A Simple Prediction Model for Higher Heat Value of Biomass Hongliang Qian, †,‡,# Xiaojing Guo, §,# Sudong Fan, ⊥ Kiros Hagos, † Xiaohua Lu, † Chang Liu,* ,† and Dechun Huang* ,‡ † State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 210009, China ‡ School of Engineering, China Pharmaceutical University, Nanjing, 210009, China § Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, China ⊥ NANTEX Industry Co., Ltd, Zhenjiang, 212006, China ABSTRACT: A simple prediction model, based on ultimate analysis of bio- mass which is leveraged to predict higher heating value (HHV), was proposed in this paper. In the literature there are two facts offering some bases for the study. One is that oxygen (O) content is not an accurate value in the calculation of the reductance degree as well as the heat of combustion per unit of oxygen consumed of the biomass, and as a result, the determination of HHV turns out to be inaccurate, too. The other is that the O variable does not contribute to the overall physical interpretation of the HHV from the perspective of mathematics (the p-value), and therefore, a modified reductance degree of biomass was pre- sented, whereas O content was neglected. According to the modified reduc- tance degree, HHV per gram of oxygen consumed of one biomass was identified to be nearly a constant. Thus, two theoretical prediction models for the bio mass with and without sulfate (HHV′ = 873.52(C/3 + H + S/8), HHV″ = 874.08(C/3 + H)) were established. The comparison between mean absolute error (MAE) of Thornton’s method and 15 recently established empirical correlations shows that the MAE of the two predic- tion models is the least, which serves as strong evidence for the good HHV predictive capability of the two models, and their easy-to-operate quality as well. Furthermore, the coefficients of the two models are almost the same value, which indicates that the S content also has negligible effect on HHV. The final model that we proposed is model 2 (HHV″ = 874.08(C/3 + H)). 1. INTRODUCTION In a broad sense, the term “biomass” means organic material generated via a spontaneous or induced biological process. As an energy source, biomass includes certain types of wood, energy crops, marine algae, agricultural and silviculture residues, and certain animal, industrial, and human wastes. 1,2 The theory of material and energy balances is widely cited in analyzing the processes associated with solar energy. The utilization of biomass is frequently required for engineering analysis and design. One of the most important properties in material and energy balances is the heating value. 3 The heating value of a biomass fuel can be figured out experimentally by employing an adiabatic bomb calo- rimeter which measures the enthalpy change between reactants and products. 4 The use of bomb calorimeter, though relatively simple in operation and accurate in calculation, may not always be accessible to researchers. To circumvent this problem, researchers together with their respective elemental analyzer, usually make proximate or ultimate analysis that will provide data, and there- after work out the heating value via established empirical corre- lations. 5 Many of the previous attempts were made to correlate the HHV with data from proximate and ultimate analysis. One of the earliest and most popular correlations is the Dulong correlation 6 which was first introduced in the late 1800s and based on the data from the ultimate analysis of coal. Vargas-Moreno 7 reviewed the mathematical models for predicting the heating value of biomass materials, and among these models many have relied on the results of proximate and ultimate analysis and those of structural analysis or chemical or physical determinations. In biochemical engineering, the carbon weight fraction in a dry microbial biomass, the number of equivalents of available electrons per gram atom carbon (reductance degree) in biomass, and the heat of reaction per equivalent of available electrons transferred to oxygen, are all relatively constant. 3 Erickson et al. 8 have capitalized on the average values of these regularities with considerable success in his analysis of microbial growth and product formation, which states that the heat of combustion is directly proportional to the quantity of oxygen consumed in the combustion process. With Thornton’s method as a groundwork, Patel 3 presented a method which utilizes the weight fraction carbon on a dry basis and employs the reductance degree so as to predict the heat of combustion of renewable resources. In the field of fires, the heat of combustion per unit of oxygen consumed is measured for evaluating the rate of heat release of fuel. Huggett 9 designed a method on the basis of the generalized idea Special Issue: Proceedings of PPEPPD 2016 Received: June 28, 2016 Accepted: November 3, 2016 Article pubs.acs.org/jced © XXXX American Chemical Society A DOI: 10.1021/acs.jced.6b00537 J. Chem. Eng. Data XXXX, XXX, XXX-XXX