OPTIMIZATION OF THE REFUELLING SYSTEM OF COMPRESSED NATURAL GAS VEHICLES

• Main Author: Dinh Thi, Hoang Lan
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi Petronas 2005
• Subjects: TP Chemical technology
• Online Access: http://utpedia.utp.edu.my/7746/1/2005%20-%20OPTIMIZATION%20OF%20THE%20REFUELLING%20SYSTEM%20OF%20COMPRESSED%20NATURAL%20GAS%20VEHICLES.pdf; http://utpedia.utp.edu.my/7746/
• Institution: Universiti Teknologi Petronas

Compressed Natural Gas (CNG) is increasingly becoming an important fuel for automobiles due to the considerable reduction of air pollution compared with gasoline and diesel, and reduction of oil dependence. However, its application has not become widespread in Malaysia yet mainly due to the high operating cost of developing the infrastructure for filling stations. The objective of the present studyis to model the compression and flow mechanism in the storageand deliverysystemof natural gas in the filling stations, so that an improved understanding on the elements leading the high operating cost of the process can be established, and then solutions for future optimization could then be made. This paper is based on theoretical modelling of the compressible gas flow using Fanno Flow concept, taking place in a dispenser unit i.e. from the cascaded CNG storage tanks (sources) at a filling station to the CNGstorage tank of an automobile (receiver). The cascaded CNG storage tanks are held at a constant pressure of 24.8 MPa (3600psig) and the maximum allowable pressure set for the car storage tank is 21 MPa (3000 psig). The mathematical model developed by using MATLAB software is able to simulate the pressure distribution along the dispenser unit, the Mach number at the pipe entrance and exit, and differential changes in the vehicle storage tank in terms of pressure, temperature and gas content. From this model, the energy required for compression of gas, which is necessary to produce high pressurized source, is calculated. The results have shown that a new filling scheme, as a series of three sources, with increasing pressures of 2 MPa, 10 MPa and 24.8 MPa, is able to reduce 17.5% energy requirement for gas compression compared with the current compression system. This is based onthe assumption of empty vehicle tankas initial condition. In short, all the objectives were achieved, which successfully makes the project the basis for the future optimization study on Natural Gas Vehicles. in