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。     

可燃气体检测报警器的应用

可燃气体检测报警器由探测器与报警仪表构成 ,主要用于可燃气体产生、使用、储存的室内、外危险场所 ,监测泄漏情况。当被测场所空气中存在可燃气体时 ,探测器将感知信号传输到报警仪表。仪表显示出可燃气体爆炸下限的百分比浓度值 ,当可燃气体浓度超过报警设定值时发出声光报警信号 ,提示值班人员采取安全措施 ,避免燃爆事故发生。固定定装式检测器一经安装就位 ,它所处的位置就犹如一个监视岗哨 ,其所及范围只限于视野所及。对检测器而言 ,则对接受可燃气的浓度作出反应 ,所以选定安装场所的问题十分重要。对于要监测一个三维空间且规模较…     

可燃气体检测报警器的应用及布点安装位置的选择

可燃气体检测报警器由探测器与报警仪表构成 ,主要用于可燃气体产生、使用、储存的室内外危险场所 ,可监测泄漏情况。当被测场所空气中存在可燃气体时 ,探测器将感知信号传输到报警仪表 ,仪表显示出可燃气体爆炸下限的百分比浓度值。当可燃气体浓度超过报警设定值时发出声光报警信号提示 ,值班人员采取安全措施 ,避免燃爆事故发生。固定安装式检测器一经安装就位 ,它所处的位置就犹如一个监视岗哨 ,其所及范围只限于视野所及 ,对检测器而言则视接受可燃气的浓度作出反应 ,所以选定安装场所十分重要。对于要监测一个三维空间且规模较大的工业…     

R32在模拟空间的泄漏点火试验研究

建立R32泄漏点火模拟试验室。开展R32在不同泄漏速率下的自由沉降试验,发现R32在垂直高度方向上存在明显的浓度梯度,且泄漏过程中在距地面10 cm处的3个测点的R32浓度在燃烧上下限之间的时间均为6 min左右,在靠近地面位置的R32浓度接近100%;开展R32在一定速率泄漏时遇到蜡烛明火后的燃烧特性试验,发现改变R32泄漏位置、蜡烛位置和数量、点火方式等,R32均不会发生火焰蔓延现象。     

分体式空调器使用R290作为制冷剂的泄漏研究

HCFCs和HFCs类制冷剂存在ODP和GWP值比较高的缺点。R290具有良好的环保性能,但是其易燃易爆的特点是其使用的最大阻碍。为确定室内机发生泄漏所形成的燃爆范围,开展实体实验,研究了在不同房间面积、不同泄漏位置,不同泄漏速度条件下,R290泄漏到室内浓度分布情况。结果表明,室内机发生泄漏时,仅在其附近可能形成燃爆区域。燃爆范围仅存在于泄漏过程中,一旦泄漏停止后,燃爆范围会迅速消失。     

宿迁市计量测试所对安全防护类计量器具可燃气体报警器进行集中检定

正近日,宿迁市计量测试所对全市辖区内10家危化品企业在用的安全防护类计量器具可燃气体报警器进行了集中检定。可燃气体报警器由探测器与报警控制器构成,广泛应用于石油、燃气、化工等存在可燃气体的石油化工企业中,用以检测室内外危险场所的气体泄漏情况,是保证生产和人身安全的重要仪器。当可燃气体报警器检测到气体浓度达到报警点时,可燃气体报警器就     

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...     

火箭发射场液氢泄漏扩散特征CFD模拟分析

通过CFD软件并结合自定义函数(UDF)功能对不同工况下的液氢泄漏扩散过程进行模拟并进行分析,不同的泄漏压力、泄漏孔位置、外部来流风向对液氢泄漏扩散具有重要的影响。分析数值模拟结果表明:随着压力的增加,液氢低温危害区以及氢气可燃区面积增大;泄漏口距离地面越近,整个氢气浓度分布的可燃区面积增大;上部吹风有利于氢气的稀释进而减少泄漏危害性。     

可燃气体报警器的应用及常见故障处理

可燃气体报警器由探测器与报警仪构成。广泛应用于石油、燃气、化工、油库等存在可燃气体的石油化工行业,用以检测室内外危险场所的泄漏情况,是保证生产和人身安全的重要仪器。当被测场所存在可燃气体时,探测器降气信号转换成电压信号或电流信号传送到报警仪表,仪器显示出可燃气体爆炸下限的百分比浓度值。当可燃气体浓度超过报警设定值时发出声光报警信号提示．值班人员及时采取安全措施,避免燃爆事故发生。     

可燃气体报警器的应用和常见故障处理

可燃气体报警器由探测器与报警仪构成,广泛应用于石油、燃气、化工、油库等存在可燃气体的石油化工行业,用以检测室内外危险场所的泄漏情况,是保证生产和人身安全的重要仪器。当被测场所存在可燃气体时,探测器将气信号转换成电压信号或电流信号传送到报警仪表,仪器显示出可燃气体爆炸下限的百分比浓度值。当可燃气体浓度超过报警设定值时发出声光报警信号提示,值班人员及时采取安全措施,避免燃爆事故发生。     

Full-scale experiment to evaluate the combustion hazard of refrigerants with low global-warming potential in a conceivable accident scenario

A full-scale experiment based on a realistic foreseeable leak accident scenario was conducted with two refrigerants with low global-warming potential (GWP). The assumed accident scenario was that of the leakage of low-GWP refrigerant from a variable-refrigerant-flow air-conditioning system into a general narrow karaoke space, with an open flame present in the region where the low-GWP refrigerant accumulated. Even in the absence of mechanical ventilation, neither ignition nor flame propagation occurred if the amount of “LFL equivalent”, that the calculated interior concentration corresponded to the lower flammable limit, was leaked and mixed sufficiently. Even when the leak amount was “UFL equivalent”, that the calculated interior concentration corresponded to the upper flammable limit, ignition and flame propagation could be prevented by means of a suitable ventilation system. The maximum pressure rise was 4–6 kPa. Finally, no transition from laminar combustion to turbulent combustion was observed.     

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.     

全卤代烃CF3I和CF4的阻燃能力实验

实验测量了多组含CF3I或CF4的制冷剂混合物的爆炸极限,绘制了爆炸极限数据曲线和数据表格,确定了不同摩尔比例制冷剂混合物的爆炸三角区和临界爆炸比.参照文献中已得出的部分实验结论,通过分析比较得出全卤代烃CF3I和CF4比N2、CO2等"惰性气体"以及含氢卤代烃R134、R134a、R125等更能有效抑制可燃制冷剂的燃...     

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。     

Safety testing of domestic refrigerators using flammable refrigerants

A domestic refrigerator with flammable refrigerant was tested according to the methods specified in the safety Standard, IEC/EN 60335-2-24.The tests were all carried out as specified in the Standard. Some of the test specifications were straightforward but some tests ambiguous and gave different results depending on the method used.The method of testing the protection of the refrigeration circuit does not simulate the type of damage that could be caused by defrosting with a knife. The simulation of a leak in a protected cooling circuit is not specifically defined. The concentration of refrigerant in the compartment with the protected circuit depended on the method used to prevent foam from entering the capillary tube (either 140 or 17,500 ppm). The position and direction of a simulated leak in the compressor compartment is not specified in the Standard but had a significant effect on the concentration distribution (643–240,000 ppm). The sudden release of an accumulation of refrigerant caused peaks in the concentration that could not be measured by the response time of the measuring instrument specified (28,500–8000 ppm in 1.5 s).     

三元混合工质R32/R125/R134a的组分浓度变化特征线及其对循环性能的影响

混合工质的充灌或泄漏都可能造成制冷空调系统中工质组分浓度发生变化,影响系统性能.本文研究了R407系列混合工质组分浓度变化的特性,获得了组分浓度变化的特征线,并研究了当组分浓度沿特征线变化时,制冷空调系统循环性能的变化规律,可用于指导采用R407工质的系统设计.     

Experimental research on the performance of the diffusion absorption refrigerator with mixed fluoride refrigerants

A diffusion absorption refrigerator (DAR) operating with mixed fluoride refrigerants was built to obtain low refrigerating temperature at low generating temperature. Two groups of mixed fluoride refrigerants, R23/R134a and R23/R32/R134a, were tested experimentally. The N,N-dimethylformamide (DMF) and helium were used as the absorbent and inert gas, respectively. For the DAR with R23/R134a, the refrigerating temperature was not obviously influenced by the concentration of R23 in the mixed refrigerant vapor or the amounts of helium. For the DAR with R23/R32/R134a, an optimal concentration of R32 in the mixed refrigerant vapor and an optimal pressure were both found to achieve the lowest refrigerating temperature which was −28.8 °C at a generating temperature of 106.9 °C, and a refrigerating temperature of −23.7 °C was obtained at an extraordinarily low generating temperature of 83.3 °C. It showed the promising potentials of DAR operating with mixed fluoride refrigerants in applications of low temperature refrigeration and efficient utilization of the low-grade thermal energy.     

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.