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Numerical Assessment of Convective Heat Transfer Coefficients in Buildings Conditioned by Parallel Split Systems

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Abstract

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.

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Acknowledgements

The authors thank the National Council for Scientific and Technological Development (CNPq) of the Ministry of Science, Technology, Innovation and Communications (MCTIC) of the Brazilian Government for the financial support and the Federal University of Technology—Paraná for the resources made available.

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Authors and Affiliations

  1. Department of Mechanics, Federal University of Technology – Paraná, Ponta Grossa, PR, 84017-220, Brazil

    Gerson H. dos Santos, Guilherme A. C. Taborda & Luiz E. M. Lima

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  1. Gerson H. dos Santos
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  2. Guilherme A. C. Taborda
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  3. Luiz E. M. Lima
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Correspondence to Gerson H. dos Santos.

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dos Santos, G.H., Taborda, G.A.C. & Lima, L.E.M. Numerical Assessment of Convective Heat Transfer Coefficients in Buildings Conditioned by Parallel Split Systems. Arab J Sci Eng 45, 8945–8953 (2020). https://doi.org/10.1007/s13369-020-04547-x

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