Experimental analysis and comparison between CO2 transcritical power cycles and R245fa organic Rankine cycles for low-grade heat power generations
Experimental analysis and comparison between CO2 transcritical power cycles and R245fa organic Rankine cycles for low-grade heat power generations
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DOI：
10.1016/j.applthermaleng.2018.03.058
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发表时间：
2018-05
影响因子：
6.4
通讯作者：
L. Li;Y. Ge;Xiang Luo;S. Tassou
中科院分区：
文献类型：
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作者：
L. Li;Y. Ge;Xiang Luo;S. Tassou
在两个不同的试验台上进行了实验研究，以调查和比较性能的CO2跨临界功率循环（T-CO2）和R245 fa有机朗肯循环（ORC）的低品位热发电。每个试验台都由一些基本部件组成，包括带高速发电机的涡轮膨胀机、翅片管空气冷却冷凝器、液体泵和板式气体发生器/蒸发器。80 kWe微型燃气轮机热电联产机组的废气被用作T-CO2和R245 fa ORC发电系统的热源，热油流通常被用作传热介质。这两个试验台已完全投入使用并安装了仪器，进行了全面的实验研究，以检查各种重要操作参数对系统性能的影响。这些包括在恒定的散热器（环境）参数下的工作流体质量流率和热源输入等。结果表明，在固定热源输入的情况下，在较高的工质流量下，R245 fa ORC或T-CO2系统的涡轮机发电量和总效率均得到显著提高。定量分析表明，当CO2和R245 fa的质量流量分别从0.2 kg/s增加到0.26 kg/s和从0.23 kg/s增加到0.27 kg/s时，相应的涡轮机发电量分别提高了88.2%和27.3%，而相应的涡轮机总效率分别提高了35.4%和7.5%。另一方面，当工质质量流量固定时，随着热源输入的增加，R245 fa ORC或T-CO2系统的涡轮机发电量和总效率显著增加。从百分比上看，当T-CO2和R245 fa ORC系统的热源输入分别从52 kW增加到60 kW和61 kW增加到68 kW时，相应的涡轮机发电量分别增加了47.7%和63%，而各自的涡轮机总效率分别增加了8.65%和1.08%。此外，两个系统的循环点温度和压力在较高的工作流体质量流率或较高的热源输入下显示出类似的增量。此外，CO2气体发生器和R245 fa蒸发器的传热分析可用于设置在换热器出口处的工作流体过热的有效控制。测试结果和分析对于评估和比较两种系统在不同操作条件、设计结构和组件下的操作至关重要，并且可以显著有助于优化组件选择和系统性能控制。
In this study, experimental investigations were conducted on two different test rigs to investigate and compare the performances of CO2transcritical power cycles (T-CO2) and R245fa organic Rankine cycles (ORC) for low-grade heat power generations. Each test rig consisted of a number of essential components including a turboexpander with a high speed generator, finned-tube air cooled condenser, liquid pump and plate-type gas generator/evaporator. The exhaust flue gases from an 80 kWe micro-turbine CHP unit were utilised as heat sources for both T-CO2and R245fa ORC power generation systems and hot thermal oil flow was applied commonly as a heat transfer medium. Both test rigs were fully commissioned and instrumented from which comprehensive experimental investigations were carried out to examine the effects of various important operational parameters on system performance. These include working fluid mass flow rate and heat source input etc. at constant heat sink (ambient) parameters. Results showed that with a fixed heat source input, the turbine power generation and overall efficiency of the R245fa ORC or T-CO2system could be improved significantly at higher working fluid mass flow rates. Quantitatively, when the CO2and R245fa mass flow rates increased respectively from 0.2 kg/s to 0.26 kg/s and from 0.23 kg/s to 0.27 kg/s, the corresponding turbine power generation increased by 88.2% and 27.3% while the respective turbine overall efficiency enhanced by 35.4% and 7.5%. On the other hand, the turbine power generation and overall efficiency of the R245fa ORC or T-CO2system increased variably with higher heat source input when the working fluid mass flow rate is fixed. In percentage, when the heat source inputs of the T-CO2and R245fa ORC systems increased respectively from 52 kW to 60 kW and 61 kW to 68 kW, the corresponding turbine power generation increased 47.7% and 63% while the respective turbine overall efficiency enhanced 8.65% and 1.08%. In addition, the cycle point temperatures and pressures of both systems revealed similar increments at higher working fluid mass flow rates or at higher heat source inputs. Furthermore, heat transfer analyses of both CO2gas generator and R245fa evaporator can be used to set up efficient controls of working fluid superheating at the heat exchanger outlet. The test results and analyses are essential in evaluating and comparing both systems’ operations at different operating conditions, design structures and components, and can significantly contribute towards optimal component selections and system performance controls.