内燃机余热能转化热力单元和材料性能强化设计和集成优化研究报告

摘 要：该报告对蒸发器和冷凝器内部能量传递机理进行研究，探索了蓄热过程传热传质的强化机理与方法，建立内燃机废热有机朗肯循环单螺杆膨胀机实验台。在前几年工作的基础上，2013年度该研究的主要进展如下：（1）研究组建立了烟气-有机工质蒸发器和空冷冷凝器传热的数学模型，编制了蒸发器和冷凝器的设计分析程序，进行了247 kW柴油机废气余热有机朗肯循环烟气蒸发器和空冷冷凝器的设计计算，计算获得了管翅式蒸发器总换热量、各区换热量及其进出口参数随内燃机工况的变化规律。研制了螺旋盘管强化传热钛管和波纹管烟气蒸发器和弯曲型平行流冷凝器。（2）提出了一种螺旋管熔盐蓄热换热器的创新方案，建立了蓄热换热器的数学模型，并进行了螺旋管蓄热换热器和套管式蓄热换热器的设计计算。搭建了套管式蓄热换热单元性能测试实验系统，进行了套管蓄热换热器的蓄热、放热和传热试验。（3）分析去年试验存在的问题，更换了适合该系统余热负荷的Φ155 mm螺杆的单螺杆膨胀机，研制了螺旋盘管钛管烟气蒸发器和弯曲型平行流冷凝器，重新选择了多级离心泵，优化了有机朗肯循环流程，建立了247 kW柴油机废气余热有机朗肯循环试验台，进行柴油机变工况废气余热有机朗肯循环试验，获得了不同发动机工况下有机朗肯循环系统性能参数（输出功率、膨胀机效率、有机朗肯循环效率、换热量等）随发动机工况变化的性能规律。（4）该课题组选取了8种滑移温度不同的非共沸混合工质，研究了内燃机变工况下，非共沸混合工质对有机朗肯循环余热回收系统性能的影响，对比分析了4种纯工质、4种共沸混合工质和4种非共沸混合工质对变工况下车用柴油机有机朗肯循环余热回收系统性能的影响。（5）提出比转数作为有机朗肯循环工质泵的选型指标，给出了蒸发温度为100 ℃，冷凝温度为45 ℃时不同工质所需泵的比转数随功率的变化关系，并给出了不同比转数适用泵的建议。进行了旋喷泵的性能试验，获得了不同频率下泵的扬程和效率随流量的变化规律。

关键词：内燃机 余热 有机朗肯循环 单螺杆膨胀机

Abstract：Main progresses of the project in 2013 are as follows： （1） Mathematical models on heat transfer of flue gas - organic working fluid evaporator and air cooling condenser were established. Design analysis program of evaporator and condenser were developed. Design for organic Rankine cycle （ORC） of 247 kW diesel waste heat of flue gas evaporator and air condenser was made. By analyzing the heat transfer characteristics of an ORC evaporator applied on an R425 diesel engine， the mechanism of the total and zone heat transfer rates， inlet and outlet parameters with engine speed and load were obtained. Spiral titanium coil tube evaporator， bellows evaporator and curved parallel flow condenser were developed. （2） An innovative concept for spiral coil heat exchanger with molten salt thermal storage was proposed. Mathematical models of heat exchanger with thermal storage were established， and calculation for spiral coil and sleeve heat exchanger with storage was performed. Experiments on heat storage， discharge and heat transfer of sleeve heat transfer unit were made. （3） By replacing with a single screw expander of Φ155 mm， multi-stage centrifugal pump， spiral titanium coil tube evaporator and curved parallel flow condenser， an modified ORC waste heat recovery system from exhaust gas of 247 kW diesel was made. The performances with engine power were tested. （4） The first law and second law of thermodynamics are utilized to investigate the variation of net power output， thermal efficiency， exergy efficiency and mass flow rates of 8 kinds of zeotropic mixtures under various operating conditions of a diesel engine. The waste heat recovery efficiency （WHRE）and power output increasing rate （POIR） are also presented and studied. （5） Specific revolution was proposed as the selection indicator of organic Rankine cycle working fluid pump. The relation between specific revolution and power for different working fluid pump was given under the evaporation temperature of 100 ℃ and the condensing temperature of 45 ℃.Suitable pumps for different specific revolutions were recommended. A rotary jet pump performance test was conducted， and the variations of head and efficiency with frequencies were obtained.

Key Words：Internal combustion engine；Waste heat；Organic rankine cycle；Single screw expander

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