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Electromagnetic (EM) heat exchangers (HX) are systems that convert EM energy into heat or mechanical work. One potential design consists of a porous lossy ceramic material heated by EM waves with a compressible gas coolant. EM heating of ceramics is nonlinear, since the loss factor is temperature dependent. Designing such EM HXs requires an understanding of coupling between temperature, the electric field, and gas dynamics at the pore scale. To mimic this microscale phenomenon, a single channel with a high-speed gas coolant in perfect thermal contact with a thin solid ceramic layer is considered, with an applied plane-wave electric field propagating normal to the channel walls. From a thin-domain asymptotic analysis, the conservation laws reduce to a Rayleigh flow in the gas coupled with averaged thermal energy conservation equations at leading order. The model predicts that the kinetic energy of the gas increases up to 12.5 times the inlet value when thermal runaway occurs in the ceramic region for the cases considered, and thermal choking is possible when the coolant reaches the sonic state. Local maxima of efficiency occur on a discrete set of ceramic thicknesses that correspond to Fabry–Bragg resonances of the electric field. [ABSTRACT FROM AUTHOR]

A systematic-study is conducted using an innovative technology for paper drying by applying ultrasound mechanism. The advantages include greater energy efficiency, lower drying time and temperature, improvement of the product quality, and it is considered a green technology. The effects of initial moisture content, thickness, and refining condition are studied for different types of pulps (hardwood and softwood) using 23 factorial design of experiments. Analysis of Variance show that in the range of the studied parameters, thickness has the maximum effect on ultrasonic drying time followed by the initial moisture content. In addition, using a linear regression model, a relationships for the total time of drying is provided. The results confirmed that ultrasonic drying is more efficient at higher moisture content and higher thickness of the sample. These results are related to the structural characteristic of the samples such as porosity, pore distribution, and surface roughness. [ABSTRACT FROM AUTHOR]

The compressible flow between a slider and a moving rough surface is examined asymptotically and numerically in the limit of very small gap height. The roughness is assumed to consist of a well-defined periodic pattern of grooves whose amplitude and wavelength are of the order of the gap height. A two-scale homogenization analysis is employed to determine a non-linear elliptic partial differential equation governing the leading order pressure in the gap on the scale of the slider. The equation involves coefficient functions that are determined numerically by averaging Stokes flows on the scale of the patterned roughness. Numerical results are obtained for the cases of transverse and longitudinal roughness for both no-slip and slip-flow boundary conditions, and for the limiting case of large bearing number. Comments and a brief analysis are given on the reduction of the governing equation for pressure in the conventional limit of long wavelength of the surface roughness. [ABSTRACT FROM AUTHOR]

An integrated set of courses, or Integrated Course Block (ICB), developed for incoming first-year students at the Franklin W. Olin College of Engineering, is presented. Bound by a common theme of 'Kinetic Sculptures', the individual courses in this ICB are mathematics (single variable calculus and ordinary differential equations), physics (kinetics and dynamics of linear and rotational motion, thermodynamics and fluids), and an open-ended engineering project. The project part of the ICB allows students to explore the motion through the design of kinetic (moving) sculptures while utilizing the mathematics and physics concepts learned in the accompanying courses. This paper considers the 'Kinetic Sculptures' ICB from the pedagogical and epistemological points of view by presenting its implementation and discussing the results and analysis of three student surveys taken during three semesters, and seven semesters after participating in the ICB. [ABSTRACT FROM AUTHOR]