板式换热器及其热力系统的运行特性和高级[火用]分析

Operating characteristics and advanced exergy analysis of plate heat exchangers and their thermal system

针对不同换热设备组合之间以及换热设备在系统中的[火用]分布情况进行了研究,建立了高级[火用]分析模型,将换热设备与系统的[火用]损进一步分割成不可避免性部分和可避免性部分,计算相应的[火用]损失和[火用]效率,确定换热设备与系统中能量损失的主要部位,并在有机朗肯循环(organic Rankine cycle,ORC)系统试验台中进行验证,为换热设备及其热力系统的运行优化提供科学依据。结果表明,不同的换热面积对换热设备的能效有着非常大的影响,同时常规[火用]分析和高级[火用]分析提出了不同的系统优化次序。高级[火用]分析表明,蒸发器可避免[火用]损占蒸发器[火用]损的41.2%~60.0%,冷凝器可避免[火用]损占冷凝器总[火用]损最高可达91%~97%,整个ORC系统有52.5%~66.3%的[火用]损可以避免,有很大的改造潜力,且发现不合理设计的管道也会影响ORC系统性能。

The exergy distribution of different heat exchanger combinations and the heat exchanger in the thermal system were studied,and an advanced exergy analysis model was established to further divide the exergy destruction into unavoidable parts and avoidable parts.The main energy loss in the heat exchanger and thermal system were determined by the calculation of the corresponding exergy destruction and exergy efficiency.It was verified in the organic Rankine cycle(ORC)system text rig,which provided a scientific basis for the optimization of the heat exchangers and thermal system operation.The results showed that different area of heat exchanger had a great impact on the energy efficiency of heat exchanger.And the traditional exergy analysis and the advanced exergy analysis provided different optimization sequences.The advanced exergy analysis showed that the avoidable exergy destruction in evaporator accounted for 41.2%-60.0%while the condenser could avoid 91%-97%.The ORC system had 52.5%-66.3%exergy destruction that could be avoided,which had great potential for optimization.In addition,it was found that unreasonable design of the pipeline would also affect the ORC system performance.