Investigation on thermodynamic properties of ethanol plus gasoline blended fuel

The heat capacities (C-p) of ethanol, unleaded gasoline 930 (where the "93" represents the octane number), and gasohol (which consisted of 10 wt % ethanol and 90 wt % unleaded gasoline 93(#)) were measured by adiabatic calorimetry in the temperature range of 80-320 K. For the gasoline, a glass-liquid transition was found at 92.42 K; for the gasohol, a glass-crystal transition and a solid-liquid transition were observed, at 93.17 and 150.86 K, respectively. The enthalpy and entropy of all of the transitions were derived based on the C-P data. For the gasoline, the enthalpy and entropy of the glass-liquid transitions were determined to be 6.80 J g(-1) and 0.0736 J K-1 g(-1), respectively; for the gasohol, the enthalpy and entropy of the glass-crystal transition were determined to be 9.93 J g(-1) and 0.107 J K-1 g(-1), respectively, and the enthalpy and entropy of 1 the solid-liquid phase transition were determined to be 9.99 J g(-1) and 0.0662 J K-1 g(-1), respectively. The polynomial equations of C(P)with respect to the thermodynamic temperature T, were established through the least-squares fitting. According to the thermodynamic relationship and the equations, the thermodynamic functions of the gasoline and the gasohol, and the excess thermodynamic functions of the gasohol, were derived.