In a significant stride towards enhancing the efficiency of marine LNG operations, a recent study published in the ‘Journal of Engineering and Applied Science’ has introduced a novel approach to improve the performance of boil-off gas (BOG) reliquefaction systems on LNG carriers. The research, led by Hassan A. R. El-Shoubashy from the Department of Mechatronics at Alexandria Higher Institute of Engineering & Technology (AIET), explores the integration of passive diffusers into the BOG and mixed refrigerant (MR) cycles, promising substantial thermodynamic and economic benefits.
At the heart of this study is the installation of six stationary diffusers upstream of each compressor within the BOG and MR cycles. This seemingly simple modification has been shown to yield remarkable improvements in the overall performance of reliquefaction systems. Simulation results using Aspen HYSYS revealed a 16.42% increase in the coefficient of performance (COP), a 16.07% improvement in exergetic efficiency (FOM), and a 14.12% reduction in specific power consumption. These enhancements translate to significant cost savings, with the energy cost for a 10-day voyage dropping by 14.85%, from $9892 to $8423.
The study also noted a 18.19% increase in total heat rejected to seawater, which, while indicating a higher heat load, is a trade-off for the substantial gains in efficiency and cost-effectiveness. However, the increased compressor discharge temperatures led to a 68.48% rise in total plant irreversibility, a factor that the researchers acknowledge and suggest could be mitigated with further optimization.
For maritime professionals, these findings present a compelling opportunity to enhance the performance of LNG carriers. The integration of passive diffusers into existing reliquefaction systems could lead to significant operational cost savings, making LNG transportation more economically viable. Moreover, the improved energy efficiency aligns with the maritime industry’s growing focus on sustainability and reducing carbon footprints.
El-Shoubashy emphasized the practical implications of the study, stating, “The results confirm that integrating passive diffusers can significantly enhance the thermodynamic and economic performance of marine LNG reliquefaction systems.” This research not only offers a tangible solution to improve current operations but also paves the way for future innovations in the field of LNG transportation.
As the maritime sector continues to evolve, such advancements are crucial in meeting the dual challenges of economic competitiveness and environmental sustainability. The study published in the ‘Journal of Engineering and Applied Science’ serves as a testament to the potential of innovative engineering solutions in driving progress within the maritime industry.