New Bio-Inspired Multiphase Thermal Functional Fluid

Abstract

AbstractEfforts in harvesting the potential benefits of mimicking the gas exchange in alveolar capillary for channel heat transfer processes has led to a new bio-inspired multiphase thermal functional fluid (MTFF). This MTFF is originally conceived as encapsulated phase-change material particles, with diameter comparable to the channel size, flowing with the cooling liquid. The two main benefits of this new MTFF are not only the phase-change effect of the particles in the heat transfer process, but also the specific geometry of the particle and channel leading to the sweeping of the boundary layer in the channel. This last effect is believed to be responsible for the very high efficiency of the gas exchange taking place in the alveolar capillaries. Preliminary numerical simulation results seem to confirm the benefit of both effects. A groundbreaking experimental apparatus, designed as a pumpless flow loop, uses vortical effects created by a magnetic stirrer to set the liquid and particles of the MTFF in motion, overcoming the settling and clogging difficulties so characteristic of a multiphase fluid flow. Experimental tests, with octadecane paraffin (EPCM) particles or with acrylonitrile butadiene styrene (ABS) plastic particles (with no latent heat capacity), both flowing in water, have been performed and the results compared to results obtained with clear (of particulates) water flow. All tests indicate the advantages of using the MTFF in comparison to clear water, even at relatively low particle concentrations. Moreover, the tests seem to confirm the same behavior found in capillary blood flow, namely the detrimental effect of increasing the particle concentration beyond an optimum concentration, either leading to a reduction in the boundary layer sweeping effect or to an increased competition among particles for the heat transfer. This effort highlights the importance of learning from efficient biological systems.KeywordsMass Transfer ProcessHeat Transfer ProcessCapillary MembraneHeated ChannelAlveolar CapillaryThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.