Spray evaporation heat transfer of R-141b on a horizontal tube bundle

The spray of R-141b coolant on a horizontal staggered tube bundle was used to investigate the performance of spray cooling heat transfer in a compact heat exchanger system. The test tube used in the present work is a 19.1 mm (3/4 inch) diameter copper tube, heated by an electrical resistor. The spra y nozzle has a full cone shape with its hydraulic diameter at 2 mm. The ave rage heat transfer coefficients were calculated by measuring the mean tube surface temperature and the vapor temperature. Pool boiling experiments wer e also conducted and compared with spray cooling data under the same test c onditions. The dry-out phenomenon was observed once the surface heat flux a pproached the critical heat flux (CHF). In this study, a liquid film collec tor is specifically designed for each tube to prevent the dry-out phenomeno n. The heat transfer performance for spray cooling with a liquid film colle ctor was found to be much better than the performance of pool boiling under both low and high heat fluxes. (C) 1998 Elsevier Science Ltd. All rights r eserved.