Curve Fits for Thermodynamic Properties of Butanol Fuel

Butanol is an important industrial chemical and a promising biofuel. However, for the butanol applications in engines, studies are not as extensive as the case of ethanol or biodiesel. Therefore, there is a lack of information regarding the thermodynamic and combustion parameters of internal combustion engines operation using butanol fuel. To evaluate the combustion calculations and the thermodynamic simulation of internal combustion engines, several references from the literature can be used to obtain the thermodynamic and combustion routines. The most complete models are based on polynomials curve fits to the thermodynamic data (specific heat, enthalpy and entropy) of the fuels. The goal of this study is to evaluate the coefficients of the thermodynamic property curves of butanol fuel, so that the fuel can be included in the routines for internal combustion engines calculations. The calculations were firstly performed for ethanol fuel to validate the method and the estimated parameters were evaluated with statistical analysis. The results have shown that the estimated parameters are reliable for the type of fuels considered in this study. Then, the same methodology of parameter estimation was applied to butanol fuel. The estimated parameters for butanol can be considered sufficiently accurate to simulate spark ignition internal combustion engine operation using this fuel.