Abstract In recent years, growing interest in engine efficiency, because of international regulations in the maritime sector, necessitates studies about new operational techniques. Ships have been operating at reduced speeds in recent years and, the liner temperatures of marine diesel engines vary significantly at reduced loads, which increase the heat loss from main engine. The research focuses on revealing the energy efficiency enhancement potential by decreasing heat loss through jacket water during reduced loads without any permanent modification. The heat loss reduction is achieved by means of higher coolant (glycol–water mixture) temperatures, to keep the liner temperatures at their maximum permissible temperatures. The methodology is calculating the energy balance and efficiency increment at reduced loads of main engine by modelling. The model have been validated with the digital twin of a two-stroke Sulzer-12RTA84C marine diesel engine. The simulated results comprise in-cylinder pressures, exhaust gas temperature and pressure, scavenge pressure, engine speed, turbo-charger, indicated power and heat transfer rate. Liner temperatures, affecting the heat transfer rate, are investigated in variable operating loads of the main engine. The study shows that keeping the liner temperature of the engine at the maximum continuous rating’s temperature, has respectable efficiency advantages under different operating loads. 0.5% reduction in fuel consumption could be achieved, coming with 127.8 tons fuel and 398 tons CO2 reduction in a year. Additionally, waste heat recovery system calculations were carried out and additional 48.8 tons of fuel could be saved in the generation of electricity. In total 176.6 tons of fuel and 550 tons of CO2 emission reduction could be achieved. As a result, the controlled cylinder wall temperatures can be considered as one of the methods to solve the efficiency and emission problems in ships in the near future.

中文翻译：

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基于模型方法的船用柴油机汽缸套温度控制提高能效效果分析

摘要 近年来，由于海事部门的国际法规，对发动机效率的兴趣日益浓厚，因此需要研究新的操作技术。近年来船舶低速运行，船用柴油机在减载时缸套温度变化很大，增加了主机的热损失。该研究的重点是通过在减少负载期间减少夹套水的热量损失来揭示提高能源效率的潜力，而无需进行任何永久性修改。通过提高冷却剂（乙二醇-水混合物）温度来减少热损失，以将衬里温度保持在其最高允许温度。该方法是通过建模计算主机负载降低时的能量平衡和效率增量。该模型已通过二冲程 Sulzer-12RTA84C 船用柴油发动机的数字孪生进行验证。模拟结果包括缸内压力、排气温度和压力、扫气压力、发动机转速、涡轮增压器、指示功率和传热率。影响热传递率的衬里温度在主机的可变运行负载下进行了研究。研究表明，将发动机缸套温度保持在最大连续额定温度，在不同的工作负荷下具有显着的效率优势。可实现燃料消耗减少 0.5%，一年减少 127.8 吨燃料和 398 吨二氧化碳。此外，还进行了余热回收系统计算，并增加了 48 个。发电可节约燃料8吨。总共可实现176.6吨燃料和550吨二氧化碳减排。因此，在不久的将来，控制汽缸壁温度可以被认为是解决船舶效率和排放问题的方法之一。