The isothermal vapor–liquid equilibria of diethyl carbonate (DEC) + isooctane/n-heptane/toluene systems were measured using a simple quasi-static ebulliometer at temperatures ranging from 303.15 to 323.15 K. The validity of the experimental apparatus was checked by comparing the measured vapor pressure of pure DEC, isooctane, n-heptane, and toluene with the published data and obtaining average absolute deviations less than 1.2%. The experimental data were correlated using the Wilson, nonrandom two-liquid, and universal quasichemical models with average absolute deviations in vapor pressure between calculated values and experimental data of 1.0%, 1.0%, 1.0% respectively, for isooctane + DEC system; 0.9%, 0.9%, 0.9%, respectively, for n-heptane + DEC system; and 1.0%, 1.1%, 1.1%, respectively, for toluene + DEC system. The experimental vapor pressure data for all systems show strongly nonideal solution with positive deviation from Raoult’s law. The systems studied show that no azeotropic point is exhibited by the systems.

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Light naphtha is not reliable used as automotive fuel because of its low octane number (RON) and high vapor pressure. To utilize light naphtha as fuel, blending process may be used to obtain usable gasoline fuel. Diethyl carbonate (DEC) can be used as blending agent with light naphtha because its high octane number and low vapor pressure. Therefore in this work, the vapor pressure and octane number (RON) of DEC–light naphtha blends were measured to study the effect of DEC in light naphtha blending. The vapor pressure measurements show that vapor pressure of DEC–light naphtha blends decreased while the DEC fraction increased. The pseudo binary analysis approachment was used to correlate the vapor pressure experimental data and predict the vapor pressure of light naphtha + DEC blends. The Wilson and nonrandom two-liquid (NRTL) model are giving good correlation and prediction result with average absolute deviation (AAD) less than 1.3% meanwhile the Hildebrand & Scatchard model give quietly poor result with AAD value of 4.4%. The RON measurements show that the RON values of the blends increased while the DEC fraction increased. The DEC is successfully used as blending agent into light naphtha with 30% v/v optimum fraction.

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Natural gas is used as fuel in industries, power plants, commercial installations, and households. In its application, natural gas leaks can be considered as a major hazard because of its flammable and explosive nature. In addition to fuel, heat and oxygen sources, fires and explosions can occur if the concentration of natural gas in the air is between Low Flammable Limit (LFL) and Upper Flammable Limit (UFL). If the release of natural gas is not ignited, it will immediately form a Vapor Cloud Explosion (VCE) that can cause an explosion if it meets ignition point. Therefore, a research on dispersion patterns in a particular area or space is needed to minimize hazards and to develop safety procedures and regulations. This research aims to determine the external parameters that affect the dispersion and explosion caused by natural gas by using FLACS software from PT. Gexcon Indonesia. This software can display overpressure graphs of time and 3D visuals of simulations. The external parameters consist of vent size (5.4 m2 and 2.7 m2), wind direction, lighter position (center and back), day and night condition, and the presence of a obstacle (with and without obstacle). From the research results by the simulations, it is obtained that the highest overpressure value when there is an obstacle with a vent size of 2.7 m2; wind direction from the north; night condition, and back ignition point is 0.503 bars at 40, 835 s which can cause most buildings to collapse and the death rate to increase.