In present paper

the heat transfer characteristics of subcooled flow boiling in vertical rectangular narrow channels of different size at atmospheric pressure were investigated experimentally by using deionized water as working fluid

under the working conditions that width δ from 3 mm to 4 mm

mass flux G=143 & 300 kg·m-2·s-1

inlet subcooling ΔTsub=17 &25℃

heat flux q from 1 W·cm-2 to 20 W·cm-2. The visualization experiments were conducted to study the characteristics of bubble nucleation on the heating wall in the same area

then obvious channel size effects were found out

including effects on onset of boiling

heat transfer coefficient

active nucleation site density

bubble departure diameter and bubble departure frequency

etc.