Search Results (6)

Compressed natural gas (CNG) refueling stations operate under highly dynamic thermodynamic conditions, requiring accurate modeling and optimization to ensure efficient performance. In this study, a dynamic simulation model of a CNG station was developed using MATLAB-SIMULINK, including detailed subsystems for multi-stage compression, cascade storage, and vehicle tank filling. Real gas effects were incorporated to improve prediction accuracy of the pressure, temperature, and mass flow rate variations during fast filling. The model was validated against experimental data, showing good agreement in both pressure rise and flow rate evolution. A two-stage multi-objective optimization approach was applied using Taguchi experimental design and gray relational analysis (GRA). In the first stage, storage pressures were optimized to maximize the number of vehicles filled and gas mass delivered, while minimizing compressor-specific work. The second stage focused on optimizing the volume distribution among the low, medium, and high-pressure tanks. The combined optimization led to a 12.33% reduction in compressor-specific energy consumption with minimal change in refueling throughput. These results highlight the critical influence of pressure levels and volume ratios in cascade storage systems on station performance. The presented methodology provides a systematic framework for the analysis and optimization of transient operating conditions in CNG infrastructure. Full article

Due to ecological and economic advantages, natural gas is used as an alternative fuel in the transportation sector in the form of compressed natural gas (CNG) and liquefied natural gas (LNG). Development of infrastructure is necessary to popularize vehicles that use alternative fuels. Selected positive factors from EU countries supporting the development of the CNG market were discussed. The process of natural gas vehicle (NGV) fast filling is related to thermodynamic phenomena occurring in a tank. In this study, the first law of thermodynamics and continuity equations were applied to develop a theoretical model to investigate the effects of natural gas composition on the filling process and the final in-cylinder conditions of NGV on-board composite cylinder (type IV). Peng–Robinson equation of state (P-R EOS) was applied, and a lightweight composite tank (type IV) was considered as an adiabatic system. The authors have devised a model to determine the influence of natural gas composition on the selected thermodynamic parameters during fast filling: Joule–Thomson (J-T) coefficient, in-cylinder gas temperature, mass flow rate profiles, in-cylinder mass increase, natural gas density change, ambient temperature on the final natural gas temperature, influence of an ambient temperature on the amount of refueled natural gas mass. Results emphasize the importance of natural gas composition as an important parameter for the filling process of the NGV on-board composite tank (type IV). Full article

The hydrogen economy refers to an economic and industrial structure that uses hydrogen as its main energy source, replacing traditional fossil-fuel-based energy systems. In particular, the widespread adoption of hydrogen fuel cell vehicles (HFCVs) is one of the key factors enabling a hydrogen economy, and aggressive investment in hydrogen refuelling infrastructure is essential to make large-scale adoption of HFCVs possible. In this study, we address the problem of effectively designing a hydrogen supply network for refuelling HFCVs in urban areas relatively far from a large hydrogen production site, such as a petrochemical complex. In these urban areas where mass supply of hydrogen is not possible, hydrogen can be supplied by reforming city gas. In this case, building distributed hydrogen production bases that extract large amounts of hydrogen from liquefied petroleum gas (LPG) or compressed natural gas (CNG) and then supply hydrogen to nearby hydrogen stations may be a cost-effective option for establishing a hydrogen refuelling infrastructure in the early stage of the hydrogen economy. Therefore, an optimization model is proposed for effectively deciding when and where to build hydrogen production bases and hydrogen refuelling stations in an urban area. Then, a case study of the southeastern area of Seoul, known as a commercial and residential center, is discussed. A variety of scenarios for the design parameters of the hydrogen supply network are analyzed based on the target of the adoption of HFCVs in Seoul by 2030. The proposed optimization model can be effectively used for determining the time and sites for building hydrogen production bases and hydrogen refuelling stations. Full article

Compressed natural gas can be globally used as fuel for combustion engines to reduce CO₂ emission without negative impact on economy. Lack of refueling infrastructure is one of reason why NGVs shares only ~1.6% in total vehicle fleet worldwide. Operational tests of CNG home fast refueling station were performed to investigate: (i) natural gas demand, m³/h; (ii) energy consumption, kW/h; and (iii) total cost of one refueling. Two scenarios for operational tests were developed to monitor and collect data. Safety tests for leakage, fill pressure change, interrupted power and gas supply, temperature, and unexpected failures were performed. This article present results of operational and safety tests of compressed natural gas home, fast refueling station (CNG-HRS) based on one stage hydraulic compressor. The average duration of HRS full operating cycle was 7 h and 32 min (buffering and refueling mode). The average electric energy and natural gas consumption for one full cycle was 5.52 kWh and 7.5 m³, respectively. Safety tests results for leakage, fill pressure change, interrupted power and gas supply, temperature and unexpected failures demonstrated valid operation of HRS which positively affects the general safety level. To compare HRS with large scale CNG refueling infrastructure the costs of 1 Nm³ CNG was estimated for both solutions. Results shows that home refueling appliance might be become a solution for filling the gap in CNG refueling infrastructure. Full article

There is growing agreement that refueling station location plans that aim to encourage public adoption of alternative fuel vehicles (AFVs) should include sites near freeways in urban areas. Little is known, though, about the refueling behavior of early AFV adopters in these locations, which can involve travel on complex and congested roadways. To address this, an intercept travel survey collected data from 158 drivers of compressed natural gas (CNG) vehicles who refueled at CNG stations near freeways in greater Los Angeles, California. Results show that these stations met refueling demand from across the majority of the metropolitan area, and the distribution of local and distant refueling demand was consistent except for the downtown station. Drivers also considered these stations to be safe and accessible. Nearly half of drivers did not include another local stop in conjunction with their refueling trip that required leaving and returning to the freeway. These respondents refueled on longer trips with lower fuel tank levels, while refueling at the station that minimized deviation. Refueling downtown negatively influenced refueling in this manner. These findings should be considered when recommending station sites near freeways in future AFV infrastructure plans. Full article

Building a competitive and resource-efficient transportation system involves the achievement of a number of ambitious goals. Two of the main instruments in the European transportation policy in this field address the significant reduction of GHG emissions and oil dependency in transportation. Alternative fuels and compressed natural gas (CNG) in particular have huge potential for achieving these goals. The main problem that limits its wide utilization is related to the insufficient number of CNG refueling stations, especially along highways and routes from the core TEN-T network where no gas pipelines are available. Therefore, the aim of this research is to study a possible solution to building daughter CNG refueling stations which can be used as basis for formulating some recommendations for their accelerated construction along TEN-T core network as well as providing some initial knowledge to be used later for more comprehensive research. The research is based on the case-study method, which allows the presentation of the described best practice. The process of data collection is based on semi-structured interviews, study of normative documents, observation of daily sales and direct observations which were processed with the help of qualitative and quantitative methods for time series analysis—trend and seasonal component as well as descriptive statistics tools. Scientific literature and research as well as secondary data provided by international institutions are also used. Full article