渔船柴油机余热利用系统设计与热力学分析

Design and thermodynamic analysis of waste heat utilization system of fishing boats diesel engine

为充分利用渔船柴油机余热,提出一种以CO_(2)为工质的新型余热利用技术,通过能源梯级利用,实现发电、制冷、制淡水的三联供系统。建立船舶余热驱动的CO_(2)超临界发电、跨临界制冷及蒸馏制淡水循环系统的热力学稳态模型,并以排气温度293℃、排气热量1668 kW的Wärtsilä6L45B型船舶柴油机为例,模拟分析关键热力参数对系统性能、余热利用的影响。研究结果表明,该余热利用系统可为渔船提供6.7~284.0 kW的净发电量,同时可为船上-40℃的速冻库和4℃的食品保鲜库分别提供22~150 kW和194~1311 kW的冷量用于速冻、保鲜或舱内空调,并提供5.25~12.75 t/d的淡水;通过控制膨胀机入口压力和海水淡化温度,灵活控制系统输出的净发电量、中低温冷量和淡水量以满足渔船在航行、捕捞等工作阶段对不同能量的需求。通过柴油机余热利用技术提供的电能、制冷量以及淡水,可减少渔船对柴油的消耗,具有明显的节能效果,为远洋作业渔船的余热利用提供参考。

In order to utilize the waste heat of the diesel engine of the fishing boat,a new waste heat utilization technology using CO_(2) as working medium was proposed.Through the cascade utilization of energy,the triple supply system of power generation,refrigeration and seawater desalination was realized.By establishing the thermodynamic steady-state model of CO_(2) supercritical power generation,CO_(2) trans-critical refrigeration and seawater desalination system driven by the waste heat of the diesel engine,theoretical simulation calculation was carried out based on heat conservation and mass conservation,and the influence of key parameters on system performance was analyzed.Taking the Wärtsilä6L45B marine diesel engine with an exhaust temperature of 293℃and an exhaust heat of 1668 kW as an example,the research results showed that the waste heat utilization system could provide 6.7~284.0 kW net power generation for fishing boats,and could provide 22~150 kW and 194~1311 kW refrigeration capacity for-40℃quick freezing storehouse and 4℃food fresh-keeping storehouse on board respectively,which could be used for quick freezing of fishing catch and fresh-keeping of vegetables and food or air conditioning on board.In addition,it could provide 5.25~12.75 t/d of fresh water output.The system could flexibly distribute the power generation,refrigeration and seawater desalination produced by the system by controlling relevant thermal parameters to meet the changes of energy demand in different stages of the ship.The power generation,refrigeration capacity and fresh water provided by the diesel engine waste heat utilization technology can reduce the consumption of diesel oil by fishing boats,with obvious energy-saving effect.The research of this technology can provide a reference for the waste heat utilization of fishing boats.