混合式间接空冷系统性能试验的不确定度研究

Uncertainty of performance test for mixed indirect air cooling system

结合空冷发电机组的空冷系统性能试验标准,推导了采用通用特性曲线计算空冷系统性能保证值时的不确定度计算通用公式,并应用该公式计算出某混合式间接空冷系统性能试验结果的不确定度为0.032 5。从不确定度分布可知,进、出塔水温、循环冷却水流量、凝汽器压力是影响试验结果不确定度的主要参数。从试验测点数目、仪器精度、测量参数波动等方面对不确定度进行了分析评价,结果表明:进、出塔水温应采用多重测点;循环冷却水流量测量仪器的精度提高1%可使试验结果的不确定度降低约0.005 3;选择合适的试验时间,控制测量参数的波动范围可有效降低试验结果的不确定度。

Combining with the performance test standards for air cooling system,the universal formula of the uncertainty calculation for thermal performance guarantee value by general characteristic curve method was derived.By this formula,the performance tests uncertainty for a mixed indirect air cooling system was determined as 0.032 5.It can be seen from the uncertainty distribution that,such factors as water temperature at inlet/outlet of the tower,circulating cooling water flow and pressure in condenser were main parameters affecting the tests uncertainty.The uncertainty was evaluated from several aspects,like measuring point number,instrument accuracy,parameter fluctuation range and so on.It indicated that the water temperature at inlet/outlet of the tower should be measured at multiple points;the uncertainty of the test results can be reduced by about 0.005 3by enhancing the accuracy of flow measurement instrument for circulating water of 1%;selecting appropriate test time and controlling the measuring parameters fluctuation be within a reasonable range can effectively reduce the uncertainty of the test results.