility Assessment of Fast Numerical Simulations for Real-Time Monitoring and Control of PEM Fuel Cells

Computational models that ensure accurate and fast responses to the variations in operating conditions,such as the cell tem-perature and relative humidity(RH),are essential monitoring tools for the real-time control of proton exchange membrane(PEM)fuel cells.To this end,fast cell-area-averaged numerical simulations are developed and verifi ed against the present experiments under various RH levels.The present simulations and measurements are found to agree well based on the cell voltage(polarization curve)and power density under variable RH conditions(RH=40%,RH=70%,and RH=100%),which verifi es the model accuracy in predicting PEM fuel cell performance.In addition,computationally feasible reduced-order models are found to deliver a fast output dataset to evaluate the charge/heat/mass transfer phenomena as well as water production and two-phase fl ow transport.Such fast and accurate evaluations of the overall fuel cell operation can be used to inform the real-time control systems that allow for the improved optimization of PEM fuel cell performance.

高压氧舱恒湿平压系统的设计

目的:设计一种高压氧舱恒湿平压系统,以消除舱内静电火花造成的危害,保证氧舱的安全运行。方法:该系统的硬件主要由加湿装置、除湿装置、平压装置、主控制器、压力传感器、温湿度传感器等组成。其中,加湿装置主体为经过特殊加工后的防爆过滤瓶;除湿装置采用工业级风机过滤单元(fan filter unit,FFU),由蒸发器、冷凝器、风轮3个部分组成;平压装置主要由电磁阀和减压管路组成;主控制器选用EX3G-C系列PLC触摸屏一体机,温湿度传感器选用NWSF-1AT型号温湿度传感器,压力传感器选用TXYS-G1K2HN3型变送器。系统的软件控制程序采用指令表语言编程,通过PID(proportional-integral-derivative)控制算法实现整体控制。结果:经过测试,该系统可使高压氧舱内相对湿度恒定在70%,使舱内极难产生静电。结论:该系统能够调节氧舱内的湿度、减少静电火花产生,保证舱内治疗的安全。

江阴靖江长江隧道大体积混凝土抗裂技术研究

江阴靖江长江隧道是国内在建最大直径盾构隧道,其明挖段主体结构混凝土最大厚度达2.2 m,面临着较大的开裂与渗漏风险。在水化与膨胀历程双重调控技术的基础上,进一步研究了高吸水树脂(SAP)的湿度历程调控对混凝土抗裂性能的影响。室内试验结果表明,SAP可显著提高自生体积膨胀变形并优化变形历程,且基本不影响胶凝材料水化放热历程;工程现场试验结果表明,在湿度、水化、膨胀历程多重调控作用下,混凝土温升值降低了4.5℃,温升阶段单位膨胀变形增大206.7%,温降阶段单位收缩变形减小27.5%,为解决裂缝控制难度较大结构的收缩开裂难题提供了材料技术方案。

换热器面积对双蒸发温度空调系统性能影响的模拟研究

建立了双蒸发温度空调系统仿真模型来研究改变换热器面积对系统性能的影响。搭建了双蒸发温度空调系统实验台,在实验工况下改变压缩机频率(30~120 Hz)和送风量(400~1 000 m^(3)/h),得到空调机组总制冷量Q_(c)、总显热制冷量Q_(s)和显热比SHR,验证了所建模型精度。在模型中改变换热器面积(48盘管、60盘管、72盘管)进行系统运行调节范围的研究。结果表明:随着换热器面积的增加,系统Q_(c)、Q_(s)和SHR的调节范围在整体扩大,最大增幅分别为5.0%、13.8%、11.8%。当送风量为1 000 m^(3)/h,压缩机频率为30 Hz,换热器面积从48盘管增至60盘管、72盘管时,Q_(s)的增幅分别为9.8%和13.8%,表明换热器面积增至60盘管时Q_(s)增长效果显著,再增加换热器面积,Q_(s)虽有所增大但增幅放缓。最后提出一种以所需制冷量为目标,依据环境温湿度调节范围设计换热器面积的方法。

内抹调湿砂浆外墙吸放湿特性及对负荷影响分析

本文从建筑围护结构节能出发,以内抹WSE(木质纤维Wood fibre、海泡石Sepio⁃lite、膨胀珍珠岩Expanded perlite)基复合调湿保温砂浆外墙为研究对象,将其与内抹普通砂浆外墙对比,分析吸放湿特性及其对负荷的影响.研究使用COMSOL Multiphysics有限元软件的建筑材料热湿耦合模型,分析环境湿度变化与外墙之间的湿迁移变化,以及与外墙的传热传质.以夏热冬冷典型气候地区长沙为例,分析内抹WSE基复合调湿保温砂浆外墙的负荷及潜热负荷占比,同时选取夏热冬暖地区广州和寒冷地区北京对比分析外墙的全年能耗.研究发现,内抹WSE基复合调湿保温砂浆外墙的吸放湿速率远大于内抹普通砂浆的外墙,并能长时间保持高速的吸放湿状态,同时比内抹普通砂浆墙体节省22.31%~23.85%的全年负荷.墙体在吸湿过程中,温升与吸湿速率能力体现出一致性,表明墙体内表面湿迁移对温度有着重要影响,并且湿迁移越大对温度影响越大.墙体在放湿过程中,温度迅速下降是放湿速率快的表现.内抹WSE基复合调湿保温砂浆墙体具有优良的吸放湿特性和节能潜力,可用于建筑围护结构节能.

基于迭代学习的楼宇空调湿度控制研究

传统楼宇变风量空调控制方法,存在对被控系统数学模型的精度要求较高以及抗干扰能力弱的不足,因此限制了变风量空调系统的应用。针对变风量楼宇空调系统运行时存在的重复干扰与系统模型精度问题,采用迭代学习控制方法对变风量空调空气湿度进行控制。将变风量空调空气调节过程看成间歇过程,并且将室内空间湿度控制过程当作间歇过程对目标轨迹的跟踪问题,设计迭代学习控制器,使被控系统能够获得更好的精度和鲁棒性,实现变风量空调的高精度湿度轨迹跟踪。

基于窄带物联网的茶叶灭虫控制系统研究

为克服当前物联网在丘陵地区农业生产过程中存在通信距离短、消耗功率大、终端数量易饱和等问题,以茶叶虫害防治为研究对象,将窄带物联网技术与农业生产相结合,实时精准监测土壤温湿度,并根据土壤温湿度数据变化远程控制茶叶灭虫电磁阀启闭状态,设计了智能茶叶灭虫控制系统,并优化了超级电容太阳能电源管理、无线传感网络监测、远程监测控制等核心技术及关键模块。试验结果表明:系统运行稳定,能通过窄带物联网技术实时监测、传输土壤温湿度信息,终端可实时远程控制茶叶灭虫电磁阀,实时启闭茶叶灭虫系统,达到了实时精准监测和远程控制的目的。研究弥补了当前物联网在农业生产中应用的不足,提高了太阳能电源使用效率,延长了蓄电池使用寿命,可为我国智慧农业发展提供参考。