High flux boiling in low flow rate, low pressure drop mini-channel and micro-channel heat sinks

Abstract

Due to the need for practical cooling technologies which could dissipate high heat fluxes, an experimental study of pressure drop and CHF in mini-channel ( D = 2.54 mm) and micro-channel ( D = 510 μm) heat sinks of 1 cm heated length was performed using R-113. Test conditions included inlet subcooling ranging from 10 to 32°C and a range of low flow rates up to a maximum of 95 ml min −1. The tests yielded CHF values for both heat sinks in excess of 200 W cm −2 with the advantage of both low flow rates and low pressure drops ( ΔP < 0.32 bar) as compared to high-flux, single-phase micro-channel heat sinks. Key features of the miniature heat sinks include a lack of inlet subcooling effect on CHF and superheated outlet conditions at the lowest flow rates. A single CHF correlation was developed for both heat sinks. The paper will illustrate the use of the CHF correlation and a generalized model for pressure drop as predictive tools in assessing the merits of different channel sizes in incorporating miniature heat sink technology into high heat flux cooling schemes. Overall, the mini-channel's performance proved superior to the micro-channel due to pressure drops less than 0.01 bar for comparable CHF values as well as the reduced likelihood of clogging and the relative ease in fabricating the mini-channel.