Effect of the cell size of a honeycomb porous plate attached to heated surface on the CHF in saturated pool boiling

The critical heat flux (CHF) in saturated pool boiling of water was investigated experimentally on the heated surface with the attachment of honeycomb porous plates. In a previous study, the CHF was shown experimentally to be enhanced to more than twice that of a plain surface in the case of a honeycomb porous plate with a vapor escape channel of 1.4 mm in width and 1.0 mm in plate thickness. It was considered that the enhancement resulted from the capillary supply of liquid onto the heated surface and the release of generated vapor through the channels. In the present paper, the vapor escape channel width was varied in the range of 1.4 mm to 7.9 mm, which was smaller than the Taylor instability wavelength (approximately 15.6 mm), and the effect of the channel width on the saturated pool boiling CHF of water has been investigated. The CHF values predicted by capillary limit models were compared with measured values. As a result, it became clear that the main mechanisms for CHF enhancement using a honeycomb porous plate were due to liquid supply to the heated surface as a result of not only capillary suction but also the inflow of liquid through vapor escape channels from the top surface.