Surface temperature changes of building materials affect the calculation of heat flow and thus the energy use in heating and cooling. The surface heat transfer coefficient , limiting the heat flow between material sur...Surface temperature changes of building materials affect the calculation of heat flow and thus the energy use in heating and cooling. The surface heat transfer coefficient , limiting the heat flow between material surface and ambient air is normally taken as a constant. In this study we propose a time-dependent function . We estimate from unidirectional heat flow experiments with transient and steady-state conditions. Using temperature measurements and the conservation of energy at the surface including convective and irradiative boundary conditions, the value of was obtained both using Finite Difference and Taylor Polynomials methods. Numerical solutions of temperature distribution as function of time were improved with the obtained -functions compared to with constant . There were no clear difference between on different materials, and the final values observed were in the order of magnitude expected from the literature.展开更多
循环温度的准确预测是保证尾管固井施工安全、提高固井质量的基本前提。目前预测方法中实测井温成本高,经验法和API RP 10B反映的是一个区域的平均循环温度,现有的循环预测模型没有针对尾管固井复杂的工艺流程。为科学预测循环温度,根...循环温度的准确预测是保证尾管固井施工安全、提高固井质量的基本前提。目前预测方法中实测井温成本高,经验法和API RP 10B反映的是一个区域的平均循环温度,现有的循环预测模型没有针对尾管固井复杂的工艺流程。为科学预测循环温度,根据尾管固井施工流程及井下传热特点建立二维温度模型,通过实测井温验证了模型具备较高的精确度,平均误差仅有1.6℃。数值模拟结果表明:对深井而言,冷浆的降温效果很小;钻井液循环阶段与尾管注水泥时刻温度变化规律不同;φ177.8mm尾管固井和φ127mm尾管固井最高循环温度系数分别为0.79和0.84,经验系数法高估循环温度。展开更多
文摘Surface temperature changes of building materials affect the calculation of heat flow and thus the energy use in heating and cooling. The surface heat transfer coefficient , limiting the heat flow between material surface and ambient air is normally taken as a constant. In this study we propose a time-dependent function . We estimate from unidirectional heat flow experiments with transient and steady-state conditions. Using temperature measurements and the conservation of energy at the surface including convective and irradiative boundary conditions, the value of was obtained both using Finite Difference and Taylor Polynomials methods. Numerical solutions of temperature distribution as function of time were improved with the obtained -functions compared to with constant . There were no clear difference between on different materials, and the final values observed were in the order of magnitude expected from the literature.
文摘循环温度的准确预测是保证尾管固井施工安全、提高固井质量的基本前提。目前预测方法中实测井温成本高,经验法和API RP 10B反映的是一个区域的平均循环温度,现有的循环预测模型没有针对尾管固井复杂的工艺流程。为科学预测循环温度,根据尾管固井施工流程及井下传热特点建立二维温度模型,通过实测井温验证了模型具备较高的精确度,平均误差仅有1.6℃。数值模拟结果表明:对深井而言,冷浆的降温效果很小;钻井液循环阶段与尾管注水泥时刻温度变化规律不同;φ177.8mm尾管固井和φ127mm尾管固井最高循环温度系数分别为0.79和0.84,经验系数法高估循环温度。
