A. Shitzer

Bio: A. Shitzer is an academic researcher. The author has contributed to research in topics: Enthalpy of fusion & Heat flux. The author has an hindex of 1, co-authored 1 publications receiving 7 citations.

Thermal Management of an Avionics Module Using Solid-Liquid Phase-Change Materials

Abstract: A combined experimental and computational investigation of transient thermal control of an avionics module using phase-change material (PCM) is reported. The cone guration examined was a honeycomb core e lled with an organic PCM, n-triacontane, heated from the bottom. Experiments were conducted to evaluate the thermal performance of the PCM device by measuring temperatures at various locations as functions of time until the module temperature reached an acceptable maximum limit. An analysis of melting inside a single honeycomb cell, considering effects of natural convection, showed that, for the power levels and the cell geometry considered, the effect of natural convection on melting was negligible. A system-level analysis of the PCM-e lled device followed. Timewise variations of temperatures at various locations from the model were in good agreement with the experimental data. Times for complete melting, maximum temperature variations within the honeycomb, and evolution of melt shapes are presented as functions of power levels.

Application of phase change materials for passive thermal control of plastic quad flat packages (PQFP): a computational study

Abstract: A transient three-dimensional analysis was performed for passive thermal control of a plastic quad flat package (PQFP) by incorporating phase change material (PCM) under the printed wiring board (PWB). Governing conservation equations for mass, momentum and energy were solved by an implicit finite volume numerical technique. The effects of phase change were modelled by a single domain enthalpy-porosity technique. To study the effects of thermal conductivity of the board, a total of four cases were considered with two different board materials. It was found that passive cooling with PCM can arrest the temperature rise for a substantial time, for the power level considered. A higher board thermal conductivity resulted in a reduction in temperature levels. The melt region for a lower thermal conductivity of the board was found to be localized near the package footprint, while, for a higher board conductivity, the melt region extends along the board.

Performance Analysis of Heat Sinks With Phase-Change Materials Subjected to Transient and Cyclic Heating

Abstract: Phase-change cooling technique is a suitable method for thermal management of electronic equipment subjected to transient or cyclic heat loads. The thermal performance of a phase-change based heat sink under cyclic heat load depends on several design parameters, namely, applied heat flux, cooling heat transfer coefficient, thermophysical properties of phase-change materials (PCMs), and physical dimensions of phase-change storage system during melting and freezing processes. A one-dimensional conduction heat transfer model is formulated to evaluate the effectiveness of preliminary design of practical PCM-based energy storage units. In this model, the phase-change process of the PCM is divided into melting and solidification subprocesses, for which separate equations are written. The equations are solved sequentially and an explicit closed-form solution is obtained. The efficacy of analytical model is estimated by comparing with a finite-volume-based numerical solution for both transient and cyclic heat loads.

Heat dissipation in microelectronic systems using phase change materials with natural convection

Abstract: The present study is an initial investigation of the use of phase change materials with natural convection for the dissipation of thermal energy in a model of an integrated circuit (IC) acting as a heat source. A 1.91cm diameter long copper cylinder filled with a phase change material (PCM), P-116 Sunoco wax, was used as the heat exchange structure. The effectiveness of the PCM cylinder was found to be a strong function of the geometrical arrangement. With the cylinder of PCM positioned on top of the heating cartridge (which simulated the IC heat source), the gravitationally induced natural convection currents are shown to play a significant role in dissipating the heat generated by the cartridge. In an inverted position the effects of natural convection currents were not apparent. The effective thermal conductivity of the cylinder containing the melted wax was at least an order of magnitude higher when positioned above the heating cartridge than when positioned below. Pictures of the melting process were...