A regenerative supercritical-subcritical dual-loop organic Rankine cycle system for energy recovery from the waste heat of internal combustion engines
A regenerative supercritical-subcritical dual-loop organic Rankine cycle system for energy recovery from the waste heat of internal combustion engines
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DOI：
10.1016/j.apenergy.2016.12.122
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发表时间：
2017-03
期刊：
影响因子：
11.2
通讯作者：
E. Wang;Zhibin Yu;Hongguang Zhang;Fubin Yang
中科院分区：
文献类型：
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作者：
E. Wang;Zhibin Yu;Hongguang Zhang;Fubin Yang
有机朗肯循环（ORC）系统被认为是一种很有前途的从内燃机（IC）发动机排出的废热中回收能量的技术。然而，这种废热通常以完全不同的温度包含在冷却剂和废气中。单个 ORC 系统通常无法有效地从这两个废热源中回收能量。双回路 ORC 系统本质上具有两个级联的 ORC，可分别从发动机的废气和冷却剂中回收能量，以应对这一挑战。这样，能量回收的整体效率就能得到大幅提高。本文研究了一种再生式双回路 ORC 系统，该系统使用一对环保制冷剂 R1233zd 和 R1234yf 作为工作流体，从压缩天然气 (CNG) 发动机的废热中回收能量。与以往大多数仅关注 ORC 系统的研究不同，本研究将 ORC 系统和 CNG 发动机作为一个集成系统进行分析。因此，ORC系统是根据CNG发动机在各种运行条件下的废热源的真实数据进行分析的。采用数值模型来分析所提出的具有四对工作流体的双回路循环的性能。还详细分析和讨论了再生热交换器和其他几个关键操作参数的影响。然后在预先测量的实际发动机工况下分析集成发动机-ORC 系统的性能。还分析了所提出的系统在非设计条件下的性能。获得的结果表明，对于类似应用，所提出的双环 ORC 系统比其他 ORC 系统可以获得更好的性能。
Organic Rankine cycle (ORC) system is considered as a promising technology for energy recovery from the waste heat rejected by internal combustion (IC) engines. However, such waste heat is normally contained in both coolant and exhaust gases at quite different temperatures. A single ORC system is usually unable to efficiently recover energy from both of these waste heat sources. A dual loop ORC system which essentially has two cascaded ORCs to recover energy from the engine’s exhaust gases and coolant separately has been proposed to address this challenge. In this way, the overall efficiency of energy recovery can be substantially improved. This paper examines a regenerative dual loop ORC system using a pair of environmentally friendly refrigerants, R1233zd and R1234yf, as working fluids, to recover energy from the waste heat of a compressed natural gas (CNG) engine. Unlike most previous studies focusing on the ORC system only, the present research analyses the ORC system and CNG engine together as an integrated system. As such, the ORC system is analysed on the basis of real data of waste heat sources of the CNG engine under various operational conditions. A numerical model is employed to analyse the performances of the proposed dual loop cycle with four pairs of working fluids. The effects of a regenerative heat exchanger and several other key operating parameters are also analysed and discussed in detail. The performance of the integrated engine-ORC system is then analysed under actual engine operating conditions which were measured beforehand. The performance of the proposed system under off-design conditions has also been analysed. The obtained results show that the proposed dual loop ORC system could achieve better performance than other ORC systems for similar applications.