地采暖地板蓄热性能模型构建与验证

The Construction and Verification of Heat Storage Performance Testing Model of Wood Materials Used for Floor Heating

【目的】提出一种基于密闭绝热检测室的地采暖地板蓄热性能检测方法,以实现地采暖地板蓄热性能的检测。【方法】首先,介绍密闭绝热检测室的结构以及地采暖地板蓄热性能检测方法。然后,构建检测室物理模型,根据流体力学定律建立三维非稳态传热的质量守恒方程、动量方程和能量守恒方程,并给出模型的边界条件和计算初值,将材种为白桦、水曲柳、西南桦和柞木的地采暖地板样本分别放置在检测室底部中心托举网上,作为内部热源,根据设定的数值模拟参数,通过流体力学计算软件FLUENT对所建立的地采暖地板蓄热规律方程进行迭代求解,对检测室内温度分布随时间变化的过程进行分析。最后,以第1 000步(步长为10 s)采样时刻为例,以平均相对误差和相关系数为评价依据,将检测室温度分布计算结果与地采暖地板蓄热性能分析仪的实测数据进行对比,从而评判所构架模型与检测仪器的一致性。【结果】相对误差均小于1.5%,相关系数均大于0.98。不同样本所对应的温度平衡时间计算值均小于实测值,不同样本所对应的平衡温度计算值也均小于实测值。【结论】所构建的模型和检测仪器能够准确反映不同材种地采暖地板样本对检测室内温度场变化规律的影响,并可实现不同材种地采暖地板蓄热性能的检测。

【Objective】 In order to detect the thermal storage capacity of wood materials used for floor heating, a method based on an airtight and thermal-insulated testing device is firstly proposed.【Method】 Firstly, the structure of airtight and thermal-insulated testing device was illustrated, and the testing method was introduced. Then, the physical model of testing device was built up, the mass conservation equation, momentum equation and energy conservation equation of three-dimensional unsteady heat transfer were established according to the three laws of fluid mechanics. The preheated wood samples from Betula platyphylla, Fraxinus mandshurica, Betula alnoides and Quercus mongolica, which could be used for floor heating, were set at the middle of the bottom of the testing device, as heat source. After setting up the initial values and boundary conditions of the model, the CFD software FLUENT was used with certain numerical simulation parameters to solve the unsteady heat transfer equations established before, and the temperature distributions in the testing device at different periods were analyzed and discussed. Furthermore, taking the 1 000 step result as an example, the temperature distribution result from the numerical model and the measured temperature data of the testing device were compared and evaluated based on the average relative error and correlation coefficient. And by doing these, the consistency of the established heat transfer model and the testing device was evaluated.【Result】 The relative error is lower than 1.5%, and the correlation coefficient is higher than 0.98. In addition, the simulated time to reach temperature equilibrium of all different samples are less than the measured values, and the simulated equilibrium temperature distributions of different sample are lower than the measured values.【Conclusion】 The model and testing device we developed can accurately demonstrate the temperature distribution and variation of different wood samples, and thus it can be used to evaluate the heat storage performance of different wood floor materials used for floor heating system.