Abstract

An appreciable part of primary energy input to a marine diesel engine is rejected as waste heat. Thus, through marine diesel engine waste heat recovery significant amount of secondary energy can be produced to satisfy the auxiliary power requirement of the marine ship. In present study, a CO₂-organic fluid cascading cycle is considered for the utilization of the waste heat released by the marine diesel engine. R290, R600 and R1233zd (E) are considered as the working fluids of the bottoming cycle for their lower global warming potentials. The analysis revealed that power output of the cascading cycle is comparable to that of the baseline transcritical CO₂ power cycle. However, for similar power output, operating pressure in the flue gas-CO₂ heat recovery unit of the transcritical CO₂ power cycle is significantly higher compared to that of the cascading cycle. Thus, possible leakage due to very high operating pressure of a conventional CO₂ power cycle can be addressed by using the cascading system. Bare module costs per unit power output of cascading cycles are also significantly smaller. It is also apparent from the study that the marine diesel engine waste heat recovery through the CO₂-organic cascading cycle would lead to 8–9.5% annual fuel saving. Reduced fuel consumption will also result in lesser CO₂ emission from the marine ship.

Graphic abstract

摘要

输入到船用柴油机的一次能源的相当一部分作为废热被拒绝。因此，通过船用柴油机废热回收，可以产生大量的二次能量以满足船舶的辅助功率需求。在本研究中，考虑利用CO _2-有机流体的级联循环来利用船用柴油机释放的废热。R290，R600和R1233zd（E）因其较低的全球变暖潜能而被视为底部循环的工作流体。分析显示，级联循环的功率输出与基线跨临界CO ₂功率循环的功率输出相当。但是，对于类似的功率输出，烟气-CO ₂中的工作压力与级联循环相比，跨临界CO ₂功率循环的热回收单元明显更高。因此，通过使用级联系统，可以解决由于常规CO ₂功率循环的非常高的工作压力引起的可能的泄漏。级联循环的每单位功率输出裸模块成本也大大降低。从研究中还可以明显看出，通过CO _2-有机级联循环回收船用柴油机废热将每年节省8–9.5％的燃料。减少的燃料消耗也将导致海上船舶的CO ₂排放量减少。

图形摘要