Numerical study of using different Organic Rankine cycle working fluids for engine coolant energy recovery
Numerical study of using different Organic Rankine cycle working fluids for engine coolant energy recovery
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DOI：
10.1016/j.egypro.2017.12.533
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发表时间：
2017-12
期刊：
影响因子：
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通讯作者：
Fenfang Chen;Yiji Lu;Xiaoqiang Chen;Zhi Li;Xiao-li Yu;A. Roskilly
中科院分区：
文献类型：
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作者：
Fenfang Chen;Yiji Lu;Xiaoqiang Chen;Zhi Li;Xiao-li Yu;A. Roskilly
发动机余热回收技术尤其是有机朗肯循环（ORC）技术，以获得更高的综合热效率，降低发动机排放，提高燃油经济性，得到了广泛的研究。冷却剂能量约占燃料能量的30%，可作为ORC系统的热源。研究了发动机在使用不同的有机朗肯循环（ORC）工质时，发动机受热部件的热状态，以避免热交换器将冷却剂传递给ORC工质造成的热卢什。提出了一种计算发动机内部传热的固液耦合传热计算方法，该方法可以同时求解固体区和流体区的温度场。仿真结果通过一台6缸中型柴油机以水为系统冷却剂时的实验数据进行了验证。然后使用仿真模型预测使用不同ORC工作流体的温度分布，并研究不同ORC工作流体对发动机受热部件的冷却效果的影响。已选择加热部件的最高温度作为评估参数。结果表明，在设计工况下，选用ORC工质作为发动机冷却液是不可行的，会导致发动机过热。进一步的研究表明，增加冷却剂的质量流量可以降低被加热部件的热状态，但即使在原始质量流量的200%以下仍然不能满足冷却需求。分析了冷却剂出口温度和火用的变化规律。
Engine waste heat recovery technology especially Organic Rankine cycle (ORC) has been widely studied in order to achieve higher overall thermal efficiency, reduce the engine emissions and improve the fuel economy. The coolant energy occupies around 30% of the fuel energy can be used as the heat source for ORC system. This paper studies thermal status of the engine heated components when using different ORC working fluids as engine coolant to avoid the heat loos using heat exchanger to transfer coolant to the ORC fluid. A Solid-Liquid Conjugated Heat Transfer (SLCHT) calculation method is developed to calculate the heat transfer inside the engine, which can solve the temperature field of both solid zone and fluid zone. The simulation results have been validated by the experimental data from a 6-cylinder medium duty diesel engine, when water is the coolant in the system. The simulation model is then used to predict the temperature profile using different ORC working fluids and investigate the influence of different ORC working fluids on the cooling effects of the engine heated parts. The maximum temperature of the heated components has been selected as the evaluation parameters. The results reveals that applying selected ORC working fluids in engine as coolant is not practical under the designed conditions, which will make the engine overheated. Further investigation showed that increasing mass flow rate of the coolant can decrease the thermal status of the heated components but still cannot meet the cooling demands even under 200% of the original mass flow rate. The variations of the coolant outlet temperature and exergy were also analysed.