HEAT TRANSFER FROM HORIZONTAL SURFACE TO THE POOL OF AQUEOUS SOLUTIONS

Abstract

The present investigation pertains to experimental studies of Boiling heat transfer from horizontal surface to the pool of aqueoUs salt solutions under atmospheric and subatmospheric pressures. The aqueous salt solutions were of sodium carbonate, sodium nitrate and sugar. The heating surface consisted of a horizontal stainless steel tube of 70 mm 0 d, 5 mm thickness and 244 mm length. The surface temperature of the tube was measured at three different positions on its circumference by means of copper-constantan thermocouples. They were placed in three axial holes in the thickness of the heating tube. These holes were at its top-, the side- and the bottom-positions having penetration lengths of 127 mm, The liquid temperatures were also measured at the corresponding positions in the bulk of the solutions. The experimental data were conducted to account for the effects of the heat flux, the pressure and the adlitir-1 of salts on the boiling of distilled water. The heat flux ranged from 9,974 W/m2 to 35,725 W/M2 and pressure from 17.60 kN/m2 to 97,60 kN/m2, For aqueous solutions the con-centration of sodium carbonate was from 5 wt percent to 35 wt percent ; whereas those of sodium nitrate and sugar from 2.5 wt percent to 30 wt percent and 5 wt percent to 45 wt percent respectively. 11 The heating surface exhibited distinct thermal response to the changes in heat flux and also to the changes in pres-sure and concentration of the salt in the pool of the solu-tions...