Conjugate free convection from an array of discrete heat sources with water and nano-encapsulated phase change particle in a cold enclosure

Abstract

The present works investigates the conjugate free convection in a cold enclosure containing a hot circular cylinder. An array of discrete heat sources are attached to the cylinder surface. The free space between the enclosure and the cylinder was filled with a heterogeneous mixture of water and nano-encapsulated phase change particle (NEPCP). This nanoparticles have an outer shell and a core inside. Specifically, the NEPCP core can absorb thermal energy on charging state or releases energy on discharging state. The governing parameters considered are the number of heated segment, 1≤n≤4, the heat source thickness, 0≤A≤0.1, the fusion temperature, 0.1≤Θf≤0.5, the heating intensity, 104≤Ra≤106, and the NEPCP concentration, 0≤ϕ≤0.05. The results shows that the Θf, n, A, and Ra modify the position and size of the area of phase change zone. The maximum Nusselt number was found at different angular positions depending on the heat source arrangement. The maximum value increases by increasing the NEPCP concentration, but its position almost unchanged by adjusting the concentration. There is critical A=Ac and max(ϕ) for the optimum arrangement of discrete heat source.