Flow and Heat Transfer Characteristics of Ammonium Alum Hydrate Slurry Treated with Surfactants

The flow and heat transfer characteristics of an ammonium alum hydrate slurry treated with drag-reducing surfactants have been investigated experimentally. Ammonium alum hydrate has a high latent heat of 251 kJ/kg, and its fusion temperature is 51 degrees C when the concentration of ammonium alum in water is 35 wt%. The friction coefficient and the heat transfer coefficient for melting were measured from a pipe flow with a diameter of 13 mm. From the results, it was found that the ammonium alum hydrate slurry treated with surfactants shows the effective drag reduction in a pipe flow. It was also found that the heat transfer of the slurry with the surfactants is reduced slightly; in particular, this was true in the case of a high temperature difference between the slurry and heating water flowing outside a test tube. However, the heat transfer coefficient of the slurry with surfactants divided by pressure loss was very high, and particle growth due to particle agglomeration could be reduced by the surfactants. From this, it was concluded that the ammonia alum hydrate slurry with the surfactant is a promising system as a heat transportation medium.