Construction calorific value model for pig manure based on organic element contents

To discuss the feasibility of using organic element contents of pig manure to predict calorific value, the paper built a prediction model of gross calorific value and net calorific value based on the contents of organic elements. 160 pig manure samples were collected, and their C,H,N,S,O element contents were measured by EA3000 and gross calorific value and net calorific value were measured by IKA-C2000 bomb calorimeters. Simple correlation analysis result showed that the contents of C,H,N had very significantly positive correlation with calorific value, while the contents of S and O had no significantly positive correlation with calorific value. 120 samples were selected to build the model, results indicated that the calorific value prediction model based on C,H,N element contents using multiple linear regression analysis could accurately use C,H,N to predict calorific value of pig manure. The determination coefficient of the prediction model of gross calorific value and net calorific value were 0.836 and 0.785 respectively. In the 40 samples used for the external validation, the root-mean-square error of gross calorific value was 621.31 J/g, and the relative root-mean-square error was 3.74%; the root-mean-square error of net calorific value was 620.85 J/g, and the relative root-mean-square error was 4.06%. It was concluded that the calorific value prediction model of pig manure based on organic element contents by built using multiple linear regression analysis method could predict the gross and net calorific values accurately.