Artificial Neural Network Modelling of Heat Transfer to Canned Particulate Fluids under Axial Rotation Processing

Abstract

Artificial neural network models were developed for the overall heat transfer coefficient (U) and the fluid to particle heat transfer coefficient hfp in canned Newtonian fluids with and without particles, and the model performances were compared with the dimensionless correlations for both free and fixed axial modes of agitation. Part of the experimental data were used for training and testing, and a portion was used for cross validation. The average errors (RMS), associated with predicted hfp and U values in fixed and free axial mode were a function of the ANN variables: number of hidden layers, number of neurons in each hidden layer, learning rule, transfer function and number of learning runs. RMS values not significantly different with number of hidden layers between one and three, and the associated RMS was minimal with a high R2 value with one hidden layer and 8 neurons. The combination of the Delta-rule and TanH transfer function also gave the lowest RMS and the highest R2. The highest R2 was achieved for the data set with 85% used for training and testing and 15 % for the cross validation in both modes of rotation, and therefore this combination was used for the development of neural network models. Mean relative errors (MRE) for ANN models were much lower compared with MRE associated with dimensionless correlations; 75-78% lower for hfp and 66% lower for U in fixed and free axial mode with particulate in liquid. Without particulates, in comparison with dimensionless correlations, the MRE for ANN models were 37% lower in end-over-end mode and 76% lower for free axial mode. Overall, ANN models yielded much higher R2 values than dimensionless correlations. The ANN coefficient matrix is included so that the models can be implemented in a spreadsheet.