Study on flow and heat transfer characteristics of Encapsulated Phase Change Material (EPCM) slurry in Double-Pipe Heat Exchanger

摘要

Microencapsulated phase change material (MPCM) slurry as a working fluid was numerically investigated for thermal energy conservation systems due to its high heat capacity associated with the PCM. A mathematical model of a double pipe heat exchanger was developed to conduct the numerical analysis based on the EulerianEulerian flow model. During simulation, it was considered that MPCM slurry flows through the inside pipe of the heat exchanger, whereas high-temperature plain water flows at the annulus side of the heat exchanger. The accuracy of the model was verified with experimental data and showed a good agreement. The effect of particle concentration, Reynolds number, and particle diameter was considered to investigate the energy transport characteristics of the MPCM slurry. The results showed that particle concentration significantly affects the heat transfer performance of MPCM slurry, and it promotes pressure drop due to an increase in viscosity. The highest average heat transfer coefficient of the slurry showed at 15 volume fraction; it was also significantly affected by the particle diameter greater than 100 mu m. The local heat transfer coefficient of water and MPCM slurries were compared at a Reynolds number of 6838, and PCM-based HTFs showed a higher local heat transfer coefficient. Furthermore, a ratio of h/Delta P was presented to study the energy transport performance of MPCM slurry at different particle concentrations and compared with plain water, and it was found out that 10 volume fraction showed better performance as HTF (Heat Transfer Fluid).