Numerical study of the flow and heat transfer characteristics of microencapsulated phase change slurry

Abstract

ABSTRACTMicroencapsulated phase change material (MPC) slurry is created by combining phase change material with a carrier fluid that has superior heat transfer properties compared to ordinary water. MPC slurry is conventionally investigated as heat storage and working fluid in a variety of applications to reduce power consumption. This study numerically investigates the impact of several critical parameters on the heat transfer coefficient (HTC) of MPC slurry in a circular pipe, using Eulerian–Eulerian model. The right triangle curve, one of equivalent specific heat model (ESHM), was applied to evaluate the influence of different critical variable values specified as Tin = 305 K, qwall = −125~−200 kW/m2, αv = 0~15%, Re = 6290~13838, and D = 10~25 mm. The results show that increasing the velocity develops local HTC and reduce the rate of heat transformation. Phase change processing takes roughly twice as long at 1.1 m/s as at 0.5 m/s. Additionally, the results demonstrate that a high concentration of MPC slurry is advantageous for energy storage, as the temperature of MPC slurry is maintained over a considerable distance in cooling conditions. At a velocity of 0.8 m/s, the outlet bulk temperature of MPC slurry at various concentrations is 2–6 K higher than that of water. Furthermore, the evaluation reveals that the HTC was largely determined by pipe size, which was the primary factor. The findings of this study are useful for optimizing energy systems that require thermal energy management.KEYWORDS: Microencapsulated phase change materialEulerian–Eulerian modelflow characteristicsequivalent specific heat modelCFD Nomenclatures A=interfacial area, m2cp=specific heat capacity, KJ/kg KD=diameter of the pipe, mmh=heat transfer coefficient, kW/m2 KK=thermal conductivity, W/m KLH=latent heat, J/kgP=pressure, PaQ=heat flux, kW/m2Re=Reynolds numberT=temperature, Kv=velocity, m/sZ=length along the pipe, mSubscripts = b=bulk MPC slurryl=liquid phasem=massp=MPC particles=solid phasesl=phases interactionw=carrier fluid (water)Greek letters=α=volume fractionμ=viscosity, N/m2 sρ=density, kg/m3Disclosure statementNo potential conflict of interest was reported by the author(s).