Experimental Study on Flow Characters of Salt Hydrate Slurry in Phase Change Temperature Range

Abstract

One of the efforts in minimizing energy consumption chiller type air conditioning system is the use of phase changing material in secondary refrigerant. Secondary refrigerant functions to obtain heat from the air to cool a room and to release heat in chiller evaporator. Based on working temperature of secondary refrigerant, the fluid can flow in liquid form, and can also be in fluid solid form or slurry at the temperature of its phase change. This research studies the effect of temperature toward flow characteristics, with the parameter analyzed being the pressure decrease and friction coefficient. Besides that, in order to support data analysis, it was initiated by viscosity testing, density and concentration of solid mass. Data taken were viscosity, density, solid mass concentrate, and pressure difference found in copper pipe. Data were taken for several fluid temperatures, and at pressure decrease was added by variation of flow speed. Hydrate salt tested were CaCl₂ and Na₂HPO₄. Viscosity and density increased with the decrease in temperature. The formation of solid particles within phase change temperature range also gave an impact on the increase in the value of viscosity and density. Pressure drop increased when using hydrate salt fluid. The use of CaCl₂ solution resulted in the highest pressure decrease. This salt hydrate has far higher viscosity and density compared to water. This has an effect toward an increase in pressure drop. This increase started to be significant in the phase change temperature area in which solid particle started to form. The same thing happened in the friction coefficient value.