On the hydrodynamic characterization of a passive Shape Memory Alloy valve. (22nd January 2015)

• Record Type: Journal Article
• Authors: Waddell, A.M.; Punch, J.; Stafford, J.; Jeffers, N.
• Is Part Of: Applied thermal engineering. Volume 75(2015:Jan.)
• Page Start: 731
• Page End: 737
• Publication Date: 2015-01-22
• Subjects: Passive valve -- Thermal management -- Shape Memory -- Forced convection -- Loss coefficients; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2014.09.073
• Languages: English
• ISSNs: 1359-4311

Abstract

Abstract: An attractive approach to the thermal management of next generation photonics devices (heat fluxes > 10 2 W/cm 2 ) is micro-channel cooling, and micro-valves will be required for refined flow control in the supporting micro-fluidic systems. In this paper, a NiTi Shape Memory Alloy (SMA) micro-valve design for passive flow control and thermal management was prototyped at the macro scale and hydrodynamically characterized. The dynamic behavior of the valve was observed and the loss coefficient ( ζ v ) derived from pressure-flow measurements. The hydrodynamic characterization study is important because ζ v is sensitive to Re and geometry in the flow regime of the micro-fluidic system. Static replicas of the SMA valve geometry were tested for low Re (110–220) and a range of opening ratios ( β ) in a ø1 mm miniature channel. The loss coefficients were found to be sensitive to flow rate and decreased rapidly with an increase in Re . A correlation was developed to interpolate ζ v from a given Re and β . The valve loss coefficients obtained in this work are important parameters in the modeling and design of future micro-fluidic cooling systems. Highlights: A miniature normally closed passive SMA valve for micro-fluidic cooling of Photonics devices is demonstrated in this paper. The passive dynamic behaviour of the valve in response to temperature change is observed. The design is hydrodynamically characterized through pressure-flow measurements. A correlation for head loss across the valve as a function of Re and blockage ratio is presented.