Evaluation of liquefied natural gas losses during bunkering and accompanying working operations
Object and purpose of research. This paper studies the process of liquefied natural gas (LNG) evaporation during storage, bunkering and accompanying operations. The work purpose consists in evaluation of LNG losses in course of its transportation that is required for economical estimation of its effectiveness, estimation of reasonability of LNG use as fuel in transport, as well as for design of bunkering barges. Materials and methods. The process of LNG evaporation is described using a thermodynamic model based on equations of heat exchange between the LNG liquid phase, its vapors, as well as a cargo tank and environment. The equations are solved in a computer imitating model realized in AnyLogic environment. The model reproduces both thermodynamic processes and random dynamics of ambient air temperatures. During the work mass numerical experiments with the thermodynamic model were performed, to analyze the results of which regressions analysis methods were used. Main results. Within the study a special simulation model based on laws of thermodynamic equilibrium in phase solutions was developed. The model permits to describe LNG behavior and phase transformations during its storage in vessel tanks of C type, as well as during cooling and bunkering of such containers. Analysis of the computed results based on this model permitted to generate sufficiently simple regressional relationships to evaluate LNG losses in course of various operations with it. Conclusion. The obtained results could be used for both searching for most effective configurations of the LNG small-displacement transportation system at the early stages of LNG bunkering barges design and for economical estimation of reasonability of LNG use as bunker fuel.