THE PRESENT ARTICLE USES A LUMPED MODELING TO PREDICT THE TEMPERATURE CHANGES OF A VARIABLE RATE CNG CHARGE PROCESS FOR MULTI COMPONENT SYSTEMS. ARTIFICIAL NEURAL NETWORKS (ANNS) ARE USED TO PREDICT VARIOUS REAL NATURAL GAS PROPERTIES AT ANY DESIRED TEMPERATURE AND PRESSURE. THE CNG TANK TEMPERATURE INITIALLY DROPS SHARPLY (DUE TO THE JOULE-THOMSON EFFECT) AND THEN SLOWLY INCREASES TO A LIMITING TEMPERATURE HIGHER THAN THE ORIGINAL RESERVOIR TEMPERATURE. FOR MULTI-COMPONENT SYSTEMS THIS TEMPERATURE FLUCTUATION HAS A STRONG EFFECT ON THE NUMBER OF PHASES INVOLVED. THE SIMULATION RESULTS CLEARLY SHOW THAT THE CONDENSATION PHENOMENON DURING THE CHARGE PROCESS HAS A CRUCIAL EFFECT ON BOTH CORRESPONDING TEMPERATURE AND PRESSURE PROFILES.

IN THIS WORK, SATBILITY CALCULATIONS AND DETERMINATION OF GAS HYDRATE STRUCTURE IN EQUILIBRIUM CONDITIONS BY USING MINIMIZATION OF TPD FUNCTION FOR METHANE-WATER SYSTEM (SI), PROPANE-WATER SYSTEM (SII) AND METHANE-METHYL CYCLO PENTANE-WATER SYSTEM (SH) WERE PERFORMED. BASED ON RESULTS, AT 274 K AND 275 K TEMPERATURES, THE LIQUID PHASE OF METHANE-WATER SYSTEM AT 27 BAR AND 30 BAR PRESSURES, PROPANE-WATER SYSTEM AT 1.7 BAR AND 2.5 BAR PRESSURES AND METHANE-METHYL CYCLO PENTANE-WATER SYSTEM AT 9.6 BAR AND 10.1 BAR PRESSURES WAS DECOMPOSED. AS A RESULT OF DECOMPOSITION OF LIQUID PHASE FOR THESE SYSTEMS, TWO NEW PHASES, A NEW LIQUID PHASE AND HYDRATE PHASE WERE FORMED. SUBSEQUENTLY, MULTIPHASE FLASH CALCULATIONS IN ORDER TO DETERMINE THE AMOUNT AND COMPOSITION OF STABLE PHASES IN EQUILIBRIUM STATE WERE PERFORMED. FOR MINIMIZATION OF TPD FUNCTION, ALGORITHM GENETIC WAS USED. THE RESULTS SHOW GOOD ACCURACY WITH DATA OF HERIOT WATT UNIVERSITY HYDRATE MODEL (HWHYD).

GAS HYDRATE FORMATION IS UNDESIRED IN GAS PROCESSING AND DISTRIBUTION. GAS HYDRATES MAY FORM, EVEN NO LIQUID PHASE PRESENT IN THE SYSTEM. WHEN THE WATER CONTENT OF GAS MIXTURE IS LESS THAN THE WATER CONTENT OF SATURATED GAS, AT LOW TEMPERATURES AND HIGH PRESSURES, HYDRATE IS FORMED AND GAS-HYDRATE EQUILIBRIUM IS ESTABLISHED. HYDRATE FORMATION IN THE PRESENCE OF LIQUID WATER, IS ADDRESSED IN MANY OF PAPERS AND WELL MODELED BUT THERE IS LITTLE INFORMATION ABOUT GAS HYDRATE IN THE ABSENCE OF LIQUID WATER. THEREFORE, IT IS IMPORTANT TO HAVE A THERMODYNAMIC MODEL THAT CORRECTLY PREDICTS GAS HYDRATE FORMATION WITHOUT AN AQUEOUS PHASE. ...