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Simulation study on utilising cold energy fuel to liquefy captured CO2 on LNG-fuelled vessels

Li Zijian, Zhao Xizhi, Cao Rui, Yang Hualin, Li Boyang, Diao Fujun, Zhang Rui

Polish Maritime Research

2025

nr 3

131--146

This study addresses the issues of abundant cold energy in fuel and the high energy consumption of CO2 liquefaction capture by the shipboard carbon capture system in LNG-fuelled vessels. Two liquefied CO2 schemes are proposed: an LNG cold energy and refrigeration cycle integrated CO2 liquefaction system (Scheme 1) and an LNG cold energy and seawater diversion liquefied CO2 system (Scheme 2). The two systems are simulated in Aspen HYSYS software and, based on the simulation data, multiple thermodynamic parameters of the system, including exergy efficiency, cold energy utilisation rate, and energy consumption, are calculated under different vessel operating conditions, thereby verifying the feasibility of the system. On this basis, the systems are optimised, enhancing their overall performance. Through a comparative analysis of the two schemes, Scheme 1 was selected to conduct an economic analysis of typical vessel routes and calculations were conducted to determine the reduction in energy consumption and the decrease in carbon emissions achieved by utilising LNG cold energy for CO2 liquefaction and capture. The results prove that the system should have good practical applications.

Utilization of waste C30 concrete in permeable mortar: mechanical property, permeability mechanism, life cycle assessment

Wang Chao-qiang, Zeng Ze-yu, Li Heng-feng, Yang Fei-hua

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 4

art. e267, s. 1--25

Destruction of old buildings generates waste concrete and powder. In addition, the city's drainage system is gradually struggling to keep up with the demands. Therefore, this study takes the recycled aggregate and powder generated from the crushing of waste C30 concrete as the research object, and investigates the impacts of both on the permeable mortar and summarizes the permeability mechanism and hydration mechanism of permeable mortar. Carbon emission reduction calculations and life cycle assessment were performed for both. The study’s findings demonstrated that the extent of volcanic ash reaction increases and then decreases with increasing grinding time. Considering the activity and economy, the regenerated powder with a grinding time of 5 min was selected, and its activity index was 83%. By exploring the performance of the two, the permeable mortar with 10% of recycled micronized powder and 50% of recycled aggregate has good mechanical properties and water permeability, and its permeability coefficient is about 1.57 mm/s, continuous porosity is 21.8%, and the compressive strength is 18.7 Mpa. The permeable mortar has a quality loss rate of 5.01% and a strength loss rate of 25.1% at the 17th freezing and thawing cycle. Recycled aggregates and recycled powders produce far fewer carbon emissions during production and transportation than natural sand and cement. Currently, permeable bricks are mainly used as construction materials for sidewalk pavements. Recycled permeable mortar is more convenient, environmentally friendly, and stronger than permeable bricks, so the research results will provide basic theoretical support for replacing permeable bricks with recycled permeable mortar.