A numerical study of water-based microencapsulated phase change material (MEPCM) slurry flow through a wide rectangular microchannel is performed using an in–house FORTRAN based solver. Eulerian-Eulerian two-phase approach, which is more accurate than the commonly used single-phase approach, is used in this study for modeling MEPCM-water slurry flow. Compact finite difference scheme with sixth-order accuracy is used for discretizing convective terms in the governing equations of liquid and solid phases. An extensive parametric study is performed using two phase change materials, namely n-octadecane and n-eicosane. Results show that significant enhancement of heat transfer is observed for the MEPCM-water slurry compared to pure water when particles undergo melting. It is also observed that the heat transfer enhancement increases with an increase in particle concentration. A drop of 2.6 K in mean temperature is observed for the slurry compared to water when 20% volume concentration of MEPCM-water slurry is used. For a 5% volume concentration of n-octadecane MEPCM-water slurry at a wall heat flux of 100kW/m2, there exists an optimum Reynolds number around 200, at which the heat transfer performance of the slurry is maximum. Results show that a significant change of the local Nusselt number with a decrease in particle size from 13.2 μm to 0.5 μm. Present results show that using a combination of different phase change materials with varied melting temperatures can help maintain the melting of particles throughout the channel, leading to enhancement of heat transfer performance. The present results are validated with numerical and experimental results available in the literature. © 2020 Elsevier Ltd