Abstract
The object of the study is to clarify experimentally the variation of the vapor concentration of binary mixtures generated during nucleate boiling in a saturated pool under various boiling conditions. The generated vapor concentrations in the bulk vapor layer were measured for binary mixtures of waterβethanol and ethanolβacetone under various liquid concentrations, heat fluxes, and liquid layer heights from heated thin wires at atmospheric pressure.
Two methods of measuring concentration, namely, the dew point method and the laser absorption method, were used. The dew point measurement utilized a copper heat transfer block installed in the center of the vapor layer in the boiling vessel. The commencement of condensation on the surface was observed directly via a microscope used for determining the dew point by controlling its temperature. A laser light having a wavelength of 3.39 Β΅m was used for the laser light absorption method utilizing its absorptive property against ethanol vapor.
The measurement of the concentrations of the bulk vapor was carried out for various superheats of heated wires, the depth of liquid mixture layer, and the liquid concentrations. They were almost independent of those parameters and were almost in equilibrium with bulk liquid conditions even under higher surface superheats and lower liquid heights. Also, the measured results using both methods were in close agreement. Β© 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(8): 595β605, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10060