非共沸工质与纯工质在ORC系统中的特性比较研究

工质的特性是影响ORC(有机朗肯循环)系统性能的重要因素之一。建立了65~100℃低温地热水有机朗肯循环发电系统数学模型,将R245fa分别与R601a和R227ea以不同比例混合作为ORC系统的工质,比较了非共沸混合物和纯物质两类工质对ORC系统循环净功、热效率和火用效率的影响。研究结果表明:无论是纯工质还是非共沸工质,系统的循环净功、热效率和火用效率都随着热源温度的升高而增大。工质在相变过程中是否存在温度滑移,是影响ORC系统性能的重要因素之一。在65~100℃的热源条件下,综合考虑3个评价指标,当R245fa配比为0.1~0.7时,R245fa/R601a混合物的循环净功、热效率和火用效率分别提升0.012~2.48 k W、0.005%~1.15%和0.08%~10.7%;当R245fa配比为0.5~0.9时,R245fa/R227ea混合物的循环净功、热效率和火用效率分别提升0.049~4.25 k W、0.057%~1.75%和0.21%~16.1%。     

Material Compatibility of Hexamethyldisiloxane as Organic Rankine Cycle Working Fluids at High Temperatures

The organic Rankine cycle(ORC) is a promising technology for industrial waste heat recovery and renewable energy utilization. High temperature ORCs have attracted particular interest because of their high thermal efficiencies and outputs. The material compatibility of working fluid is a significant limitation for the working fluid selection and system design for high temperature ORCs. This work presents a method for studying the material compatibility of ORC working fluids based on the calculate...     

低温有机朗肯循环的工质选择及系统性能分析

选取R123,R141b,R245ca,R245fa,R601,R601a作为有机朗肯循环的工质,在不同蒸发温度条件下,对其热力循环特性进行了计算分析,以热力学第一定律和第二定律为基础进行了比较.结果表明,R141b是适合本循环系统的最佳工质.同时还研究了汽轮机进口温度和进口压力对该系统的净功量、吸热量及热效率的影响.     

低温太阳能热力发电有机朗肯循环工质的选择

为了筛选出适宜于低温太阳能热力发电有机朗肯循环的工质,根据 PR 状态方程计算和分析了采用 11 种低沸点有机流体工质的低温太阳能发电朗肯循环的热力性能.结果表明:随着工质临界温度的升高,有机透平进口处的最大蒸发压力基本呈下降趋势;在凝结温度与有机透平进口温度一定的情况下,临界温度越高的流体,其循环热效率越高;使用正已烷和正戊烷能获得较高的循环热效率,凝汽器中的凝结压力比较适中,是比较适合用作低温太阳能热力发电有机朗肯循环的工质.     

Parametric Analysis of Dry Hydrocarbons on the Performance of Organic Rankine Cycle Improved by Working Fluid Reheating

In this paper, the performance of organic Rankine cycle with a two‐stage turbine and internal heat exchanger, considering different dry hydrocarbons as working fluid, has been analyzed. This thermodynamic analysis is done using Engineering Equation Solver version 8.379 software. The influence of working fluid reheating has been studied and the critical temperatures for the thermal and exergy efficiencies are determined. Results show that thermal and exergy efficiencies increase with working fluid reheating and also through a two‐stage turbine. RC‐318 is a good replacement for R‐236fa, R‐113 has a better efficiency than R‐236fa, R‐245fa, and iso‐butane and finally cyclohexane can achieve the highest efficiency. Although the maximum value of efficiencies for each one of working fluids are different, but all of these maximum values almost happen at a unique value of relative pressure of the cycle. The same result has been presented for variation of turbine inlet temperature.     

不同工质对太阳能有机朗肯循环系统性能的影响

循环工质的特性是影响有机朗肯循环系统性能的重要因素之一,在不同的蒸发温度条件下,选取R600、R600a、R245fa、R236fa、R236ea、R601、R601a、RC318及R227ea共9种有机工质,基于热力学第一定律和第二定律对其热力循环特性进行了计算分析,并对各有机工质的蒸发压力、热效率、功比和不可逆损失等进行了比较.结果表明：R245fa作为太阳能低温热发电朗肯循环系统的循环工质具有较高的热效率和效率,并且产生的系统总不可逆损失较小,是一种较理想的有机工质;其次,R236fa和R236ea作为系统循环工质也具有较为良好的性能.     

低温余热有机朗肯循环发电系统工质选择

对有机朗肯循环系统工质的优化选择已逐渐从单一优化目标向多目标发展,但所选的优化目标及优化方法普遍存在主观性较强的问题.针对上述问题,从环保性、安全性等方面对工质进行初选,得到了R123、R245fa、R245ca和R601等9种工质,然后采用主成分分析法对工质的热效率、循环净功和不可逆损失等7个热力性能指标进行了分析计算,得到了两个较为客观的综合评价指标,并在不同蒸发温度下对工质的综合热力性能进行了分析.结果表明:R601做功能力较强,综合效率较高,是该循环系统较为理想的工质.     

利用低品位热能的有机物朗肯循环的工质选择

工质对低品位热能有机物朗肯循环的安全性、环保性、经济性和高效性具有很大的影响.本文首先对61种工质的热力学、物理、化学、环保、安全和经济特性进行了研究,并从中挑选出11种符合上述特性的候选工质,然后对这些候选工质的干湿性、饱和性质和循环热效率进行了研究,确定了8种适合低品位热能有机物朗肯循环且具有潜力的工质,它们是丙烷...     

Design and testing of the Organic Rankine Cycle

We propose a new type of environmentally friendly system called the “Organic Rankine Cycle” (ORC) in which low-grade heat sources are utilized. This system combines a circulated thermosyphon with a turbine system. The working fluid used in this study is an organic substance which has a low boiling point and a low latent heat for using low-grade heat sources. A numerical simulation model of the ORC is made in order to estimate its optimum operating conditions. An experimental apparatus is also made in this study. From the numerical simulation, it is suggested that HCFC-123 gives higher turbine power than water which is a conventional working fluid, and operating conditions where saturated vapor at the turbine inlet would give the best performance. From the experimental results, HCFC-123 improves the cycle performance drastically. In addition, the turbine made for trial use in this study gives good performance.     

基于有机朗肯循环低温余热利用研究

文章应用PR方程编制了有机工质热物性计算程序,对多种有机工质的朗肯循环进行了热力计算,研究了各主要参数对朗肯循环性能影响的规律。在给定余热条件下,采用模拟退火算法对循环的主要参数进行优化,得出了整个循环在净输出功率最大时的最优参数值,并比较了以R236fa为工质的有机朗肯循环和常规朗肯循环的对外做功能力。     

基于有机朗肯循环的APU余热回收系统性能分析

为有效利用飞机辅助动力装置（Auxitlary Power Unit , APU）排气余热,基于有机朗肯循环（Organic Rankine Cycle, ORC）发电系统,构建了APU余热回收系统。系统以APU排气余热为输入,驱动ORC做功,输出电能,为机载设备提供二次能源。结合工程热力学原理,建立系统热力学模型,并通过Matlab编程对余热回收系统进行了仿真计算及性能分析。仿真结果表明,系统功率及效率随飞行马赫数增加而降低;APU余热回收系统在飞机低音速飞行时有良好的性能;马赫数小于1时,系统功率在12 kW以上,效率在11%以上,耗气率低于0.0262 kg/kJ。     

Study on the Control Strategy of Free Piston Expander-Linear Generator Used for Organic Rankine Cycle Waste Heat Recovery

This study presents a free piston expander-linear generator (FPE-LG) for engine waste heat recovery.The control strategies based on displacement (control strate...     

分级抽汽回热式太阳能低温有机朗肯循环系统的热力性能分析

研究了分级抽汽回热式太阳能低温有机朗肯循环系统的热力性能。以R600和R245fa作为循环工质,利用热力学第一定律和第二定律,在不同的蒸发温度和膨胀比的条件下,对分级抽汽回热式系统和基本有机朗肯循环系统的热力性能变化进行比较和分析,指出分级抽汽回热式系统的热效率和效率更高,产生的不可逆损失更小,具有更优越的性能。     

车用有机朗肯循环各参数对发动机性能的影响

针对有机朗肯循环系统,选取五氟丙烷(R245fa)、乙醇、三氟氯丙烯(R1233zd)、环戊烷等4种工质进行研究,通过试验分析蒸发温度、膨胀比、等熵效率、过热度等参数对系统净功率、热效率的影响。结果表明,增大膨胀机等熵效率可提高系统净功率,在燃烧完全的情况下4种工质中选用乙醇和R1233zd更利于改善发动机燃油率,并对有机朗肯循环系统中的膨胀比、过热度和蒸发温度等参数的选择提出建议。     

有机朗肯循环系统回收低温余热的优势

当前国内传统余热发电系统都是利用水蒸气的朗肯循环。举例分析了目前我国低温余热回收状况,进而通过和传统水蒸气余热发电系统的对比,阐述了有机朗肯循环(ORC)在回收低温余热领域的优势以及国内外实际应用情况。最后提出了对于国内发展ORC余热发电系统的建议。     

有机朗肯循环与再热式循环低温热源发电系统热力性能研究

针对120℃以下的低温余热热源,探讨了基本有机郎肯循环发电系统和再热式有机朗肯循环发电系统模型的基本原理.从热力学第一定律角度出发,研究了纯工质R245fa和非共沸混合工质R21/R245fa在基本有机郎肯循环系统中,以及纯工质R245fa在再热式有机郎肯循环系统中,三种形式的有机郎肯循环系统热力性能随蒸发温度的变化情况.与纯工质基本有机郎肯循环系统相比,再热式有机郎肯循环最大可提高系统净输出功7.08％,而混合工质对提高整个系统热力性能具有较大的优势,净输出功和热效率最大可提高4.67％和2.91％.     

不同有机工质下的燃气分布式能源光热补偿供能系统研究

为了提高能源利用率,实现节能减排,以总能系统概念为基础,采用燃气和太阳能为能源,水蒸气与有机工质为工作介质,建立燃气分布式供能系统的热力模型和能效模型,对其热经济性和有机工质进行了计算与筛选。以国内某机场分布式能源站机组为例,基于太阳能的能源补充作用以及有机工质气化潜热小的特性,建立燃气分布式能源光热补偿供能系统,经热经济性计算与分析,结果表明:在100%、75%、50%制冷(制热)工况时、新模型在维持原机组总热耗的情况下,机组冷源损失减少,热经济性提高;经过对3种有机工质的筛选,R245FA是较适合于新模型的有机工质。     

Thermal Economy Analysis of Steam-Organic Fluid Combined Cycle Power Generation Model Based on Different Working Fluids

以NZK660-24.2/566/566机组为例,建立了可减少汽轮机冷源热量、增加发电量的蒸汽-有机工质联合循环发电模型.为了筛选出适合新模型的工质,根据工质性质设定新模型的运行参数,通过采用排汽温度为55.3℃及35℃的原机组及新模型的热经济性指标对9种有机工质的热力性能进行了分析.结果表明：与原机组在排汽温度为35℃时相比,当机组热耗相同时,新模型的发电热效率提高,不同工质的发电效率提高幅度不同,而且空冷面积变小;随着工质临界温度的升高,低压缸2的进口压力和排汽压力呈下降趋势;新模型采用环保工质R365MFC时,低压缸2的进、出口压力较为适宜,且排汽未通过湿蒸汽区,可获得较高的热效率.     

混合工质组分对ORC系统性能影响实验研究

针对低品位热能的特点,利用搭建的有机物朗肯循环(ORC)系统实验装置,对采用不同组分混合工质R600a/R601a的ORC系统性能进行实验研究,获得系统和部件特性随组分的变化规律。实验结果表明:随着混合工质中的R600a组分的增大膨胀比减小,下降幅度为38.4%,涡旋膨胀机效率受R600a组分变化的影响较小,在60%附近上下波动;净发电功率、工质吸热量和蒸发过程温度滑移量都随着R600a组分的增大先增大后减小,在R600a组分为0.4处,混合工质具有最大的净发电功率、吸热量和温度滑移量,净输出功率比纯R601a高出25%。这说明非等温相变特性可以使混合工质的吸热过程更好地与热源流体的放热过程相匹配,从而提高热能利用率,增加发电功率。     

Performance Analysis of a Multistage Centrifugal Pump Used in an Organic Rankine Cycle(ORC) System under Various Condensation Conditions

In an organic Rankine cycle(ORC) system, the working fluid pump plays an important role in the system performance. This paper focused on the operating characteristics of a multistage centrifugal pump at various speeds and condensation conditions. The experimental investigation was carried out to assess the influence of the performance of the pump by the ORC system with special attention to actual net power output, thermal efficiency as well as back work ratio(BWR). The results showed that an increase in the pump speed led to an increase in the mass flow rate and expand in the operating range of the outlet pressure. The mass flow rate decreased nonlinearly with the increase of the outlet pressure from 0.22 to 2.41 MPa; the electric power consumption changed between 151.54 and 2409.34 W and the mechanical efficiency of the pump changed from 7.90% to 61.88% when the pump speed varied from 1160 to 2900 r/min. Furthermore, at lower pump specific speed the ORC system achieved higher thermal efficiency, which suggested that an ultra-low specific speed pump was a promising candidate for an ORC system. The results also suggested that the effects of condensation conditions on the pump performance decreased with the pump speed increasing and BWR was relatively sensitive to the condensation conditions, especially at low pump speed.