A heat transfer parameter at air interfaces in the BLOCK model for building thermal environment

A temperature-based zonal model (BLOCK model), proposed by Togari et al. [21], is improved in this study through determining a heat transfer factor between air layers. This factor has not been reasonably clarified and theoretically determined. Such shortage has long limited the applications of the model to building thermal environment and energy. In the present work, it is clarified to the combined laminar and turbulent diffusion of energy in the airflows. A physical definition is presented based on the one-dimensional thermal transport equation without advective and transient terms. Computational fluid dynamics (CFD) is used to calculate the values of the factor at air interfaces specified and to verify the physical definition. Calculated values are found to agree well with those assumed to reproduce the experimental data by Togari et al. [21], and are able to represent the thermal gradients observed in the experiments. This study intends to clarify and explain the nature of heat transfer factor between air layers in the BLOCK model and to promote its real applications.