有限空间内制冷剂掠遇障碍物的扩散分布特性和燃爆区域研究

Diffusion Distribution Characteristics and Flammable Areas of Refrigerants Encountering Obstacles in Confined Spaces

制冷剂泄漏至有限空间内掠遇障碍物后会出现不同的扩散和分布特性,分析制冷剂物性对于制冷剂掠遇障碍物后扩散过程和分布的影响,对可燃制冷剂泄漏所形成燃爆区域的预测具有重大意义。选择R717、R290、R32和R1234yf为泄漏制冷剂,探究制冷剂泄漏至有限空间后掠遇较高和较低两种类型障碍物的扩散和分布特性,详细分析工质物性参数对制冷剂扩散过程及燃爆区域的影响。结果发现:制冷剂泄漏后掠遇较高的障碍物会产生不同程度的刚性膨胀,密度小的制冷剂迅速朝着与泄漏方向相反的方向运动,并在空间顶部聚集,密度大的制冷剂沿着障碍物表面向地面运动。随着测点高度降低,R717的质量分数从2.04%降至0.024%,R1234yf的质量分数从0.192%增至1.64%。泄漏孔下方R290和R744的质量分数分别为0.92%和1.27%,制冷剂密度接近时,黏度大的制冷剂质量分数更高。形成的可燃区域主要存在于较高障碍物的上方,随着泄漏量增大,燃爆区域在y-z截面上逐渐向地面延伸;制冷剂泄漏后掠遇较低障碍物主要在泄漏孔下方堆积,并沿着较低障碍物的表面逐渐向空间其他低质量分数区域扩散。密度较小的制冷剂分布较为均匀,随着制冷剂密度增大,制冷剂在泄漏孔下方堆积显著。竖直方向上,随着测点高度降低,R1234yf和R717的质量分数分别从0.066%和1%增至2.12%和1.14%。燃爆区域主要存在于泄漏孔下方障碍物与墙体围成的角落,随着制冷剂泄漏量增大,燃爆区域沿着较低障碍物的表面向地面延伸。

Refrigerants exhibit different diffusion and distribution characteristics when they encounter obstacles after leaking into confined spaces.The influence of the thermophysical parameters of refrigerants on their diffusion and distribution after encountering obstacles thus needs to be analyzed to facilitate the prediction of flammable areas during the leakage of flammable refrigerant.In this study,R717,R290,R32,and R1234yf were selected.The diffusion and distribution characteristics of the refrigerants encountering high and low obstacles in a confined space were investigated,and the influence of the thermophysical parameters of the refrigerants on the diffusion process and flammable area were analyzed in detail.The results indicated different patterns of rigid collision when the refrigerants encountered a high obstacle after leakage.Refrigerant with lower densities diffused rapidly in the direction opposite to the leakage direction and gathered at the top of the space,whereas refrigerants with higher densities diffused along the surface of the obstacle to the ground.As the height of the measurement point decreased,the mass concentration of R717 decreased from 2.04%to 0.024%,and the mass concentration of R1234yf increased from 0.192%to 1.64%.The mass concentrations of R290 and R744 below the leakage hole were 0.92%and 1.27%,respectively.When the densities of the refrigerants were similar,the refrigerant with a higher viscosity had a higher mass concentration.The flammable area was primarily located above the high obstacle,and as the refrigerant leakage increased,the flammable area in the y-z section of the space gradually extended to the ground.When refrigerants encountered low obstacles after leakage,they accumulated below the leakage hole and gradually diffused to other low mass concentration areas of the space along the surface of the low obstacle.The distribution of refrigerants with lower densities was more uniform.As the densities of refrigerants increased,they accumulated significantly below the leakage hole.As the height of the measurement point decreased,the mass concentrations of R1234yf and R717 increased from 0.066%and 1%to 2.12%and 1.14%,respectively.The flammable area was mainly located in the corner surrounded by the low obstacle and the wall below the leakage hole.With an increase in refrigerant leakage,the flammable area extended to the ground along the surface of the obstacle.