Design of transit-time difference ultrasonic heat meter based on TDC-GP21

According to the transit-time difference measurement method,we proposed a design scheme of ultrasonic heat meter based on TDC-GP21.The measurement unit TDC-GP21 mainly completes transit-time measurement and inlet,outlet temperature measurement functions.Control unit and data processing unit based on MSP430F4152 of TI corporation complete functions including peripherals control,data analysis,temperature compensation algorithm,flow pattern compensation algorithm and low power consumption control.The design meets the Town Construction Professional Standard CJ 128-2007,and furthermore,some performances can be improved.

Design and Implementation of an Ultrasonic Heat Meter Based on MSP430F437

Flowing with the reform of the hot water heating method in China, heat meter will enter into households in the near future. A portable ultrasonic heat meter is designed in this paper. The meter uses chip microprocessor MSP430F437 as the data process core, and uses ultrasonic flow sensor to measure flow rate of the hot water, and capture input and output temperatures of the hot water using the thermal resistance sensor Ptl000, and then household energy consumption is calculated via temperature difference between input temperature and output temperature of the hot water multiplied by volume of hot water that is calculated though flow rate integration of hot water. In order to test the performance of the proposed heat meter, experiments is carried out. Both the temperature and flow measurement results satisfy the requirements of accuracy and the heat meter is effective in the heat measurement.

Study on the Wireless Heat Meters

The design of a new type heat meters based on RFID technology are presented in this paper. By use of RFID technology in heat meters, the data can be exchanged between heat meters and heat supplying department by RF cards. The information can be transmitted in a non-contact way. In this way, the purpose of automatic identification can be achieved. The experimental study of the heat meters is also performed in the paper. The results show that the new type of heat meters can meet the demands of users. Compared with the ordinary heat meters, the new type of heat meters have the advantages of small in meter volume, high accuracy, no impact of water quality and good reliability.

Study of errors in ultrasonic heat meter measurements caused by impurities of water based on ultrasonic attenuation

Impurity is one of the main factors that affect the measurement accuracy of an ultrasonic heat meter. To study the effects of different impurity species and concentrations on the accuracy of heat meters, flow tests were carried out for the suspending of calcium carbonate and yellow mud. By analyzing the attenuation characteristics of the ultrasound amplitude in different impurity concentrations and species, the influence of the impurities on the heat meter measurement accuracy is evaluated. In order to avoid the inaccuracy caused by the sediment of the reflective bottom surface, a vortex generator is put ahead of the reflective surface. According to the test, the calcium carbonate suspension with a mass concentration of 1%, which influences the heat meter accuracy severely, is used as the flow media. The influence of the vortex generator on the calcium carbonate suspension flow field in the heat meter body is studied with numerical simulations. The results of this paper provide some theoretical guide on improving the heat meter measurement accuracy when the water contains impurities.

THE INFLUENCE OF DIFFERENT DESIGN PARAMETERS AND WORKING CONDITIONS ON CHARACTERISTICS OF HEAT METERS

In this article, the UDF technology in Fluent software is used to simulate three-dimensional flow fields and to obtain various flow parameters. The standard k -ε model and the RNG k -ε model are both used to calculate the inner flow field of the basal meter, and a comparison of the calculated results between two models shows that RNG k - ε model is more effective for calculations of the inner flow of rotary wing mechanism. The influence of tip clearance on the characteristics of the basal meter is studied. The influence of the bottom ribs on the heat meter is evaluated by the numerical simulation method. This article also simulates the flow of disturbance located at the inlet of the basal meter, and shows that a swirl located at the front of the basal meter can affect the stability of the heat meter.

FLUID CHARACTERISTICS OF ROTARY WING HEAT METER WITH SINGLE-CHANNEL

Fluid characteristics of a rotary wing heat meter with single-channel were studied through theretical analysis, numerical simulation and experiments. The obtained results show that the number of vanes can obviously influence the heat meter, but the water temperature seldom influence the meter , and the optimal number of vane is 6-8.

THE CALCULATION OF THE PROFILE-LINEAR AVERAGE VELOCITY IN THE TRANSITION REGION FOR ULTRASONIC HEAT METER BASED ON THE METHOD OF LES

The measurement accuracy of an ultrasonic heat meter depends on the relationship of the profile-linear average velocity.There are various methods for the calculation of the laminar and turbulence flow regions,but few methods for the transition region.At present,the traditional method to deal with the transition region is to adopt the relationship for the turbulent flow region.In this article,a simplified model of the pipe is used to study the characteristics of the transition flow with specific Reynolds number.The k-εmodel and the Large Eddy Simulation（LES）model are,respectively,used to calculate the flow field of the transition region,and a comparison with the experiment results shows that the LES model is more effective than the k-εmodel,it is also shown that there will be a large error if the relationship based on the turbulence flow is used to calculate the profile-linear average velocity relationship of the transition flow.The profile-linear average velocity for the Reynolds number ranging from 5 300 to 10 000 are calculated,and the relationship curve is obtained.The results of this article can be used to improve the measurement accuracy of ultrasonic heat meter and provide a theoretical basis for the research of the whole transition flow.

Numerical study of impurity distribution in ultrasonic heat meter body

Based on a discrete phase model, the numerical simulation is carried out for the flow fields of different size calcium carbo- nate suspensions in the ultrasonic heat meter body. The flow characteristics and the impurity distribution in the ultrasonic heat meter body are analyzed. The errors of the ultrasonic heat meter in measuring calcium carbonate suspensions of particles of 10 micrometers and the causes are analyzed by simulation and experiment. Results show the effects of the impurities on the value of the k coeffi- cient and the sound attenuation on the reflection path due to the particle distribution are the two main factors that influence the mea- surement accuracy.

The analysis of flow characteristics in multi-channel heat meter based on fluid structure model

In this paper, a fluid structure interaction（FSI） model is used to study the internal flow field and the measurement performance of a multi-channel flow meter. The RNG k- ε turbulent model and the finite element model are used separately in the fluid domain and the structure domain to obtain the meter factor K and the deformation of the structure. The meter factor K of the flow meter is obtained through the FSI model at temperatures of 20 ℃, 50 ℃ and 80 ℃. The calculated results show the thermo expansion of the structure can significantly influence the measurement performance of the flow meter. The meter factor of the flow meter is also measured experimentally, and the comparison between the experimental results and the calculated results shows the validity of the fluid-structure interaction model. In order to reduce the measurement error, the meter factor K should be modified as the water temperature changes.

RESREARCH ON FLUID CHARACTERISTIC WITHIN THE ROTATING-WING HEAT METER

In order to improve the performance of rotating-wing heat meter and reduce the cost of development, the three dimensions numerical calculations of the intemal fluid characteristic within a heat meter are carried out based on the standard k-e turbulent mode, the finite volume method and SIMPLE algorithm. The speed field and pressure distribution within heat meter are analyzed according to the result of numerical calculation. The flux measurement accuracy and pressure loss of basal meter are forecasted according to the calculated results. The calculated results of the impeller＇s rotating speed are compared with experimental results and prove the validity of the calculated results. This researches shows the calculated results can forecast the performance parameters of basal meter and can provide great help for design of the heat meter.

The Application and Simulation of Fuzzy Adaptive PID in Household Heating Metering System

After heat is metered in each house unit,the heating system is regulated by variable flow.The temperature of the return w ater is controlled to regulate the flow to realize the temperature regulation.According to the characteristics of the temperature control w ith big inertia,pure time-delay and degeneration,a fuzzy adaptive PID controller is designed w ith the advantages of the fuzzy control and PID algorithm,and the simulation model is established according to the characteristics of heating metering system.Simulation results show that the fuzzy adaptive PID controller proposed has small overshoot,short oscillation cycle,high precision and strong anti-jamming capability in comparison w ith conventional PID controller,w hich could meet the requirement of the dynamic and steady-state performance of the heating process.

储热技术研究展望

近年来,储热技术被广泛认为是实现碳中和、碳达峰的一项关键技术备受关注。通过从CNKI、Web of Science等数据库中筛选储热技术相关文献,运用CiteSpace软件进行知识映射,展开系统分析、统计及可视化,绘制出储热技术研究力量合作网络图谱,展示该技术研究力量的分布与科研合作情况。同时针对关键词进行分析,总结储热技术的研究热点、研究前沿及发展趋势,指出相变储热和混合储热模式是未来研究的重点。针对储热材料稳定性差、使用寿命短,有机相变材料成本高、安全性低,系统设备初始造价高、成本回收期长等储热技术现存问题,从政策干预和市场需求角度提出了改进建议。

基于微型空间相机的红外加热笼仿真与设计

在航天器热控技术领域,常采用红外加热笼模拟各表面的到达外热流,但随着模拟表面特征尺寸的逐渐变小,需要重新评估该模拟方法的合理性和准确性。本文基于某微型空间相机,以对外热流最为敏感的散热面为研究对象,开展红外加热笼仿真分析与优化设计的研究。采用有限元法建立红外加热笼-黑片热流计的系统仿真模型,分析了传统红外加热笼控制方法对模拟表面总到达能量和热流密度均匀性的影响。基于上述结果,通过适当扩大加热笼尺寸和调整热流计粘贴位置,提高模拟表面的热流密度均匀性,保证总到达能量满足保守设计原则。对比分析得出,优化设计前后散热面热流密度的统计方差由102.0下降至27.0、均匀性提升效果显著。本文研究内容也可为其他空间微小表面外热流的准确模拟提供参考、借鉴。

基于平面热源-热流计法确定墙体热阻的影响因素分析

通过试验验证了平面热源-热流计法测试墙体热阻的可行性,并利用ANSYS软件建立墙体二维传热模型,通过模拟计算研究了平面热源加热面积、墙体两侧温差、测点布置和双面加热对墙体热阻值的影响。研究结果表明:墙体冷热侧温差越大,达到稳定传热时间越长,导致热阻值误差更大,建议墙体两侧温差在20℃时进行热阻测试;加热面积从0.3 m×0.3 m增大到1.2 m×1.2 m,使得一维传热区大小从0.11 m增加到0.27 m,热阻值误差降低至0.5%;测试测点应布置在靠近水泥砂浆层的区域;双面加热测试热阻值误差比单面加热低2%。

装配式被动房墙体传热系数测试与能耗模拟

以河北省保定市某装配式被动房为研究对象,采用热流计法对其东、西两侧围护结构主体部位的传热系数进行现场测试。基于测试结果,利用DeST能耗模拟软件模拟该建筑理论计算和实测传热系数下的全年能耗,得出理论计算与实测条件下利用传热系数计算的能耗偏差。结果表明该装配式被动房东、西两侧围护结构主体部位的实测传热系数相比.于理论计算值分别偏高偏差为103%。以期通过传热系数现场测试过程与能耗误差值的范围为今后进一步研究装配式被动建筑提供参考。

热计量仪表在采出水余热利用项目中的应用

采出水余热利用是一种重要的能源回收方式,热计量仪表在采出水余热利用项目中起关键作用。介绍了热计量仪表在采出水余热利用项目中的应用,分析了热计量仪表的分类、选型与安装使用要求,研究了测量误差源,提出了测量误差控制措施。通过介绍,对采出水余热利用项目中热计量仪表的使用、测量误差的减小、测量准确性和可靠性的提高具有参考价值。

套管式地埋管换热器节能特性的研究与应用

大庆油田进入开发后期存在着一定数量的废弃井,采用套管式地埋管换热器可以获取到废弃井的中深层的地热能。首先对废弃井转换为地热井的可行性进行分析,通过确定中深层地埋管换热方式,建立外入内出型传热计算模型并对废弃井结构改造。再具体分析大庆油田的地层土壤温度分布和确定边界条件,得出符合现实的理论计算公式。进一步分析套管式地埋管换热器取热评价指标与传热影响因素研究,得到流体流量和进口温度对传热影响因素,及循环流体进口温度对运行特性的影响对取热效率的影响规律。最后,通过对两种工况的废弃井现场试验,得到套管式地埋管换热器平均换热量为478.5 kWh。为利用大庆油田1700口废弃井的节能改造找到了一条切实可行的出路。

热计量供暖用户用热行为的实测与分析

热计量供暖模式下用户的用热行为对供热能耗有着重要影响。为了解我国北方地区热计量用户冬季用热行为现状,采用调研与实地测试相结合的方式,对天津市20个热计量用户的室内热环境、调节供暖末端、开关窗行为进行了研究。结果显示,在热计量供暖模式下用户的用热行为缺乏科学合理性,主要表现为:积极调节用户比例较低;冬季室内温度设定值较高,最高达29.38℃,开窗现象较为严重;热计量供暖的宣传力度不足,15.38%的用户表示“不知道如何调节”供暖末端阀门;温控阀存在调节作用失灵问题。53.85%的用户表示温控阀调节功能差。

集中供热末端调控及分户热计量系统的实现

实现分户热计量收费是我国供热体制改革的主要目标之一,有效的末端调控和合理的计量收费策略,是关系着供热体制改革能否顺利推进的重要因素。给出了一种基于ZigBee技术实现的供热末端调控系统,可根据场所人员活动规律自动进行分区、分时段调控室内温度,节约热力资源,提高供热效率,降低取暖费用。同时,给出了一种按照供热效果进行统计分析的模型,提出了一种改善分户热计量的新方法;以每栋楼的用热总量计算该栋楼的总供热费用,按照用户的供热面积、实际供热效果和用热量相结合,计算每个用户的热效值和整栋楼总热效值,分摊计算出每个用户的取暖费用,使每个用户的取暖费用真实地反映其用热效果。

单侧热绝缘热流计校准装置的研制

热流计是量化热能转移的仪器。为解决非对称平面热流计、热流传感器校准的难题,基于绝对法原理,对保护板法进行改进,建立一种单侧热绝缘的热流计校准装置,由主加热器、绝热层、保护加热器、功率输出系统、温度反馈调节系统和数据采集系统组成,装置可溯源至标准功率计。在400~1 000 W/m2范围内对装置进行验证,测试结果与传统保护板法热流计校准装置标定结果基本一致。根据测试结果评估电流源偏差、背向和侧向热损失、蓄热损失、测量重复性、面积不一致、装载方式对测量结果的影响。经过实验和分析,该装置的不确定度可以达到3%以内。