Microwave Technology Using Low Energy Concentrated Beam for Processing of Solid Waste Materials from Rapana thomasiana Seashells

Abstract

The solid waste of Rapana thomasiana seashells both from domestic activities and natural waste on seashore can be used to obtain viable products for medical applications. However, conventional technologies applied for sintering the materials require massive energy consumption due to the resistance heating. Microwave heating represents an advanced technology for sintering, but the stability of the process, in terms of thermal runaway and microwave plasma arc discharge, jeopardizes the quality of the sintered products. This paper aims to present the results of research focused on viable heating technology and the mechanical properties of the final products. A comparative analysis, in terms of energy efficiency vs. mechanical properties, has been performed for three different heating technologies: direct microwave heating, hybrid microwave heating and resistance heating. The results obtained concluded that the hybrid microwave heating led to final products from Rapana thomasiana solid waste with similar mechanical properties compared with resistance heating. In terms of energy efficiency, the hybrid microwave heating was 20 times better than resistance heating.

Hydroxyapatite from Natural Sources for Medical Applications

“…To investigate the mechanical properties of the sintered specimens, all tests (compressive strength evaluation, micro-hardness measurement, and wear test) have been conducted in accordance with the international standards in force [ 39 , 40 ], but also based on our previous experience [ 41 , 42 ].…”

Reducing NOx Emissions through Microwave Heating of Aftertreatment Systems for Sustainable Transport in the Inland Waterway Sector

“…The reflection of microwaves from the ceramic core towards the microwave generator is minimized by using a matching load autotuner Tristan 6000 W from Muegge GmbH (Germany, Reichelsheim, 2008) with three stub tuners driven by step motors. In order to obtain a resonant circuit, the length of the three stub tuners can be determined based on the Smith Chart diagram, representing a nomogram for solving problems with transmission lines and matching circuits in radio frequency engineering (see Figure 4) [37][38][39]. Lengths d1, d2, and d3 can be calculated based on Equation ( 5):…”

“…The measurement unit consists of NOx sensors connected to a MGT 5-LON Gas Analyzer with MDO 2-LON Opacimeter, and temperature sensors (type K, range: 0-1300 °C) The reflection of microwaves from the ceramic core towards the microwave generator is minimized by using a matching load autotuner Tristan 6000 W from Muegge GmbH (Germany, Reichelsheim, 2008) with three stub tuners driven by step motors. In order to obtain a resonant circuit, the length of the three stub tuners can be determined based on the Smith Chart diagram, representing a nomogram for solving problems with transmission lines and matching circuits in radio frequency engineering (see Figure 4) [37][38][39]. The reflection of microwaves from the ceramic core towards the microwav tor is minimized by using a matching load autotuner Tristan 6000 W from Muegg (Germany, Reichelsheim, 2008) with three stub tuners driven by step motors.…”

Microwave Soldering of Low-Resistance Conductive Joints—Technical and Economic Aspects

“…However, microwave technology cannot be applied directly to all classes of materials. Metals, in the solid state, reflect microwaves [11][12][13], but indirect heating can be applied if are used ceramic susceptors [14][15][16][17][18]. On the other hand, most ceramic materials are good absorbers of microwaves and, depending on the loss factor coefficient, can be sintered [19] for obtaining powerful magnets for motors and actuators [20], or inductive sensors for different sensing applications [21].…”