Review on thermal energy storage with phase change: materials, heat transfer analysis and applications

The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

An introduction to heat transfer

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Numerical Heat Transfer And Fluid Flow

This paper explores the recent research developments in high-heat-flux thermal management. Cooling schemes such as pool boiling, detachable heat sinks, channel flow boiling, microchannel and mini-channel heat sinks, jet-impingement, and sprays, are discussed and compared relative to heat dissipation potential, reliability, and packaging concerns. It is demonstrated that, while different cooling options can be tailored to the specific needs of individual applications, system considerations always play a paramount role in determining the most suitable cooling scheme. It is also shown that extensive fundamental electronic cooling knowledge has been amassed over the past two decades. Yet there is now a growing need for hardware innovations rather than perturbations to those fundamental studies. An example of these innovations is the cooling of military avionics, where research findings from the electronic cooling literature have made possible the development of a new generation of cooling hardware which promise order of magnitude increases in heat dissipation compared to today's cutting edge avionics cooling schemes.

Assessment of high-heat-flux thermal management schemes

Active devices, such as synthetic jets and oscillating plate agitators were found to be effective in cooling of high-heat-flux electronics. These devices generate unsteady flows, thinning the thermal boundary layer and enhancing turbulent transport. However, the active devices cause extra power consumption due to flow friction and separation. It is important to understand the factors influencing power consumption in these devices if they are to be applied in cooling system designs. The present study analyzes fluid damping and power consumption in high-frequency (about 1000 Hz) synthetic jets and oscillating plate agitators driven by piezoelectric stacks. This analysis is done numerically, since it is difficult to measure fluid damping. In the simulations, the moving part of the active device is modeled with the moving wall boundary condition. The mesh is updated and the flow is calculated every time the moving part changes its position. The coherent vortex structures generated by theses active devices, like vortices in the synthetic jet cavity or in the oscillating plate tip gap region, are found to cause fluid damping and power consumption. Fluidic power consumption levels with different geometries and different operating frequencies and amplitudes are studied. A correlation is developed to predict fluidic power consumption at different operating conditions.Copyright © 2012 by ASME

Fluid Damping and Power Consumption of Active Devices Used in Cooling Electronics

\n Modern gas turbines are subjected to very high thermal loading. This leads to a need for aggressive cooling to protect components from damage. Endwalls are particularly challenging to cool due to a complex system of secondary flows near them that wash and disrupt the protective coolant films. This highly three-dimensional flow not only affects but is also affected by the momentum of film cooling flows, whether injected just upstream of the passage to intentionally cool the endwall, or as combustor cooling flows injected further upstream in the engine. This complex interaction between the different cooling flows and passage aerodynamics has been recently studied in a first stage nozzle guide vane. The present paper presents a detailed study on the sensitivity of aero-thermal interactions to endwall film cooling MFR (cooling mass flow to mainstream flow ratio). The test section represents a first stage nozzle guide vane with a contoured endwall and endwall film cooling injected just upstream of it. The test section also includes an engine-representative combustor-turbine interface geometry with combustor cooling flows injected at a constant rate. The approach flow conditions represent flow exiting a low-NOx combustor. Adiabatic surface thermal measurements and in-passage velocity and thermal field measurements are presented and discussed. The results show the dynamics of passage vortex suppression and the increase of impingement vortex strength as MFR changes. The effects of these changes of secondary flows on coolant distribution are presented.

Terrence W. Simon

Papers

Fluid Damping and Power Consumption of Active Devices Used in Cooling Electronics

Effects of Endwall Film Coolant Flow Rate on Secondary Flows and Coolant Mixing in a First Stage Nozzle Guide Vane

Exploration of the influence of heat conduction on the temperature distribution in turbine blades

Pool boiling heat transfer with an array of flush-mounted, square heaters

Experimental validation of a boundary layer convective heat flux measurement technique