多联式空调压缩机故障原因分析

本文探讨了多联式空调压缩机常见故障,分析了各故障的原因,并提出预防措施。     

数码涡旋与变频涡旋空调系统性能比较

通过对变频涡旋压缩机和数码涡旋压缩机从工作原理上进行分析,指出了各自适合的应用范围;对当前市场上流行的变频和数码多联空调机组进行了综合比较,阐述了这两种空调机组各自的优势和不足;指出了进一步研究和推广两种空调系统需要解决的问题.     

数码涡旋与变频多联式空调系统夏季运行特性的比较

通过对数码涡旋多联式空调系统的夏季运行状况的实验研究,获得了数码涡旋多联式空调系统中各台室内机制冷量随时间的变化规律;指出室内机的运行率与平均负荷率相关,分析了系统总制冷量和压缩机输入功率在工作过程中的运行特性.此外,结合已有的变频多联式空调系统相应的研究结果,对两者进行了比较,指出了两者之间的不同点.     

浅议格力GMV数码多联空调机组

本文首先介绍了数码涡旋压缩机原理,然后阐述格力GMV数码多联空调机组运行原理、机组特点和优势.     

多联空调机组模糊控制探讨

模糊控制策略对空调性能起着关键的决定作用,多联空调机组模糊控制需要综合考虑多台室内机和室外机的工作情况,结合多机的温差、温度变化率等因素决定压缩机工作频率和制冷剂流量。本文提出一种模糊控制简化方法,通过实验认为该模糊控制方法在空调室内温度变化大时,控制系统响应快;温差较小时能稳定运行,空调机组运行动静态性能较好,能满足舒适性空调控制要求。     

制冷剂散热技术在变频水源多联式空调机组中的应用

为了改善变频水源多联式空调机组中压缩机变频模块的散热效果,提出一种制冷剂散热技术,通过试验对比该技术与常规散热技术用于变频水源多联式空调机组的差异。结果表明,二者制冷性能基本相同,前者制热性能比后者有一定的提升,采用制冷剂散热技术的机组可维持变频模块温度的稳定性(45～70℃);采用制冷剂散热技术的机组外围钣金不需要开散热孔,因此机组的噪声有所降低。     

多联式空调（热泵）机组在南方地区的应用

阐述了多联式空调（热泵）机组的发展历程,介绍了多联式空调（热泵）机组在我国南方地区的应用情况,分析了多联式空调（热泵）机组在中国南方地区迅速发展的原因,指出多联式空调（热泵）机组应用的部分要点。     

多联式空调（热泵）机组室外机压缩机四倍频噪声波动原因分析及改善

某型号多联式空调(热泵)机组室外机压缩机四倍频噪声存在波动，最高在60 dB(A)以上，影响产品舒适性。为了分析室外机压缩机四倍频噪声波动的原因，对压缩机结构噪声传递路径上各节点的振动特性进行测试，同时分析压缩机单体振动和噪声特性，确定室外机压缩机四倍频噪声波动是由压缩机单体振动波动引起。分析压缩机内部结构参数及噪声数据发现，定转子间隙是影响压缩机四倍频噪声的关键参数。改善压缩机生产和检验工艺，将定转子间隙控制在0.48 mm以上，室外机压缩机四倍频噪声可以控制在50 dB(A)以内。     

浅谈数码涡旋技术在多联式中央空调的应用

通过对数码涡旋技术的分析,讨论了该技术在多联空调中的应用价值,举例说明在钢铁行业中多联空调的优点.     

多联式空调(热泵)机组压缩机回油问题研究

压缩机的回油问题是多联式空调(热泵)机组设计中的关键问题之一,特别是在低温工况下,压缩机启动过程很容易出现空油现象,使得机组可靠运行存在较大风险。本文从控制和系统部件2个方面出发,对压缩机不同工况下出现的空油现象进行分析。试验结果表明,降低启动阶段压缩机升频速率、调整电子膨胀阀开度、减小气液分离器回油孔径、增大油分离器容积等均可改善空油现象,实际工程中可根据具体情况选择合适的改善方案。     

A Bridge to the World--Congratulations to the launch of China Standardization

After years of expedition in the journey of standardization, we've conquered milesand miles to be standing here.     

量传比变化对检定压力变送器的影响

本文说明了量传比变化对检定压力变送器的影响及实例评定.     

Response to Letter to the Editor

Sir, Response to ‘Are all photon radiations similar in largeabsorbers?—A comparison of electron spectra’ byA. M. Kellerer and H. Roos When the ICRP adopted a quality factor—and subsequentlya radiation weighting factor—that gives equal weight todifferent photon radiations, it did not, necessarily imply thatequal     

二次空气量对超细粉体分级机细料得率的影响分析

本文从理论上分析颗粒在分级机内运动分布,将分级空间划分为“分极内区”和“分级外区”,给出分级机细料得率定义,并指出影响分级得率的主要因素,着重提出在不影响细粒粒径的前提下,在分级机底部引入二次空气,并利用实验证实,当二次空气量补引入后,分级机分级得率可增大到７０％以上．     

浅谈仪器收发的重要性及要求

本文对计量仪器收发的重要性作了具体分析,对管理上存在的问题和收发人员的素质提出了更高要求.     

Aerosol formation due to a dental procedure: insights leading to the transmission of diseases to the environment

As a result of the outbreak and diffusion of SARS-CoV-2, there has been a directive to advance medical working conditions. In dentistry, airborne particles are produced through aerosolization facilitated by dental instruments. To develop methods for reducing the risks of infection in a confined environment, understanding the nature and dynamics of these droplets is imperative and timely. This study provides the first evidence of aerosol droplet formation from an ultrasonic scalar under simulated oral conditions. State-of-the-art optical flow tracking velocimetry and shadowgraphy measurements are employed to quantitatively measure the flow velocity, trajectories and size distribution of droplets produced during a dental scaling process. The droplet sizes are found to vary from 5 µm to 300 µm; these correspond to droplet nuclei that could carry viruses. The droplet velocities also vary between 1.3 m s⁻¹ and 2.6 m s⁻¹. These observations confirm the critical role of aerosols in the transmission of disease during dental procedures, and provide invaluable knowledge for developing protocols and procedures to ensure the safety of both dentists and patients.     

Experimental protocol to determine the ability of PET to crystallise

PET [poly(ethylene terephtalate)] is a semi-crystalline thermoplastic that is very suitable for forming processes and is widely used in various technologies. For specific applications, it is necessary to avoid the crystallization of the material by quenching from the melting state while for other applications this crystallization is required. It follows that the ability of PET to crystallize could be a crucial industrial problem, particularly because of the large range of PET proposed by plastic suppliers. This work deals with a calorimetric method able to discriminate this aptitude between various PET rapidly and to give a criterion of crystallizability.     

Application of the parameter of defect resistance to the evaluation of the susceptibility of structural steels to brittle fracture

We present the results of low-temperature tests for impact toughness and uniaxial tension of 10 KhSND and 12KhN3… shipbuilding steels. We demonstrate the applicability of the parameter of defect resistance D₂ (suggested earlier) to the comparative characterization and classification of steels according to their toughness. Translated from Problemy Prochnosti, No. 3, pp. 96–103, May–June, 1997.