Pipe diameter effect on flow and heat transfer characteristics of ammonia alum hydrate slurries with additives

In this study, pipe diameter effect on flow and heat transfer characteristics of ammonia aluminium sulfate dodecahydrate (ammonia alum hydrate: AlNH4(SO4)2·12H2O) slurries with drag reducing surfactants and poly(vinyl alcohol) was investigated. Pressure loss and heat‐transfer coefficients of ammonia alum hydrate solutions and slurries were measured with double‐pipe heat exchangers with different inner tube diameters. Measurement results indicated that pseudo‐laminarization by the surfactant caused drag‐reduction effect and its saturated magnitude was affected by inner tube diameters. Pseudo‐laminarization also produced heat transfer reduction effect and its magnitude was not affected by inner tube diameters. Calculation results of Colburn's j‐factor divided by friction factors indicated that heat transportation efficiency of the hydrate solutions/slurries with additives was increased due to the contribution of drag‐reduction effect.