超临界二氧化碳离心压缩机性能预测模型研究

Research on performance prediction model of supercritical carbon dioxide centrifugal compressor

压缩机作为超临界二氧化碳(S-CO2)动力循环的核心部件,对其开展部件级实验研究,测试压缩机及其附属设备的工作特性将至关重要;而建立精准的闭式S-CO2压缩回路系统仿真模型是选取回路关键参数、建立系统控制策略的必要准备工作,也是保证压缩机可在测试参数下稳定运行的重要前提。本文针对测试回路中压缩机的热力学模型进行了研究,并对S-CO2压缩机的运行性能进行了预测,基于传统压缩机一维损失模型,对比预测结果与公开文献实验数据,发现传统压缩机模型在偏离设计工况条件下存在较大误差,需要对其进行修正。本文引入流量系数,其定义为质量流量和转速的比值,以运行工况流量系数和设计工况流量系数比值作为修正因子,对传统损失模型进行修正。通过与桑迪亚国家实验室公开的实验数据对比可以发现,修正模型预测结果与实验值的变化趋势和数值大小保持一致,最大误差不超过3%,能够较好预测S-CO2压缩机运行时的变工况特性。

Compressor is the core component of supercritical carbon dioxide(S-CO2)power cycle.It is essential to carry out component-level experimental research on it and detect the working characteristics of the compressor and its auxiliary equipments.Building an accurate closed-loop simulation model of closed S-CO2 compression loop is a necessary preparation for selecting the loop key parameters and establishing the system control strategy,which is also an important prerequisite for the stable operation of compressor under test parameters.In this paper,the thermodynamic model of the compressor in the test loop is studied,and the operation performance of the centrifugal compressor in S-CO2 compression loop is predicted.Based on the conventional one-dimensional loss model of the compressor,the prediction result is compared with the experimental data in the open literatures.It finds that,the conventional compressor model has a large error under the deviating design conditions,which needs to be corrected.Therefore,flow coefficient is introduced,which is defined as the ratio of mass flow and rotation speed.Then,by taking the ratio of flow coefficient under working condition to that under design condition as the correction factor,the conventional loss model is corrected.Compared with the experimental data in Sandia National Laboratory,it can be found that the prediction results of the corrected model are highly consistent with the change trend and numerical value of the experimental values,and the maximum error does not exceed 3%,which can better predict the variable operating characteristics of the S-CO2 compressor during operation.