直热式空气源CO2热泵热水器系统运行特性试验研究

设计了一种直热式空气源CO₂热泵热水器系统,利用试验研究的方法研究了环境温度、气冷器冷却水入水温度及流量对系统性能的影响。试验结果表明:设计的空气源CO₂热泵热水器系统,其系统能效系数(COP_h)基本达到了国家标准;环境温度、气冷器冷却水入水温度以及流量对系统COP_h、系统制热量以及气冷器出水温度的影响显著。通过调节热泵热水器系统低温热源温度、气冷器冷却水入水温度及流量,可改善系统COP_h,提高系统制热量以及气冷器出水温度。     

热泵空气侧制热量测量方法的探讨

介绍了一种新的测量热泵制热量的方法－比率法,并和常用的两种方法进行了比较和讨论,并根据空气侧制热量的实际测量,在误差分析的基础上得出了结论。     

热力膨胀阀容量测试系统的设计

针对目前热力膨胀阀容量测试设备自动化程度低、测试精度低等缺点,依据国标QC/T663—2000的测试方法,设计了一套热力膨胀阀容量测试系统。在硬件设计上,该系统由开度测试装置、制冷剂流量测试装置和控制模块组成。在软件设计上,利用Visual Basic 6.0开发了一套可视化的测试软件。容量测试结果表明,该系统能较好地实现热力膨胀阀的容量测试,其测试精度达到了1.0%。     

空气源热泵热水机组压缩机矩形橡胶圈的有限元分析

通过理论推导,得出了影响空气源热泵热水机组矩形橡胶圈密封性能的主要参数.利用ANSYS建立了矩形橡胶密封圈密封结构的有限元模型,对影响矩形密封圈性能的因素进行了分析.结果表明,橡胶圈和密封槽的摩擦系数越大和橡胶材料弹性模量值越高,可以密封的压力值也越高;密封槽外壁与密封圈之间间隙值增加,密封结构的密封能力下降;矩形圈密封面处的接触压力随工作压力的增加而增大,且能够满足密封要求等有意义的结果.将有限元结果和理论分析结果相比较,验证了有限元方法的有效性.方法和结果对相关密封结构的设计具有一定的指导意义.     

A metrological analysis of the in-situ evaluation of the performance of a gas engine-driven heat pump

When evaluating the performance of a gas heat pump (GHP), in addition to tests at set points in an environmental chamber, field tests are often useful to verify also the GHP behaviour at real running conditions. Indeed, GHP comfort, maintainability, serviceability and installation procedure information is also obtained by means of an in-situ evaluation of its performance. In this work attention is paid firstly to the definition of the GHP performance parameters and to the consequent quantities to be measured and monitored. Therefore, this paper contains a short survey of measurement sensors suitable and convenient for an in-situ evaluation of GHP performance as well as the related metrological analysis (overall uncertainty evaluation). The present paper is only the first part of a wider study carried out by the authors. The experimental results of the in-situ performance evaluation of a small-size GHP will be presented in further publications.     

用热源叠加原理研究圆孔车削温度场

基于移动热源法及热源叠加原理,对圆孔车削温度场进行研究。提出局部温度场和总温度场的分析方法,推导出瞬时圆环热源温度场的描述方程,为圆孔工件的工程实际热问题提供了理论计算方法。     

Experimental study of ventilation performance of a novel integral-type air conditioner with heat recovery using R290

The leaking safety of air conditioner using R290 has been a research hotspot in recent years, one method to lower the risk of explosion after leakage is utilizing ventilation. For fresh air conditioner, it's common to use thermal anemometry and differential pressure flowmeters to measure ventilation flow rate. However, there is non-negligible error especially under low air volume flow rate conditions. In this paper, a novel integral-type air conditioner with heat recovery using R290 is proposed. And the relevant influencing parameters are analyzed and experimentally studied. The results show that tracer gas method is an effective way to measure ventilation flow rate, and the novel integral-type air conditioner can meet the needs of the ventilation standards. The air volume flow rates of indoor unit fan and outdoor unit fan are dominant factors affecting ventilation flow rate. The outlet area of exhaust air duct is more sensitive than the inlet area of fresh air duct in exerting influence on ventilation flow rate, while the indoor temperature has a mild impact on ventilation flow rate.     

地源热泵U型管换热器夏季工况试验分析

U型管换热器设计是土壤源热泵系统应用的关键,埋管深度、管内流速、土壤初始温度、运行模式等都是影响其性能的主要因素,利用上海地区所建设的不同埋深U型换热器(60m,90m)土壤源热泵试验装置,进行了夏季工况试验,测得热泵运行前土壤初始温度分布;测试了热泵机组间歇和连续运行时换热器的换热情况;还针对不同埋管内冷却水流速,测得到了单位孔深换热量,结果表明增加冷却水流速并不能一味地提高其每延米换热量,埋管内冷却水流速存在一个最佳值。     

R417A喷气增焓热泵热水器低温环境下的变流量特性分析

主要研究了R417A在喷气增焓空气源热泵系统中的替代应用,重点分析了低温环境下R417A替代R22的可行性。在对带闪蒸器的涡旋式压缩机喷气增焓热泵系统的热力学分析基础上,通过试验测试确定了R22和R417A 2种制冷剂在系统中的最佳充注量,随后在热水器一次加热循环条件下改变电子膨胀阀的开度以实现对循环补气量和系统流量的调节,分析了R22和R417A 2种系统在标准工况(20、15℃)、冬季工况(7℃、6℃)及低温工况(-7℃、-8℃)下的制热量、COP、吸排气压力及补气压力等试验数据,得出结论:喷气增焓空气源热泵系统处于最佳状态时,Pm≈(PePc)1/2;环境温度越低,R417A替代R22的优势越明显,即R417A更适合在低温环境下替代R22。     

地源热泵地下岩土热物性现场热响应测试方法研究

为了准确决定埋管现场岩土热物性值,建立了一套现场热响应测试装置,详细分析了测试原理、装置流程与数据处理方法,并应用所建装置与数据处理模型对一地源热泵工程进行了实测与分析,获得工程所在地土壤原始平均温度为17.7～17.9℃,土壤等效导热系数为1.78W/(m.K),等效容积比热容为2580kJ/(m3.K),单位长度钻孔热阻为0.163(m.K)/W。同时,为了提高测试精度,必须采用稳压电源及做好外露管道保温措施,数据处理上应舍弃测试初期10h的测试数据。试验验证表明,本文所建立的地下岩土热物性测试装置与分析模型是可行的,可应用于实际地源热泵工程中地下岩土热物性的测试。     

基于能量管理的多热源热水系统监测与控制关键技术研究

针对太阳能空气源热泵多热源热水系统(SAMW)运行参数检测与控制技术要求,以系统最优能效比为设计目标,提出了基于能量管理的可视化远程监测与控制系统设计方法.采用“PC+ PLC”为控制核心,以CenturyStar为平台,开发了系统监控软件,并构建了实验平台.测试结果表明:该监控系统运行稳定、可靠,能够对SAMW系统的工况参数进行自动监测、存储分析和过程控制,实现了SAMW系统对用能的合理调配,提高了系统热效率和技术文档管理水平.     

非线性系统源输入计算的键合图法

本文介绍了非线性系统源输入计算的键合图法,在考虑到独立贮能场与非独立贮能场并存在的情况下,推导出非线性系统源输入计算的统一公式,该方法具有格式化的特点,特别适合于在计算机上自动实现,最后给出具体算例。     

工程机械虚拟疲劳试验建模方法研究

通过分析工程机械结构的特殊性和疲劳特性的不同,提出了适合于工程机械整车虚拟疲劳试验的建模方法.在此基础上,以某工程机械为对象,在ADAMS中对其工作装置和底盘系统分别进行了建模.在随后的基于模态应力恢复的虚拟疲劳试验中,成功预测了该工程机械零部件的疲劳寿命,验证了该建模方法在工程机械可靠性验证试验中的有效性.     

A novel technique of using a thyristor driven pump as the final control element and flow indicator of a flow control loop

In the present paper, design of a flow control loop using a thyristor driven pump as final control element has been described. In this technique, the load current of a thyristor driven pump motor has been utilized as a mass flow sensing parameter of a fluid passing through a pipeline. This thyristor driven pump has been utilized as a final control element of a flow control loop and the speed of the pump has been selected as the manipulated variable. The non-linearity between the thyristor input signal and pump output has been eliminated by using a modified PID control technique with inverse derivative control action. Thus without using any conventional flow meter and control valve only the thyristor driven pump has been utilized both as the final control element and flow indicating device by using the proposed technique. The whole system has been designed, fabricated and tested by using tap water as the flowing liquid through a pipe line. The experimental results along with the theoretical analysis are compared and reported in the paper.     

A new visual tracking method for the analysis and characterization of jet flow

In this paper, we develop a new method to track the evolution of bubbles or droplets in jet flow. Proposed tracker fuses shape and motion features of the individually detected droplets in 2D shadow images and employs the Bhattacharyya distance to assign the closest one among candidate droplet regions. Distinct from the existing droplet tracking techniques in the literature, shapes of the target droplets were not assumed to be circles or ellipses. Instead evolving droplet contours were extracted and analyzed. Proposed tracking algorithm could achieve real time performance with 16 fps in MATLAB environment. Single, double and triple droplets were tracked with the average accuracy of 87%, 87% and 83%, respectively. Experimental results were then evaluated to explain the underlying jet phenomena.     

A subspace method for the blind extraction of a cyclostationary source: Application to rolling element bearing diagnostics

The need for blindly separating mixtures of signals arises in many signal processing applications. A class of solutions to this problem was recently proposed by the so-called blind source separation (BSS) techniques which rely on the sole knowledge of the number of independent sources present in the mixture. This paper deals with the case where the number of sources is unknown and statistical independence may not apply, but where there is only one signal of interest (SOI) to be separated, which is cyclostationary. It proposes a blind extraction method using a subspace decomposition of the observations via their cyclic statistics. This method is first developed for instantaneous mixtures and is then extended to the convolutive case in the frequency-domain where it does not suffer from the permutation problem as does classical BSS. Experiments on industrial data are finally performed and illustrate the high performance of the proposed method.