中文摘要：

为探讨低温有机朗肯循环系统冷热流体之间的传热特性,以新型二元非共沸混合工质R13I1＋R601a为例,建立基于电站锅炉烟气余热吸收的蒸发器换热模型。考虑非共沸工质相变温度的滑移与烟气温度变化的匹配特性,并借助物性计算软件Refprop 8.0考虑温度对非共沸工质物性的影响,分析了不同烟气流量、工质配比条件下蒸发器内的温度及温差分布,以及对过程火用损失的影响。结果显示：通过控制烟气流量可有效避免蒸发器内部温差极值点的出现;同时,研究还发现混合工质R13I1＋R601a在0.8/0.2和0.7/0.3两种配比下换热曲线线性度较高,与烟气热源拟合较好,更有利于换热。R601a含量比例在0.2～0.3之间变化时,会出现温差由极大值向极小值转变。通过对混合工质组分更为细化的研究,有望得出更佳配比,进而提高整个有机朗肯循环系统的效率。

英文摘要：

In order to explore the heat transfer characteristics of low-temperature organic Rankine cycle （ORC）, a steady-state model of evaporator was set up with novel HCs/fire-suppressants zeotropic mixture of R13I1＋R601a as the working fluid and exhaust gas from power generating units as the heat source. Considering the couple between the phase change temperature gliding of zeotropic mixture and variation of gas temperature, as well as the temperature dependant of physical properties of working fluid with the fluid database Refprop 8.0, the influences of gas flow rates and mixture composition on the heat transfer process and temperature distributions in evaporator were analyzed. The exergy loss during heat transfer was also investigated. The analytical results show that pinch points inside the evaporator can be avoided by controlling the gas flow rate. The results also demonstrate that the temperature curves of R13I1＋R601a mixture at the ratio of 0.8/0.2 and 0.7/0.3 are near-linear, matching well with temperature variation of gas flow, which benefits to heat transfer process. Moreover, when R601a content ranges from 0.2 to 0.3, the temperature differences change from the maximum to the minimum. So it is possible to get a more perfect temperature matching for the smaller exergy loss and higher ORC efficiency with further optimization.