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Subject: search.filters.subject.moisture content

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    Mathematical Models of Natural Rubber Sheets Drying: Difference Acid Coagulation Cases
    (2024-05-01)
    Eakvanich, Visit
    ;
    Kalasee, Wachara
    ;
    Lakachaiworakun, Putipong
    ;
    Dangwilailux, Panya
    ;
    Wattana, Wassachol
    The mathematical model for drying process is a useful tool in process optimization and drying chamber design. The research purposes of this study were to investigate the influence of drying temperature on drying time and the modelling the drying kinetics of the natural rubber (NR) sheets. The NR sheets which produce from commercial formic acid, commercial acetic acids, and ammonia plus commercial formic acid were studied at drying temperature of 40, 50, and 60°C and air speed of 0.5 m/s. The results indicated that the drying time was substantially reduced with an increase in temperature. The moisture content ratio of rubber sheets produce from commercial formic acid coagulation was similar to the sheets produce from commercial acetic acids coagulation. However, the drying time of them were longer than the drying time of the sheets produce from ammonia plus commercial formic acid coagulation. Finally, the logarithmic model was the best model which suitable to predict the moisture content ratio of the sheets drying with all experimental condition.
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    The Response of Natural Esters when Being Under a Direct Current Electric Field for a Long Time
    (2024-01-01)
    Thungsook, Kittisak
    ;
    Manger, Rene
    ;
    Zink, Markus H.
    ;
    Kobus, Maja
    ;
    Pattanadech, Norasage
    This study examines the dielectric behavior of natural esters exposed to a DC electric field over an extended period of time. The dielectric response was investigated by using polarization and depolarization current measurements. The natural ester sample was subjected to a DC electric field of 0.1 kV/mm, 0.5 kV/mm, 1 kV/mm, 1.5 kV/mm, and 2 kV/mm, respectively. Besides, the moisture content of natural esters was also controlled using a natural method. The test results showed that after being exposed to an electric field for an extended period of time of the natural ester, different forms of charge accumulation might be found partly depending on the initial condition of the investigated natural ester.
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    Accurate Assessment of Moisture Content and Degree of Polymerization in Power Transformers via Dielectric Response Sensing
    (2023-10-01)
    Kunakorn, Anantawat
    ;
    Pramualsingha, Sarawuth
    ;
    Yutthagowith, Peerawut
    ;
    Nimsanong, Phethai
    ;
    Kittiratsatcha, Supat
    Power transformers are essential apparatuses used to transfer electrical energy from one voltage-level circuit to another. For reliable systems, preventive maintenance of the transformers is required to ensure good services of all mechanical, electrical, and insulation parts. Oil-immersed paper is most often used for transformer insulation. To ensure such good insulation performance and for assessing insulation conditions, advanced transformer sensing, monitoring, and effective assessment techniques are required. This paper introduces an effective technique for assessing the insulation conditions in power transformers, which are crucial for ensuring reliable energy transfer. The method utilizes advanced transformer sensing and monitoring, focusing on oil-immersed paper insulation commonly used in transformers. The technique employs dielectric response sensing, obtained from frequency-domain spectroscopy tests, to estimate degrees of polymerization (DP) and percentages of moisture content (PMCs) in the oil-immersed paper insulation. These parameters are well-known indicators of insulation performance. The approach is based on the weighted k-nearest neighbor regression, using a database of dielectric loss factors at low frequency and oil conductivities. To overcome limited data availability, linear interpolation and extrapolation techniques are applied to enlarge the database. Experimental verification and comparison with a previously developed method demonstrate the proposed technique’s superiority in accuracy and complexity. The maximum deviations of DP and PMC in the validation cases are 6.2% and 18.7%, respectively. In addition, to evaluate the validity of our proposed method in the case of a real power transformer, a comparative analysis of the DP and PMC values determined by the proposed method with those obtained through a previously developed and complicated approach was performed. The predicted results indicate that the DP and PMC values of the oil-immersed insulation fall within the ranges of 800 to 1000 and 1.5 to 2.0, respectively, which agree with the results determined by the complicated approach and closely align with real conditions. By offering a reliable and advanced means of assessing insulation conditions, this technique contributes to the preventive maintenance and overall efficiency of power transformers.
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    AC Breakdown Characteristics of Different Moisture Content Pressboards Impregnated with Natural Ester
    (2021-04-01)
    Pattanadech, Norasage
    ;
    Kittikhuntharadol, Yannaphol
    ;
    Pannil, Pittaya
    Biodegradable materials are necessary for saving the environment. Natural ester is alternative liquid insulation that can be biodegraded and used in a transformer. Insulation system in a transformer, liquid insulation cooperates with solid insulation such as cellulose. Pressboard is the main kind of cellulose used in the transformers. Normally, the characteristics of solid insulation can be investigated and analyzed by diverse methods. This paper represents the study of AC breakdown voltage of non-impregnation, 8-hours, and 16-hours impregnated pressboard with natural ester with different moisture content. To vary the moisture content of the pressboards, they were heated at 100 degrees Celsius for 12 hours and 24 -hours in a vacuum oven. After that, the Coulometric Karl Fischer method was used to determine the moisture content. Before impregnation, the natural ester was heated at 100 degrees Celsius for 12-hours in another vacuum oven. To investigate AC breakdown voltage, electrode configuration and test circuit were set-ups according to IEC 60243-1. From the test result, higher' moisture content caused clearly lower AC breakdown voltage of the pressboards.
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    A reflectometer using antenna mixers
    (2016-03-07)
    Inrun, R.
    ;
    Vichianchai, R.
    ;
    Leekul, P.
    ;
    Kittiyanpunya, C.
    ;
    Krairiksh, M.
    This paper presents a sensor for monitoring moisture content of paper. The reflection coefficient of paper at various moisture contents are measured and used for determining humidity of paper. The resultant IF output of 50 MHz from the reflectometer operating at the frequency of 2.40 GHz and 2.45 GHz shows an obvious difference in reflection coefficient for dry and wet paper depicting the feasibility to design a moisture content sensor.