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Zonal modelling of hot rooms.

Author(s) : TONG Y., SHI M. H., HE J. P.

Summary

When studying physical parameters of hot rooms, experiments verify that there is an apparent phenomenon of thermal stratification in vertical direction. It is especially true for tall big spaces. So in this study, a whole space can be divided into several layers, physical parameters (temperature, pressure, harmful gas's concentration, etc.) of each layer can be considered to be relatively stable and identical. Heat and mass are exchanged among each layer or among layers and external surroundings by limited potential differences. This may be called a "lumped parameter method" which provides a way of understanding indoor air quality. Based on this basic idea of zone simulation, this paper analyses heat and mass characteristics of two types of hot rooms and established their equilibrium models (two sets of ordinary differential equations). Models synthesized processes of heat release, entrainment, plume, air flows of openings. In these equations, variables were only functions of time, but affected mutually. Stiff problems of these equations could not be evitable, because several time constants different in dimension existed there. A Gear algorithm was adopted, which was just used to solve stiff problems. According to this algorithm, two VC++ programs were written and operated. Results of pressure and temperature of each zone and zone's interface height were plotted in rectangular coordinates. By comparison of these results with those obtained from CFAST software, merits and demerits of this model were analyzed.

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Pages: ICR07-E2-1562

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Details

  • Original title: Zonal modelling of hot rooms.
  • Record ID : 2008-0766
  • Languages: English
  • Source: ICR 2007. Refrigeration Creates the Future. Proceedings of the 22nd IIR International Congress of Refrigeration.
  • Publication date: 2007/08/21

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