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R-134a/Distilled Water Spray Droplets Size(d32)Distribution and Velocity/Temperature Measurements

Water and R-134a sprays as they impinge on the flat endplate of a circle are studied experimentally. In order to optimize water and R-134a sprays cooling efficiency, a detailed characterization and understanding of the spray formation is essentially needed. The effects of the jet exit velocity and Weber number on spray segregation are investigated. An optical image system was used to quantify the droplet size and distribution. LDV measurements were used to characterize the local velocity and velocity fluctuation distribution from a commercial available nozzle in both axial and radial directions. It is found in the water spray that local mean droplet diameter (SMD) decreases as jet exit velocity increases and as jet proceeds further downstream as well. Furthermore, the SMD and radial velocity are found to be the largest at the outer edges of the water spray. In contrast, the radial velocity is found to be the smallest at the outer edges of the R-134a spray. The SMD and radial velocity continuously decrease across both the water spray and R-134a spray toward the jet axis; while the corresponding axial velocity is the maximum there. Moreover, the R-134a spray jet heat transfer in non-boiling regime was shown to be dependent on the velocity of the impinging jets in terms of Weber number and other related parameters which are in good agreement with those of previous studies.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0713105-110240
Date13 July 2005
CreatorsTien, Chi-Hsun
ContributorsC.J. Ho, Shou-Shing Hsieh, Chin-Chia Su
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0713105-110240
Rightsoff_campus_withheld, Copyright information available at source archive

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