Machine learning approaches for estimating apricot drying characteristics in various advanced and conventional dryers

Drying plays a crucial role in preserving the quality of agricultural products. Nevertheless, suboptimal conditions in drying systems have an adverse effect on drying characteristics and energy efficiency. Machine learning approaches are innovative and reliable that have been successfully used to solve such challenges and achieve optimization in drying processes. In this study, five machine learning approaches (multilayer perceptron [MLP], gaussian processes [GP], support vector regression [SVR], k-nearest neighbors [kN], and random forest [RF]) were used to estimate moisture content and moisture ratio of apricot in five various dryers (convective [CV], microwave [MW], infrared [IR], microwave-convective [MW-CV], and infrared-convective [IR-CV]). Also, the values of specific energy consumption (SEC) and effective moisture diffusivity (D-eff) were calculated in these dryers. Accordingly, the best result of the D-eff (3.14 x 10(-10) m(2)/s) and the minimum value of the drying time (130 min) and SEC (18.67 MJ/kg) were obtained using MW-CV hybrid dryer. While the lowest values of D-eff (2.09 x 10(-11) m(2)/s) and highest drying time (18.5 h) and SEC (209.34 MJ/kg) were detected in CV dryer at 50 degrees C. The best correlation coefficients (R) for the estimation of moisture content were gained using RF technique for k-fold cross validation and train-test split with the values of 0.9908 and 0.9912, respectively. Moreover, moisture ratio results showed that the MLP achieved the highest R value over 0.9985 for both validation methodologies. In the discrimination of the drying methods, the MLP had the greatest accuracy as 82.00% and 86.00% for k-fold cross validation and train-test split, respectively. The results showed that the RF and ML models could potentially be used for estimation and discrimination for drying applications.

Automated summary

This study used machine learning approaches to estimate moisture content and moisture ratio of apricot in different dryers, and calculated specific energy consumption and effective moisture diffusivity. The results showed that the hybrid dryer achieved the best drying performance and lowest energy consumption, while the convective dryer performed the worst under suboptimal conditions. The RF technique showed excellent correlation in moisture content estimation, while the MLP had high accuracy in moisture ratio estimation and drying method discrimination.