内嵌管式辐射地板的频域热特性分析

基于经典有限差分原理建立了内嵌管式辐射地板的频域有限差分(FDFD)模型,同时采用Fluent软件建立了内嵌管式辐射地板的CFD模型作为参考模型,将内嵌管式辐射地板FDFD模型在典型频域点的计算结果转换成时域内的幅值与相角,并与CFD模型的计算结果进行对比.FDFD模型能准确预测内嵌管式辐射地板的热特性.采用FDFD模型进一步计算了不同厚度绝热层的辐射地板的频域热特性,分析了绝热层厚度对内嵌管式辐射地板热特性的影响.结果表明,在高频区域,绝热层厚度对地板传热的影响较小,而在低频区域内影响较为明显,尽管绝热层厚度取到40mm,地板下表面仍存在较大的热流损失,约占管道热流的16%.

Study of the Frequency Thermal Characteristics of Pipe-embedded Radiant Floors

A two-dimensional frequency-domain finite-difference (FDFD) model was developed on the basis of the classical finite-difference principle for a pipe-embedded concrete radiant floor to predict its frequency thermal responses. In the meantime, a CFD for this floor was also developed for this floor by using a reference model. The calculated frequency thermal responses of the floor by using FDFD model at typical frequency points were expressed in the form of amplitude and phase lag in time domain, and were then compared with the results by using CFD model. The results indicate that the FDFD model can predict the thermal characteristics accurately. The FDFD model was used to predict the frequency thermal characteristics of the pipe-embedded concrete radiant floor with insulation of different thicknesses, and the effects of the insulation thickness on the thermal responses of the pipe-embedded concrete radiant floor were analyzed and presented. The results indicate that the effect of the insulation thickness on the heat transfer of the floor is obvious in low frequency range while not obvious in high frequency range. Even if the thickness of the insulation is 40mm, the heat loss from the bottom surface of the floor constitutes about 16% of the heat transfer on the pipe surface and cannot be neglected.