基于射线法超临界流体在拟临界点处热物性研究  

Study of the Thermophysical Characteristics of a Supercritical Fluid at the Quasi-critical Point Based on the Ray Method

作　　者：赵于[1] 毕勤成[1] 胡日查[1] 

机构地区：[1]西安交通大学动力工程多相流国家重点实验室,陕西西安710049

出　　处：《热能动力工程》2013年第3期252-256,323,共5页Journal of Engineering for Thermal Energy and Power

基　　金：国家重点基础研究发展计划(973计划)基金资助项目(2009CB219805)

摘　　要：在压力p=22～25 MPa,管内质量流速G=1 000～1 500 kg/(m2.s),流体温度t=200～420℃参数范围内,利用放射源(Cs-137)释放出的单束伽马射线采用动态测量方法对垂直上升管内超临界流体物性进行了比较系统的实验研究。在实验的基础上,针对射线本身灵敏度较高的特性,得出了环境温度、试验段与放射源距离两个特征参数对流体射线计数率(Count Rate)的影响,前者在较小的变化范围内对计数率影响不大,而距离也反映出了能量衰减也按负指数规律变化。23 MPa时质量流速为1 000、1 500 kg/(m2.s)的两条曲线计数率随温度的变化规律十分相似,数值与理论吻合度较好,23与25 MPa下的测量结果表明,压力对于伽马射线测量结果影响不大。When P = 22 to 25 MPa and the mass flow speed inside a tube G = 1 000 to 1 500 kg /(m2 s) and the temperature of the fluid t = 200 to 420 ℃,experimentally studied in a comparatively systematical way were the physical characteristics of the fluid in a critical flow inside a vertical riser by making use of a single beam of gamma ray and adopting the dynamic measurement method.On the basis of the test and in the light of the characteristics of the radioactive ray having a relatively high sensitivity,the influence of two characteristic parameters,i.e.the ambient temperature and distance between the test section and the radioactive source,on the radioactive ray count rate of the fluid was obtained.The former has little influence on the count rate in a relatively small variation range and the distance also reflects that the energy attenuation will follow a variation law of a negative exponent.The variation laws of both count rate curves with the temperature when the mass flow speed is 1 000 kg /(m2 s) and 1 500 kg /(m2 s) respectively at 23 MPa are very similar and the values thus obtained from the curves are in very good agreement with the theoretical ones.The measurements at 23 MPa and 25 MPa respectively show that the pressure has little influence on the measurements by making use of the gamma ray.

关 键 词：超临界流体 伽马射线密度计 计数率 放射源 临界压力区 

分 类 号：O359[理学—流体力学] O551[理学—力学]