<![CDATA[The increasing biodiesel blending ratio in diesel fuel in Indonesia has drawn attention from vehicle manufacturer, who demand higher biodiesel quality. Water content is one of the critical quality parameters of biodiesel. Coulometric Karl Fischer titration is a commonly used for water content measurement method, however it is costly. This study investigates the feasibility of using a capacitive sensor based on phase shift angle detection to measure water content in biodiesel. Variations in biodiesel water content will change the capacitance of the sensor, which will be converted by an electronic circuit into an electronic signal output. The phase of the output signal is the one to be observed. Experiments were conducted over two different capacitance ranges (ΔC), namely 7.1-7.6 pF and 25.1-25.6 pF, a series of capacitors were used as a dummy sensor. A clear trend of phase shift angles and capacitance values correlation was observed. The strongest correlation was obtained in the ΔC range of 7.1-7.6 pF, whith input signal amplitude 10.27 V (S1) and 6.24 V (S2). The linear trendline slope was 27.62, sensitivity 27.07 degree/pF, and with a coefficient of determination (R2 ≈ 0.98). The selected capacitance measurement range has significant influence on the measurement performance and, consequently, should be considered in determining the dimensions of the capacitive sensor. This result demonstrate that the proposed phase shift based capacitive sensing method is a promising and cost-effective approach for biodiesel water content measurement.]]>
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