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    Experimental investigation into the performance of cutting betel nut machine via response surface methodology and desirability function
    (2022-01-01)
    Bulan, Ramayanty
    ;
    Siregar, Kiman
    ;
    Wardhana, Muhammad Yuzan
    ;
    Lubis, Hamzah Hambali
    ;
    Thamren, Dewi Sartika
    Cutting betel nut machines are increasingly being designed by engineers using local material. However, the performance of the cutting betel nut machine is influenced by the moisture content of the betel nut and the rotational speed of the machine. In this study, the performance of cutting a betel nut machine under moisture content of betel nut and rotational speed of the machine was studied using response surface methodology (RSM) and desirability function. Central Composite Design (CCD) coupled with RSM and desirability function was employed to evaluate the impact of moisture content of betel nut (34.68–50.54%, w.b.) and rotational speed (600–1000 rpm) on machine capacity (kg/hr), efficiency (%), and losses (%) responses. The desirability function was then used to optimize moisture content and rotational speed yielding maximum machine capacity and efficiency at lower losses. Three verification experiments were run to ensure the empirical relationships were valid. Optimum requirements of process parameters have been seen at which moisture content of 50.54% (w.b.) and rotational speed of 1000 rpm was achieved in maximum machine capacity of 44.16 kg/hr at higher efficiency (92.72%) and lower losses (6.31%). The model's conclusions were very consistent with the confirmed values. The results proved that an appropriate performance of the machine can be achieved using moisture content of betel nut and rotational speed of machine cutting betel nut.
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    Performance of ethanol-fuelled solid oxide fuel cells: Proton and oxygen ion conductors
    (2007-09-15)
    Jamsak, W.
    ;
    Assabumrungrat, S.
    ;
    Douglas, P. L.
    ;
    Laosiripojana, N.
    ;
    Suwanwarangkul, R.
    This paper investigates the performance of ethanol-fuelled solid oxide fuel cells (SOFCs) with two types of solid electrolytes, namely oxygen ion-conducting (SOFC-O<sup>2-</sup>) and proton-conducting electrolytes (SOFC-H<sup>+</sup>). Our previous work reported that the SOFC-H<sup>+</sup> shows superior theoretical performance over the SOFC-O<sup>2-</sup> electrolyte. However, in this work when all resistances are taken into account, the actual performance of the SOFC-O<sup>2-</sup> (Ni-YSZ|YSZ|YSZ-LSM) becomes significantly better than that of SOFC-H<sup>+</sup> (Pt|SCY|Pt). The maximum power density of the SOFC-O<sup>2-</sup> is about 34 times higher than that of the SOFC-H<sup>+</sup> when operated at an inlet H<inf>2</inf>O:EtOH ratio of 3, a fuel utilization factor of 80% and a temperature of 1200 K. Then the required values of the total resistance of the SOFC-H<sup>+</sup> to achieve the same power density as the SOFC-O<sup>2-</sup> were determined. It was found that due to the superior theoretical performance of the SOFC-H<sup>+</sup>, it is not necessary to reduce the SOFC-H<sup>+</sup> total resistance to the same values as the one for SOFC-O<sup>2-</sup>. The study also indicates that reduction of only the electrolyte resistance is not sufficient to improve the SOFC-H<sup>+</sup> performance and, therefore, the other resistances including activation, electrodes and interconnect resistances need to be reduced simultaneously. Finally, the improvement of the electrolyte resistance by changing its resistivity and thickness is discussed. © 2007 Elsevier B.V. All rights reserved.
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    The result analysis of economic distribution transformer design in Thailand
    (2002-12-01)
    Suechoey, Boonlert
    ;
    Bunjongjit, Sulee
    ;
    Kando, M.
    Thailand's medium-sized industries, with demands rating from 30 - 999 kW., currently need to develop distribution transformers that provide the highest efficiency regarding the transformer low losses and lowest costs. This is partly because the energy authorities that provide the electricity have fixed the transformer losses. In this paper, the result analysis of transformer design is presented. The considered factor include efficiency, losses throughout the transformer costs. The analysis includes an example of calculation and selection.