HEAT-TRANSFER TO BOILING LIQUIDS IN A SINGLE VERTICAL TUBE THERMOSIPHON REBOILER

An experimental investigation of heat transfer to boiling liquids has been carried out on a single tube natural circulation reboiler. Experi ments were performed with distilled water, methanol, benzene, toluene, and ethylene glycol to cover a wide range of boiling points and therm ophysical properties. The heat transfer section consisted of an electr ically heated stainless steel tube 25.56 mm I.D. and 1900 mm long. Uni form heat flux values were used in the range of 4.1 to 43.0 kW/m2, whi le inlet liquid subcooling was varied from 0.5 to 11.6-degrees-C. Liqu id submergence levels were maintained around 100, 75, 50, and 30%. All the data were generated with increasing heat flux at atmospheric pres sure. The effect of heat flux and liquid submergence on the variation of wall and liquid temperatures have been graphically presented and di scussed. The heat transfer coefficients in the nonboiling and boiling regions for all the test liquids have been correlated by two separate correlations in terms of dimensionless groups. The experimental result s are compared with different correlations given in the literature.