Experimental analysis of a coiled stirred tank containing a low cost PCM emulsion as a thermal energy storage system

• Published in: Energy (Oxford) Vol. 138; pp. 590 - 601
• Main Authors: Delgado, M., Lázaro, A., Mazo, J., Peñalosa, C., Marín, J.M., Zalba, B.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2017; Elsevier BV
• Subjects: Coils; Cost analysis; Energy consumption; Energy storage; Enthalpy; Experiments; Fluid flow; Flux density; Heat transfer; Heat transfer coefficients; Low cost; PCM emulsion; PCM slurry; Phase change materials; Power efficiency; Reynolds number; Stirred tank; Stirring; Temperature; Thermal energy; Thermal energy storage density; Stirred tank; PCM emulsion; Thermal energy storage density; PCM slurry
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2017.07.044

This article presents the results of heat transfer coefficient and volumetric energy density measurements in an agitated tank containing a low-cost phase change material emulsion, heated by water flowing in a coil. For the stirring a three-stage impeller is placed in the central axis of a 46 l commercial tank. By measuring the temperature dependency on time and solving the transient enthalpy balance, the heat transfer coefficient between the helical coil and the agitated phase change material emulsion is determined, based on the impeller Reynolds number. The thermal energy storage efficiency has also been analysed. This phase change material emulsion shows a phase change temperature range between 30 and 50 °C. Its solid content is about 60% with an average size of 1 μm. The results have shown that the overall heat transfer coefficient is around 3.5–5.5 times higher when a stirring rate of 290–600 rpm is used. Furthermore, even at the lowest stirring rate, the thermal energy storage efficiency improves from 76-77%–100%, without detriment to the energy consumption of the stirrer. •A coiled stirred tank with a low cost PCM emulsion has been experimentally analysed.•It improves the storage efficiency, achieving the maximum storage capacity.•The overall heat transfer coefficient is 4 times higher due to the agitation.•The overall heat transfer coefficient reaches similar values to those of conventional water tanks.