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A study of pool boiling at atmospheric pressure from single-layered enhanced structures was conducted for a dielectric fluorocarbon liquid (PF 5060). The parameters investigated in this study were: (a) Heat flux (1-45W∕cm2); (b) width of the microchannels (65-105μm); and (c) microchannel pitch (0.2-0.7mm). The boiling performance of the enhanced structures was found to increase with the increase in channel width and decrease in channel pitch. A simple single line curve fit is provided as a practical way of predicting the data over the entire nucleate boiling regime. The exponent n in the single line power curve fit was found to be between 1 and 2. The modes of boiling from an enhanced structure proposed by previous researchers were unable to explain the boiling curves obtained in this study. The present data are explained in light of the contribution from the top finned surface of the enhanced structure.

In this paper, high performance RF integrated balanced-filters were proposed and designed for single band WiMAX front end application. This FEM includes an on-chip RF power amplifier and one switch, with two receive and one transmit paths. In addition to module size requirement, the WiMAX standard presents several passive design challenges: 1) The power amplifier (PA) provides an increase in rated power, hence a higher transmit gain which forces a more stringent output spurious/harmonic levels specification. 2) Received unwanted signals and blockers levels deplete the linearity performance of the receiver lineup.The module was designed on a multilayer organic (MLO) substrate. The highly integrated, fully shielded RF module incorporates embedded passive components including filters and baluns. Simulated results show excellent electrical performance with low insertion loss, high rejection and good return loss. Additionally, the module exhibits excellent thermal stability over the range of operating parameters.

A study of pool boiling at atmospheric pressure from single-layered enhanced structures was conducted for a dielectric fluorocarbon liquid (PF 5060). The enhanced structures were fabricated in copper with an overall size of 10 mm × 10 mm and 1 mm thickness. Parallel microchannels were cut on the bottom surface. The top surface also had parallel microchannels, aligned 90 degrees to those on the bottom surface. This resulted in an array of pores at the intersection of the microchannels. The structures were included in a natural circulation flow loop, consisting of an evaporator section, connecting tubes and a condenser. The transparent evaporator chamber contained the boiling enhancement structure. A cartridge heater embedded into a square copper rod (9 mm × 9 mm in cross section) provides heat to the enhanced structure from the bottom. The parameters investigated in this study were: a) heat flux (0.5–35 W/cm2); b) confinement (the open top and closed top cases have been studied); c) width of the microchannels (65μm–105μm). The boiling performance of the enhanced structures was evaluated by comparison with that of a flat surface with the same overall dimensions.

A visualization study of pool boiling at atmospheric pressure from plain and enhanced structures was conducted with PF 5060 as working fluid. The single layer enhanced structures were fabricated in copper and were 1 mm thick. The parameters investigated in the present study are heat flux, width of microchannels and overall structure width. A monochrome CCD camera with attached magnifying lens served as the main tool for observation of the boiling process from the structures. The nucleate boiling regime for a plain surface is usually divided into two sub-regimes: the isolated bubbles regime and the coalesced bubbles regime. For enhanced structures, the increase in geometric complexity leads to different flow regimes that may establish under different heat fluxes. This study evaluates these regimes using movies and still photographs. A comparison with the plain case is made and the differences highlighted.