变压器热点温度作为运行经济性、安全性的关键指标,是设备在线监测及状态评估中的重点。该文对变压器内部散热进行研究,着眼于饼式绕组及其油道结构,基于能量流向建立绕组温度变化的物理模型。基于这一模型,在一台内置分布式传感光纤的1...变压器热点温度作为运行经济性、安全性的关键指标,是设备在线监测及状态评估中的重点。该文对变压器内部散热进行研究,着眼于饼式绕组及其油道结构,基于能量流向建立绕组温度变化的物理模型。基于这一模型,在一台内置分布式传感光纤的110kV三相ONAN变压器上开展试验研究,使用分布式光纤测温(distributed temperature sensing,DTS)技术对运行状况下的绕组整体温度分布进行实时监测,分析绕组在ONAN冷却方式下的散热状况。在变压器启动初期,绕组各处散热量较低,温升速率较快。约2 h后,各饼散热量基本与损耗相一致,散热率可达98%以上,因此将这一阶段称为准稳态。准稳态阶段,绕组整体散热率基本一致。负载变化前期不同位置散热量的差异是温度梯度形成的主要原因。基于DTS手段及散热器进出口处油温,提出绕组每饼平均对流换热系数的计算方法,基于无量纲数建立绕组内外表面局部对流换热系数的计算方法,对不同位置、负载率下两种对流换热系数的变化规律进行分析获得了绕组运行过程中对流换热系数分布规律及变化趋势。展开更多
The mathematical model has been estublished for the simulation of steel coil＇s heat transfer during annealing thermal process in HPH （high performance hydrogen） furnace. The equivalent radial thermal conductivity i...The mathematical model has been estublished for the simulation of steel coil＇s heat transfer during annealing thermal process in HPH （high performance hydrogen） furnace. The equivalent radial thermal conductivity is adopted by statistical analysis regression approach through the combination of a large quantity of production data collected in practice and theoretical analyses. The effect of the number of coils on circulating flow gas is considered for calculating the convection heat transfer coefficient, The temperature within the coil is predicted with the developed model during the annealing cycle including heating process and cooling process. The good consistently between the predicted results and the experimental data has demonstrated that the mathematical model established and the parameters identified by this paper are scientifically feasible and the effective method of calculation for coil equivalent radial heat transfer coefficient and circulating gas flow has been identified successfully, which largely enhances the operability and feasibility of the mathematic- model. This model provides a theoretical basis and an effective means to conduct studies on the impact that foresaid factors may imposed on the steel coil＇s temperature field, to analyze the stress within coils, to realize online control and optimal production and to increase facilily output by increasing heating and cooling rates of coils without producing higher thermal stress.展开更多
文摘变压器热点温度作为运行经济性、安全性的关键指标,是设备在线监测及状态评估中的重点。该文对变压器内部散热进行研究,着眼于饼式绕组及其油道结构,基于能量流向建立绕组温度变化的物理模型。基于这一模型,在一台内置分布式传感光纤的110kV三相ONAN变压器上开展试验研究,使用分布式光纤测温(distributed temperature sensing,DTS)技术对运行状况下的绕组整体温度分布进行实时监测,分析绕组在ONAN冷却方式下的散热状况。在变压器启动初期,绕组各处散热量较低,温升速率较快。约2 h后,各饼散热量基本与损耗相一致,散热率可达98%以上,因此将这一阶段称为准稳态。准稳态阶段,绕组整体散热率基本一致。负载变化前期不同位置散热量的差异是温度梯度形成的主要原因。基于DTS手段及散热器进出口处油温,提出绕组每饼平均对流换热系数的计算方法,基于无量纲数建立绕组内外表面局部对流换热系数的计算方法,对不同位置、负载率下两种对流换热系数的变化规律进行分析获得了绕组运行过程中对流换热系数分布规律及变化趋势。
基金This work was supported by the Anhui Provincial Science Foundation of China(No.2003KJ014ZD).
文摘The mathematical model has been estublished for the simulation of steel coil＇s heat transfer during annealing thermal process in HPH （high performance hydrogen） furnace. The equivalent radial thermal conductivity is adopted by statistical analysis regression approach through the combination of a large quantity of production data collected in practice and theoretical analyses. The effect of the number of coils on circulating flow gas is considered for calculating the convection heat transfer coefficient, The temperature within the coil is predicted with the developed model during the annealing cycle including heating process and cooling process. The good consistently between the predicted results and the experimental data has demonstrated that the mathematical model established and the parameters identified by this paper are scientifically feasible and the effective method of calculation for coil equivalent radial heat transfer coefficient and circulating gas flow has been identified successfully, which largely enhances the operability and feasibility of the mathematic- model. This model provides a theoretical basis and an effective means to conduct studies on the impact that foresaid factors may imposed on the steel coil＇s temperature field, to analyze the stress within coils, to realize online control and optimal production and to increase facilily output by increasing heating and cooling rates of coils without producing higher thermal stress.
