• Title/Summary/Keyword: MECHANICAL ENERGY

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Analysis of the Thermal/Mechanical Energy in Food Extrusion Process (식품 압출성형공정의 열 및 기계에너지 분석)

  • Chung, Moon-Young;Lee, Seung-Ju
    • Korean Journal of Food Science and Technology
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    • v.29 no.1
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    • pp.65-71
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    • 1997

  • The energy supplied by motor of extruder, being known mostly to be dissipated as heat, was classified into two kinds of energy: a thermal energy by heat dissipation and a purely mechanical energy. The thermal energy was defined as a energy in terms of temperature rise and the mechanical energy as the motor energy minus the heat dissipated energy. A method to derive the thermal energy and the relative mechanical energy (the mechanical energy calculated regarding the mechanical energy at the lowest screw speed as zero) under the condition of constant barrel temperature was developed by which an extrusion case was analyzed. When extruding com grits with moisture $(27{\sim}37%)$ at low barrel temperature $({\leq}80^{\circ}C)$, the thermal energy slightly increased with increase in the moisture content, whereas the relative mechanical energy increased to a great extent. When increasing the screw speed, the thermal energy was nearly kept constant, whereas the relative mechanical energy largely varied. It is concluded that as the moisture content increases, the role of the mechanical energy becomes more effective than the heat energy dissipated from the motor energy.

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Review on the Recent Advances in Composite Based Highoutput Piezo-Triboelectric Energy Harvesters (압전-마찰전기 복합 소재 기반의 고출력 에너지 하베스팅 기술 개발 리뷰)

  • Rasheed, Aamir;Park, Hyunje;Sohn, Min Kyun;Lee, Tae Hyeong;Kang, Dae Joon
    • Ceramist
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    • v.23 no.1
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    • pp.54-88
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    • 2020

  • Global effort has resulted in tremendous progress with energy harvesters that extract mechanical energy from ambient sources, convert it to electrical energy, and use it for systems such as wrist watches, mobile electronic devices, wireless sensor nodes, health monitoring, and biosensors. However, harvesting a single energy source only still pauses a great challenge in driving sustainable and maintenance-free monitoring and sensing devices. Over the last few years, research on high-performance mechanical energy harvesters at the micro and nanoscale has been directed toward the development of hybrid devices that either aim to harvest mechanical energy in addition to other types of energies simultaneously or to exploit multiple mechanisms to more effectively harvest mechanical energy. Herein, we appraise the rational designs for multiple energy harvesting, specifically state-of-the-art hybrid mechanical energy harvesters that employ multiple piezoelectric and triboelectric mechanisms to efficiently harvest mechanical energy. We identify the critical material parameters and device design criteria that lead to high-performance hybrid mechanical energy harvesters. Finally, we address the future perspectives and remaining challenges in the field.

  • https://doi.org/10.31613/ceramist.2020.23.1.05 인용 PDF KSCI