A realistic vapour phase heat transfer model for the weathering of LNG stored in large tanks

Abstract

A new non-equilibrium model relevant to LNG weathering in large storage tanks under constant pressure has been developed. It treats the heat influx from the surroundings into the vapour and liquid phases separately and allows for heat transfer between the two phases. The main heat transfer mechanisms in the vapour phase are assumed to be advection, due to upward flow of evaporated LNG, and conduction.It has been observed that the vapour temperature increases monotonically as a function of the height, in agreement with recent experimental results. In all the simulations performed the vapour to liquid heat transfer was small, also in line with recent experimental findings, and is estimated to contribute less than 0.3% to boil-off gas rates. The results of this work indicate that the heat transfer by the advective upward flow dominates the energy transfer within the vapour, while the natural convection, in the body of the vapour, can be neglected. The initial liquid filling has a pronounced effect on all the relevant variables, leading to a decrease in vapour temperature and boil-off gas temperature and an increase in boil-off rates. A rule of thumb for estimating the boil-off gas temperature in industrial storage tanks is provided.

Analytical solutions for the isobaric evaporation of pure cryogens in storage tanks

“…In order to provide analytical solutions for the evaporation of a pure cryogen, in a cylindrical storage tank under constant pressure, we take Huerta and Vesovic model of LNG weathering [43] as the starting point. Only the relevant features of the weathering model are summarized in this work, and the interested reader is referred to the original work for the full description.…”

“…In section 2 we derive analytical solutions based on the non-equilibrium weathering model of Huerta and Vesovic [43]. In section 3 we validate the developed analytical solutions, by comparing to the numerical results for the evaporation of liquid methane and nitrogen, and provide the range of their validity.…”

“…Most work on the evaporation of cryogens under isobaric or nearly isobaric conditions focuses on modelling of LNG weathering. Early models have assumed that both vapour and liquid cryogen are in thermal equilibrium [17,20,21,23,24,26,[34][35][36][37][38][39][40], while the most recent weathering models [25,32,[41][42][43][44], have incorporated a non-equilibrium approach, based on experimental and industrial data; thus, the vapour is treated as superheated with respect to the liquid and acts as an additional heat source.…”

Dynamic simulation of fuel tank aging for LNG‐fueled ship apparatus in an X‐DF Otto cycle engine

“…In this study, the thermodynamic properties of each stream are calculated by using the Peng‐Robinson equation of state, which is widely used in the oil and gas industry . Also, the standard van der Waals (vdW) mixing rules for a, b that require the knowledge of binary interaction parameters quoted by Danesh was used …”

Evolution Process of Liquefied Natural Gas from Stratification to Rollover in Tanks of Coastal Engineering with the Influence of Baffle Structure

“…The maximum deviation of the roll time and the peak value are less than 15%. Felipe et al [38] provided a rule of thumb for estimating the temperature of evaporated gas in industrial storage tanks and developed an unbalanced model related to LNG evaporation from large storage tanks at constant pressure. Federica et al [39] used CFD technology to simulate the self-pressurization behavior of cryogenic storage tanks.…”