Optimized performances comparison of organic Rankine cycles for low grade waste heat recovery

An organic Rankine cycle (ORC) can be applied to recover the low-grade waste heat. In this paper, the performances of five different types of ORC are evaluated. These configurations include a simple ORC, an ORC with an internal heat exchanger (IHE), an ORC with an open feed organic fluid heater (OFOH), an ORC with a closed feed organic fluid heater (CFOH), and an ORC with a reheater. First, the feasible working region is defined for an ORC operating together with an internal combustion engine. Subsequently, the thermal efficiency of each ORC is maximized using a genetic algorithm. Finally, the characteristics of each ORC are analyzed and compared using a combination of the first law and second law method. Our analysis indicates that the ORC with an IHE showed the best thermodynamic performance. The ORC with an OFOH and the ORC with a CFOH are sub-optimal while the simple ORC and the ORC with a reheater are the last choice. The effects of the expander inlet pressure, the condenser outlet temperature and the expander isentropic efficiency on system performance of each ORC were also analyzed.     

基于CFX对管式换热器在烟气余热回收中的改进

通过对换热器结构特点的分析,提出在换热管外壁添加圆形翅片以此来提高管式空气换热器的余热回收。利用CFX软件模拟分析新型换热器的传热特性,通过分析翅片厚度、翅片间距、翅片高度得出,翅片厚度为0.8mm、翅片间距为3mm、翅片高度为12.5mm,换热器的换热性能最佳。     

无机传热技术及其工业应用

无机传热技术具有钢-水热管技术的优点，并解决了钢-水热管应用温度范围窄、常用工质热管易爆管和使用寿命短的缺陷。用该技术制造的空气预热器、余热锅炉等设备已成功地应用于石油行业，用于回收余热或进行工艺加热，并取得了良好的社会效益。     

集装箱船余热回收系统中温差发电模块的热电耦合分析

随着热电发电、热电制冷技术研究的不断深入,热电在船舶余热回收方面有了重大突破.以集装箱船余热回收系统中温差发电模块为研究对象,考虑了热电模块热端和冷端温度差存在温度变化的实际情况,运用ANSYS软件建立了热电单P-N结模型,分析了热电单元温度场的分布规律,得到了温差发电系统的输出特性,根据分析结果进行了温差发电模块用于...     

Exergo-economic analysis of finned tube for waste heat recovery including phase change heat transfer

In this paper, an exergo-economic criterion, i.e. the net profit per unit transferred heat load, is established from the perspective of exergy recovery to evaluate the performance of finned tube used in waste heat recovery. Also, the dimensionless exergy change number is introduced to investigate the effect of the flow (mechanical) exergy loss rate on the recovered thermal exergy. Selecting R245fa as a working fluid and exhaust flue gas as a heat source, the effects of the internal Reynolds number Re _i, the external Reynolds number Re _o, the unit cost of thermal exergy ? _q, the geometric parameter of finned tube η _o β and the phase change temperature T _v etc. on the performance of finned tube are discussed in detail. The results show that the higher T _v and η _o β, and lower Re _i may lead to the negligible flow (mechanical) exergy loss rate. There exists an optimal value of Re _i where the net profit per unit transferred heat load peaks, while the variations of Re _o, ? _q and T _v cause monotonic change of the net profit per unit transferred heat load. The phase change temperature exerts relatively greater influence on the exergo-economic performance of finned tube in comparison with other parameters. And there exists a critical phase change temperature, where the net profit per unit transferred heat load is equal to zero.     

Performance of organic Rankine cycle using waste heat from electric vehicle battery

The battery of an electric vehicle (EV) must be appropriately cooled to prevent battery overheating while driving. Waste heat from EV batteries is typically recovered and used for indoor heating instead of generating electricity. In this study, an organic Rankine cycle (ORC) using electric vehicle (EV) battery heat as a heat source was designed with a particular focus on the turbine. The mean-line design of a single-stage axial-flow turbine was performed, and the turbine performance was analyzed. The isentropic efficiency of the designed turbine was 0.75, and the electrical power was approximately 100 W. The thermal efficiency of the ORC was 4.23 % at a working fluid temperature of 25 °C at the condenser outlet. This used 2.24 kW of battery heat, which is approximately 78 % of the EV battery waste heat considered in this study. Therefore, applying the ORC to an EV recovers a significant amount of waste heat from the battery to reduce the battery temperature and generate electricity. Furthermore, we present an operation method that can improve the thermal efficiency of the EV ORC and is applicable in situations where the evaporation and condensation are not constant.

     

An investigation on the performance of a Brayton cycle waste heat recovery system for turbocharged diesel engines

A Brayton cycle waste heat recovery (WHR) system for turbocharged diesel engines was proposed and the performance of a diesel engine integrated with the proposed system was investigated. The waste heat recovery system is integrated with the turbocharging system of diesel engines, using the turbocharger compressor as the Brayton cycle compressor. The engine cycle simulation code GT-Suite 7.0 was used to investigate the performance of a diesel engine integrated with the WHR system. A Brayton cycle turbine was designed and its performance was simulated with a through-flow model. The turbocharging system of the original engine was modified and the energy flow distribution between the diesel cycle and the Brayton cycle was optimized. Results show that the fuel economy of the diesel engine can be improved by 2.6% at high engine speed and 4.6% at low engine speed under engine full load operating conditions when equipped with the Brayton cycle WHR system. The influence of turbocharger parameters on the WHR engine performance was invesgated.     

Development of a 200 kW ORC radial turbine for waste heat recovery

Journal of Mechanical Science and Technology - There has recently been a growing interest in sustainable energy converters. One such technology is the organic Rankine cycle, which uses conventional...     

纯电动汽车动力驱动系统参数优化设计及性能仿真研究

纯电动汽车动力驱动系统的参数设计,如电池容量、电动机功率、传动比以及它们之间的合理匹配,对纯电动汽车的续驶里程和动力性等都有显著的影响。本文主要研究将优化理论应用到纯电动汽车动力驱动系统的优化设计中,以实现驱动系统各个部件参数的最佳匹配,充分发挥纯电动汽车整体性能,通过仿真试验证明了该方法的正确性和有效性。     

基于模糊自整定PID的电动汽车驱动控制系统的研究

在以转子磁场定向的电动汽车驱动用异步电动机矢量控制的基础上,采用模糊自整定PID控制的方法,使PID的参数随着系统控制性能的变化进行在线调整以克服系统的非线性和时变性对系统的不利影响.仿真结果表明,采用模糊自整定PID控制的电动汽车异步电动机驱动系统具有良好的调速性能.     

Model predictive controller-based multi-model control system for longitudinal stability of distributed drive electric vehicle

Distributed drive electric vehicle(DDEV) has been widely researched recently, its longitudinal stability is a very important research topic. Conventional wheel slip ratio control strategies are usually designed for one special operating mode and the optimal performance cannot be obtained as DDEV works under various operating modes. In this paper, a novel model predictive controller-based multi-model control system (MPC-MMCS) is proposed to solve the longitudinal stability problem of DDEV. Firstly, the operation state of DDEV is summarized as three kinds of typical operating modes. A submodel set is established to accurately represent the state value of the corresponding operating mode. Secondly, the matching degree between the state of actual DDEV and each submodel is analyzed. The matching degree is expressed as the weight coefficient and calculated by a modified recursive Bayes theorem. Thirdly, a nonlinear MPC is designed to achieve the optimal wheel slip ratio for each submodel. The optimal design of MPC is realized by parallel chaos optimization algorithm(PCOA)with computational accuracy and efficiency. Finally, the control output of MPC-MMCS is computed by the weighted output of each MPC to achieve smooth switching between operating modes. The proposed MPC-MMCS is evaluated on eight degrees of freedom(8DOF)DDEV model simulation platform and simulation results of different condition show the benefits of the proposed control system.     

Thermodynamic analysis of a dual loop cycle coupled with a marine gas turbine for waste heat recovery system using low global warming potential working fluids

Journal of Mechanical Science and Technology - The combined use of generation and propulsion gas turbines and steam turbines is efficient and can meet the environmental regulations. In this study,...     

前置后驱车辆传动系统扭转振动建模仿真与优化

车辆动力传动系统的扭转振动(简称扭振)表现对于车辆舒适性有极大的影响,为了解决某前置后驱车辆传动系统的扭振控制,结合机械动力学知识通过LMS AMEsim软件建立车辆传动系统模型,与实测数据进行比较以验证模型的可靠性。通过扭振频率与模态分析,确认发动机与传动系统在35.2334 Hz下有共振发生,通过优化离合器参数可使扭振得到很好的控制,同时也提出通过多目标遗传算法对传动系统多参数进行优化,更好地提高传动系统的扭振表现。     

iFIX在余热发电监控系统中的应用

根据水泥窑纯低温余热发电系统工艺特点及控制要求,设计了基于iFIX组态软件的余热发电监控系统。该系统具有强大的监视、控制和管理功能,能够实时地显示被监控设备的各种数据,同时完成报警、趋势曲线、历史记录、报表打印等功能。运行结果表明,该系统很好地满足了水泥生产线余热发电控制要求。     

微型电动汽车热泵空调系统设计与试验研究

为了提高某微型电动汽车有效续航里程,对其原有空调系统及换热器进行了改进设计与研究,新热泵空调系统采用4个电磁阀对其冷暖模式进行切换,通过焓差室对换热器和系统的性能进行了测试.首先比较了两种不同流程布置室外微通道换热器的换热能力;进而分别将原空调系统换热器和所设计换热器应用于该热泵空调系统,试验研究了压缩机转速和环境温度...     

不同道路条件下汽车恒速下坡控制仿真研究

实现汽车恒速下坡控制对于提高汽车运输效率和安全性具有重要意义。针对加装液力缓速器汽车恒速下坡控制的特点,通过分析汽车下坡缓速制动过程,建立汽车下坡缓速器制动仿真模型。根据缓速器缓速制动原理设计了基于Matlab/Stateflow逻辑控制的恒速控制器,在Matlab/Simulink中选取混凝土、卵石、砂石等不同路面条件对汽车恒速下坡过程进行仿真分析,得出了充液率调节值对车速变化的影响关系,得到了汽车在不同路面条件下实现恒速制动的充液率合理调节取值。仿真结果表明液力缓速器单独作用于汽车制动可以实现恒速下坡控制,路面条件与液力缓速器充液率调节值大小对恒速控制性能有着重要的影响。     

余热回收风机轴承失效分析及应急措施

针对风机滚动轴承出现的不明原因的开裂故障,通过调研分析,最终找到了失效原因,并提出了有效的现场抢修方法。     

电动汽车驱动电机轴承寿命可靠性试验研究

针对电动汽车国产驱动电机轴承寿命短、可靠性低的问题,通过对电动汽车驱动电机轴承工作特性进行分析,提出了电动汽车驱动电机轴承寿命可靠性的模拟试验参数和一种台架模拟试验机的设计方法。对国内外同型号驱动电机轴承样品的台架进行了模拟试验对比。结果表明:国内外驱动电机轴承寿命可靠性的主要差距来源于润滑、密封和耐高低温性能等方面;该结果可为国产驱动电机轴承寿命的可靠性提升提供技术改进方向的参考。     

合成氨废热锅炉结构设计

首先介绍了化工行业余热利用的重要性以及废热锅炉在余热回收方面的巨大潜力。同时介绍了依照国内相关标准设计制造的高温高压卧式前置废热锅炉的结构特点。结合废热锅炉的特殊工况以及管壳程内介质流动情况,在管程入口处设置单程波纹管,换热管采用三重套管式换热,管箱密封采用Ω型密封,支座采用可变弹簧支座,根据各部位操作温度的不同,使用了低碳钢、耐热钢不锈钢等。对上述几个方面进行了详细分析,以期为前置废热锅炉结构设计提供借鉴和帮助。