CHF of Pool Boiling on Microwires

The present paper reports a new series of experimental data of CHF (critical heat flux) of pool boiling on cylinders. Platinum wires of 30 mm in length are simultaneously used as heaters and thermometers. Their diameters are 0.1, 0.06, and 0.025 mm, respectively. FC-72 and acetone are used as working fluids. The range of the subcooling is from 0 K to about 50 K. The gaps between CHF and MHF (minimum heat flux) become narrower and narrower with the decrease of the heater diameter. But it exists even in the saturated pool boiling on the smallest wire in the present study. The dependence of CHF on the subcooling in acetone differs from that in FC-72 though the data locate in the similar range of Bond number in the two different kinds of working fluids. It indicates that interactions between the influences of the subcooling and size on CHF will be important for the small Bond number, and that there may exist some other parameters, which may be material-dependant, in addition to the Bond number that play important roles in the CHF phenomenon with small Bond number.