Development of a new fast drying determinant method using resistivity for the industry of coconut shell charcoal briquettes

The charcoal briquette industry faces the problem of the method for determining the drying stop during its production. The combustion method as the main method is time-consuming. The test needs 3 hours to get the result. In order to find a new fast method for drying determinant, the resistivity method was proposed for rainbow coconut shell charcoal briquettes. The briquettes had a length of 3.8 cm, height of 2.2 cm, and width of 2 cm with a half-tubular top side. 50 samples of each three drying conditions (wet, half-dry, and dry) of the same drying batch were collected. These conditions were determined by a drying expert of a coconut shell charcoal briquette company. Then, the resistances were measured and the geometrical factor was applied to find their resistivities. A model of resistivity in the cross-sectional layer was also applied to find the coefficients of front-tail, base-top, and side-side directions. These coefficients became a special way to find the position of the wet part in half-dry briquettes. The results of the work show that resistivities in combination with their distribution can potentially be used for fast drying stop determinant. The wet and dry briquettes have a resistivity difference order of 102. The resistivities of the wet and dry briquettes are 450 kiloohms and 28 megaohms for every centimeter of length, respectively. The half-dry and dry briquettes have the same order of resistivities. However, the resistivity distribution of both conditions is very different. The dry briquettes have homogenous resistivities among the measurements emphasizing the drying process of the solid. It was also found that the half-dry briquette has a surface dry part until 0.55 cm depth. The center of the briquette is still wet