Pool boiling of ethanol and FC-72 on open microchannel surfaces

Abstract

The paper presents experimental investigations into pool boiling heat transfer for open microchannel surfaces. Parallel microchannels fabricated by machining were about 0.3 mm wide, and 0.2 to 0.5 mm deep and spaced every 0.1 mm. The experiments were carried out for ethanol, and FC-72 at atmospheric pressure. The image acquisition speed was 493 fps (at resolution 400 × 300 pixels with Photonfocus PHOT MV-D1024-160-CL camera). Visualization investigations aimed to identify nucleation sites and flow patterns and to determine the bubble departure diameter and frequency at various superheats. The primary factor in the increase of heat transfer coefficient at increasing heat flux was a growing number of active pores and increased departure frequency. Heat transfer coefficients obtained in this study were noticeably higher than those from a smooth surface.

Study of pool boiling heat transfer with FC-72 on open microchannel surfaces

“…Thermal and visualization measurements were made at the measurement stand, Fig. 1 [5][6][7][8], which allowed measuring the temperature difference between the working fluid and the heating surface and determining the heat flux. These parameters are necessary to determine the boiling curves.…”

“…Studies on pool boiling heat transfer with water, ethanol, FC-72 and Novec-649 from tunnel structures, microfins, microchannels, microcavities [5][6][7][8] and boiling heat transfer with FC-72 flowing in narrow channels [9][10][11][12][13] have been conducted at the Kielce University of Technology for more a decade.…”

Comparison of the 1D and 2D calculation models used for determination of the heat transfer coefficient during flow boiling heat transfer in a minichannel

“…The application of an enhancement of the heated plate surface may increase the intensity of heat transfer [5,6]. In the literature, [7][8][9][10] the results of pool boiling heat transfer when the enhancement of the heated surface was applied in the form of mini-fins were described.…”

Pool boiling visualization of Novec-649 and FC-72 on copper microchannels

“…The Kielce University of Technology has been conducting studies on pool boiling heat transfer with water, ethanol, FC-72 and Novec-649 from tunnel structures, microfins, microchannels, microcavities [6][7][8][9][10] and boiling heat transfer with FC-72 flowing in narrow channels [11][12][13][14][15] for more than a decade.…”