Choked Flow Characteristics of Subcritical Refrigerant Flowing Through Converging-Diverging Nozzles

Entropy

Zhenying Zhang²  Lili Tian¹  Lirui Tong² 

[1] Department of Foreign Languages, Tangshan College, Tangshan 063000, China; E-Mail:;Institute of Architecture and Civil Engineering, Hebei United University, Tangshan 063009, China; E-Mails:

关键词: refrigeration system;    nozzle;    choked flow;    critical mass flow rate;   

DOI  :  10.3390/e16115810

来源: mdpi

【 摘 要 】

This paper presents the experimental results the choked flow characteristics of a subcritical refrigerant through a converging-diverging nozzle. A test nozzle with a throat diameter of 2 mm was designed and developed. The influence of operating conditions on the choked flow characteristics, i.e., the pressure profile and mass flow rate under choked flow conditions are investigated. The results indicate that the choked flow occurs in the flow of subcritical refrigerant through nozzles under the normal working conditions of air-conditioners or heat pumps. The pressure drop near the throat is about 80% of the total pressure drop through the nozzle. The critical mass flux is about 19,800 ~ 24,000 kg/(s·m²). The critical mass flow rate increases with increasing the upstream pressure and subcooling. Furthermore, the relative errors between the model predictions and the experimental results for the critical mass flux are also presented. It is found that the deviations of the predictions for homogeneous equilibrium model and Henry-Fauske model from the experimental values are −35% ~ 5% and 15% ~ 35%, respectively.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland