Volume 63

Experimental Investigation of Outlet-Manifold Effects in Jet-Impingement Boiling on Pin-Fin Surface using HFE-7000 Aqbal Ahmad, Shau-Wai Cheng, Chi- Chuan Wang

Abstract

The study experimentally examines the influence of outlet-manifold on the thermal performance and thereby the energy efficiency of a two-phase jet-impingement cooling system using HFE-7000 as the working fluid, enabling more effective energy utilization in high-heat-flux applications. The test section features a fixed 3×16 jet array with a jet diameter of 1.5 mm and a jet-to-jet pitch of 2.5 mm. A comparative analysis is conducted between a symmetric double outlet manifold and a more compact single outlet (side-in/side-out) configuration, highlighting design choices that optimize energy transfer rates. Results demonstrate that the double-outlet design yields superior heat transfer performance across the operating range, exhibiting a consistently lower wall superheat at a given heat flux and a reduced thermal resistance, which collectively contribute to lower overall energy demands for cooling. A significant enhancement in critical heat flux (CHF) was observed, with the double-outlet manifold achieving 53 W/cm², compared to 29.1 W/cm² for the single-outlet design at a mass flux of 78 kg/m²·s, allowing for sustained high-power operation with minimized energy penalties. The lowest recorded thermal resistances were 0.036 °C/W for both manifold types, though the dual-outlet design sustained this performance over a broader range, promoting broader energy-efficient deployment. Furthermore, the study examines the impact of manifold design on temperature uniformity across the heated surface, revealing that the outlet configuration plays a critical role in mitigating temperature gradients and ensuring equitable energy distribution in thermal management systems.

Keywords Heat transfer performance, Jet impingement, CHF, thermal resistance