Pool Boiling Heat Transfer from Tubes with and without Basic Surface Modification for Enhancement

Preparation, measurement and analysis of the microstructure of evaporator surfaces

“…New treatment methods for special macro cavities are required for an interpretation of the real enhancement effects, i.e. for the description of the local mechanism in bubble formation and heat transfer [5,6,11].…”

“…The macro cavities show comparatively simple shapes of ca. 120 × 250 × 50 µm 3 [5,10,11,15]. The previous microstructure (e.g.…”

“…Their microstructure is treated by emery grinding or sandblasting by the same procedure. Different materials, forms and sizes of the heating surfaces are used: copper, CuNi and stainless steel tubes (D = 15 mm [3,4], D = 24.0-25.4 mm [5,6]), copper plates (15 × 200 mm [7]), and tubes coated galvanically by gold [8], and plates sputtered with layers of different material [9]. Macro cavities have been prepared by a rolling process similar to the industrial processes [10,11].…”

Circumferential temperature distribution during nucleate pool boiling outside smooth and modified horizontal tubes

“…The difference between the maximum and the minimum temperature value in circumference was about 4 K. Bier et al [3] have conducted research on refrigerant R11. The maximum temperature difference was about 0.07 K. Gorenflo and co-workers [4][5][6][7][8] carried out a systematic study regarding bubble formation on tubes with defined roughness or on surfaces modified by macrostructures for enhancement of heat transfer. Experiments with different organic fluids were performed in order to obtain results over wide range of reduced pressure.…”

Heat transfer and bubble formation in pool boiling: Effect of basic surface modifications for heat transfer enhancement

“…In the experiments, a new, slightly modified version of the so-called standard apparatus for pool boiling heat transfer measurements is used which is described in detail in [31,41], together with the outlines of the experimental procedure. Combined with the heat transfer measurements, bubble formation is recorded by photographs and by a high speed digital video system (Fa.…”