| In this study, a new cooling concept using encapsulated phase-change particles flowing with water in a parallel-plate mini-channel is presented. This novel concept is inspired by the gas exchange process in alveolar capillaries, where red blood cells (RBCs) flow with blood plasma, yielding very high gas transfer efficiency. Another important characteristic of alveolar capillary blood flow, which is related to the high efficiency of the lungs, is the snug fitting of the RBCs into the capillaries. Hence, preliminary results of experimental tests using particles with diameter similar to the flow channel spacing flowing with water through a heated parallel-plate channel test module are presented and analyzed in Chapter 3. The particles are octadecane paraffin (C18 H38), a phase-change material, encapsulated in a thin melamine shell. The temperature distribution along the heated surface of the channel is measured for various water flow rates, with and without particles, and with different numbers of particles. Results are reported in terms of the channel heated surface average temperature and the average heat transfer coefficient.;This study also considers modeling and simulation of the particulate enhanced convection in Chapter 4. The effect of flow velocity and particle concentration on the local heat transfer of the flow is also investigated. Time-dependent moving-mesh models, incorporating both melting and solidification, are utilized for simulating a single particle flow. Particulate flow using particles with phase-change material (PCM) in the cooling fluid enhances the convective energy transport by the fluid mainly in two ways: (1) by "storing energy" in latent heat form; and, (2) by "mixing" the flow field. The high energy storage density and small temperature variation during the heat transfer process provided by the encapsulated phase-change material has made the first role particularly interesting in recent years to many investigators. The objective of Chapter 5 is to determine, latent heat and of the mixing effects on the convection enhancement. To obtain the latent heat effect, the tests are repeated with ABS (Acrylonitrile-Butadiene-Styrene) plastic particles with no latent heat capacity (in the current test operating temperature range). We measured the temperature distribution along the heated surface of the channel for various heat fluxes, and velocities, with octadecane (C18H38 ) paraffin and ABS plastic particles. The results have been also compared with clear water coolant flow. |
