Heat transfer enhancement performance of microencapsulated phase change materials latent functional thermal fluid in solid/liquid phase transition regions

Microencapsulated phase change materials latent functional thermal fluid(MPCM-LFTF) has been applied in mini-channels heat sink(MCHS) as a promising cooling medium. The experimental platform for hydraulic and heat transfer characteristics of MCHS was designed to investigate the influence of phase transition process on heat transfer enhancement performance. The three-region melting model with solid region(Region 1), phase transition region(Region 2) and liquid region(Region 3) was established to obtain the local bulk mean temperature in MCHS. The relationship between the dimensionless phase transition region(DPTR) and effectiveness of heat transfer enhancement was revealed. Moreover, the mechanism of heat transfer enhancement by phase change behavior was discussed. The results show the melting start point shifts to the right by 0.090 m, and local Nusselt number increases by 7.79% due to increasing Reynolds number. As Stephen number increases, the melting start point moves to the left by 0.028 m. Meanwhile, the length of Region 2 is shortened by 14.09%. The figure of merit(FOM) reaches the peak value of 2.92 at α=1.0. Therefore, the relationship between the outlet temperature and effectiveness of heat transfer enhancement was established through DPTR. Optimal effectiveness can be achieved quickly by only monitoring the outlet temperature of MPCM-LFTF.