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

This paper investigates heat transfer enhancement of an air-cooled plate-fin heat sink by introducing actively-driven agitating plates within its channels. The investigation was computationally conducted with a single actuated plate in a single channel constructed as two fin wall surfaces and one fin base surface. As air flows through the channel, the plate is vibrated transversely to agitate the channel flow and thereby enhance heat transfer. The channel flow and the actuated plate are considered to be driven by a fan and a piezoelectric stack, respectively. A Coefficient of Performance (COP), ratio of total heat dissipated from the fin channel to total electric power to drive the fan and the agitator plate, is employed to evaluate overall heat transfer enhancement. A short plate, i.e. a plate is only placed at the entrance of the channel, has been shown to possess higher COP than a longer plate, i.e. a plate that is extended to be over most of the channel. For the short plate, COP is higher when it is actuated than when it is stationary. Detailed turbulence-kinetic-energy contours indicate that the higher COPs are due to turbulence generated along the plate edges and streamwise acceleration and deceleration of the bulk channel flow; both are induced by the vibration of the plate. Within regions where the plate is present, the generated turbulence and the acceleration and deceleration augment heat transfer. For a short plate, the turbulence and unsteadiness are transported downstream of the actuated plate to increase heat transfer in that region. However, such turbulence and unsteadiness are drawn out of the channel without full benefit of agitation and heat transfer enhancement when the plate is long, as the plate’s trailing edge is already close to the channel exit. This leads to a conclusion that the short plate is a better choice for active heat transfer enhancement.Copyright © 2012 by ASME

Comparison of Heat Transfer Enhancement by Actuated Plates in Heat-Sink Channels

Numerical modeling of three-dimensional heat transfer and fluid flowthrough interrupted plates using unit cell scale

Perovskite solar cells (PSC) have outstanding potential to be low-cost, high-efficiency photovoltaic devices. The PSC can be fabricated by numerous techniques; however, the power conversion efficiency (PCE) for the two-step-processed PSC falls behind that of the one-stepmethod. In this work, we investigate the effects of relative humidity (RH) and dry air flowon the lead iodide (PbI2) solution deposition process.We conclude that the quality of the PbI2film is critical to the development of the perovskite film and the performance of the PSCdevice. LowRHand dry airflowused during the PbI2 spin coating procedure can increase supersaturation concentration to formdenser PbI2 nuclei and a more suitable PbI2 film.Moreover, airflow-assisted PbI2 drying and thermal annealing steps can smooth transformation from the nucleation stage to the crystallization stage.

https://iopscience.iop.org/article/10.1088/2053-1591/aab8b4/pdf

Control of PbI2 nucleation and crystallization: Towards efficient perovskite solar cells based on vapor-assisted solution process

Subcooled flow boiling over a thin, low-capacitance surface on a concave wall

Experiments are conducted on a flat recovery wall downstream of sustained concave curvature in the presence of high free-stream turbulence (TI∼8%). This flow simulates some of the features of the flow on the latter parts of the pressure surface of a gas turbine airfoil. The combined effects of concave curvature and TI, both present in the flow over a turbine airfoil, have so far little been studied. Computation of such flows with standard turbulence closure models has not been particularly successful. This experiment attempts to characterize the turbulence characteristics of this flow. In the present study, a turbulent boundary layer grows from the leading edge of a concave wall then passes onto a downstream flat wall. Results show that turbulence intensities increase profoundly in the outer region of the boundary layer over the recovery wall. Near-wall turbulent eddies appear to lift off the recovery wall and a “stabilized” region forms near the wall. In contrast to a low-free-stream turbulence intensity flow, turbulent eddies penetrate the outer parts of the “stabilized” region where sharp velocity and temperature gradients exist. These eddies can more readily transfer momentum and heat. As a result, skin friction coefficients and Stanton numbers on the recovery wall are 20% and 10%, respectively, above their values in the low-free-stream turbulence intensity case. Stanton numbers do not undershoot flat-wall expectations at the same ReΔ2 values as seen in the low-TI case. Remarkably, the velocity distribution in the core of the flow over the recovery wall exhibits a negative gradient normal to the wall under high free-stream turbulence intensity conditions. This velocity distribution appears to be the result of two effects: 1) cross transport of kinetic energy by boundary work in the upstream curved flow and 2) readjustment of static pressure profiles in response to the removal of concave curvature.Copyright © 1993 by ASME

/pdf/effects-of-free-stream-turbulence-intensity-on-a-boundary-42iwvwqgk9.pdf

Terrence W. Simon

Papers

Comparison of Heat Transfer Enhancement by Actuated Plates in Heat-Sink Channels

Numerical modeling of three-dimensional heat transfer and fluid flowthrough interrupted plates using unit cell scale

Control of PbI2 nucleation and crystallization: Towards efficient perovskite solar cells based on vapor-assisted solution process

Subcooled flow boiling over a thin, low-capacitance surface on a concave wall

Effects of free-stream turbulence intensity on a boundary layer recovering from concave curvature effects