This research evaluates the efficiency of working fluids in direct adsorption solar collectors by incorporating magnetite (Fe3O4) nanoparticles. Samples with Fe3O4 concentrations ranging from 0% to 1% were evaluated under direct solar exposure conditions. It was determined that the nanofluids exhibit higher thermal efficiency than pure ethylene glycol, indicating that magnetite enhances solar radiation absorption. However, higher nanoparticle concentration was observed to decrease the Specific Absorption Rate (SAR), likely due to lower radiation penetration. These results suggest that SAR could be a useful selection criterion for formulating nanofluids in DASC collector applications.
Hyperthermia is a cancer treatment that utilizes magnetic nanofluidic and magnetic induction. The experimental evaluation techniques used to validate heat transfer and changes in thermal diffusivity include the use of phantom models to simulate human tissue and infrared thermography. The present study applies phantom models with magnetic inserts, which pose challenges in determining temperature distribution due to their location and depth, affect thermal contrast. Processing thermograms is crucial for identifying areas of interest, which enables the development of new hyperthermia evaluation techniques.
This paper used digital photoelasticity to evaluate the temporal variations of the stress field in an epoxy-metal embedded actuator. Stress variations were generated with magnetic induction heating-cooling cycles and they were analyzed with frames of a color digital video acquired with a circular polariscope. A phase wavelength stepping algorithm and an unwrapped standard algorithm were applied to obtained unwrapped map. The modification of the fields of bi-material stresses opens the opportunity to generate photoelastic actuators, in consequence they can be used as phase modulators. In consequence, digital photoelasticity is an excellent technique to characterize this effect in bimaterials.
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