Performance-based design of LNG container on small-scale LNG carrier through multi-objective optimization

Abstract

Small-scale liquefied natural gas (SSLNG) carrier has drawn an increasing investment attention because of its flexible carrier capacity. However, the cargo loss and cold energy waste due to the evaporation from LNG container on SSLNG carrier are significant, which should be cut down as much as possible. In many cases, the evaporation of LNG is inhibited through the specified optimal strategies, but the influences of these strategies on economic cost and environmental impact are disregarded. In addition, these strategies are generally added to the project after that the initial design of LNG container has already been drawn up, which are not flexible and adaptable. Based on the aforementioned challenges, a novel MOPSO based optimal design methodology for LNG container is proposed, which specifies the energetic, economic and environmental (3E) performances of LNG container as objective functions. Moreover, aiming to deal with the complex geometric relationship between SSLNG carrier and LNG containers, the refined heat transfer models of LNG containers are constructed, and the constraint conditions are set according to the requirements of ship performance. The effectiveness of proposed methodology is demonstrated by its application to the two different types of LNG containers in the case study. The optimal results reveal that it is possible to optimize the energy consumption, economic cost as well as environmental impact of LNG containers, simultaneously. The proposed multi-objective optimization methodology provides a useful tool for the optimal LNG container geometry determination on SSLNG carrier.