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The use of phase change materials (PCM) in heatsink designs are gaining attention due to its many favorable properties. Some PCM heatsinks designs have been suggested for use with thermoelectric cooling devices (TECs), however, the heatsink designs are often arbitrary where PCM is just added to voids within the heatsink to improve the thermal properties. There is a need to systematically understand the effects of PCM on TEC performance. While a numerical model is key to such systematic study and optimization, the application involves multiple physical phenomena and the resulting model can be prohibitively expensive to run. In this contribution, a numercical model using computational fluid dynamics (CFD) is built to predict the performance of PCM heatsink for use with TECs as cooling wearable. Experiments are calibrated and carried out to prescribe the boundary conditions and ensure that the multiphysics phenomena are accurately captured. The numerical methodology described here can be used for design optimizations of PCM heatsinks to be used in conjunction with TECs. Our numerical model shows that for maximum TEC efficiency, the PCM should be kept at a liquid fraction of less than 40%. • A numerical model to predict the performance of PCM heatsink for use with TEC is presented. • Experimental work carefully set up and calibrated to confirm validity of developed numerical model. • The numerical model is well validated with experiment results of TEC on human skin. • The numerical model is designed to be computationally reasonable using CFD. • Results show that PCM liquid fraction should be kept less than 40% for maximum efficiency. [ABSTRACT FROM AUTHOR]

The generation and formation characteristics of air bubbles have significant impact on the performance of the membrane bioreactor system. Experiments were conducted in a tank filled with Glycerine-Water solutions so as to investigate the impacts of liquid viscosity on the bubble formation characteristics. Nozzle size ranging from 2 to 10 mm, air inlet flow rate ranging from 300 to 1500 cc/min and liquid viscosity ranging from 6 to 850 cP have been investigated. Methods to compute the non-linear characteristics such as bubble diameter and bubble rising velocity have been identified. The nonlinear behaviour of the air bubbles were further correlated to the dimensionless numbers such as Reynolds number, Eötvös number and Galilei number. A bubble shape regime was constructed so as to classify the distinct regions of the air bubbles generated from different viscous solutions. Coalescence of bubbles were studied extensively and the impact of liquid viscosity on the bubble flow regimes were presented. [ABSTRACT FROM AUTHOR]