Numerical investigation of the effect of thermophysical properties of liquids on convective heat transfer in devices

Natural convection was investigated in a rectangular case with a 3x3 array of chips mounted flush, placed on a front vertical wall at a constant temperature and cooled by the opposite wall. The influence of the body aspect ratio and various thermophysical properties of liquids on heat transfer was considered. To study heat transfer inside the enclosure, simulations were performed for four enclosure aspect ratios (A = 1.0, 5.0, 7.5, 20.0) and five different media (air, water, FC-40, FC-72, FC-88). The numerical results show that the highest velocities are observed in air, while the lowest velocities were observed in water, and in the three dielectric fluids FC-40, FC-72, FC-88. The maximum air velocity values for the W component were obtained at a height of Z = 5.5. It is noticed that with a decrease in the ratio of the sides of the body, the fluid flow rate increases. The maximum Nu number value was found by the case was filled with FC-72 and FC-88 dielectric fluids, and the minimum Nu value was found in air. To make sure that the chosen numerical methods, the computer program were implemented correctly, a test problem was performed. Good agreement was found between the obtained results. Using the obtained numerical results, it will be possible to give a preliminary assessment when choosing a fluid and body aspect ratio for effective cooling of chips in devices.