SPRAY EVAPORATION HEAT TRANSFER OF R-14LB ON A HORIZONTAL TUBE BUNDLE

摘要

The spray of R-14lb 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 19.1mm (3/4 inch) diameter copper tube, heated by an electrical resistor. The spray nozzle has a full cone shape with its hydraulic diameter at 2 mm. The average heat transfer coefficients were calculated by measuring the mean tube surface temperature and the vapor temperature. pool boiling experiments were also conducted and compared with spray cooling data under the same test conditions. The dryout phenomenon was observed once the surface heat flux approached the critical heat flux (CHF). In this study, a liquid film collector is specifically designed for each tube to prevent the dry-out phenomenon. The heat transfer performance for spray cooling with a liquid film collector was found to be much better than the performance of pool boiling under both low and high great fluxes.