Abstract:
Heat transfer to Kraft pulp black liquor has been studied as a function of flow velocity, bulk temperature, wall temperature and subcooling for liquor concentrations from 15% to 65%. The experiments were carried out by circulating the liquor through an annulus with an electrically heated inner tube. Regimes of laminar and turbulent flow under forced convective and subcooled nucleate boiling were investigated. For laminar forced convective heat transfer, boundary layer analysis provided an equation which reliably predicted the measured data. Under turbulent forced convective conditions the Petukov correlation gave excellent agreement. The Root Mean Square Error for all the laminar and turbulent heat transfer data was 7%. The combined correlations of Chen and Gorenflo were found to predict the measured subcooled boiling data satisfactorily with a Root Mean Square Error of 8%.