炭酸カルシウムの高温壁面への析出挙動

抄録

For the purpose of obtaining the essential information of scaling in heat exchangers, microscopic observations were made for CaCO₃ deposition from a flowing solution onto initially clean heat-transfer surfaces. The growing rates of CaCO₃ crystals were measured by changing Reynolds number and supersaturation degree of the bulk solution, material and temperature of the heat-transfer surface. The growing rate was found to be relatively well correlated with the supersaturation degrees of the solution adjacent to the surface, deduced from the equilibrium relationship between the species in the carbonic solution. The nucleation rate was also estimated by measuring the change of the cumulative number density of deposited crystals against time. The crystals were formed on the surface with a constant nucleation rate over time, but the factors which dominate the nucleation rate could not be determined.