Numerical and experimental investigation of heat transfer characteristics of liquid flow with Micro-Encapsulated Phase Change Material.

摘要

This numerical and experimental study investigates the heat transfer characteristics and corresponding pressure drop of a liquid flow with Micro-Encapsulated Phase Change Material (MEPCM). In addition, this study numerically explores the effect of presence of MEPCM on the heat transfer characteristics of a liquid in a rectangular cavity driven by natural convection.;Unlike pure liquids, the heat transfer characteristics of MEPCM slurry can not be simply presented in terms of corresponding dimensionless controlling parameters such as Peclet number or Rayleigh number. In the presence of phase change particles, the controlling parameters' values change significantly along the tube length due to the phase change.;In the experimental work, MEPCM mass concentration is varied between 0--20 percent with average particle diameter of 10 microm. Tube wall temperature profile, fluid inlet and outlet temperatures, pressure drop across the tube length are measured and the corresponding Nusselt number is determined for various operating conditions.;The experimental results are used to validate the numerical model predictions. The numerical model results show good agreement with the experimental data under various operating conditions. The good agreements between the numerical predictions and experimental data are partially due to the direct utilization of the actual melting curve of the MEPCM in the numerical simulations. This study identifies the significance of the direct employment of the actual melting curve in the numerical simulations.;The experimental and numerical results show significant enhancements in heat transfer coefficient (higher than 50%) and reduction in tube wall temperature (higher than 40%). The numerical results reveal that the presence of MEPCM in the working fluid slows the growth of the thermal boundary layer and the strong dependence of the heat transfer coefficient on the location of the melting zone interface.;The effect of MEPCM on the heat transfer characteristics of natural convection in a rectangular cavity driven by two parallel vertical plates at different temperatures is numerically investigated. The numerical results show significant increase in heat transfer coefficient (up to 80%). This increase is a result of the MEPCM latent heat and the increased volume expansion coefficient due to MEPCM volume change during melting.