This paper presents a novel insight for the forced convective heat transfer enhancement of microencapsulated phase change material slurries flowing through a circular tube with constant heat flux. The influence of various factors is analyzed in detail by using an effective specific heat capacity model, validated with the results available in the literature. It is found that the conventional Nusselt number correlations for internal flow of single phase fluids are not suitable for accurately describing the heat transfer enhancement with microencapsulated phase change material suspensions, and a modification is introduced that enables evaluation for the convective heat transfer of internal flows.