Numerical Calculation of Heat Transfer Coefficient of Liquid Flow With NPCM in Microchannels

A continuum model is applied to the numerical simulation of the laminar hydrodynamic and heat-transfer characteristics of suspension with nano phase change material (NPCM) particles in a microchannel. The analytical/numerical formulation based on CFD modeling technique, and the computer code is developed. Local wall-to-suspension heat transfer coefficients are calculated by the simultaneous solution of the conservation of mass, momentum and thermal energy equations. By providing detailed information on the local behavior of the wall-to-suspension heat transfer coefficients, preliminary calculations expose that there exists a particle-depleted layer next to the wall under the laminar flow condition. It plays an important role on the heat transfer between the suspension and the wall under the laminar flow condition. The main contribution of NPCM particles is the increase in the thermal capacity under the laminar flow condition. The qualitative comparison with the experimental observations and measurements on the flow and heat transfer of microencapsulated PCM slurry in circular duct indicates that the preliminary results are reasonable. It interprets the observation in the literature where heat transfer between the suspension and the wall is weaker than that between the pure fluid and the wall for laminar flow conditions.