A prime factor for improving buildings energy efficiency is the correct understanding of heat transfer phenomena within the enclosures for accurate assessment of conduction loads through the building envelope. The magnitude and the interaction between convective and radiative heat transfer modes may have a significant impact on heating or cooling loads and, therefore, on the buildings energy performance. However, the radiation heat transfer mode produces a secondary effect on the airflow. The conductive and radiative heat transfer modes are estimated from models traditionally employed by the building energy simulation codes, with reasonable accuracy. However, significant uncertainties may appear related to internal Convective Heat Transfer Coefficients (CHTC) due to complex geometries, buoyancy effects, and thermal asymmetries as well as effects associated with the natural ventilation and the furniture presence. Concerning forced or mixed convection, the CHTC validity found in the literature is often a matter of doubt due to internal airflow patterns caused by different air inlet/outlet configurations. Therefore, to better understand the airflow patterns created by split-type air conditioners, two-dimensional computational fluid dynamic simulations are performed, providing data for the CHTC assessment for the floor, vertical walls, and ceiling. Different forced airflow rates and surface temperatures are applied to analyse the influence of air recirculation through the evaporator, which remains barely explored, in the literature. Comparisons with the existing correlations and the impact of the internal CHTC on the energy consumption of a split air conditioner are exposed and discussed.

改善建筑物能效的主要因素是正确理解外壳内的传热现象，以准确评估通过建筑物围护结构的传导负荷。对流传热模式和辐射传热模式之间的大小和相互作用可能会对供热或制冷负荷产生重大影响，从而对建筑物的能源性能产生重大影响。但是，辐射传热模式会对气流产生辅助影响。传导和辐射传热模式是根据建筑能源模拟代码传统上采用的模型估算的，具有合理的准确性。但是，由于复杂的几何形状，浮力效应，内部对流传热系数（CHTC）可能会出现重大不确定性，热不对称性以及与自然通风和家具存在相关的影响。关于强制对流或混合对流，在文献中发现的CHTC有效性经常由于由不同进气/出气口构造引起的内部气流模式而令人怀疑。因此，为了更好地理解分体式空调机产生的气流模式，进行了二维计算流体动力学模拟，为地板，垂直墙和天花板的CHTC评估提供了数据。应用不同的强制气流速率和表面温度来分析通过蒸发器的空气再循环的影响，在文献中几乎没有对此进行探讨。