Análise do escoamento monofásico de água em microcanais: desenvolvimento e caracterização de um trocador de calor para o resfriamento de sistemas eletrônicos

Abstract

There is an industrial interest in research and development of microchannel heat exchangers due to the need for heat dissipation in compact systems. Cooling electronics is an example of an application that requires high heat dissipation applied, enabling a safe operating temperature. For the design of a microchannel heat exchanger, look for a minimum pressure loss, or maximum heat transfer, and an adequate and uniform temperature distribution. The present study is aimed at the development of a microchannel heat exchanger for use in electronic systems. The Constructal Design Method concomitant with an optimization were used to find the best performing geometry design, the one that allows the least flow restrictions. Straight channel geometry and branch channel level Y-channel geometry were evaluated and compared by numerical simulation, considering the temperature distribution, heat transfer coefficient and pressure loss. The geometries were fabricated in 3D printing on a silver alloy and evaluated on an experimental bench. Microchannel heat exchangers are characterized with liquid water flow in a single-phase state. The data obtained are pressure, temperature, flow rate and heat flux. The flow was laminar with Reynolds from 163 to 628, with mass flux in the range of 355 to 1,388.5 kgm-2s-1 and heat flux of 14 to 19 Wcm-2 for rectangular geometry. For Y-channel geometry with a branch level, Reynolds was in the range of 196 to 752, mass flux of 533 to 2,073.5 kgm-2s-1 and a heat flux of 16.5 to 23.5 Wcm-2. The Y-channel geometry enabled greater heat transfer with a greater pressure difference compared to channel geometry straight. For channel geometry straight, the convective heat coefficient was 14.2 kWm-2K-1 and the pressure loss was 7.2 kPa. While the Y-channel geometry, the convective heat coefficient was 24.3 kWm-2K-1 and the pressure loss was 15.9 kPa. Thus, increased heat transfer in exchange for increased pressure loss.