R-134a spray dynamics and impingement cooling in the non-boiling regime

R-134a spray as it impinges on the flat endplate of a circle is studied experimentally. In order to optimize R-134a spray cooling efficiency, a detailed characterization and understanding of liquid spray formation is essentially needed. An optical image system was used to quantify the spray flow structure. LDV measurements were used to characterize the local velocity/and velocity fluctuation distribution from a commercial available nozzle in both axial and radial directions. The radial velocity are found to be the largest at the outer edges of the spray, and they continuously decrease across the spray toward the center axis; while the corresponding axial velocity is the maximum there. Moreover, spray heat transfer in non-boiling regime was shown to be dependent on the velocity of the impinging spray in terms of Weber number and other related parameters which are in good agreement with those of previous studies. (c) 2006 Elsevier Ltd. All rights reserved.