Three separated phase's equations regarding nano‐encapsulated phase change material/multi‐walled carbon nanotube–Fe3O4–water mixture in a porous half‐annulus collector with corrugated wall using Buongiorno's model: Brownian and thermophoresis effects - Abu‐Hamdeh, Nidal H.; Melaibari, Ammar A.; Alquthami, Thamer S.; Khoshaim, Ahmed; Oztop, Hakan F.; Karimipour, Arash (Mathematical Methods in the Applied Sciences, 2026)