基于纳米复合PCM集蓄热构件的建筑太阳能供暖特性研究

设计一种基于吸光型纳米复合相变材料(PCM)模块化集蓄热构件,将其应用于建筑太阳能采暖,以降低能耗和碳排放。开展石墨烯-石蜡复合相变材料的制备和物性测试,建立PCM集蓄热数学模型,并结合典型气候工况进行供热特性的数值模拟,研究定风量情况下蓄热层厚度和空气流道宽度对供暖特性的影响,分析通风速度对送风温度、日供热量以及太阳能供暖保证率的影响。研究结果表明:添加石墨烯后的纳米复合PCM相对于纯石蜡的集热效率约提升了60%;对于具有18 m^(2)采光面积的集蓄热构件,当通风速度为1.0 m/s时,太阳能集蓄热墙具有较为优异的供暖性能,此时供给室内的日供热量、日平均热效率和供暖保证率分别为112.5 MJ、67.6%和90.0%,室内能够达到20℃的设定温度的时间为13 h。

基于PCM的圆极化贴片天线辐射和散射性能一体化设计

针对贴片天线现有设计存在的辐射性能不足及未考虑散射性能的现状,提出了采用极化转换超表面(PCM)改善辐射性能及提升散射性能的一体化设计.通过在偏置馈电方形切角贴片天线周围布局顺序旋转超表面单元并改变排布方式,有效地改善了辐射性能及提升了散射性能.仿真结果表明,最优化布局超表面天线实现了3 dB轴比带宽为5.02~5.39GHz,峰值增益为9.50 dB;相比初始天线,增益平均提升了4.78 dB,工作带宽实现了平均增益8.76 dB与-13.81 dBsm的低RCS;通过改变顺序旋转布局方式,实现了RCS最大缩减量为22.36 dB,比初始布局提高了8.67 dB.通过特征模分析法及散射原理分析验证了本文设计的天线具有良好的辐射和散射性能,该天线有望提升雷达天线隐身与辐射性能.

基于PCM的太阳能储能水箱研究进展

在建筑节能领域,太阳能是一种备受青睐的清洁能源.然而,太阳能本身的不稳定性及不连续性极大的影响了其应用效果.相变储能技术以其巨大的相变潜热、相变过程温度恒定等优点受到广泛关注,是太阳能存储技术中应用较为广泛的一种技术.为总结相变储能技术在太阳能存储领域的应用效果及研究现状,本文综述了国内外基于相变储能材料(PCM)的太阳能储能水箱的研究进展.通过对太阳能相变储能水箱中PCM的性能改进、相变储能水箱结构优化设计、相变储能水箱性能提升等问题的现有研究进行总结分析,归纳出目前基于PCM储能的太阳能储能水箱在应用中的优势与不足.最后,提出改善太阳能相变储能水箱性能的研究思路,分别对PCM的融化率、强化传热方法、技术经济性、储能水箱应用场景、多能耦合供热性能匹配等问题进行了展望,旨在为太阳能相变储能水箱的深入研究与应用提供帮助和借鉴.

PCM设备电容参数整体校准方法研究

半导体行业中普遍使用的工艺过程监控设备(PCM设备),是芯片产品中测环节必不可少的测量设备。PCM设备电容参数的准确测量,是保证与电容制作相关工艺参数的重要手段。针对国内PCM设备电容参数暂无溯源途径现状,根据其测试原理,研究了基于在片电容标准件的整体无损校准方法。采用增加绝缘层的半导体工艺,研制了高稳定性、频响至1 MHz、电容低至0.5 pF的在片电容标准件,满足了国内PCM设备电容参数自动校准需求,测量不确定度优于1%。研究了PCM设备电容参数溯源方法,从而保证了芯片产品PCM图形电容量值测量结果的准确一致,提高了计量效率。

Entropy Assessment on Environmental Influence of Condense Heat in Recovery System in Air-Conditioning Refrigerating Machine

This paper presented an entropy evaluation method for the influences of condense heat recovery system on the environment.Aiming at the damage of the condense heat to the environment,an entropy of resource loss and an emission entropy from the condense heat recovery system in the air conditioning refrigerating machine were introduced.For the evaluation of the entropies,we developed a new algorithm for the parameter identification,called the composite influence coefficient,based on the Least Squares Support Vector Machine method.By simulation,the numerical experiments shows that the Least Squares Support Vector Machine method is one of the powerful methods for the parameter identification to compute the damage entropy of the condense heat,with the largest training error being-0.025(the relative error being-3.56%),and the biggest test error being 0.015(the relative error being 2.5%).

Impact of summer office set air-conditioning temperature on energy consumption and thermal comfort

To explore the relationship between summer office set air-conditioning temperature and energy consumption related to air conditioning use to provide human thermal comfort,a comparison experiment was conducted in three similar offices at temperatures of 24,26 and 28 ℃ respectively. A thermal comfort questionnaire survey was conducted. It is demonstrated that air-conditioner energy consumption at the set temperature of 28 ℃ is 113% and 271% lower than at 26 ℃ and 24 ℃,respectively. A linear relationship exists between air-conditioner energy consumption and the indoor and outdoor temperature difference. When comfortably dressed,over 80% of research participants accept the set temperature of 28 ℃. The regression analysis leads to a neutral temperature of 26.2 ℃ and an acceptable temperature of 28.2 ℃ for over 80% of the research participants subjects,indicating that the current 26 ℃ set temperature for offices in summer,required by Chinese General Office of the State Council,can be increased to 28 ℃. Moreover,analysis of predicted mean vote(PMV) index shows that a set temperature of 27 ℃,not 26 ℃,is sufficiently comfortable for office staff wearing long-sleeve shirts,long pants and leather shoes.

Selection of Weather Parameters for Air-Conditioning System Design for Buildings with Long Thermal Lag

Two building factors-a longer thermal lag of more than one hour for building envelops and a lag of indoor radiation to convert into cooling load-have impact on the instantaneous heat input and instantaneous cooling load.So the two factors should be taken into account when selecting the weather parameters for air-conditioning system design.This paper developed a new statistic method for the rational selection of coincident solar irradiance,dry-bulb and wet-bulb temperatures.The method was applied to historic weather records of 25 years in Hong Kong to generate coincident design weather data.And the results show that traditional design solar irradiance,dry-bulb and wet-bulb temperatures may be significantly overestimated in many conditions,and the design weather data for the three different constructions is not kept constant.

The Experiment and Simulation of Solid Desiccant Dehumidification for Air-Conditioning System in a Tropical Humid Climate

The aim of this research was to study and design a solid desiccant dehumidification system suitable for tropical climate to reduce the latent load of air-conditioning system and improve the thermal comfort. Different dehumidifiers such as desiccant column and desiccant wheel were investigated. The ANSYS and TRASYS software were used to predict the results of dehumidifiers and the desiccant cooling systems, respectively. The desiccant bed contained approximately 15 kg of silica-gel, with 3 mm average diameter. Results indicated that the pressure drop and the adsorption rate of desiccant column are usually higher than those of the desiccant wheel. The feasible and practical adsorption rate of desiccant wheel was 0.102 kgw/h at air flow rate 1.0 kg/min, regenerated air temperature of 55?C and at a wheel speed of 2.5 rpm. The humidity ratio of conditioning space and cooling load of split-type air conditioner was decreased to 0.002 kgw/kgda (14%) and 0.71 kWth (19.26%), respectively. Consequently, the thermal comfort was improved from 0.5 PMV (10.12% PPD) to 0.3 PMV (7.04% PPD).

An Energy-Saving Control Strategy on Central Air-Conditioning System

An energy-saving control strategy based on predictive control for central air-conditioning systems is proposed in this paper. The cold load model is developed to describe the dynamic characteristics of temperature control systems, and then parameters in the cold load model and in the central air-conditioning system model are estimated. Generalized predictive control (GPC) is used to establish an optimization model to minimize the consumption of energy and the control error of temperature. The simulated annealing (SA) algorithm, combined with quadratic programming, is adopted to solve the optimal problem. Contrasted with the simulation of traditional PID control, the results prove the effectiveness of this proposed strategy.

Application of Fuzzy Comprehensive Evaluation to Air-conditioning Competitive Power Analysis

As the conceptual design of air-conditioning is done using the theory of Quality Function Deployment (QFD),cus- tomer requirements should be understood and the product competitive power be analyzed as exactly as possible for new product de- signing.Lots of information in the process of this research is fuzzy and uncertain,but traditional QFD can not deal with it well. Fuzzy theory can solve the problem.So a fuzzy model for analyzing product competitive power is formulated in this paper to im- prove traditional QFD,after that it is applied to analyze air-conditioning competitive power.When air-conditioning competitive power is analyzed using this model,firstly the importance weight of the customer requirements o fair-conditioning is determined us- ing the Analytic Hierarchy Process (AHP) weighting process,then air-conditloning competitive power is evaluated using fuzzy comprehensive evaluation.It is proved that the model is feasible and has good applicability.

Application of Dual Throttling Air-Conditioning System to Explosion-Proof Frequency Converter

An explosion-proof dual throttling air-conditioning system was put forward to solve the heat dissipation and internal dewing problems of explosion-proof frequency converter in the underground coal mine. This study investigated the feasibility and benefits of explosion-proof dual throttling cooling and dehumidification air-conditioning system applied to the explosion-proof frequency converter. The physical model of dual throttling air-conditioning system was established and its performance parameter was described by mathematical method. The design calculation of the system has also been done. The experimental result showed that the system reached the steady state at the refrigeration mode after running 45 min, and the maximum internal temperature of the flame-proof cavity was 31.0 ℃. The system reached the steady state at the dehumidification mode after running 37 min. The maximum internal relative humidity and temperature of the flame-proof cavity were 33.4% and 36.3 ℃, respectively. Therefore, the proposed system had excellent ability of heat dissipation and avoided internal dewing. Compared with water cooling system, it was more energy-saving and economical. The airflow field of dual throttling air-conditioning system was also studied by CFD simulation. It was found that the result of CFD numerical simulation was highly consistent with the experimental data.

Simulation of Artificial Intelligence for Automotive Air-conditioning System

The artificial intelligence is applied to the simulation of the automotive air-conditioning system ( AACS )According to the system's characteristics a model of AACS, based on neural network, is developed. Different control methods of AACS are discussed through simulation based on this model. The result shows that the neural- fuzzy control is the best one compared with the on-off control and conventional fuzzy control method.It can make the compartment's temperature descend rapidly to the designed temperature and the fluctuation is small.

基于PCM联合检测技术的某天然气长输管道防腐层检测及开挖验证

本文介绍了某埋地天然气长输管道的基本情况和目前的管道防腐层检测技术,使用PCM技术对某埋地天然气长输管道进行了检测,并对检测出的防腐层破损点进行了破损程度进行了测定。为检验本次检测效果对检测出的防腐层露点进行了开挖验证,对影响本次检测精度的几点因素进行了总结,提出了提高检验精度的几点建议。

Research on the Arrangement of Dew Point Temperature Detectors of Capillary Plane Radiation Air-Conditioning

Based on analysis of the reason and process of condensation on ceiling radiant cooling panels, two kinds of arrangement of detectors are put forward. The physical model is established, the results show that detectors are arranged as the form of triangle is more suitable. It can not only satisfy the use requirement but also it is economical and practical. Finally we can conclude that the inlet water temperature 0.5°C higher than dew point temperature is safe and reliable.

基于PCM/CAE集成的虚拟装配检测及工艺优化

开发了基于点云模型(PCM)/CAE集成的虚拟装配检测系统,将PCM与CAE模型进行了集成。聚焦虚拟装配检测过程中的误差分析问题,研究了基于仿真的零部件制造与装配误差分析方法。为了使一个存在各种变形与制造误差的零件达到理想或设计目标的装车状态,采用了多目标优化方法,实现了基于CAE仿真的虚拟装配分析与装配工艺优化。

Analysis of Solar Direct-Driven Organic Rankine Cycle Powered Vapor Compression Cooling System Combined with Electric Motor for Office Building Air-Conditioning

Solar energy powered organic Rankine cycle vapor compression cycle(ORC-VCC)is a good alternative to convert solar heat into a cooling effect.In this study,an ORC-VCC system driven by solar energy combined with electric motor is proposed to ensure smooth operation under the conditions that solar radiation is unstable and discontinuous,and an office building located in Guangzhou,China is selected as a case study.The results show that beam solar radiation and generation temperature have considerable effects on the system performance.There is an optimal generation temperature at which the system achieves optimum performance.Also,as a key indicator,the cooling power per square meter collector should be considered in the hybrid solar cooling system in design process.Compared to the vapor compression cooling system,the hybrid cooling system can save almost 68.23%of electricity consumption.

PV/PCM系统热控特性机理及实验研究

以光伏/相变材料(PV/PCM)热控系统结构为研究对象,开展光电热转换、传输、存储及温度控制机理研究,建立PV/PCM二维有限元热控分析模型。开展了相变材料热导率、熔点、厚度、太阳辐照度等对PV/PCM内部温度分布及太阳电池温度控制特性影响研究。设计了PCM的峰值熔点分别为42.9℃、46.7℃和58.1℃三种PV/PCM实验样机,在模拟光源条件下,开展实验测试,三种样机太阳电池温度控制在50℃内的时间分别为1.6 h、1.45 h和1.18 h,输出功率与无PCM热控太阳电池平均输出功率相比分别增加8.76%、6.95%和3.9%。

Analysis of Fresh Air Volume of Air-conditioning System for Railway Vehicles

The relevant standard requirements both in domestic and abroad provide the basis for designing air-conditioning system of railway vehicles present. However, there are great differences in the fresh air volume indicators among different standards requirements, and the requirements of each vehicle procurement contracts are also different. The design of air-conditioning become difficult above these. In this paper, the fresh air volume of different type railway vehicles is analyzed from health and equipment electricity consumption according to the railway vehicles air-conditioning system standard requirements in domestic and abroad. Some advises for designing air-conditioning system of railway vehicles through the fresh air volume calculation and comparison for domestic air-conditioning system of railway vehicles was provided.

Zynq7020的PCM遥测数据测试系统设计

飞行器在地面测试以及飞行试验过程中,广泛采用脉冲编码调制(PCM)技术实现遥测数据的高速采集和稳定传输。针对目前要求遥测数据传输速率高、容量大、实时性强的特点,设计了基于Zynq7020的PCM遥测数据测试系统。该系统以Zynq7020为主控中心,通过CPCI总线实现上位机通信,能够模拟弹上设备向遥测采编发送装置发送LVDS数据,并实现两路PCM数据的实时高速采集与存储。经过反复测试验证,PCM数据未发现任何丢帧现象,可以满足飞行器地面测试的需要。

基于TRNSYS平台的PCM层储能电炉蓄热过程的数值模拟研究

为有效解决电能供需矛盾、改善储能电炉蓄热能力,研究基于TRNSYS平台的PCM层储能电炉蓄热过程的数值模拟方法。以蓄热式储能电炉物理模型为基础,在TRNSYS软件中建立储能电炉数学模型,采用PCM层分析储能电炉蓄热过程,实现建模、整理数据、求解、分析处理于一体的储能电炉蓄热数值模拟操作。实验结果表明:电炉体积为20 m^(3)、蓄热流量为25 m^(3)/h、蓄热温度23/13℃时电炉蓄热率最高;蓄热流量越小蓄热量越高,且蓄热流量对蓄热率影响显著;蓄热电炉上、中、下部温度总体变化趋势均为蓄热-平稳-蓄热,蓄热电炉内流体流速越大蓄热时间越短;蓄热式储能电炉内渐变螺距蓄热装置相较于恒定螺距蓄热装置的蓄热时间短;蓄热式储能电炉相变蓄热材料融化时间随密度增加而增加;当相变蓄热材料密度较小时,相变蓄热材料的平均流速大。