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An Experimental Study of Jet Impingement and Spray Cooling

An experimental investigation was carried out to examine the jet impingement and spray cooling. There are three parts in this study. The first part was investigated the effects of jet impinging positions on heat transfer from rib-roughened (square and semi-circular) channels with rotational speeds of up to 600 rpm. Results were presented for rotating number (Ro), jet impinging position, surface roughness and jet Reynolds number effects on local Nusselt numbers. The second part was studied instantaneous velocity fields for a single slot liquid microjet using MPIV. The streamwise mean velocity fields and flow evolutions with six nozzle-to-target spacing ratios of 0.86, 1, 1.2, 1.5, 2 and 3 and for eight jet Reynolds numbers Re of 50, 100, 150, 200, 250, 300, 350 and 400 were measured and calculated. The third part was investigated the flow field and heat transfer mechanism for water spray and cryogen (R-134a) spray cooling. An optical image system was used to quantify the droplet size and distribution and Laser Doppler Velocimetry (LDV) measurements to obtain the local velocity distributions. The effects of mass flow rate and average droplet velocity, and spray exit-to-target distance on the surface heat flux including the corresponding critical heat flux (CHF) were explored for R-134a which may enhance the current cryogen spray cooling (CSC) technique that assists laser therapy of dermatoses.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0720106-130031
Date20 July 2006
CreatorsTsai, Huand-Hsiu
ContributorsChao-Kuang Chen, Shou-Shing Hsieh, Chi-Hui Chien, C.J. Ho, Chin-Chia Su, Ru Yang, Ying-Huei Hung, Peng-Sheng Wei, Ming-Huei Yu
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageEnglish
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0720106-130031
Rightswithheld, Copyright information available at source archive

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