STUDIES OF NUCLEATE POOL BOILING OF LIQUIDS ON IN-LINE HORIZONTAL CYLINDERS OF DIFFERENT MATERIALS

Abstract

The present investigation attempts to Conduct experimental data for the nucleate pool boiling of satu-rated pure liquids on two in-line horizontal test cylinders of the same material, placed one over the other, at atmos-pheric and subatmospheric pressures under the condition of constant heat flux. The test surface comprised of two in-line horizontal hollow cylinders, with electric heaters placed inside, arranged one over the other, 75 mm apart in vertical plane. The effective heating length, the outer diameter and the thickness of each test cylinder were 105 mm, 30 mm and 6 mm respectively. The 24 gauge copper-constantan thermocouples measured the surface temperatures of the test cylinders circumferentially at the top-, the side- and the bottom-position. To measure the test liquid temperatures at the corresponding positions, travelling thermocouple probes were employed. The experimental data were obtained to account for the effects of heat flux, pressure, physico-thermal pro-perties of the boiling liquids and materials of the test cylinders on the boiling heat transfer and also the effect of the rising vapour bubbles from the lower test cylinder on the average heat transfer coefficients of the upper test cylinder. The heat flux ranged from 18,189.2 to 46,483.4 W/m2, while pressure from 31.47 to 98.13 kPa. The test ii liquids investigated were distilled water, isopropanol and methanol. The materials cf construction of the test cylin-ders were stainless steel (AISI 304), brass (70% Cu, 30% Zn) and copper (electrolytic)...