CONTENTS & COMMENT CONTENTS


Front Cover The publishers would like to thank Weiss Technik UK Ltd for the use of their images on the front cover of Climatic & Vibration Testing 2017


2 & 3 Telescope travels


to Texas for testing The James Webb Space Telescope endures a rigorous process of vibration and climatic testing on its long journey to becoming spaceworthy.


5 New vibration


sensing options A series of new products due out this year addresses industry requirements for miniature impedance heads, longer connection distances and wireless communications


7 & 8 Wind of change


for emission testing The complex regulatory framework for vehicle emission testing takes an interesting twist by demanding climatic considerations to be taken into account.


10 Technology events Important dates for your diary


11 New companies New companies to the Test House Directory


12 A safe haven for


data collection Sampling sensor data for vibration monitoring in hazardous environments brings challenges in connecting industrial data collectors with intrinsic safety.


15, 16 & 18 Company Guide A guide to Climatic & Vibration Testing suppliers.


20 Continuous machine


fitness checking Acoustic and vibration condition monitoring systems are being developed to warn machine operators of problems that may be on the horizon.


© Concorde Publishing Ltd 2017 Join us online at https://goo.gl/inAElE or scan the QR Code, right Follow us on Twitter @eeonlineorg Climatic & Vibration Testing 2017 /// 1 The source guide for engineers, scientists and technicians


Jumping droplets extinguish hotspots


T


he performance of electronic devices is often constrained by their inability to evenly dissipate the waste heat they produce. While a few options for hotspot cooling


do exist, they don’t work well for mobile hotspots, which move according to ever-changing computing tasks or power-amplification demands. Thermoelectric cooling, for example, is best for a fixed hotspot location. Electrowetting requires external power input. Flat-plate heat pipes are remarkable for their removal of heat through horizontal spreading which is much more effective than high thermal conductivity copper or even diamond heat sinks, but they lack a vertical mechanism to dissipate heat. Now that’s about to change, thanks to the work of a group of researchers from Duke University and Intel using a “jumping droplet” technique. A discovery made in the lab of Chuan-Hua Chen, an associate professor in the Department of Mechanical Engineering and Materials Science at Duke University follows from an observation that when two water droplets merge together on a water-repellent (superhydrophobic) surface, the merged droplet spontaneously jumps perpendicular to that surface. They further established that the out-of-plane jumping motion is driven by surface energy initially stored on the droplets and released upon drop coalescence. This effect can locally cool hot spots. The jumping droplet vapour chamber consists of two parallel plates: a


superhydrophobic surface and a sponge-like (superhydrophilic) surface. “When a hotspot appears on the superhydrophilic surface saturated with water, it drives the working fluid to vaporise,” Chen said. “The water vapour condenses on the opposing superhydrophobic surface, and rejects the waste heat. As condensate droplets grow and merge, the coalescence- induced jumping motion returns the working fluid back to the superhydrophilic surface. This ‘jumping return’ enables continuous operation of the vapour chamber to dissipate heat.” The main advantage of the jumping droplet technique is “its mechanism to perpendicularly return the working fluid to the hotspots,” Chen said. “And because jumping droplets are driven by intrinsic surface energy, the technique is independent of external forces and gravitational orientation.” The group’s jumping droplet technique cools mobile hotspots without


any active power input, similar to flat-plate heat pipes. Because the performance of computers and power electronics depends so


heavily on their ability to dispose of heat waste, this new method could enable faster computing and longer lifetimes for electronics. Going forward, they are looking at material choices to best exploit their new technique.


Andy Pye, Editor


Concorde Publishing Ltd 100 Borough High Street, London SE1 1LB, UK Tel: +44 (0)20 7863 3079 Email: cvt@concordepublishing.com Web: www.EnvironmentalEngineering.org.uk


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