Heat Transfer and Fluid Flow in Micro and Mini Scale Devices

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This proposal is concerned with the development of robust models for predicting the thermal-fluid performance characteristics of complex internal flow systems. Simple and complex flow architecture is found in compact heat transfer devices for refrigeration, electronics cooling, automotive cooling, solar heating, and in countless other process flows. Complex flows are also found in new compact energy devices such as fuel cells, micro-fluidic “lab on chip” devices, micro-systems, MEMS, and other next generation technologies. There is a need for fundamental study, both theoretical and experimental, to better ascertain the performance characteristics and to develop predictive models for use in specialized or generic simulation codes. This proposal aims to study several fundamental problems now facing designers of systems utilizing compact and micro-flow architecture. Several focus areas have been chosen for this grant cycle. These include: single and two phase flow in micro- and mini-channels for use in compact and enhanced heat transfer devices and experimental and theoretical modelling of heat transfer and fluid flow in electronics packaging systems. These devices promote heat transfer through two ways, namely, increased heat transfer coefficients and increased surface area. The penalty for enhancing heat transfer in a compact heat exchanger is increased pressure drop or reduced mass flow rate for fixed pressure drop. The proposed research involves theoretical and experimental analysis of the thermal and hydrodynamic characteristics of complex internal flows and parallel development of optimized flow architectures. Optimum design of compact heat transfer devices is best achieved when accurate models are available for predicting the thermal-hydraulic performance of a particular device geometry. Finally, the engineer needs to optimize these designs considering many parameters, such as size (weight and volume) and cost, in addition to the required heat transfer and pumping power. The design of new devices using modern methods such as Entropy Generation Minimization or Constructal Theory is also actively pursued. These methods when applied to finite systems, allow for the optimal distribution of material and give the system freedom to morph under the fixed constraints of pressure drop, surface area, and volume. Applications of the proposed research include improving performance of energy systems, heat recovery, and thermal management of electronics and electronics systems. Significant progress in these areas has been made during the last cycle, leading to approximately 40 archival journal publications and the completion of 3 PhD and 2 Master's theses. It is expected that the new problems being considered in this proposal will be equally fruitful.**