A sensitivity analysis of a cryogenic carbon capture system on a LNG ship engine

The maritime transport industry, accounting for 3% of global emissions of CO 2 , is actively reducing its CO 2 emissions and Cryogenic Carbon Capture (CCC) appears as a promising solution for LNG-fuelled vessels due to its high capture performance (above 90%) and its ability to use fuel as a cold source. While CCC systems have been widely studied, the impact of coupling with the engine remains insufficiently explored. This paper investigates the influence of engine parameters on the capture process using a numerical CCC coupled with a 1D model of a 300 kW LNG engine. It highlights the role of a heat recovery loop and shows that the system can operate under three distinct modes governed by the heat capacity ratio of the gas-LNG heat exchanger. Engine parameters strongly affect this ratio and consequently, the system performance. The excess air ratio λ and gas treatment ratio degrade both capture performance and energy efficiency, with capture rate decreasing from 99% to 50% when λ increases from 1.2 to 3.2 or when the gas treatment ratio rises from 10% to 45%. Engine load amplifies these effects, while CCC operating pressure has a stronger impact on system efficiency than on performance, with a 40% reduction in power consumption when the pressure is halved. Reducing operating pressure or recovering energy from low-carbon exhaust gas appears as a promising approach to lower the energy penalty.