Flexible polymeric hollow fiber heat exchangers for electronic systems
Cooling electronics boxes often requires extraction of high heat fluxes from closed boxes with many heat producing components. The direct use of ventilation is sometimes limited by demands to use hermetic units or the need to extract heat from a specific place in a large and complicated system. A liquid system introduced inside of the electronic box can be used for this purpose. Unfortunately, metallic heat exchangers have a number of shortcomings in these applications, including significant weight as well as cost and space demands. Polymeric heat exchangers consisting of hollow fibers were proposed a decade ago and can be used as an alternative in such applications. Flexible polymeric hollow fiber heat exchangers were prepared and tested in liquid air conditions. These heat exchangers use plastic capillaries with an outer diameter of 0.5 0.8 mm and a wall thickness of 10% of the outer diameter. They consist of flexible fibers and can be used in narrow slots and/or in shaped channels. These heat exchangers are effective even in natural convection applications because of their high heat transfer intensity on micro objects. Experimentally obtained overall heat transfer coefficients in water/air applications are up to 250 W/m2 K for forced convection and up to 80 W/m2 for natural convection. The use of plastic and non corrosive materials is advantageous in electronic systems where high heat fluxes must be extracted safely from difficult to access spaces or from hermetically sealed boxes.
2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)