Microencapsulated phase change material (MPCM) and carbon-nanotube based nanofluids have both been investigated as heat transfer coefficient enhancers separately. In this paper, we investigate the potential manifold benefit of using a blend of both as a new heat transfer fluid. The effect of percentage of MPCM that undergoes phase change and the composition of the new blend of heat transfer fluid have been investigated. A computer simulation code reveals that the best composition for the MPCM-nanofluid blend depends on the actual percentage of phase change that takes place in the process. Better heat transfer rates can be achieved when high quantity of MPCM undergoes phase change.