Control of Flow Maldistribution in Parallel Microchannels

Modern tactical energy systems, such as soldier portable power and cooling systems, utilize microchannels in heat sinks and heat exchangers to efficiently transfer heat from one source to another. For improved efficiency and cooling of high heat loads, two-phase flows involving convective boiling of high latent heat fluids are used. Formation and growth of vapor bubbles inside microchannels can lead to blocking effects resulting in flow maldistribution together with non-uniform spatial and temporal conditions. This may lead to increased pressure-drops, local burn-outs and a drastic decrease in performance of the systems under consideration. Similarly, particulates in microchannels can clog branches of microchannels leading to undesirable flow distributions.

In this work, we performed an integrated study combining high-fidelity numerical modeling of two-phase flows through microchannels (as shown in the adjacent figure) with advanced active control strategies that activate microvalves after sensing flow conditions and pressure drops. We developed a standardized interface between the parallel FRS technique for fluid motion and MATLAB-based model predictive control strategy. This interface facilitates active sensing of the pressure drops in each channel and subsequent actuation of the microvalves to eliminate flow maldistribution. This interface is general enough such that it can be used for coupled CFD-control simulations applied to several other problems such as active control of flow over the wings of a micro-air vehicle, optimization of angle of attack for high lift and low drag, control of a microchannel based reactor used to produce solar fuels, among others.

This work was a collaboration between our group and Schmitt Research Group.

A coupled CFD-control simulation designed to quickly remove bubble from the top channel.

 

• Mathieu, M., Patton, C., Schmitt, J., and Apte S.V., 2009, Direct simulation based model-predictive control of flow maldistribution in parallel microchannels, Journal of Fluids Engineering, accepted for publication. (PDF)

• Martin, M., Patton, C., Schmitt, J., and Apte, S.V., Direct simulation based model-predictive control of flow maldistribution in parallel microchannels, Proceedings of the ASME 2009 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference, DETC2009-8731, San Diego, CA, Augut 2009. (PDF)

• Martin, M., 2009, Numerical simulation of flow maldistribution in microchannels using fully resolved simulation, M.S. Thesis, School of Mechanical Industrial and Manufacturing Engineering, Oregon State University, Corvallis, OR. (PDF)