A study of bubble behavior and boiling heat transfer enhancement ender electric field

The effect of a D.C. electric field on nucleate boiling hear transfer for refrigerants, R11, R113, and FC72, was investigated experimentally in a single-tube shell/tube heat exchanger by using the temperature control method of wall superheat. Also the behavior of bubble under nonuniform electric field produced by wire electrodes was studied by numerical calculation. For R11, the electrohydrodynamic (EHD) enhancement for boiling hear transfer was observed for all ranges of wall superheat tested. However the enhancement in boiling heat transfer disappeared if the wall superheat exceeded 13 degrees C for R113, and no electric field effect on the boiling heat transfer was observed for FC72. An application of approximately 5 kV was enough to eliminate the boiling hysteresis for R11 and R113. Numerical study of the electric field in a single medium has hinted that the bubbles are forced away from the hearing surface and toward the electrostatic stagnation point by the dielectrophoretic force. Such modified bubble motion terms out to promote the boiling heat transfer if one uses proper electrode configuration.