可燃制冷剂R32室内空调器泄漏扩散特性的实验研究

制冷剂R32具有良好的环保特性和热工性能,但其可燃性限制了它的应用推广,因此需要对R32的安全性进行分析。实验研究了分体壁挂式空调用制冷剂R32在空调运行时,蒸发器不同泄漏位置和不同泄漏速度对室内R32浓度分布的影响,得出R32在空调运行时的泄漏扩散特性。研究表明:可燃性制冷剂R32在室内机蒸发器处发生泄漏时,泄漏过程可分为快速泄漏阶段和低速泄漏阶段;蒸发器出口泄漏比蒸发器入口泄漏危险性高;仅在蒸发器出口大流量泄漏时,室内机附近区域R32浓度最大值为16.79%,超过可燃下限(14.4%)16.6%。可燃浓度持续了22 s,存在着火的可能性,但概率较低;排风作用对各测点的浓度衰减影响强烈,可有效降低室内R32的浓度。     

工质泄漏对HCs商用制冷系统性能影响的理论分析

建立混合工质R290／R600a在系统中发生泄漏的模型，对系统存在泄漏点时系统内工质组分配比随不同泄漏情况发生时的变化进行分析，其后对相应的系统性能的变化进行了研究。     

泄漏管直径对R290空调器使用安全性的影响

易燃易爆特性是R290作为制冷剂应用于空调器的一大阻碍。本文通过模拟R290空调器的泄漏,得出空调器关机状态下发生泄漏后,对不同泄漏孔径的泄漏率及泄漏量与泄漏时间的关系。试验结果表明,对于安装高度为2.8 m,充注量为300 g的壁挂式空调器,泄漏孔径在0.7 mm以下时,使用空间的R290浓度是安全的;对于地面摆放的整体式空调器,泄漏孔径为0.2 mm及以上时,在高度0.75 m以下的局部空间会出现R290浓度超标。     

R290家用空调器安全性实验研究

针对R290家用空调器可能出现的各种危险情况,进行各类模拟实验研究。研究结果表明:R290空调器系统内部出现的点火源不会引爆R290;系统泄漏的R290在空调器内聚集,在遇到点火源的情况下R290会发生爆炸,但爆炸不对空调器造成损伤;泄漏在使用空间的R290,只有在泄漏量足够大且存在点火源的情况下,才有R290被点燃的可能。     

R290分体式空调器室内泄漏安全性实验研究

采用实验研究的方法,模拟出房间空调器使用中可能出现的各种制冷剂泄漏的情况,对0.5 mm和4 mm两种泄漏孔径、260 g和350 g两种充灌量以及在室内外机连接管上加装电磁阀开关等不同情况下R290制冷剂在空调房间内的分布规律进行了实验研究。实验结果表明房间空调器内制冷剂充灌量和泄漏口径的大小对房间安全性有着很大的影响,而在室内外机连接管上加装电磁阀可以有效地减缓R290的泄漏速率,提高R290分体式空调器的安全性。     

R290/R600a混合工质制冷系统泄漏点对系统性能的影响

混合工质在不同位置的泄漏所引起的系统中工质对组分比例发生变化会对制冷系统的性能产生很大影响。根据混合法则,从理论上研究R290/R600a工质对泄漏率在5%~40%范围内8种泄漏率条件下,系统工质对组分变化的规律。按照理论计算的要求建立制冷系统工质泄漏实验台,对实验台在4种泄漏率条件下的蒸发压力、冷凝压力、制冷量和COP进行研究。计算和实验结果表明,在蒸发器出口和冷凝器入口处的泄漏使低沸点组分R290在工质对中的比例增大,系统制冷量增加且COP下降;在蒸发器入口和冷凝器出口处的泄漏使高沸点组分R600a在工质对中的比例增大,系统制冷量下降且COP上升。     

多联机室内机电子膨胀阀制冷剂内泄漏对制冷综合性能系数的影响

本文研究了多联机室内机电子膨胀阀(EEV)内泄漏对制冷综合部分负荷性能系数(IPLV)的影响。本文进行了两组实验研究,研究结果表明:第一组实验时,有一台室内机膨胀阀始终存在内泄漏,最终IPLV为4.53;第二组实验时,关闭的内机膨胀阀没有明显内泄漏,最终IPLV为4.72,比第一组数据提高了4.2%。从实验结果看出,部分负荷下不开机的室内机膨胀阀存在内泄漏,会导致测试的部分负荷制冷量下降,最终导致多联机IPLV降低。因此在进行多联机IPLV测试时需要关注室内机电子膨胀阀的内泄漏。     

R290家用空调器泄漏安全性实验研究

利用模拟实验,对R290家用空调器在使用过程中发生泄漏的情况进行模拟,研究制冷剂的分布及遇点火源燃烧或爆炸的情况。研究结果表明,空调器运行过程中发生泄漏不会产生危险;当空调器处于关机状态,且泄漏率小于80g/min时,空调器使用空间相对安全。     

采用R290和R32的家用空调器全生命周期碳排放研究

运用全生命周期评价方法分别对R290和R32分体式家用空调进行碳排放对比研究.结果 表明:R290空调生命周期碳排放约为R32空调的85％;在原材料获取和回收处置阶段,虽然R32在所有材料中重量占比不到1.1％,却产生了高达78％的碳排放,说明用R290替代R32具有显著的环境效应.虽然提高制冷剂回收率和降低泄漏率有利...     

R290制冷剂在商用冷柜上的应用研究

制冷剂R290作为一种环保制冷剂,已在小型全封闭系统中逐渐推广应用。R290作为一种可行的制冷剂用在商用冷柜上具有良好的能效,但对于丙烷的易燃性必须采取切实可行的措施。本文根据长期的设计和应用经验,在分析了R290制冷剂应用特性的基础上,给出了R290的工作压力、充注量等应用特性,给出了与之匹配的材料选择、系统节流装置的选用,在冷柜系统及结构设计方面给出了控制制冷剂泄漏量、避免泄露的制冷剂聚集、避免出现点火源、避免点火源与可燃源共同存在等安全措施。     

Indoor leakage test for safety of R-290 split type room air conditioner

The selection of alternative refrigerants for the room air conditioner (RAC) industry has, in recent years, been a significant challenge. According to the literature, flammable refrigerants may be one of the potential options. In particular, R-290 (propane) has a major possibility to be the chosen working fluid for the next generation of RACs because of its environmental and unique thermo-physical properties. However, its use is hindered by its flammability and the resulting concerns on safety. In this paper, the safety implications of using R-290 are examined through evaluating the effects of certain variables upon the concentrations of leaked refrigerant into a room. R-290 is leaked under different scenarios and its distributions inside room are measured. The results are interpreted with respect to the requirements of RAC safety standards, where it is found that the requirements may need more detailed verifying for wall type RAC.     

Experimental research on the explosion characteristics in the indoor and outdoor units of a split air conditioner using the R290 refrigerant

Currently, the most common refrigerants used in household split air conditioners are R22 and R410A. Due to environmental concerns, benign options such as R290 (propane) are under consideration as an alternative. However, R290 is flammable, which poses additional fire and explosion risks. The ignition source and location of the leak that may appear within the indoor and outdoor units were analysed. A series of experiments were carried out to better understand the ignition hazard. The explosion characteristics associated with the indoor and outdoor units were studied whereby the overpressure arising from ignition of R290 was measured at different locations. According to the internal volume of indoor and outdoor units, the amount of R290 that should be deposited inside the indoor and the outdoor units is 7 g and 16 g respectively, to form a stoichiometric concentration. The explosion overpressure in the indoor and outdoor units is sufficiently low so as to not damage the air conditioner system. However, if R290 is ignited during the leak, the indoor or outdoor unit will be burned.     

Research on the flammability hazards of an air conditioner using refrigerant R-290

Currently, hydrochlorofluorocarbons and hydrofluorocarbons are the most common refrigerants used for air conditioners. Due to ozone depletion and high global warming potential, environmentally benign options such as hydrocarbons are under consideration. Whilst R-290 (propane) has favourable system performance, environmental characteristics and cost, it is a flammable substance, thereby posing additional risks. This study addresses the associated flammability concerns through a number of risk-related sub-studies. These include evaluating the distribution of R-290 following a leak in room, overpressure arising from ignition of a flammable mixture, severity of a secondary fire and total heat release rate in the event of an external fire imposed upon an R-290 system. It is found that the possibility of refrigerant existing within the flammable range is limited only to the region very close to the indoor unit. Besides, low overpressures in the event of ignition and limited additional heat flux in the event of external fire were registered.     

R1234yf整车汽车空调泄漏扩散研究

新能源电动汽车热管理系统与传统乘用车不同,对采用热泵空调系统并利用液冷冷却电池的新能源电动汽车,制冷剂充注量比传统汽车空调增加了400～800 g.若使用可燃制冷剂,泄漏扩散至乘员舱,燃烧风险将增大.本文通过数值模拟对R1234yf制冷剂在蒸发器破损泄漏随送风进入乘员舱后的浓度变化过程和最高浓度进行了动态监测.结果表明...     

Equipment design and installation features to disperse refrigerant releases in rooms—part II: determination of procedures

There is always a risk of leakage of refrigerant into a room that refrigeration and air conditioning equipment occupies. Mitigation of build-up of flammable concentrations from leakage through appropriate equipment construction and installation criteria minimises the potential for ignition. This paper is the first part of an investigation into design and installation measures to disperse leaked flammable refrigerant. It mainly describes the experiments and provides an analysis of the data. The paper describes a purpose built test facility, which was used to carry out experiments to study the dispersion of carbon dioxide to simulate leaked refrigerant. By measuring carbon dioxide concentrations and making flow visualisation, the effects of parameters such as equipment airflow and installation height were observed. The observed trends provide guidance for designing refrigeration and air conditioning equipment, which helps to ensure rapid dispersion of flammable concentrations in the event of a leak of flammable refrigerant. A second paper (Part II) discussed the development of numerical correlations, which are used in the resulting design procedure.     

Detection of capacitor electrolyte residues with FTIR in failure analysis

Detecting leakage from liquid aluminum electrolytic capacitors is not easy. Typically there is very little evidence of leakage because the electrolyte is volatile and leaves behind only trace residues. Liquid aluminum electrolytic capacitors are known to cause catastrophic failures where there is complete loss of functionality due to a short or open circuit. In the study presented in this paper, printed circuit board assemblies from a test and measurement system used in a clean room environment failed. Two units failed, causing burning in a particular area on the printed circuit board assembly. The failure area included several surface mount liquid aluminum electrolytic capacitors, and several others were mounted very close to the burnt region. A study was initiated to evaluate the cause of failure. Careful optical inspection revealed some residues on the outer side of the rubber seals of two of the electrolytic capacitors. Through using Fourier transform infrared analysis and a process of experimentation and analysis, it was determined that the residues were produced by liquid electrolyte that leaked out of the capacitor at some point in the field. The leaked electrolyte that came out of the capacitor was believed to be the cause of failure that led to the burning of the printed circuit board assembly.     

R32制冷剂泄漏位置对浓度分布与室内安全性的实验研究

本文通过实验研究的方法,对比分析了R32制冷剂在泄漏量为3.6 kg,不同泄漏位置时,R32气体在室内不同平面的浓度扩散规律,并通过典型平面首次达到可燃下限（LFL）的时间和可燃风险时间来分析室内的安全性影响。结果表明：随着泄漏位置高度的增加,制冷剂浓度扩散速率在沿高度方向上逐渐趋于一致,浓度上升速率和浓度下降速率分别保持在约0.5%/min和0.06%/min。当制冷剂气体从房间上部水平方向泄漏改变为垂直向下泄漏时,泄漏口附近平面处最大浓度及浓度扩散速率均减小约50%,可燃危险时间减少了约78%;房间下部的的可燃危险时间随泄漏位置高度的升高而逐渐增大。当泄漏位置位于房间上部和顶部时,房间底部区域最先达到LFL值,其余位置处泄漏口附近平面处最先达到LFL值。