Heat transfer investigation of a 90° zigzag channel diffusion-bonded heat exchanger

• Published in: Applied thermal engineering Vol. 190; p. 116823
• Main Authors: Cavalcanti Alvarez, Rodrigo, Sarmiento, Andrés P.C., Cisterna, Luis H.R., Milanese, Fernando H., Mantelli, Marcia B.H.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 25-05-2021; Elsevier BV
• Subjects: Brayton cycle; Carbon dioxide; Coolers; Diffusion bonded heat exchangers; Diffusion welding; Dimensionless numbers; Experimental investigation; Fluid dynamics; Fluid flow; Heat exchangers; Heat transfer; Laminar flow; Nusselt number; Pre-cooler; Pressure; Reynolds number; Straight channels; Supercritical processes; Thermal performance; Turbulent flow; Water and CO2; Diffusion bonded heat exchangers; Nusselt number; Pre-cooler; Water and CO2; Thermal performance; Experimental investigation
• DOI: 10.1016/j.applthermaleng.2021.116823
• EISSN: 1873-5606
• ISSN: 1359-4311

•Diffusion-bonded heat exchanger with a zigzag channel experimentally investigated.•Study of water stream influence in the thermal performance of the heat exchanger.•A new Nusselt number correlation for the tested prototype is developed.•Thermal performance comparison of different zigzag channel geometries.
Supercritical CO2 (S-CO2) Brayton cycle components are subject to high pressure and temperature conditions, which are intrinsic to the operation cycle. Among the equipment used for these applications, diffusion-bonded heat exchangers are receiving more attention to be used as pre-coolers on the cycle, due to their robustness and capability of operating at the demanded conditions. Currently, limited research focused on the influence of the pre-cooler’s cold-side fluid, water, on the thermal performance of the diffusion-bonded heat exchangers. In the present study, a novel zigzag channel for the diffusion-bonded heat exchangers with square cross-section was manufactured and experimentally investigated in a water-water configuration. During the experiments, the Reynolds number of the hot and the cold sides varied from 1529 to 8313 and from 1299 to 6618, respectively, covering laminar to turbulent flow regimes. A new heat transfer correlation is proposed based on dimensionless Reynolds and Prandtl numbers, covering a large Reynolds number range not yet experimentally investigated for the water. In the laminar regime, the current geometry increases the Nusselt number up to 4.1 times when compared to a straight channel. For the complete Reynolds number range evaluated, from 1299 to 8313, the average enhancement of a diffusion bonded heat exchanger with the proposed geometry compared to a straight channel one is of 2.2 times. Therefore, the current zigzag design proposed in this study provided a significant advantage in terms of heat transfer performance.